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Geology of Volcanic and 

Subvolcanic Rocks of the 

Raton-Springer Area, 

Colfax and Union Counties, 

New Mexico

By GLENN R. SCOTT, RAY E. WILCOX, and HARALD H. MEHNERT

U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1507

Descriptions, chemical analyses, and ages 

for an alkalic sill complex and for mafic 

feldspathoidal and basaltic effusive rocks

UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1990
DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, JR., Secretary

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director

Any use of trade, product, or firm names in this publication is for

descriptive purposes only and does not imply endorsement by the

U.S. Government

Library of Congress Cataloging in Publication Data

Scott, Glenn Robert, 1918-

Geology of volcanic and subvolcanic rocks of the Raton-Springer area, Colfax and Union Counties, New Mexico / by Glenn 

R. Scott, Ray E. Wilcox, and Harald H. Mehnert.

p. cm. (U.S. Geological Survey professional paper ; 1507)

"Descriptions, chemical analyses, and ages for an alkalic sill complex and for mafic feldspathoidal and basaltic effusive rocks." 

Includes bibliographical references. 

Supt. of Docs, no.: I 19.16:1507

1. Volcanic ash, tuff, etc New Mexico Colfax County. 2. Volcanic ash, tuff, etc. New Mexico Union County. 

3. Potassium-argon dating. 4. Geology New Mexico Colfax County. 5. Geology New Mexico Union County. 

I. Wilcox, Ray E. (Ray Everett), 1912- . II. Mehnert, Harald H. III. Title. IV. Series. 

QE461.S415 1990

552'.2'0978922-dc20 89-600329

CIP

For sale by the Books and Open-File Reports Section, U.S. Geological Survey, 

Federal Center, Box 25425, Denver, CO 80225
CONTENTS

Page

Abstract ........................................................................... 1

Introduction ...................................................................... 1

Previous work ............................................................. 4

Acknowledgments and responsibility ............................... 5

Physiography .................................................................... 5

Sedimentary rocks ............................................................. 6

Structure ......................................................................... 6

Igneous rocks .................................................................... 6

Concordant intrusions ................................................... 6

Extrusions and discordant intrusions .............................. 7

Types of igneous rocks ................................................. 7

Radiometric ages ......................................................... 8

Petrography and petrochemistry .................................... 9

Chico sill complex ....................................................... 13

Slagle Trachyte .................................................... 15

Trachyte southwest of Laughlin Peak ...................... 15

Biotite trachyte southwest of Turkey Mountain ......... 17

Syenite and quartz monzonite vent rocks at

Turkey Mountain ............................................... 18

Melasyenite dike ................................................... 18

Phonotephrite and tephrite along Joe Cabin Arroyo ... 19

Page

Igneous rocks Continued

Chico sill complex Continued

Chico Phonolite .................................................... 21

Green phonolite .............................................. 21

Silver-gray phonolite ....................................... 22

Nepheline syenite dike on Point of Rocks Mesa ... 24

Ocellar analcime phonolite ................................ 26

Mafic and ultramafic dikes and sills (including lamprophyric

rocks) .............................................................. 26

Diatremes ........................................................... 30

Igneous rocks near Cimarron, New Mexico ..................... 32

Rhyodacite west of Cimarron .................................. 33

Syenite and trachyte sills east of Cimarron ............... 33

Trachyandesite of middle Pine Butte .............................. 34

Red Mountain Rhyodacite ............................................ 34

Mafic feldspathoidal rocks ............................................ 40

Basaltic to latiandesitic effusive rocks ............................ 44

Raton Basalt ........................................................ 47

Clayton Basalt...................................................... 48

Capulin Basalt ...................................................... 51

Discussion and conclusions ................................................. 53

References cited................................................................ 57

ILLUSTRATIONS

FIGURE 1.

2.

3.

4.

5.

6.

7.

8-18.

Index maps of the Raton-Springer area ............................................................................................................

Chart of sedimentary rocks exposed in the Raton-Springer area ...........................................................................

Photograph of unconsolidated sediments beneath flow of Raton Basalt ..................................................................

Photograph of tumulus or pressure dome on flow of Capulin Basalt ......................................................................

Chart of igneous rocks of the Raton-Springer area .............................................................................................

Generalized geologic map of the Raton-Springer area .........................................................................................

Diagram showing classification of volcanic and subvolcanic rocks of the Raton-Springer area in the system of La Roche 

and others.................................................................................................................................................

Photographs:

8. Columnar j ointing and white feldspar crystals in green variety of Chico Phonolite ......................................

9. Near-vertical j ointing and platy weathering in silver-gray variety of the Chico Phonolite .............................

10. Eagle Rock dike ...............................................................................................................................

11. Smoky Hill Shale Member of the Niobrara Formation brecciated by a lamprophyre dike ..............................

12. Kimberlite diatreme east of Raton ......................................................................................................

13. Volcanoes of Red Mountain Rhyodacite: Red Mountain, Palo Blanco Mountain, and Laughlin Peak.................

14. Pumiceous rhyodacitic lahar on north flank of Laughlin Peak ...................................................................

15. Dale Mountain basanite shield volcano .................................................................................................

16. Spheroidal weathering in basanite .......................................................................................................

17. Volcanic vent revealed in cross section ................................................................................................

18. Olivine basalt dike in Trinchera Pass quadrangle....................................................................................

2

6

8

9

9

12

14

22

24

28

30

31

36

37

40

41

45

45

ill
IV CONTENTS

Page

FIGURE 19. Map of paleovalleys of late Tertiary and Quaternary age ......................................................................................... 50

20. Photographs of cinder cones of Capulin Basalt: Horseshoe Crater and Capulin Mountain .............................................. 54

21. Photograph of basaltic volcaniclastics in roadcut on Capulin Mountain ........................................................................ 55

22. Diagram comparing chemical compositions of the mafic feldspathoidal rocks of Colfax and Union Counties ....................... 56

TABLES

TABLE 1. Analytical data for K-Ar ages of whole-rock samples and mineral separates in volcanic and subvolcanic rocks .................... 10

2. Analytical data for zircon fission-track ages of volcanic and subvolcanic rocks ............................................................... 11

3. Analytical data for previously published K-Ar ages of igneous rocks ............................................................................ 11

4. Chemical analyses and norms of Slagle Trachyte samples .......................................................................................... 16

5. Chemical analyses and norms of trachyte southwest of Laughlin Peak.......................................................................... 17

6. Chemical analysis and norm of biotite trachyte dike southwest of Turkey Mountain ....................................................... 18

7. Chemical analyses and norms of syenite and quartz monzonite vent rocks at Turkey Mountain......................................... 19

8. Neutron-activation analysis of syenite and quartz monzonite vent rocks at Turkey Mountain ........................................... 19

9. Chemical analysis and norm of melasyenite dike near Alamo Creek ............................................................................. 20

10. Chemical analyses and norms of phonotephrite and tephrite in the Chico sill complex .................................................... 20

11. Neutron-activation analysis of phonotephrite from Joe Cabin Arroyo ........................................................................... 21

12. Chemical analyses and norms of samples of green variety of the Chico Phonolite ........................................................... 23

13. Neutron-activation analysis of a sample of green variety of the Chico Phonolite............................................................. 23

14. Chemical analyses and norms of samples of silver-gray variety of the Chico Phonolite ................................................... 25

15. Neutron-activation analysis of a sample of silver-gray variety of the Chico Phonolite ..................................................... 26

16. Chemical analysis and norm of nepheline syenite dike on Point of Rocks Mesa .............................................................. 26

17. Chemical analyses and norms of samples of mafic dike rocks....................................................................................... 29

18. Semiquantitative six-step spectrographic analyses of rocks from diatremes ................................................................... 32

19. Neutron-activation analyses of rocks from diatremes ................................................................................................. 33

20. Chemical analysis and norm of rhyodacite west of Cimarron ....................................................................................... 34

21. Neutron-activation analysis of rhyodacite west of Cimarron........................................................................................ 34

22. Chemical analyses and norms of trachyandesite porphyry of middle Pine Butte ............................................................. 35

23. Chemical analyses and norms of Red Mountain Rhyodacite......................................................................................... 38

24. Neutron-activation analysis of a sample of Red Mountain Rhyodacite........................................................................... 40

25. Chemical analyses and norms of mafic feldspathoidal rocks......................................................................................... 42

26. Neutron-activation analysis of a sample of basanite from near Folsom.......................................................................... 44

27. Heights of basaltic and latitic flows above major nearby streams or valley floors .......................................................... 46

28. Chemical analyses and norms of samples of Raton Basalt .......................................................................................... 48

29. Chemical analyses and norms of samples of Clayton Basalt......................................................................................... 52

30. Neutron-activation analysis of a sample of olivine basalt of the Clayton Basalt from Eagle Tail Mountain .......................... 53

31. Chemical analyses and norms of samples of Capulin Basalt......................................................................................... 56
GEOLOGY OF VOLCANIC AND SUB VOLCANIC ROCKS OF THE

RATON-SPRINGER AREA, 

COLFAX AND UNION COUNTIES, NEW MEXICO

By GLENN R. SCOTT, RAY E. WILCOX, and HARALD H. MEHNERT

ABSTRACT

The most prominent geomorphic features of the Raton-Springer area 

are the widely distributed volcanic and subvolcanic rock formations, 

consisting of cinder cones, domes, lava-capped mesas, a domed sill 

complex, and dikes. Rock compositions range from mafic to salic, and 

many are alkalic. Rock names used in this report are based on the 

classification of La Roche and others (1980). Sixteen new K-Ar age 

determinations and three new fission-track age determinations are 

given here for selected rocks in this area.

The oldest dated igneous rocks, with ages from 37 to 20 m.y. (million 

years), are included among the rocks of the Chico sill complex, in the 

southeastern part of the area. This complex has an exposed area of 

about 140 square miles (363 square kilometers) and consists of alkalic 

rocks of phonolitic and trachytic compositions. The Cretaceous 

sedimentary formations intruded by this complex (Purgatoire 

Formation, Dakota Sandstone, Graneros Shale, Greenhorn Limestone, 

Carlile Shale, and Niobrara Formation) have been domed up nearly 

1,000 feet (305 meters) by the sills. From oldest to youngest in 

approximate age, the sill rocks are the Slagle Trachyte, the trachyte 

southwest of Laughlin Peak, the biotite trachyte northwest of Turkey 

Mountain, the syenite and quartz monzonite vent rocks at Turkey 

Mountain, a melasyenite dike, small bodies of phonotephrite and 

tephrite, the Chico Phonolite, and a related nepheline syenite dike on 

Point of Rocks Mesa. The Chico Phonolite consists of a gradational 

series, from green phonolite to silver-gray phonolite as silica content 

increases and alumina content decreases. Magma sources of most rocks 

of the sill complex appear to have been in the lower crust.

Several diatremes have been found in this reconnaissance study; one 

kiraberlitic diatreme just east of the town of Raton is dated at 30 m.y. 

West of Cimarron a laccolithic intrusion about 29 m.y. old consists of 

sill-like bodies of rhyodacite and microsyenite that intrude Upper 

Cretaceous sedimentary rocks. Mafic dikes, some of them lamprophyric, are common in the central and eastern parts of the area, and vary 

in age from 24 m.y. to possibly as young as 5 m.y.

A dozen or so conspicuous rhyodacitic domes scattered through the 

eastern half of the mapped area range in age from 8 to 6 m.y. and are 

here referred to as the Red Mountain Rhyodacite, formerly Red 

Mountain Dacite of Collins (1949). The domes are all petrographically 

and chemically similar, and they include the most silicic rocks of the 

area.

Manuscript approved for publication, August 13, 1989.

Mafic lava flows and cinder cones of late Miocene to Holocene ages 

cover much of the mapped area and extend eastward beyond the edge 

of the area. Mafic feldspathoidal flows, ranging in age from about 8 

m.y. to 2 m.y., form one group, which appears to consist of two 

petrochemical types one of basanites and the other of ankaratrites 

and nephelinites which are both from source magmas in the upper 

mantle.

Another major group of extrusives consists of alkali basaltic to 

latiandesitic rocks of ages from about 4 m.y. to a few thousand years, 

thus overlapping in age the mafic feldspathoidal lavas. These extrusives are divided into three groups according to age estimated on the 

basis of physiographic position and roughly controlled by a few radiometric ages. From oldest to youngest, they include a group of alkali 

basalts corresponding approximately to the Raton Basalt, a group of 

basalts, trachybasalts, latibasalts, and latiandesites corresponding to 

the Clayton Basalt, and a group of latibasalts and andesibasalts 

corresponding to the Capulin Basalt. The petrographic and chemical 

characteristics suggest strongly that the lavas of the latter two groups 

were derived from alkali basalt magmas of the first group mainly by 

contamination in the upper crust, and that the alkali basalts may be 

genetically related to the basanites of the mafic feldspathoidal lavas.

INTRODUCTION

Reconnaissance geologic mapping of the Springer and 

Raton 30'x60' quadrangles (September 1980 to May 

1982) and preparation of the resulting maps (Scott, 1986; 

Scott and Pillmore, 1989) provided much field and 

laboratory data about the igneous rocks of this part of the 

Great Plains. No published geologic map or report 

describes adequately the distribution and character of 

the alkalic rocks of this area. This report presents new 

descriptive information on field relations, chemical 

analyses, and K-Ar ages of igneous rocks in the area with 

the hope that others will be encouraged to investigate 

the geology of this interesting area in greater detail.

The city of Raton is in the northeastern part of New 

Mexico a few miles south of the Colorado State line 

(fig. 1). Springer is in the northern part of the Springer 

30' x 60' quadrangle about 40 mi (miles), or 64 km
VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

19 

Cathedral x

Rock v 

I Tooth of 

Time Ridge

Philmont\,Springer 

Scout Ranch

50 KILOMETERS

FIGURE 1. Location of the Raton-Springer area, features mentioned in the text, and 71/2-minute quadrangles covering the main study area. 

A (above), Regional setting. Number 19 near Ute Park shows locality of radiometrically dated sample 19 listed in table 2. (All other sample 

localities for tables 1 and 2 are shown on fig. 6.) B (at right), Enlarged map of the main study area. The numbered TVa-minute quadrangles 

shown in A are as follows:

1. Raton

2. Yankee

3. Dale Mountain

4. Trinchera Pass

5. Clifton House

6. Hunter Mesa

7. Johnson Park

8. Robinson Peak

9. Eagle Tail Mountain

10. Tinaja Mountain

11. Mesa Larga

12. Kiowa

13. Loco Arroyo

14. Tres Hermanos Peak

15. Pine Buttes

16. Palo Blanco Mountain

17. Abbott NW

18. Sauble Circle Dot Ranch

19. Point of Rocks Mesa

20. Lawrence Arroyo

(kilometers), south of Raton (fig. 1). The igneous rocks 

described lie in the western part of the Raton-Clayton 

volcanic field on the plains between Raton and Capulin, 

N. Mex. They extend southward 17 mi (27 km) beyond 

Farley, N. Mex., and crop out in a separate area near 

Cimarron in the Springer quadrangle. The study area,

most of which is in Colfax County, is part of the Raton 

section of the Great Plains province and is characterized 

by dissected lava-capped mesas and buttes, gravelcovered pediments, and readily erodible Cretaceous 

shale. The area slopes generally southeastward from 

8,600 ft (feet), or 2,620 m (meters), north of Raton to less
INTRODUCTION

COLORADO

104°00'

_ _ ___.__......_

COLFAX

Blosser

Eagle Tail ^\ GaP 

; Mesa

x Shoemaker 

Hill

x Tres He manos 

Peak

\

15 KILOMETERS
VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

than 6,000 ft (1,830 m) near the southwest corner of the 

study area along the Canadian River. The igneous rocks, 

which are the subject of this report, range in age from 

Oligocene to Holocene. Exposed sedimentary rocks 

range in age from Triassic to Holocene.

PREVIOUS WORK

The earliest descriptions of the area were brief: St. 

John (1876, p. 283, 305-308), Stevenson (1881, p. 281), 

Hill (1892, p. 99), and Lee (1912). The first detailed study 

was one by Lee (1922) on the geology of the Raton, 

Brilliant, and Koehler 15-minute quadrangles, which 

included a section on igneous rocks by J.B. Mertie, Jr. 

Mertie provided excellent petrographic descriptions and 

some chemical analyses, and he attempted an age 

classification that defined four periods of volcanism based 

on the height of lavas above streams and on the degree of 

weathering of the olivine in the lavas. The geology of the 

eastern part of Colfax County was first mapped by 

Griggs (1948). He divided the volcanic rocks into three 

age groups, of which two were basalt flows and the third 

was a sill complex said to be composed of monzonitic 

porphyries.

The earliest report specifically on the volcanic field, 

called the Raton-Clayton field, resulted from reconnaissance of eastern Colfax County and western Union 

County by Collins (1949), who described the regional 

geology, age, and distribution of the igneous rocks. Most 

of his work was on the basaltic rocks, which he divided 

into three periods of Quaternary extrusion: from oldest 

to youngest, the "Raton basalts," "Clayton basalts," and 

"Capulin basalts." In addition, he also described "dacite" 

volcanoes and several types of alkalic rocks, including 

phonolite and trachyte. The alkalic rocks were all 

considered to be flows erupted in the Quaternary 

between the extrusion of the "Raton basalts" and the 

"Clayton basalts."

Stobbe (1948, 1949) did a comprehensive petrographic 

and petrologic study of the rocks mapped by Collins, and 

gave the modes of each rock type, together with a few 

chemical analyses. Stobbe (1950) found that the dacite on 

the eroded volcanic cone of Laughlin Peak is mineralogically the same as other dacite bodies in the area, 

although it has a higher glass content.

The late Cenozoic erosional history of the "Raton 

Mesa" region was studied by Levings (1951), who 

followed Collins in assigning the lava flows to three 

volcanic episodes thought to be separated by discrete 

erosional episodes.

A geologic map of much of the eastern part of Colfax 

County was prepared by Wood, Northrop, and Griggs 

(1953). They continued Griggs' (1948) use of the term "sill 

complex" for "thick sills of intermediate composition" in 

the Chico Hills, but suggested that some sets of sills 

appeared to be small laccoliths. They assigned an early

Tertiary age to the sills and suggested an age similar to 

that of rocks at the Spanish Peaks in southern Colorado 

(fig. 1). They informally adopted Collins' nomenclature of 

"Raton, Clayton, and Capulin" for basalt flows of three 

different ages.

Baldwin and Muehlberger (1959) described in considerable detail the volcanic rocks of Union County, 

adjacent to Colfax County on the east. They also used the 

threefold age sequence of Collins, but suggested a 

Pliocene age. for the Raton Basalt of Collins and dated the 

Capulin Basalt of Collins at between 8,000 and 2,400 

years before the present.

Aoki (1967) found the alkaline and calc-alkaline basalts 

near Capulin Mountain (fig. 1) to be a typical circumoceanic alkaline suite characterized by high Si02 , A1203 , 

and K20 and by low Ti02. Lipman (1969) found the Raton 

Basalt of Collins to be similar in chemistry and 

petrography to basalt in the Hinsdale Formation of the 

San Juan region, Colorado, and different from the tholeiitic basalt of the Rio Grande depression near Servilleta, 

N. Mex. (fig. 1).

The radiometric ages and petrology of basaltic flows 

and dacite in that part of the Raton-Clayton volcanic field 

in the area of the Raton I°x2° quadrangle were the 

subjects of two reports by Stormer (1972a, b). The oldest 

age, determined on a dacite, was slightly greater than 

8 m.y.B.P. Flows of the Raton Basalt of Collins were 

dated at between 7.0 and 3.5 m.y.B.P. Younger flows in 

the Raton area were not dated radiometrically. Stormer 

reiterated the suggestion of Wood and others (1953) that 

the phonolitic sills appeared to represent a still earlier 

period of igneous activity, probably contemporaneous 

with the Spanish Peak intrusions. Some basalt flows that 

had been assigned by Collins to the Clayton Basalt were 

reassigned by Stormer to the Capulin Basalt, mainly 

because of petrographic characteristics. We have 

retained them as Clayton Basalt, based on their physiographic positions.

In an investigation of the content of potassium, 

thorium, and uranium in basalts of the southern Rocky 

Mountain region, Lipman and others (1973) found that 

amounts of all three elements increased away from the 

Rio Grande depression. Jones and others (1974) studied 

the strontium isotope ratios of Stormer's (1972a, b) 

volcanic suite and suggested an upper mantle origin for 

most of its magmas.

Phelps and others (1979) determined the rare-earth 

geochemistry of rocks in the Raton-Clayton volcanic field 

and found little correlation between the rare-earth 

element abundance and the major-element compositions 

of the different rock types.

The basalts near Mora, N. Mex. (fig. 1), studied by 

O'Neill and Mehnert (1980a, b) probably have a sequence 

similar to those near Raton and range in age from 8.1 to 

0.76 m.y. O'Neill and Mehnert recognized six extrusive
PHYSIOGRAPHY

events, which are related to erosion surfaces that are 

nearly contemporaneous with the flows.

Pillmore and Scott (1976) described the Quaternary 

pediments of the Vermejo Park and Raton areas. The 

heights of the pediments above stream levels suggest 

that the older pediments probably are contemporaneous 

with some of the intermediate or Clayton Basalt flows.

Phelps and others (1983) presented analyses of major 

and trace elements and strontium isotopes of 12 of the 

feldspathoidal lavas of Colfax and Union Counties. They 

suggest that most are primary melts from a portion of 

the upper mantle, which probably had been premetasomatized by C02-rich fluids.

ACKNOWLEDGMENTS AND RESPONSIBILITY

The named authors of this report are just three of the 

many U.S. Geological Survey workers who contributed 

to this study. Scott made a geologic map of the RatonSpringer area, collected rock specimens characteristic of 

each igneous unit, and had them prepared for analysis. 

Wilcox did most of the petrography. Mehnert determined the K-Ar ages of the rocks. Mutsumi Miyachi and 

Charles W. Naeser determined the fission-track ages of 

several rocks. Wilcox, assisted by Jane Jenness and 

Michelle Hutchins, made the calculations for the chemical 

classification system developed by La Roche and others 

(1980) for assignment of names to the igneous rocks. 

Kenneth Segerstrom and Wilcox visited the field area 

with Scott and gave advice on petrology and field 

relationships of the volcanic rocks. During the mapping 

by Scott, Mortimer H. Staatz was mapping the Pine 

Buttes (Staatz, 1986) and the Tres Hermanos Peak 

(Staatz, 1987) quadrangles in connection with an investigation of thorium and rare-earth mineralization in the 

Laughlin Peak area (Staatz, 1985). Staatz cooperated in 

our geologic studies, and we appreciate the use of his 

analytical data and his then-unpublished geologic maps of 

the above two quadrangles. Peter W. Lipman helped 

select rocks for K-Ar analysis, and Donald M. Cheney 

separated the minerals for dating. Charles L. Pillmore 

assisted in mapping part of the area.

We appreciate the kindness of the U.S. National Park 

Service staff at Capulin Mountain National Monument, 

who sent specimens of the basalt flows from Capulin 

Volcano for petrographic examination. Many ranchers 

were helpful during the mapping, particularly Jim Hennigan of the Hennigan Ranch, Tim Harkness of the 

McAuliffe Ranch, and John D. Carter of the Carter 

Ranch.

We are indebted to Carl Orth of the Los Alamos 

National Laboratory at Los Alamos, N. Mex., for the 

neutron activation analyses. All other new analyses were 

performed in the laboratories of the U.S. Geological

Survey. Chemical analyses with the specimen designations SM (Scott) or MHS (Staatz) are major-oxide 

(including total iron) analyses by X-ray fluorescence done 

by J.S. Wahlberg, J.E. Taggart, Jr., K.C. Stewart, and 

J.W. Baker. FeO analyses by volumetric titration were 

by J.L. Ryder, G.R. Mason and H.G. Neiman. The 

calculated Fe203 values are the difference between the 

total iron and the FeO analyses. For chemical analyses of 

specimens labeled MHS, the C02 was by coulometric 

titration, the H20 + by the Penfield method, and H20- 

by weight difference after heating the sample to 105 °C 

for 2 hours all done by H.G. Neiman. For analyses 

lacking direct determinations of H20, "volatiles" were 

calculated from values of loss on ignition, adjusted by 

assuming all ferrous iron became oxidized to ferric iron. 

Six-step semiquantitative spectrographic analyses were 

by L.A. Bradley. Fluorine contents were determined by 

the specific-ion electrode method by F.D. Newman and 

H.G. Neiman.

PHYSIOGRAPHY

The report area lies within the Raton section of the 

Great Plains province (Fenneman, 1946). The study area 

includes part of the basalt-capped mesas near Raton and 

generally lies east of the Park Plateau (Raisz, 1939), an 

area of coal-bearing rocks. Most of the area is drained 

southward by the Canadian River and its tributaries, but 

the extreme east side drains eastward through the Dry 

Cimarron River, and the northeast corner drains north 

to the Purgatoire River (fig. 1).

The physiography of the Raton-Springer area has been 

strongly influenced by igneous activity. The most 

striking features are plateaus as long as 15 mi (24 km) 

capped by dissected lava flows; buttes, some with bases 

as broad as 3 mi (5 km), formed by cinder cones and 

extrusive domes; broad, dissected hills domed by sills 

and bordered by dipping sedimentary beds; sharp ridges 

formed by igneous dikes and their baked wall rocks; and 

long tongues of basalt that have recently flowed down 

valleys. Other physiographic features are three levels of 

high gravel-covered pediments, low terraces along major 

streams, and deep valleys cut through the high basaltcovered plateaus surrounded by large landslide deposits. 

A broad southeastward-sloping plain in the southeastern 

part of the area is created by the Ogallala Formation, a 

fanlike deposit of fluvial sand and gravel of Miocene age. 

Perhaps the most scenic feature in the area is the deep 

canyon of the Canadian River.

The amount of dissection differs greatly, probably 

depending on proximity to the Canadian River and its 

tributaries. Along the Canadian River near Mills, south 

of the map area, about 1,000 ft (305 m) of downcutting 

has taken place since deposition of the Ogallala 

Formation about 7 m.y. ago. The gravel beneath the high
VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

basalt flows on the plateaus north and east of Raton is 

also considered to be Ogallala Formation because it lies 

about 1,000 ft (305 m) above modern drainage. From 

Loco Mesa to near Capulin, just east of the study area, 

however, erosion since Ogallala time is almost undetectable, drainage is not integrated, many large basins of 

ephemeral lakes are present, and the principal agent of 

erosion seems to have been wind rather than water. The 

lack of much erosion near Capulin and the large amount 

of erosion near Raton complicates the age correlation of 

lava flows between the two areas. A lava flow near Raton 

lying 1,200 ft (365 m) above modern drainage, for 

instance, may correlate with a flow near the town of 

Capulin that is only 300 ft (90 m) above modern drainage. 

Our endeavor to reconcile this complication in assignment of ages is discussed further in the later section on 

basaltic to latiandesitic effusive rocks.

SEDIMENTARY ROCKS

Figure 2 lists the sedimentary strata that crop out in 

the Raton-Springer area and vicinity. The extrusive 

rocks described here overlie most of these rock units, 

including some of the Quaternary surficial deposits. The 

sills of the Chico sill complex are interlayered with beds 

from the Dakota Sandstone up through the Smoky Hill 

Shale Member of the Niobrara Formation. In the 

southeastern part of the area intrusive bodies of rhyodacite, trachyte, and phonolite have domed Mesozoic 

(and Cenozoic?) rocks, some of which are not elsewhere 

exposed at the surface (Scott, 1986; Scott and Pillmore, 

1989).

STRUCTURE

The chief structural features of the Raton-Springer 

area are the eastern part of the Raton basin and the 

bounding Sierra Grande arch. The Raton basin is asymmetrical; the eastern limb is broad and dips gently to the 

west, whereas the western limb is narrow and dips 

steeply to the east. The axis of the basin lies west of the 

study area and trends northward parallel to the axis of 

the Sangre de Cristo Mountains. The crest of the Sierra 

Grande arch trends about N. 30° E. (Wood and others, 

1953) across the southeast quarter of the map area, 

beginning in T. 23 N., R. 24 E., south of the map area, 

and extending to T. 28 N., R. 28 E., just east of the map 

area. The arch is broad and has several small folds 

superposed on it. Intrusion of sills has increased the 

structural relief of the arch by nearly 1,000 ft (305 m); 

possibly structural weakness along the crest of the arch 

influenced the placement of the sills. Intrusion of the sills 

caused some folding and faulting of the sedimentary 

rocks, but preexisting faults and folds apparently did not 

influence igneous intrusion in any major way.

Holocene

Pleistocene

Miocene

Lower 

Tertiaryf?)

Paleocene

Upper 

Cretaceous

Lower 

Cretaceous

Upper 

Jurassic

Middle 

Jurassic

Upper 

Triassic

Alluvium, fan alluvium, sheet wash alluvium, colluvium, 

lake sediments

Eolian deposits

Pediment and terrace alluvium (at least three physiographic 

levels of pediments)

Ogallala Formation

Alluvial deposit on east flank of Palo Blanco Mountain

Poison Canyon Formation

Raton Formation

Vermejo Formation

Trinidad Sandstone

Pierre Shale

Niobrara 

Formation

Carlile 

Shale

Greenhorn 

Limestone

Graneros 

Shale

Smoky Hill Shale Member

Fort Hays Limestone Member

Unnamed upper member

Juana Lopez Member

Codell Sandstone Member

Blue Hill Shale Member

Fairport Member

Bridge Creek Limestone Member

Hartland Shale Member

Lincoln Limestone Member

Thatcher Limestone Member

Dakota Sandstone

Purgatoire Formation

Morrison Formation

Bell Ranch Formation

Exeter Sandstone

Dockum 

Group

Chinle Formation

Santa Rosa Sandstone

FIGURE 2. Sedimentary rocks exposed in the Raton-Springer area 

and vicinity, New Mexico.

IGNEOUS ROCKS

CONCORDANT INTRUSIONS

An assemblage of sills of middle Tertiary age, here 

called the Chico sill complex as used by Wood and others 

(1953), crops out in the southeastern part of the study
IGNEOUS ROCKS

area south of Laughlin Peak and east of Tres Hermanos 

Peak (fig. 1). This assemblage contains many stacked 

sill-like bodies of varied compositions, all of which are 

nearly concordant with the structure of the sedimentary 

rocks. Wood and others (1953) commented that locally 

the thick sills appeared to be small laccoliths; the 

complex is slightly elongate in a southeastern direction 

and is about 16 mi (26 km) in diameter. The igneous 

bodies are flat on bottom and top, and the ratio of 

diameter to thickness is much greater than ten. Based on 

these characteristics, we avoid the name laccolith and 

instead adopt the term sill complex as used by Wood and 

others (1953).

The sill complex has quaquaversal dips and two crosscutting central intrusions (the only vents found) on 

Turkey Mountain in the northeastern part of the Tres 

Hermanos Peak quadrangle. Strata intruded by the sill 

complex are not only gently domed but also folded into 

small anticlines and synclines superimposed on the broad 

dome. In addition, the sills and associated sedimentary 

rocks are broken by local faults having small throws. 

Most of the sedimentary rocks that bound the igneous 

rocks were contact metamorphosed to hornfels, which 

commonly is more resistant to erosion than the igneous 

rocks.

Other areas of doming by probable igneous intrusions 

lie near and west of Cimarron and at the Turkey 

Mountains, 7 mi (11 km) west of Wagon Mound (fig. 1). 

Near Cimarron, syenite and rhyodacite sills are widespread and suggest the presence of a large subsurface 

intrusion that could extend as far to the northwest as the 

valley of the Rio Grande. Peter W. Lipman (oral commun., 1982) of the U.S. Geological Survey suggested that 

these sills at Cimarron could be related to the volcanic 

rocks of the Latir Peak volcanic field, 35 mi (57 km) to the 

northwest.

Hayes (1957) suggested that the uplift of the Turkey 

Mountains, west of Wagon Mound (outside the study 

area), might have resulted from the intrusion of a 

laccolith. The mountains are about 7 mi (11 km) across, 

are fairly symmetrical, and expose several small igneous 

bodies. One of these is a mafic dike, which is described 

and dated in this report in the section "Mafic and 

ultramafic dikes and sills."

EXTRUSIONS AND DISCORDANT INTRUSIONS

Several types of extrusions and intrusions are found in 

the area. At least 10 hornblende rhyodacite volcanoes are 

known. On the east flank of Palo Blanco Mountain 

volcano (the only part of the mountain where bordering 

sedimentary rocks can be seen), sedimentary layers 

were upturned to nearly vertical during extrusion of the 

rhyodacite. A kimberlite diatreme cuts the Upper

Cretaceous Pierre Shale 2 mi (3.2 km) east of Raton. 

Many small basaltic and lamprophyric plugs are commonly associated with dike swarms of similar composition. Dikes are extremely numerous south of Eagle 

Tail Mesa and Tinaja Mountain, and in and around the 

Chico sill complex. They range widely in thickness and 

length, some being as much as 8 mi (13 km) long.

Cinder cones formed at the vents of many of the mafic 

lava flows. Some of the younger cones, such as Capulin 

Mountain, Horseshoe Crater, Cinder Butte, and Gringo 

Peak, are little eroded and nearly symmetrical. Older 

cinder cones are more eroded but still identifiable as the 

sources of some lava flows.

The lava flows are somewhat tabular sloping bodies of 

widely varying thickness. Most were deposited on 

gravel-floored stream valleys, and clasts of gravel or, 

rarely, large deposits of gravelly alluvium are visible 

beneath the flows. Figure 3 shows a succession of alluvial 

deposits beneath a basalt flow. Alluvial deposits such as 

these probably underlie most of the basalt and mafic 

feldspathoidal flow series in the area. However, large 

landslide deposits around most lava-capped mesas 

obscure the gravel. Nearly all flows were fairly viscous 

and formed aa having a rough, jagged, clinkery surface. 

On the younger flows, additional features such as lava 

spines, tumuli (pressure domes) (fig. 4), and pressure 

ridges are readily recognized. The initial pyroclastic 

eruptions commonly laid down continuous mantles of 

basaltic ash, which underlie most lava flows and overlie 

the gravel deposits in the ancient stream valleys.

We recognized 66 cinder cones in the eastern part of 

the map area and found 30 more west of Wagon Mound, 

southwest of the area. On the flanks of the cinder cones 

the beds of pyroclastic material lie at the angle of repose, 

about 30°. Although the cinder cones mark the locations 

of the main vents, most of the flows issued from the 

lower parts of the cones, not from craters high on the 

cones. Many of the cinder cones were breached, probably 

by lava tunneling from the feeder vent through the lower 

parts of the cinder cones and eroding the upper parts. 

Around a few cones the flows accumulated to such a 

thickness that the cones are largely buried.

TYPES OF IGNEOUS ROCKS

The igneous rocks are both intrusive and extrusive; 

many are alkalic and some also feldspathoidal. The 

principal varieties, arranged by age, are shown in figure 

5 and on a generalized geologic map, figure 6. The 

subvolcanic Chico sill complex contains chiefly alkalic 

rocks, such as the Slagle Trachyte and the Chico 

Phonolite.

Volumetrically, most of the exposed extrusive rocks 

are basaltic, andesitic, and latitic. The more silicic rocks 

occur in the southeastern part of the area and may be
VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

FIGURE 3. Unconsolidated sediments beneath flow of Raton Basalt on north side of New Mexico Highway 72 at east end of Johnson Mesa in the 

NEV&SEV4 sec. 21, T. 31 N., R. 27 E., Trinchera Pass quadrangle. From the top downward, the section includes basalt, 3 ft (1 m) of water-laid 

coarse, loose, black basaltic ash (fine-grained layer in photograph) 12 ft (3.6 m) of muddy lahar containing clasts of basalt, and an unmeasured 

thickness of poorly exposed tan, gravelly sand containing clasts of Precambrian rocks and basalt several inches long.

time equivalent to the Clayton Basalt. Also present in 

the area are basanite, nepheline basalt, nephelinite, 

ankaratrite, and hauyne basalt.

The Red Mountain Rhyodacite apparently is entirely 

extrusive, and at Laughlin Peak includes some waterlaid tuff and volcaniclastic lahars. Dikes and sills of 

various compositions other than those listed above 

include lamprophyre (vogesite and monchiquite; Stobbe, 

1949), tinguaite, and analcime microfoyaite; few of these 

were considered in this study.

Most rocks are porphyritic and have a fine-grained 

groundmass. Size of the phenocrysts varies widely the 

largest seen were feldspar crystals about 2 cm long in 

green phonolite. The phenocrysts in phonolite, trachyte, 

and rhyodacite commonly show flow lineation.

RADIOMETRIC AGES

The specific ages of the volcanic and subvolcanic rocks 

near Raton were poorly known when mapping of the 

Raton and Springer 30' x 60' quadrangles was begun. In 

order to establish the age of volcanic activity more 

exactly, K-Ar determinations were made of rocks that 

seemed to represent the whole range of volcanism, from 

oldest to youngest. Table 1 shows the analytical data for 

22 whole-rock or mineral separates that represent the 

major rock formations. Figures 1 and 6 show the 

locations where the radiometrically dated rocks were 

collected. The ages range from Oligocene to Holocene; 

rocks of the Chico sill complex are the oldest subvolcanic 

rocks in the area, ranging from more than 36 m.y. 

(Staatz, 1985, p. E12) to about 20 m.y.
IGNEOUS EOCKS

.w."""-" *ttr -''^xr * ~- -^f>^'

FIGURE 4. Tumulus or pressure dome on flow of Capulin Basalt in the 

SEV4 sec. 7, T. 29 N., E. 27 E., Eobinson Peak quadrangle. Flow 

probably was erupted from volcano in the NEV4 sec. 22, T. 30 N., 

E. 26 E., Johnson Park quadrangle (locally called "Burnt 

Mountain"),

Data from fission-track analysis of three samples, 

shown in table 2, yield further information on the age of 

volcanism. Radiometric ages reported previously by 

Armstrong (1969, table 1), Stormer (1972a, table 2), and 

Hussey (1971) are shown in table 3. M.J. Aldrich of the 

Los Alamos National Laboratory, Los Alamos, N. Mex., 

has recently reported (written commun., 1982) ages of 

some mafic dikes in and close to the map area. These ages 

are quoted in the discussion of mafic and ultramafic dikes 

and sills. K-Ar ages of the Slagle Trachyte, the trachyte 

southwest of Laughlin Peak, and the Red Mountain 

Rhyodacite were published by Staatz (1985) and are 

quoted in table 3 and under discussion of each of those 

units.

In addition to the above ages, 19 radiometric ages have 

recently been reported by O'Neill and Mehnert (1980b) 

for basalt flows in the southwestern part of the Springer 

30' x 60' quadrangle. Dated basalt flows in that area 

range in age from 8.34+0.50 to 0.81 ±0.14 m.y. The flows 

range in height above modern streams from 2,000 to 60 ft 

(610-18 m). Their sequence of basalt flows is similar in 

age and height above stream level to the flows near 

Raton; however, no feldspathoidal flows were recognized 

in that area.

PETROGRAPHY AND PETROCHEMISTRY

A reconnaissance petrographic examination of thin 

sections (without precise modal analyses) confirmed for 

the most part the more detailed descriptions of rocks of 

this area by Stobbe (1949). Some 63 new chemical 

analyses (18 of which were supplied by M.H. Staatz of 

the U.S. Geological Survey) are given in the following 

tables along with some previously published analyses of 

rocks of the area.

The classification of La Roche and others (1980) is used 

to assign rock names (see fig. 7A) rather than the CIPW

Holocene

Pleistocene

Pliocene

Miocene

Oligocene

Eocene and 

Pal eocene

Capulin Basalt (Qb) 2,400-8,000 years

Clayton Basalt (QTb) 0.5-2*

Raton Basalt (Tb) 3.5-4*

Mafic feldspathoidal rocks (Tba) 1.9-8.2*

Red Mountain Rhyodacite (Trm) 6-8*

Trachyandesite of Middle Pine Butte (Tta) r

Rocks 20-37* of theChico sillcompex 

Chico Pon lite20-26*

OcelJar analcime 

phonolite

Silver~gray 

phonolite (Tps)

Syenite and 

trachyte 

sills east 

of Cimarron

Nepheline syenite dike o

on Point of Rocks Mesa ^ in

CM

Green phonolite (Tpg) 

Phonotephrite (Tpt) and tephrite Jg 

(Tte) along Joe Cabin Arroyo 25* E

Melasyenite dike Q

Syenite and quartz 

monzonite vent rocks 

at Turkey Mountain 

(Tv) 29*

Rhyodacite 

west of 

Cimarron 29*

Biotite trachyte southwest 

of Turkey Mountain (Tbt)

Trachyte southwest of 

Laughlin Peak (Ttr) 32*

Slagle Trachyte (Tsl) 37*

tramafic dikes andsills (TIa) 23-65*

u 

-o

CD 

O

to^

*Radiometric ages in millions of years

FIGURE 5. Igneous rocks of the Baton-Springer area and vicinity, 

New Mexico. Shading identifies rocks of the Chico sill complex.

norms. Their parameters R± and Rz are calculated as 

follows:

#! = 4Si-ll(Na + K)-2(Fe + Ti), 

R2 =6Ca + 2Mg + Al

where Si, Na, K, and other element symbols represent 

millications (thousandths of a cation percent) of the 

element present in 100 grams of the rock. A point is 

plotted using Rl as abscissa and R2 as ordinate on the 

diagram of figure 7'A, and the rock name is taken from 

that of the area on the diagram in which the point R^R2 

values for each rock analysis plot. For those values that 

plot on or very near a boundary, both rock names are 

used.

An important use of the R^R2 diagram is to show the 

chemical relations among members of igneous rock series 

and to better enable interpretation of the magmatic
10 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

TABLE 1. Analytical data for K-Ar ages of whole-rock samples and mineral separates in volcanic and subvolcanic rocks, Raton-Springer area,

New Mexico

[Analyses for N^O and K20 by E.L. Brandt, U.S. Geological Survey. Decay constants: 40K Ae=0.581 x I(r10/yr; Xp =4.962 x I(r10/yr; 40K/K=1.167 x KT4]

Map 

No. 1

1 

2 

3 

4 

5 

6 

7 

8 

9 

10

11 

12

13

14 

15 

16

Map 

symbol

QTb 

Qtb 

QTb 

QTb 

Tb 

Tba 

Tba 

Tba 

Tba 

Trm

Trm

Trm 

Trm

Tl

TP 

Tps 

Tla

Field 

No.

80SM1 

80SM15 

80SM2 

80SM16 

80SM31 

80SM8 

80SM39 

80SM21 

80SM44 

80SM6

80SM18

80SM22A 

80SM22B

80SM37

80SM5 

80SM13 

80SM25

Lab.

No. 

DKA4415 

4419 

4416 

4427 

4422 

4418 

4421 

4420 

4423

4411 

4412

4414

4413

4385 

4387 

4386 

4388

4428 

4424

4417 

4426 

4425

Rock type

Basalt --------------

Latite/trachyandesite

Altfali KacalfSilver-gray phonolite 

Silver -gray phonolite 

Basanite (lamprophyre)

Material 

analyzed

Whole rock 

Whole rock 

Whole rock 

Plagioclase 

Whole rock 

Whole rock 

Whole rock 

Whole rock 

Whole rock

Hornblende 

Plagioclase

Hornblende3

Plagioclase

Hornblende 

Plagioclase 

Hornblende 

Plagioclase

Hornblende 

Plagioclase

Whole rock 

K- feldspar 

Hornblende

Na202 

(percent)

3.43,

5.26, 

5.26, 

5.38, 

2.88, 

3.33, 

3.98,

3.16, 

3.46,

2.42, 

6.73,

2.31,

6.71,

2.25, 

6.93, 

2.13, 

6.99,

2.07, 

6.44,

9.57, 

6.77, 

2.51,

3.43

5.21 

5.25 

5.38 

2.87 

3.42 

3.94

3.17 

3.37

2.41 

6.76

2.31

6.71

2.25 

6.95 

2.11 

7.00

2.09 

6.46

9.64 

6.81 

2.52

K202 

(percent)

1.30,

2.30, 

2.08, 

.44, 

1.29, 

1.09, 

1.50,

1.51, 

1.34,

.62, 

.35,

.63,

.40,

.58, 

.40, 

.53, 

.41,

.69, 

.30,

5.35, 

7.05, 

.70,

1.30

2.29 

2.08 

.43 

1.30 

1.14 

1.49

1.50 

1.29

.62 

.36

.65

.40

.58 

.42 

.51 

.44

.71 

.32

5.32 

7.07 

.71

40Ar 

moles/g 

xlO" 10

0.0124 

.0286 

.0273 

.0079 

.1306 

.0300 

.0710 

.0895 

.1554

.0574 

.0293

.0703 

.0636 

.0251

.0567 

.0372 

.0558 

.0366

.0696 

.0978

1.567 

2.736 

.2469

40Ar 

percent

12.4 

8.3 

20.1 

4.5 

45.6 

19.4 

50.5 

35.7 

71.9

21.5 

15.5

14.9 

14.9 

7.6

10.3 

10.0 

11.0 

14.3

18.9 

24.2

54.5 

93.1 

56.5

Age 

(m.y.±2or)

0.6610.12 

.861 .22 

.911 .10 

1.271 .71 

3.951 .19 

1.871 .21 

3.301 .15 

4.121 .25 

8.191 .31

6.431 .67 

5.721 .84

7.6 11.1 

6.9 11.0 

4.3511.33

6.7911.45 

6.3011.44 

7.4411.49 

5.971 .95

6.901 .80 

21.7912.22

20.291 .90 

25.801 .88 

24.1611.01

1 As shown on figure 6.

2 Analyses for Na20 and 1^0 done in duplicate for each sample.

3 Hornblende was analyzed isotopically on two splits of the same sample.

DESCRIPTION OF SAMPLE LOCALITIES

80SM1. South end of mesa in the NW^SEk sec. 31, 9.

T. 30 N., R. 25 E., Colfax County, Hunter Mesa

quadrangle. 10.

80SM15. West edge of mesa in the Wk sec. 15,

T. 26 N., R. 27 E., Colfax County, Lawrence Arroyo

quadrangle. 11.

80SM2. South end of Juan Torres Mesa in the SE^NE1*

sec. 26, T. 30 N. , R. 25 E. , Colfax County, Johnson

Park quadrangle. 12.

80SM16. Northeast of road on flank of Las Mesetas

in the UEk sec. 33, T. 26 N., R. 27 E., Colfax

County, Lawrence Arroyo quadrangle. 13.

80SM31. West edge of Mesa Larga in SWkSWk sec.

334, T. 29 N., R. 26 E., Colfax County, Mesa Larga

quadrangle . 14.

80SM8. North edge of mesa in the NW^NW** sec. 6,

T. 30 N., R. 28 E., Union County, Robinson Peak

quadrangle. 15.

80SM39. South edge of mesa in the SW^NWk sec. 13,

T. 26 N., R. 25 E., Colfax County, Point of Rocks

Mesa quadrangle . 16 .

80SM21. Quarry in southeastern part of Dale

Mountain in the NWk sec. 16, T. 31 N. , R. 26 E.,

Colfax County, Dale Mountain quadrangle.

80SM44. Roadcut in SE^NW** sec. 10, T. 31 N. ,

R. 25 E. , Colfax County, Yankee quadrangle.

80SM6. Western foot of Towndrow Peak in the

sec. 22, T. 31 N., R. 25 E. , Colfax County, Yankee

quadrangle.

80SM18. Dike at the west end of Cunningham Butte

in the SW^ sec. 25, T. 30 N., R. 24 E., Colfax

County, Hunter Mesa quadrangle.

80SM22 . Southern foot of Red Mountain in the

SWJ*SW*« sec. 23, T. 31 N., R. 26 E., Colfax County,

Dale Mountain quadrangle.

80SM37. Arroyo on north flank of Laughlin Peak in

the NW^SEk sec. 19, T. 28 N., R. 26 E., Colfax

County, Mesa Larga quadrangle.

80SM5. North end of Tinaja Mountain in the NE^

sec. 14, T. 28 N., R. 24 E., Colfax County, Tinaja

Mountain quadrangle.

80SM13. Southeastward facing slope at Chico in the

SEk sec. 17, T. 26 N. , R. 26 E., Colfax County,

Point of Rocks Mesa quadrangle.

80SM25. Eagle Rock dike on west side of Interstate

Highway 25 in the NE^ sec. 16, T. 28 N., R. 23 E. ,

Colfax County, Eagle Tail Mountain quadrangle.
IGNEOUS ROCKS 11

TABLE 2. Analytical data for zircon fission-track ages of volcanic and subvolcanic rocks, Raton-Springer area and vicinity, New Mexico

[Samples dated by Mutsumi Miyachi in the laboratory of C.W. Naeser, U.S. Geological Survey. Decay constant Af=7.03 x KT^vr"1 ]

Map 

No. 1

17

18

19

Lab. Fossil- track Induced- track 

Field , 

No. Rock unit density, p * density, pf 

No 

DF- (106 tracks/cm2 ) (10 6 tracks/cm2 )

80SM33 4000 Kimberlite at Raton 3.03 (928) 6.14 (940)

81SM9 3951 Hornblende syenite 3.09 (1952) 6.20 (1954) 

at Turkey 

Mountain vent.

81SM24 4001 Rhyodacite west of 5.76 (1944) 10.32 (1744) 

Cimarron.

Neutron Number 

Age 

flux, ^ of 6 (m.y.±2a) 

(10 16 n/cm2 ) grains

1.02 7 30.111.2

.971 13 29.011.6

.877 6 29.111.4

*As shown on figure 1 or 4.

2 Numbers in parentheses show total number of tracks counted in each determination.

DESCRIPTION OF SAMPLE LOCALITIES

17. 80SM33. Diatreme in a low rounded hill in the

NEkNWitSEk sec. 20, T. 31 N. , R. 24 E. , about 9,600 

ft (2,926 m) east of the Colfax County Courthouse 

on the Olen Caviness Ranch, Raton quadrangle.

18. 81SM9. Crest of eastern peak of Turkey Mountain, 

altitude 7,888 ft (2,404 m), in the center of the

SVfa sec. 11, T. 27 N., R. 25 E., Tres 

Hermanos Peak quadrangle.

19. 81SM24. Roadcut h mi east of Palisades in 

Cimarron Canyon on U.S. Highway 64, Touch-MeNot Mountain quadrangle.

TABLE 3. Analytical data for previously published K-Ar ages of igneous rocks from the Raton-Springer area, New Mexico

[All ages recalculated using new decay constants shown in table 1. n.d., no data given in original reference]

Rock Name Locality Material 

dated

K20 

(percent)(percent)

Age (m.y.) Reference

Raton Basalt 

Basanite

Red Mountain 

Rhyodacite.

Trachyte SW. of 

Laughlin Peak.

Rhyodacite west 

of Cimarron.

Slagle Trachyte

Bartletu Mesa; 36 0 51'32"

N. , 104°24'55" W. 

Urraca Mesa, 36°24 t 15" N. ,

104 0 59'18" W.

Johnson Mesa, lowest flow; 

NWi sec. 10, T. 31 N. , 

R. 25 E.

SWiSWi sec. 3, T. 27 N. ,

R. 26 E. 

NWiNEi sec. 18, T. 27 N. ,

R. 26 E. 

Cunningham Butte, sec. 31,

T. 30 N., R. 24 E.

SEiSWi sec. 6, T. 27 N., 

R. 26 E.

Palisades in Cimarron 

Canyon; 36°32 I 15" N. , 

105 0 9'30" W.

Whole rock .89 43 3.59+0.2

Whole rock 1.850 56.48 4.4+0.1

Plagioclase 1.95 64 l 7.38+0.3

Hornblende n.d. n.d.

Hornblende n.d. n.d.

Hornblende .55 23

7.7 +0.5

8.1 +0.6

2 8.4 +0.8

Stormer (1972a, 

sample 855-293).

Hussey (1971, sample M-FRL1388).

Stormer (1972a, 

sample 855-117).

Staatz (1986). 

Staatz (1985).

Stormer (1972a, 

sample 855-277).

Hornblende n.d. n.d. 32.3 +1.5 Staatz (1985).

Biotite3 3.386 60 

3.361

34.6 Armstrong (1969, 

sample 733).

i sec. 2, T. 27 N. , 

R. 25 E.

Hornblende n.d. n.d. 36.7 +1.3 Staatz (1985).

1 See table 1, sample 9, in this report for K-Ar age of another sample of this rock.

See table 1, sample 11, in this report for K-Ar age of another sample of this rock. 

^Includes 25 percent chlorite and 20 percent rock.

See table 2, sample 19, in this report for zircon fission-track age of another sample of this rock.
12 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

104°30'

37°00' _ _ ___ -COLORADO _ 

^Tb~ NEW MEXICO

104°00'

36°30'

T26N

T25 N

R28 E

15 KILOMETERS
IGNEOUS ROCKS 13

QTb

Tba

Trm

Tta

Tla

Ta

Td

Tp

Ts

Tte

Tpt

TV

Ttr

Tsl

EXPLANATION

Capulin Basalt

Clay ton Basalt

Raton Basalt

Mafic feldspathoidal rocks

Red Mountain Rhyodacite

Lahar (related to Red Mountain Rhyodacite) 

Trachyandesite of middle Pine Butte 

Mafic and ultramafic dikes and sills (Tertiary) 

Ankaratrite 

Diatreme

Chico sill complex: 

Chico Phonolite

Nepheline syenite dike on Point of Rocks Mesa

Tephrite

Phonotephrite

Vent rocks at Turkey Mountain

Trachyte southwest of Laughlin Peak

Slagle Trachyte

Holocene 

Pleistocene

Pliocene

Miocene

Miocene and 

Oligocene

-Oligocene

 Sample locality of radiometrically dated rock 

listed in table 1

FIGURE 6 (above and facing page). Generalized geologic map of the 

Raton-Springer area showing only volcanic, subvolcanic, and volcaniclastic rocks. Figure shows sample localities 1-18 of radiometrically dated rocks listed in tables 1 and 2; locality 19 is shown on 

figure IA. For a geologic map of the rocks discussed in this report 

that lie south of the area shown here, in the Springer 30'x60' 

quadrangle, see Scott (1986).

evolution and position of a rock series in the orogenic 

cycle (see for example Batchelor and Bowden, 1985). 

Here it will be used mainly to provide a consistent 

nomenclature and to show relations between the rock 

types of the area.

In the diagram, the diagonal line extending upward to 

the right corresponds to the "critical plane of silica 

undersaturation" of the Cpx-01-Ne-Qz tetrahedron of 

Yoder and Tilley (1962, p. 350). Generally, the rocks that 

plot above and to the left of this diagonal may be 

regarded as undersaturated in silica. It is worth noting 

here that the calculations of R1R2 are not affected by 

posteruption changes in the ferrous-ferric ratio, which in 

the calculation of the CIPW norm can force the appearance of spurious amounts of normative quartz and in 

some cases imply silica saturation for an originally undersaturated magmatic rock. Thus, a few rocks showing low 

values of quartz in the norm will actually seem to be 

undersaturated from their plotted positions on the R^R2 

diagram.

On figure IB the R± and R2 values of all the samples of 

the various rock units in the Raton-Springer area are 

plotted on the diagram of La Roche and others (1980), 

and the fields covered by the various mapped rock types 

are outlined.

CHICO SILL COMPLEX

The Chico sill complex occupies a broad domal area, 

about 16 mi (26 km) in diameter in the southeastern part 

of the Raton-Springer area, where the Cretaceous rocks 

have been arched upward by the intrusion of many 

nearly flat, nearly tabular, sill-like bodies of alkalic rock. 

We infer that the sills were intruded between 37 and 

20 m.y. ago from dikes or from pipelike feeders such as 

those on Turkey Mountain.

The Chico sill complex contains two principal rock 

types, the Slagle Trachyte and the Chico Phonolite. The 

phonolite is of two major types, a green variety and a 

silver-gray variety, which intergrade. Minor rock types 

within the Chico sill complex include tephrite, phonotephrite, and syenite. Most of these minor units are 

sill-like; however, most of the syenitic units form dikes 

rather than sills. The two vents on Turkey Mountain, 

containing syenite and biotite quartz monzonite, probably are plugs that formed late during intrusion of the sill 

complex and appear to be related chemically to the 

hornblende trachyte of the Slagle; however, they are not 

contemporaneous with the Slagle. Thin border zones of 

epidotized breccia cemented by iron oxide characterize 

both of the vents.

In the area of the sill complex, the igneous material 

probably makes up only about one-fourth of the thickness 

of the rocks in hillsides, the remainder being sedimentary rock, primarily Greenhorn Limestone down 

through Dakota Sandstone of Late Cretaceous age. 

However, in the Chico Hills and in the western part of 

the Pinon Hills, the igneous rock makes up the greater 

part of the hillsides (M.H. Staatz, written commun., 

1984).

Only one possible feeder has been found in the Chico 

sill complex, that on Turkey Mountain, which includes a 

vent of syenite and a vent of quartz monzonite. The 

syenite vent rock occurs at the high point on Turkey 

Mountain.

Collins (1949, p. 1034) suggested that one source vent 

of the Chico Phonolite possibly was in the steep-walled 

valley just east of Temple Peak, an area he called the 

"J.T. Rincon." The rincon is a deeply eroded structural 

dome, and Collins surmised that the vent for the Chico 

Phonolite is concealed beneath a younger (Clayton) 

basalt flow on the valley floor. That proposal now seems 

doubtful, because the rincon is floored by readily erodible 

Triassic sedimentary rock, and no vestige of a vent facies
14 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

3000

2000 -

pyroxenite,

/^peridotite

ANKARATRITE

melteigite

NEPHI1INITE 

ijolite

BASANITE 

theralite THOLEIITE 

BASALT' ( gabbronorite

TEPHRITE 

essexite

(olivine gabbro

BASALT /^"'x/ ANDESIBASALT 

PHONOTEPHRITE T^^^^/SSS-/1 9abbrodiorite

TRACHY^^^i - T~^ANDESITE IHAI.HY- \, rr^.

ANDESITE ]/ i LAM

syenodiorite// LATITE

monzoniteX diorite

RHYODACITE

granodiorite

/ 

TRACHYTE

/syenite RHYOLITE

granite

i i i i i i i i i i i i i i i i i i i i i i i i i i i i

Mafic and ultramafic 

dikes and sills

Mafic feldspathoidal roc

P/ionotephrite and

tephrite along 

Joe Cabin Arroy 

Melasyenite dike g

Rhyodacite west 

of Cimarron Biotite trachyte

southwest of

Turkey Mountain

Trachyandesite of Mjddle 

Pine Butte""'

CHICO PHONOLITE: 

reen variety

«/ /Silver-gray varie

Trachyte southwest /Vent rocks

of Lau9hlin Peak / at TurkeV

Nepheline syenite dike on o'ag'e / / Mountain 

Point of Rocks Mesa Trachyte*

-1500 -1000 1000 

R,, IN MILLICATIONS

2000 3000
IGNEOUS ROCKS 15

was found there. The J.T. Rincon dome more likely is a 

result of uplift by a subsurface igneous intrusion. A more 

likely source of the phonolite is near Trujillo Mesa, which 

is underlain by the highest phonolite sill in the area. 

Phonolite is most abundant in the southeastern part of 

the sill complex, but it also occurs at and southeast of 

Tinaja Mountain, near Tres Hermanos Peak, and near 

Laughlin Peak; these outcrops also could have been small 

intrusive centers for the phonolite.

The distribution of the Slagle Trachyte is limited to the 

area around Turkey Mountain, extending to Blosser 

Arroyo 7 mi (11 km) to the northwest, nearly to 

Shoemaker Hill 5 mi (8 km) to the west, just beyond 

Raspberry Mountain 2 mi (3.2 km) to the east, and to 

Chico Creek 6V6 mi (10.4 km) to the south.

SLAGLE TRACHYTE

The Slagle Trachyte was named by Collins (1949, 

p. 1033) for outcrops of what he called soda trachyte on 

the east side of Slagel Canyon of Rio del Piano, 1 mi 

(1.6 km) north of the Maxwell-Chico road (Tres Hermanos Peak quadrangle). However, the only trachyte 

1 mi north of the road is on the west side of the canyon; 

though not originally designated, we assume that is 

Collins' type locality. The type area of the Slagle is 

herein considered to be exposures on the west side of 

Slagel Canyon in SWV4 sec. 34, T. 27 N., R. 25 E., Colfax 

County, N. Mex. All outcrops of the Slagle Trachyte are 

within the area of the Chico sill complex, where it occurs 

as numerous sills interlayered with the sedimentary 

rocks, but also as dikes. The trachyte is a light-olivegray, hard, porphyritic rock having numerous prominent hornblende phenocrysts set in a gray finely crystalline groundmass. The rock weathers pervasively, and 

unweathered outcrops are few. Weathered trachyte is 

pale orange, dark yellowish gray, or brown; black hornFIGURE 7 (facing page). Classification of principal volcanic and subvolcanic rocks of the Raton-Springer area, New Mexico, according 

to the system of La Roche and others (1980). 

A, The RiR2 diagram of La Roche and others, showing names of 

volcanic rocks in upper case and names of plutonic rocks in lower 

case italics. R: and R2 are defined as follows:

RI = 4Si-ll(Na + K)-2(Fe + Ti) R2 = 6Ca + 2Mg+Al

where amounts of the elements are expressed as "millications" 

(thousandths of a cation percent). Oblique dashed line represents 

the "critical plane of silica undersaturation" of Yoder and Tilley 

(1962, p. 350). Mineral plotted positions: Ab, albite; An, anorthite; Di, diopside; En, enstatite; Fa, fayalite; Fo, forsterite; He, 

hedenbergite; Mgt-Ilm, magnetite-ilmenite; Ne, nepheline; Of, 

orthoferrosilite; Or, orthoclase; Qz, quartz.

B, Analyzed samples from the Raton-Springer area plotted on the 

R^R2 diagram. Each group of samples is identified by name and 

by the number of the table that lists analytical data for the group.

blende crystals, which are as large as 8 mm, gradually 

alter to pale-brown iron oxide. Where little weathered, 

the hornblende crystals reflect the sunlight brilliantly, 

and the groundmass has a slight silvery sheen similar to 

that of the silver-gray phonolite. Flow structure is well 

displayed by the hornblende crystals in dikes and sills.

The K-Ar age of a sample of Slagle Trachyte was 

reported by Staatz (1985, p. E12) as 36.7±1.3 m.y. The 

sample was from the SEViNEVi sec. 2, T. 27 N., R. 25 E., 

Colfax County, N. Mex.

All specimens of the trachyte are generally similar, 

though in some the hornblende or pyroxene phenocrysts 

are replaced by carbonate, quartz, and pyrite, and in 

others the hornblende and pyroxene occur in glomeroporphyritic groups. Xenocrysts of quartz are found 

locally.

In thin section, trachyte specimen 81SM18 (table 4, 

analysis 4) is porphyritic, bostonitic in texture, and 

contains the following: about 7 percent corroded green 

hornblende phenocrysts as much as 3 mm long, optic 

angle about (-)40°, zoned with Z:c 13°-16°, rimmed with 

opaque oxide; 6 percent plagioclase (andesine?) phenocrysts as large as 3 mm; 1 percent corroded clinopyroxene phenocrysts as large as 1 mm, optic angle about 

(+ )70°; and 1 percent opaque oxide crystals as much as 

0.4 mm long. Groundmass is dominantly dusty alkali 

feldspar but contains scattered altered plagioclase, many 

small opaque oxide crystals, and traces of apatite, titanite, and brown pyroxene(?). Scattered xenoliths of 

altered schists and other metamorphic rock were 

observed.

The trachyte specimen 81SM5 (table 4, analysis 2) is 

porphyritic and contains about 6 percent olive green 

hornblende phenocrysts; 4 percent stubby clinopyroxene 

phenocrysts as large as 1 mm, some in clumps with 

hornblende, opaque oxide, and, rarely, dark mica; scattered equant opaque oxide crystals as large as 0.1 mm; 

and sparse phenocrysts of dark mica as large as 0.4 mm. 

Groundmass is subtrachytic in texture and consists 

predominantly of dusty alkali feldspar, many tiny clinopyroxene crystals, opaque oxide grains, and apatite.

Chemical analyses of the Slagle Trachyte (table 4) 

show that Si02 ranges from 56.6 to 62.6 percent; all the 

R1R2 plotted points fall within or on the edge of the 

trachyte field in figure IB. Note that although quartz 

appears in the norm of analysis 5, the R2 parameter is 

slightly greater than Rlt and therefore the sample plots 

as unsaturated in Si02 on figure IB.

TRACHYTE SOUTHWEST OF LAUGHLIN PEAK

This medium-gray, dense, hard porphyritic rock forms 

sills southwest of Laughlin Peak interlayered with sills of 

the Slagle Trachyte and with Cretaceous sedimentary
16 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

TABLE 4. -Chemical analyses and norms of Slagle Trachyte samples from Raton-Springer area, New Mexico

[Data in weight percent, n.d., not determined]

Sample - - 

Field No. 

Lab No.--

1 

81SM19 

D242009

2 

81SM5 

D237459

3

80SM17 

D229697

4 5 

81SM18 MHS-35-80 

D242008 D229964

6 

MHS-36-80 

D229965

Maj or oxides

Si02 ---- 

A12 03 --- 

Fe 2 0 3 --- 

FeO -----

MgO ----- 

r*an - - -

Na2 0 ---- 

K2 0 ----- 

H2 0+ ---- 

H2 0- ----

Volatiles 1 

Ti02 ---- 

P2 0 5 ---- 

MnO -----

Total

Ri ------

R2 ......

Name

q ---....

wol -----

di-wo --- 

di-en --- 

di-fs ---

hy - en 

hy-fs --- 

ol-fo --- 

ol-fa ---

mt ------

il ......

ap ------

56.6 

16.5 

3.91 

1.40 

1.56

4.73 

5.84 

3.92 

n.d. 

n.d.

3.69 

0.66 

0.35 

0.14 

n.d.

99.3

La Roche

630 

908 

Trachyte/ 

tr achy ande site/ 

trachyphonolite .

0.00 

24.22 

49.78 

7.56 

0.00

1.03 

1.39 

4.70 

4.06 

0.00

0.00 

0.00 

0.00 

0.00 

3.20

1.88 

1.31 

0.87 

0.00

57.0 

17.2 

3.43 

2.74 

2.05

4.62 

5.25 

4.24 

n.d. 

n.d.

1.32 

0.79 

0.37 

0.16 

n.d.

99.2

and others

765 

941 

Trachyandesite/ 

trachyte.

Normative

0.00 

25.60 

45.39 

11.08 

0.00

0.00 

0.00 

4.12 

3.02 

0.71

1.81 

0.42 

0.27 

0.07 

5.08

0.00 

1.53 

0.90 

0.00

59.2 

17.8 

1.34 

2.11 

0.85

2.52 

7.0 

3.41 

n.d. 

n.d.

2.47 

0.42 

0.2 

0.13 

n.d.

97.5

60.7 

18.6 

3.12 

0.99 

0.73

2.17 

5.95 

4.73 

n.d. 

n.d.

1.34 

0.46 

0.25 

0.14 

n.d.

99.2

61.5 

18.1 

3.25 

0.73 

0.66

1.97 

7.10 

3.78 

0.98 

0.20

n.d. 

0.46 

0.2 

0.15 

1.14

100.2

62.6 

18.3 

3.18 

0.35 

0.3

1.21 

6.5 

4.65 

1.14 

0.13

n.d. 

0.36 

0.2 

0.11 

0.60

99.6

(1980) classification

572 

678 

Trachyte

composition

0.00 

21.21 

62.08 

7.45 

0.00

0.15 

0.00 

1.81 

0.85 

0.93

0.00 

0.00 

0.96 

1.16 

2.05

0.00 

0.84 

0.50 

0.00

711 

634 

Trachyte

3.02 

28.56 

51.45 

9.33 

0.35

0.00 

0.00 

0.00 

0.00 

0.00

1.86 

0.00 

0.00 

0.00 

2.37

1.56 

0.89 

0.61 

0.00

585 

605 

Trachyte

4.25 

22.55 

60.65 

1.27 

1.88

0.00 

0.00 

0.00 

0.00 

0.00

1.66 

0.00 

0.00 

0.00 

1.52

2.23 

0.88 

0.48 

2.62

684 

509

Trachyte

6.26 

27.93 

55.91 

0.92 

2.28

0.00 

0.00 

0.00 

0.00 

0.00

0.76 

0.00 

0.00 

0.00 

0.45

2.92 

0.70 

0.48 

1.39

DESCRIPTION OF 

SAMPLE LOCALITIES

Slagle Trachyte from 

type(?) locality in the 

NE^Stte sec. 34, T. 27 N., 

R. 25 E., Tres Hermanos 

Peak quadrangle. 

Slagle Trachyte in the 

NWJtSEJtNWJ< sec. 22, T. 26 

N., R. 25 E., Tinaja 

Mountain quadrangle. 

Slagle Trachyte from 

quarry in the NE*t sec. 1, 

T. 27 N. , R. 24 E., Tres 

Hermanos Peak quadrangle. 

Slagle Trachyte from 

hillslope in the NW^NE^t 

sec. 28, T. 27 N., R. 25 

E., Tres Hermanos Peak 

quadrangle. 

Slagle Trachyte from 

southwest end of sill, 

just north of Jimmy 

Spring Canyon in the NE*i 

sec. 36, T. 28 N., R. 25 

E., Pine Buttes quadrangle (M.H. Staatz, 1985). 

Slagle Trachyte from 

north end of dike adjacent to large sill just 

south of county road A-8 

in the SW*t sec. 36, T. 28 

N., R. 25 E., Pine Buttes 

quadrangle (M.H. Staatz, 

1985).

1 Probably mainly H2 0 and C0 2 , calculated assuming all FeO was oxidized to 

Fe 2 03 during determination of loss on ignition.
IGNEOUS ROCKS 17

rocks. According to M.H. Staatz (written commun., 

1982), phenocrysts range in size from 0.5 to 2 mm and are 

set in an aphanitic groundmass. Phenocrysts include 

greenish-brown euhedral to subhedral crystals of hornblende, which commonly are zoned; anhedral to subhedral crystals of clinopyroxene; some poorly twinned, 

zoned, euhedral sodic plagioclase, having extinction 

angles X:(010) no greater than 20°; black anhedral to 

subhedral magnetite grains; and traces of apatite and 

titanite. The groundmass is composed of a mat of 

elongate alkali feldspar crystals, a light-brown aphanitic, 

partially devitrified glass, and magnetite and other 

opaque oxides. Staining by sodium cobaltinitrite shows 

that the groundmass contains a moderate amount of 

potassium. Vugs contain well-formed crystals of smoky 

quartz and calcite. The vugs also contain bitumen, and 

bitumen forms inclusions in the quartz crystals. The 

chemical analyses and norms for the trachyte and trachyandesite southwest of Laughlin Peak are shown on 

table 5.

The K-Ar age of the rock of analysis 1 on table 5 was 

reported by Staatz (1985, p. E14) as 32.3±1.5 m.y. The 

sample came from the SE^SW1^ sec. 6, T. 27 N., 

R. 26 E., Colfax County, N. Mex.

The samples (table 5) have a low content of normative 

quartz, only about 3.5 percent. Their high potassium 

content results in 21-26 percent orthoclase in the norm 

(Staatz, 1985).

BIOTITE TRACHYTE SOUTHWEST OF TURKEY MOUNTAIN

Biotite trachyte dikes crop out lVfe-2 mi (2.4-3.2 km) 

west of Slagel Canyon in sees. 29, 32, and 33, T. 27 N., R. 

25 E., Tres Hermanos Peak quadrangle. The best 

preserved dikes are in the SWx/4 sec. 29 and in the SEV4 

sec. 32. At the latter locality the dikes make a prominent 

outcrop with large rounded knobs. The rock is light olive 

gray, yellowish-gray, pink, or red and generally is so 

dense that it does not readily weather. In thin section 

(specimen 81SM42, table 6) the texture is porphyritic 

intersertal. The rock contains about 5 percent stubby 

clinopyroxene phenocrysts as large as 2 mm, (+ )2V 60°, 

that are replaced by carbonate and quartz; 4 percent 

biotite phenocrysts as large as 1 mm, commonly in 

groups with the clinopyroxene; 2 percent poorly formed 

opaque oxides as large as 0.3 mm; and scattered apatite 

crystals as long as 0.3 mm. The groundmass contains 

kaolinized alkali feldspar laths as large as 0.2 mm, biotite 

as large as 0.3 mm, opaque oxides, and carbonate that 

permeates the interstices between feldspar crystals.

A similar rock, called a hornblende biotite trachyte, 

occurs nearby in sills intruded into the Greenhorn 

Limestone and Carlile Shale. This trachyte is light olive

TABLE 5. Chemical analyses and norms of trachyte southwest of 

Laughlin Peak, Raton-Springer area, New Mexico

[Data in weight percent]

Sample 1 2

Field No. MHS- MHS133-80 134-80

Lab No. D230348 D230349

Major oxides

1 2

MHS- MHS133-80 134-80

D230348 D230349

La Roche classification

Si02 --- 57.6

A12°3 "" 18-6 

Pg 0« - - 4.53

FeO ---- 1.44 

MgO ---- 1.5

CaO ---- 

Na20 --- 

K20 ---- 

Vols. 1 -- 

Ti02 ---

P2°5 --- 

MnO ----

3.39

5.6

3.56

1.72

0.80

0.5

0.12

Total 99.4

55.0

16.1

5.49

2.89

2.8

3.68

4.4

4.20

2.94

1.02

0.55

0.16

99.2

857

820

898

878

Name Trachyte Trachyte 

Normative composition

q --- 

or -- 

ab -- 

an - - 

c - - - 

di-wo 

di-en 

hy-en 

mt -- 

hm - - 

il -- 

ap --

3.39

21.54

48.52

13.87

0.58

0.00

0.00

82

78

2.72

1.56

1.21

3.58

25.77

38.65

12.23

0.00

1.25

1.08

6.16

7.14

0.77

2.01

1.35

1 Volatiles, probably mainly H2 0 and C02 , 

calculated assuming all FeO was oxidized to Fe20o 

during determination of loss on ignition.

DESCRIPTION OF SAMPLE LOCALITIES

1. Trachyte from small knoll, 230 m northeast of

county road A-8 in the SE'iSW'i sec. 6, T. 27 N. , R. 

26 E., Pine Buttes quadrangle (M.H. Staatz, 1985).

2. Trachyte from low hill, 380 m north of county road 

A-8 in the SWkSEk sec. 6, T. 27 N., R. 26 E., Pine 

Buttes quadrangle (M.H. Staatz, 1985).

gray and porphyritic, has an aphanitic groundmass, and 

contains hornblende, biotite, and clinopyroxene phenocrysts. These two trachytic rocks appear to be nearly 

contemporaneous. The chemical analysis and norm for 

the biotite trachyte are shown on table 6. This rock lacks 

quartz in the norm, but otherwise is chemically quite 

similar to the trachyte southwest of Laughlin Peak and 

to the Slagle Trachyte. However, hand specimens show 

little resemblance to these rocks.

A generally nonporphyritic, dark-yellowish-gray to 

pale-yellowish-brown trachyte crops out as vertical 

dikes, a few feet thick, in sec. 33, T. 27 N., R. 25 E., and 

in sec. 4, T. 26 N., R. 25 E. The rock has a trachytic 

texture and is finely crystalline to aphanitic. At its north 

end one dike contains platy phenocrysts as large as 1 inch 

(2.5 cm), apparently of feldspar, parallel to its walls.
18 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

TABLE 6. Chemical analysis and norm of biotite trachyte dike 

southwest of Turkey Mountain, Raton-Springer area. New Mexico

[Data in weight percent]

Field No.-- 

Lab No.----

Major

Si02 ------

A12 03 -----

Fe 2°3 --"- 

FeO -------

MgO ------- 

Can _

Na20 ------

Volatiles 1 - 

TS n

P P 2°5 n -"--- 

MnO -------

Total --

81SM42 

D242014

oxides

53.4

16.7

3 Q Q

3.37

0 f)Q

4.47

5

O /

3

C. O

3.99 

0.84

0.47

0.19

99.3

La Roche classification

R1 "

Name

639 

960 

Trachyte

Normative composition

or -------

ab -------

an -------

ne -------

di-wo ----

di-en

di-fs ----

ol-fo ----

ol-fa ----

mt -------

il .......

ap -------

22.51

43.96

11.88

1.39

3.41

2.47

0.63

3.91

1.10

5.90

1.67

1.17

1 Probably mainly H2 0 and C02 , calculated 

assuming all FeO was oxidized to Fe 2 0-j during 

determination of loss on ignition.

DESCRIPTION OF SAMPLE LOCALITY

Biotite trachyte from dike in NEkSEk sec. 32, T. 27 

N., R. 25 E., Tres Hermanos Peak quadrangle.

SYENITE AND QUARTZ MONZONITE VENT ROCKS AT 

TURKEY MOUNTAIN

In the summit area of Turkey Mountain in the SWV4 

sec. 11, T. 27 N., R. 25 E., are several outcrops of rocks 

similar to the Slagle Trachyte in composition but coarser 

grained. Originally these were thought to be feeders of 

the sills of the Slagle Trachyte, but they are now known 

to be much younger. Two outcrops at the main summit of 

Turkey Mountain are syenite, and another outcrop on a 

subsummit about 1,200 ft (366 m) to the southwest is 

quartz monzonite. The syenite forms prominent outcrops 

confined to the area atop Turkey Mountain. The rock is 

gray, nearly equigranular, and shows no obvious flow 

structure or alignment of hornblende crystals.

The age of the syenite at the summit of Turkey 

Mountain (locality 18 on figure 6) was determined as 

29.0±1.6 m.y. by Mutsumi Miyachi using the fissiontrack method on zircon (table 2, no. 18).

In thin section the syenite (specimen 81SM9, tables 7 

and 8) has an intergranular texture and is composed of 

the following: about 80 percent compound feldspar 

crystals as large as 1.5 mm, consisting of oligoclaseandesine cores and strongly kaolinized alkali feldspar

overgrowths; 4 percent interstitial quartz as large as 

0.2 mm; 6 percent pale-green clinopyroxene as large as 

1 mm; 4 percent opaque oxide crystals as large as 

0.2 mm; 3 percent apatite crystals as much as 0.3 mm 

length; and 2 percent titanite crystals as large as 0.4 mm.

The quartz monzonite forms knobby outcrops typical 

of granitoid rocks. It is light brownish gray to pinkish 

gray. In thin section (specimen 81SM26, tables 7 and 8) it 

is porphyritic and composed of composite feldspar phenocrysts as large as 1.5 mm, consisting of slightly saussuritized albite-oligoclase cores (about 30 volume percent) zoned to kaolinized alkali feldspar rims (about 10 

percent). The groundmass interstitial to the dominant 

feldspar crystals consists of about 20 percent quartz, as 

large as 0.2 mm, containing inclusions of euhedral feldspars; 25 percent strongly kaolinized alkali feldspar; 

10 percent albite; 2 percent biotite; 3 percent titanite; 

traces of apatite; amphibole(?) as thin pale-green needles; 

and equant crystals of a clear, colorless unknown mineral 

of moderate birefringence and high relief.

Chemical analyses of the syenite and quartz monzonite 

(tables 7 and 8) show Si02 contents of 61.8 and 66.1 

percent, respectively, which are significantly greater 

than those of the normal Slagle Trachyte (table 4). Their 

plotted positions on the RiR2 diagram of figure IB are 

well into the Si02-saturated zone but are considered to 

be within an extension of the Slagle Trachyte field. They 

probably are genetically related to the Slagle Trachyte. 

Judging from the relatively small amounts of elements 

barium and titanium, a crustal source rather than a 

mantle source is preferred for the vent rocks.

MELASYENITE DIKE

Fine-grained melasyenite crops out as a prominent 

dike in the NE. corner of the SEV4 sec. 4, T. 26 N., 

R. 27 E., Palo Blanco Mountain quadrangle. The dike is 

medium gray and contains prominent amphibole crystals 

and segregations of amphibole and a serpentine-like 

mineral. In thin section (specimen 80SM26) the texture is 

seriate, and the relative mineral composition is as 

follows: 30 percent amphibole crystals as large as 1 mm, 

which exhibit olive-brown to pale-yellowish-brown pleochroism (extinction angle Z:c about 18°, (~)2V 80°); 

25 percent labradorite plates as large as 0.6 mm; 15 

percent stubby pale-green crystals of clinopyroxene as 

large as 0.1 mm (( + )2V 60°); 15 percent white alkali 

feldspar that is interstitial and rich in inclusions; 6 

percent clear interstitial analcime(?) or sodalite(?) that is 

isotropic and has negative relief; 5 percent a dusty 

interstitial mineral that has very low birefringence and 

negative relief (zeolite?); and 3 percent opaque oxide 

crystals as much as 0.03 mm. The chemical analysis and 

norm for the melasyenite are shown on table 9.
IGNEOUS ROCKS 19

TABLE 7. Chemical analyses and norms of syenite and quartz 

monzonite vent rocks at Turkey Mountain, Raton-Springer area, 

New Mexico

[Data in weight percent]

Sample --12 1 2 

Field No. 81SM9 81SM26 81SM9 81SM26

Lab No. D237461 D242012 D237461 D242012

Major oxides La Roche classification

Si02 ---61.8 66.1 Rl -- 1006 1603

., _ ,.. , ,, , R? -- 709 596 A1 2 03 -- 17.1 17.1 N£me Syenite Quartz

Fe 2 03 -- 3.03 1.89 raonzonite

FeO ---- 1.44 0.81 Normative composition

MgO ---- 0.93 0.53 

CaO ---- 3.02 022.19 19q or " __2? 6 ' 81 ?g16^ ' 56 ^

Na20 --- 5.37 4.64 ab -- 46.24 39.90

K K2 n 0 ---- A 4.62 fi9 4.61 A fil an c ___ " Q 9 ' 07 Q0 10Q ' 31 7?

Vols. 1 -- 1.11 0.72 di-wo 1.89 0.00

Ti02 --- 0.56 0.33 J1 - J-" °'°° 2 hy-en 0.73 1.34

P2 05 --- 0.25 0.11 mt -- 3.50 1.95

M- n ,,, n nft hm -- 0.67 0.58 MnO ---- 0.13 0.08 n __ ^ Q& Q ^

Total 99.4 99.1 ap -- 0.60 0.26

1Volatiles, probably mainly H 20 and C02> 

calculated assuming all FeO was oxidized to Fe 20o 

during determination of loss on ignition.

DESCRIPTION OF SAMPLE LOCALITIES

1. Syenite vent rock from crest of Turkey Mountain, 

altitude 7,888 ft (2,404 m) in center of S\Jk sec. 

11, T. 27 N., R. 25 E. , Tres Hermanos Peak 

quadrangle . 

2. Quartz monzonite plug on southwestern spurs of 

west peak of Turkey Mountain in the SW^ sec. 11, 

T. 27 N. , R. 25 E. , Tres Hermanos Peak quadrangle.

PHONOTEPHRITE AND TEPHRITE ALONG JOE CABIN 

ARROYO

Phonotephrite and tephrite crop out as a nearly flat 

sheet in a 2 mi2 (5 km2) area along Joe Cabin Arroyo in 

sees. 28-33, T. 27 N., R. 26 E., Pine Buttes quadrangle. 

It is visibly inhomogeneous and apparently intruded 

Cretaceous sedimentary rocks. It is younger than the 

Slagle Trachyte and older than the Chico Phonolite. (See 

below.) In hand specimen the rocks are medium dark 

gray and somewhat similar to the Slagle Trachyte. 

However, they are very resistant to weathering, except 

for the formation of a 1-mm-thick brown rind, and form

prominent outcrops. 

In thin section, a tephrite from an outcrop in 

SWV4SWV4 sec. 28, T. 27 N., R. 26 E., on the east side of 

Joe Cabin Arroyo (specimen 81SM23-2, table 10,

TABLE 8. Neutron-activation analysis of syenite and quartz 

monzonite vent rocks at Turkey Mountain, Raton-Springer area, 

New Mexico

[Elemental compositions in parts per million. See table 7 for description of sample localities. 

"<" indicates element concentration is below the limit of determination, which is the value 

shown; "-"-" shows the accuracy of the test. Analyst: Carl Orth, Los Alamos National

Laboratory]

Sample ----- 1 2

Field No.--- 81SM9 81SM26 

Lab. No.---- 925109 925111

Na 42,200 ±500 36,800 ±400 

Mg 6,000 ±1,000 <3,000 

Al 96,000 ±2,000 90,000 ±2,000

Cl <200 150 ±40 

K 34,000 ±3,000 37,000 ±2,000

Ca 23,000 ±2,000 15,000 ±2,000 

Ti 2,800 ±300 2,400 ±200 

V 80 ±6 32 ±3 

Mn 1,110 ±10 843 ±8 

Cu <400 <400

Sr 1,400 ±200 1,200 ±100 

I <20 <20 

Ba 1,520 ±100 1,470 ±70 

Dy 4.2 ±0.4 3.3 ±0.3 

U 5.53±0.03 3.95±0.02

Ga <100 <100 

As <4 <3 

Br <3 <3

Sb <0 . 5 <0 . 5 

La 72.7+0.9 56.4 ±0.7

Sm 8.6 ±0.4 5.3 ±0.2 

W <6 <5 

Au <0.02 <0.01 

Sc 5.4 ±0.1 3.07+0.06 

Cr 18 ±2 6.0 ±0.9

Fe 35,000 ±1,000 21,300 ±600 

Co 8.1 ±0.3 3.3 ±0.2 

Zn 130 ±20 47 ±8 

Se 4.5 ±0.5 4.5 ±0.5 

Rb 152 ±8 139 ±8

Cs 1.5 ±0.2 2.1 ±0.2 

Ce 127 ±4 93 ±4 

Eu 2.0 ±0.1 1.22+0.07 

Tb 0.64+0.08 0.59+0.08 

Yb 3.4 ±0.2 2.7 ±0.2

Lu 0.39+0.04 0.34±0.04 

Hf 8.8 ±0.8 6.2 ±0.6 

Ta 3.0 +0.3 1.9 +0.2 

Th 27+1 18.3+0.8

analysis 2; table 11), has a complex seriate texture and is 

composed of the following- about 60 percent plagioclase, 

strongly zoned from labradorite to oligoclase, in laths as
20 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

TABLE 9. Chemical analysis and norm of melasyenite dike near 

Alamo Creek, Raton-Springer area, New Mexico

[Data in weight percent]

Field No.--- 80SM26 La Roche classification

Lab No.----- D231891 

RI ........ (.)42

Major oxides R2 -------- 1,290

Si02 ------- 47.2 

Fe 9CU ------ 3.73 

FPO * fil or -------- 20.94

MgO -------- 2 98 ab ------- 1 9 -15

"S" ,° an -------- 15.28 

CaO -------- 7.15 ^o 10 i/

Na2 0 ------- 6.14 di . wo ..... 6 72

K2 0 -------- 3.38 di-en ----- 4.73 

Volatiles 1 -- 3.92 di-fs ----- 1.41

Ti02 ------- 1.01 ol-fo ----- 2.14

P2 05 ------- 0.85 ol - fa --"- °-70 

MnO -------- 0.18 mt -------- 5.67

il -------- 2.01

Total 99.3 ap -------- 2.11

1 Probably mainly HoO and C02, calculated 

assuming all FeO was oxidized to Fe 2 0 3 during 

determination of loss on ignition.

DESCRIPTION OF SAMPLE LOCALITY

Melasyenite dike in the NE corner SEk sec. 4, T. 26 

N. , R. 27 E. , Palo Blanco Mountain quadrangle.

large as 2.5 mm; 20 percent stubby, pale-green pyroxene crystals as large as 1.2 mm, some in clots; 15 percent 

skeletal dark mica crystals as large as 1.5 mm, which 

show strong brownish-yellow pleochroism and have a 

skeletal structure so marked that in some sections the 

mica crystals appear as beads or poikilitic inclusions in 

the feldspar; 5 percent irregularly distributed opaque 

oxide crystals as large as 0.05 mm; and traces of dusty 

prisms of apatite (or eudialyte?) as large as 0.5 mm 

having pronounced basal cleavage or parting. Rare 

rounded xenocrysts of grass-green clinopyroxene are 

present. 

Another specimen (81SM23-1), from the SW1/4SW1/4 

sec. 28, T. 27 N., R. 26 E., has a porphyritic, subtrachytic texture and contains about 10 percent olive-green 

hornblende phenocrysts as long as 1.5 mm; 5 percent 

nearly colorless to pale-green clinopyroxene phenocrysts 

as large as 1.5 mm; sparse plagioclase (andesine?) phenocrysts as large as 0.5 mm, some veined; and sparse 

opaque oxide crystals as large as 0.3 mm. Groundmass is 

mostly plagioclase but also contains clinopyroxene, 

biotite, and sparse apatite, containing interstitial 

analcime(?). 

Tephrite (specimen MHS-22-82, table 10, analysis 3) 

occurs in a small area in the NEV4 sec. 32, T. 27 N.,

TABLE 10. Chemical analyses and norms of phonotephrite and 

tephrite in the Chico sill complex, Raton-Springer area, New Mexico

[Data in weight percent]

Sample--- 123 

Field no. MHS-86-81 81SM23-2 D243303 

Lab no.-- D240837 D242010 MHS-22-82

Major oxides

Si02 ----- 48.9 50.9 51.1 

A1 203 ---- 17.7 17.3 17.1 

Fe 2 03 ---- 4.26 2.78 2.94 

FeO ------ 3 40 4 27 4 42

MgO ------ 3.11 3.99 4.57 

CaO ------ 5.95 7.99 8.43

Na2 0 ----- 5.62 4.86 4.87 

K20 ------ 3.13 3.17 3.09

Volatiles 1 4.84 2.07 0.75

Ti02 ----- 1.22 1.10 1.16 

P 2 05 ----- 0.64 0.56 0.58 

MnO ------ 0.18 0.17 0.17

Total 99.0 99.2 99.2

La Roche and others (1980) classification

P ^O9 711 7^n

R2 ------ 1,140 1,395 1,467 

Name ---- Phono- Tephrite/ Tephrite 

tephrite. trachyandesite .

Normative composition

or ------ 19.65 19.29 18.54

ab ------ 31.91 27.11 25.45

an ------ 14.69 16.50 15.92

ne ------ 10.08 8.25 8.89

di-wo --- 5.11 8.58 9.48 

di-en --- 4.00 5.66 6.44 

di-fs --- 0.54 2.30 2.31 

ol-fo --- 2.96 3.20 3.59

ol-fa --- 0.44 1.44 1.42 

mt ------ 6.56 4.15 4.33

il ------ 2.46 2.15 2.24

ap ------ 1.61 1.37 1.40

1 Probably mainly ^0 and CC^ , calculated 

assuming all FeO was oxidized to Fe 2 0o during 

determination of loss on ignition.

DESCRIPTION OF SAMPLE LOCALITIES

1. Phonotephrite northwest of Joe Cabin Arroyo in 

the NE*sSE*s sec. 29, T. 27 N. , R. 26 E. , Pine 

Buttes quadrangle (M.H. Staatz, 1985). 

2. Tephrite/trachyandesite from roadcut on east 

side of Joe Cabin Arroyo in SWkSWk sec. 28, T. 

27 N., R. 26 E., Pine Buttes quadrangle. 

3. Tephrite in NWkSEkNEk sec. 32, T. 27 N. , R. 26 

E., Pine Buttes quadrangle (M.H. Staatz, 1985).
IGNEOUS ROCKS 21

TABLE 11. Neutron-activation analysis of phonotephrite from Joe 

Cabin Arroyo, Raton-Springer area, New Mexico

[Elemental compositions in parts per million. See table 10 for description of sample locality. "<" 

indicates element concentration is below the limit of determination, which is the value 

shown; "±" shows the accuracy of the test. Analyst: Carl Orth, Los Alamos National 

Laboratory]

Field No. 81SM23-2 

Lab. No. 925109

Na

Mg 

Al 

Cl

K

Ca 

Ti

V

Mn

Cu

Sr

I

Ba

Dy

U

Ga

As

Br

37,400

25,000 

87,000 

410

23,000

58,000 

7,500

156

1,400

<400

900

<20

1,470

5. 

4.

<100

<4

<3

±400

±1,000 

±2,000 

±90

±2,000

±3,000 

±400

±6

±10

±100

±80

.0 ±0.4 

.68+0.03

Sb

La

Sm

W

Au

Sc

Cr

Fe

Co

Zn

Se

Rb

Cs

Ce

Eu

Tb

Yb

Lu

Hf

Ta

Th

<0.

112

10.

<6

<0.

13.

99

58,000

21.

<9

3.

76

1.

156

2.

0.

3.

0.

6.

4.

18.

5

±1

8 ±0.3

01

9 ±0.2

±9

±2,000

6 ±0.8

7 ±0.5

±7

2 ±0.2

±5

3 ±0.1

9 ±0.1

2 ±0.2

37±0.04

1 ±0.5

3 ±0.4

2 ±0.7

R. 26 E. It is dark gray, very hard, and dense, and on 

weathering it forms only a thin grayish-orange rind. In 

thin section, according to M.H. Staatz (written commun., 

1983), the rock has a porphyritic, subtrachytic texture 

and contains the following: pale-green zoned clinopyroxene phenocrysts as large as 0.8 mm showing bright-green 

interiors, the crystals commonly in groups; hornblende 

phenocrysts, now opacite pseudomorphs, as large as 

0.7 mm; and a few plagioclase (labradorite) phenocrysts 

as large as 0.4 mm. The groundmass consists of plagioclase (zoned labradorite to oligoclase) in subparallel 

plates, abundant clinopyroxene crystals, poorly formed 

skeletal crystals of dark mica, alkali feldspar(?), and 

abundant tiny crystals of opaque oxide. Xenocrysts of 

quartz with coronas of green acmite-augite crystals are 

fairly common.

The tephrite is regarded by Staatz as most probably a 

separate sill or a flow. However, in view of the marked 

inhomogeneity of the main phonotephrite sill of the area 

and the similarity of chemical and mineralogical composition between the tephrite and the phonotephrite, we 

see no compelling reason to believe this tephrite to be a 

separate body.

CHICO PHONOLITE

The Chico Phonolite was named by Collins (1949, 

p. 1023) after exposures of this rock in the township of 

Chico, Colfax County, N. Mex. We consider the type

area of the Chico to be in sec. 17, T. 26 N., R. 26 E., 

Colfax County, N. Mex.

Three related varieties of intrusive phonolite were 

recognized in the area green phonolite, silver-gray 

phonolite, and an ocellar analcime phonolite which 

together make up a large part of the Chico sill complex. 

Except for a few dikes and a remnant of a sill on Tinaja 

Mountain, the phonolites are confined to the main area of 

the complex. The green and silver-gray varieties seem to 

be parts of a gradational series ranging from green 

phonolite having almost no alkali feldspar but abundant 

acmite, to green phonolite having twinned and platy 

alkali feldspar phenocrysts and much acmite, to silvergray phonolite having platy and twinned alkali feldspar 

phenocrysts and sparse acmite, to silver-gray phonolite 

having curved pearly alkali feldspar phenocrysts and 

very little acmite, and finally to nonporphyritic silvergray phonolite. This gradation is also well shown 

chemically in the plotted fields on figure IB. Rocks with 

the greatest amount of acmite are tinguaites. The green 

and silver-gray varieties of phonolite appear to occupy 

about equal sized areas of the sill complex.

Radiometric ages determined by the K-Ar method on 

two samples are given in table 1. These two ages suggest 

that the Chico Phonolite varieties were intruded 

between 26 and 20 m.y. ago.

GREEN PHONOLITE

The green phonolite was described by Staatz (1985) in 

a recent report on thorium and rare earth veins near 

Laughlin Peak. Contrary to Collins' report (1949, 

p. 1034), none of the green phonolite bodies was found as 

a surface flow. This rock is characterized by prominent 

columnar jointing (fig. 8A) and weathers to a thin, 

dark-yellowish-brown rind in which white feldspar phenocrysts stand out (fig. 8B). The green phonolite is very 

resistant to weathering and shows little effect except for 

the formation of a thin brown rind. In the dense vitric 

phase the phenocrysts are generally sparse; however, 

where they are locally abundant, they may reach sizes as 

large as 20 mm. Stobbe (1949, p. 1073-1076) gave the 

mineral composition as mainly soda orthoclase (having a 

pearly luster where fresh) and nepheline, with lesser 

amounts of analcime and acmite (aegirine) and rare 

acmite-diopside, magnetite, and titanite. Flow structure 

is obvious in both hand specimens and thin sections. In 

phenocryst-rich outcrops the phonolite locally has a platy 

fracture pattern parallel to the flow structure.

Two thin sections illustrate the porphyritic character 

of the green phonolite:

Our specimen 80SM29 (table 12, analysis 1; table 13), 

from the valley of the Rio del Piano, is porphyritic and 

contains about 20 percent pseudomorphs of natrolite
22 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

FIGURE 8. Characteristic features of the green variety of Chico Phonolite. A, Columnar jointing at east end of Trujillo Mesa, in the NE1/4NW1/4 

sec. 27, T. 27 N., R. 26 E., Pine Buttes quadrangle. B, Closeup showing conspicuous white alkali feldspar crystals.

after sodalite(?) as large as 0.6 mm, some with inclusions 

of apatite crystals and concentric bands of ankerite; 

sparse dark mica phenocrysts as large as 0.3 mm, having 

altered rims; sparse alkali feldspar phenocrysts as large 

as several millimeters; and sparse stubby crystals of 

green clinopyroxene. The groundmass has a taxitic texture and is mainly a mat of riebeckite (and acmite?) 

needles, having green to blue pleochroism, in an 

unknown mineral of low birefringence and strong negative relief; analcime(?) in scattered lenses is penetrated 

by riebeckite needles.

Another green phonolite (specimen 80SM27, table 12, 

analysis 3) from a quarry in sec. 16, T. 26 N., R. 27 E., 

is porphyritic and contains about 7 percent ghosts of 

amphibole(?) phenocrysts, now composed of jackstrawed 

acmite needles, some with cores of clinopyroxene or dark 

mica; 5 percent alkali feldspar phenocrysts in thick plates 

as large as 0.6 mm; 2 percent equant nepheline phenocrysts as large as 0.1 mm, many containing aligned 

inclusions; and 1 percent of an unknown isotropic mineral 

that forms stubby crystals as large as 0.7 mm with low 

negative relief. The groundmass has a tinguaitic texture 

and consists mainly of alkali feldspar, plagioclase, and 

moderate amounts of acmite needles and nepheline.

The green phonolite (table 12) has a low silica content 

and no normative quartz. All samples show more than 

25 percent nepheline in the norms. As seen in figure IB,

the green phonolites are part of a gradational series with 

the silver-gray phonolites. The neutron-activation analysis (table 13) shows low abundances of barium, chromium, magnesium, and titanium, suggesting a crustal 

origin for the phonolite.

SILVER-GRAY PHONOLITE

This unit crops out as a sill on Tinaja Mountain and as 

sills and dikes over much of the area of the Chico sill 

complex. In places the silver-gray phonolite is younger 

than the green phonolite, and in other places older. For 

instance, a dike of silver-gray phonolite cuts a green 

phonolite in the NEV4 sec. 3, T. 27 N., R. 25 E., but 

according to M.H. Staatz (written commun., 1984), the 

green phonolite generally intrudes the silver gray. For 

example, east of the county road along Joe Cabin Arroyo 

in the SEV4 sec. 32, T. 27 N., R. 26 E., a long green 

phonolite dike cuts silver-gray phonolite.

The silver-gray phonolite in most occurrences is a 

medium-gray, dense, hard porphyritic rock containing 

pearly, curved, and deformed alkali feldspar phenocrysts 

in a finely crystalline groundmass. Feldspar crystals are 

less abundant than in the green phonolite. The silvergray phonolite is more readily weathered than the green, 

and a slab about 4 inches (10 cm) thick is required in 

order to obtain a fresh interior. The rock weathers
IGNEOUS ROCKS 23

TABLE 12. Chemical analyses and norms of samples of green variety 

of the Chico Phonolite, Raton-Springer area, New Mexico

[Data in weight percent. n.d., not determined]

Sample 1 2 3 4 

Field no. 80SM29 MHS-85-80 80SM27 MHS-46-80 

Lab. no. D231893 D229968 D231892 D229967

Major oxides

Si02 ---- 51.3 53.9 54.4 54.8 

A1 203 --- 21.2 21.3 21.6 21.0 

Fe20 3 --- 1.80 2.86 2.31 2.94 

FeO ----- 0.98 0.36 0.56 0.20 

MgO ----- 0.26 0.2 0.45 0.2

CaO ----- 1.86 0.60 1.13 0.42

Na20 ---- 9.53 10.3 10.5 9.6

K20 ----- 4.29 4.14 5.33 4.96 

H20+ ---- n.d. 4.70 n.d. 4.90 

H20- ---- n.d. 0.65 n.d. 0.25

Volatiles 1 6.50 n.d. 1.65 n.d. 

Ti02 ---- 0.31 0.30 0.28 0.30 

P205 ---- 0.08 <0.1 0.07 <0.1 

MnO ----- 0.19 0.22 0.20 0.20

C0 2 ----- n.d. 0.10 n.d. 0.08 

Total 98.3 99.6 98.5 99.9

La Roche and others (1980) classification

R ...... (-1067) (-1136) (-1452) (-1109)

R2 ...... 639 497 576 469

Name ---- Phonolite Phonolite Phonolite Phonolite

Normative composition

or ------ 27.61 25.93 32.53 30.93

aV» 79O1 7G OH O1QC 77Q1

an ------ 2.61 0.00 0.00 0.00

ne ------ 30.14 28.12 33.65 25.43

ac ------ 0.00 0.60 6.75 0.77

wol ----- 1.90 0.28 0.07 0.00

di-wo --- 0.96 0.61 2.15 0.55 

di-en --- 0.71 0.53 1.16 0.48 

di-fs --- 0.17 0.00 0.93 0.00 

ol-fo --- 0.00 0.00 0.00 0.03

mt ------ 2.84 1.07 0.08 0.45

hm ------ 0.00 2.09 0.00 2.52

il ------ 0.64 0.60 0.55 0.60

ap ------ 0.21 0.13 0.17 0.12 

cc ------ 0.00 0.24 0.00 0.19

1 Probably mainly H20 and C0 2 , calculated assuming all 

FeO was oxidized to Fe 20? during determination of loss on 

ignition.

DESCRIPTION OF SAMPLE LOCALITIES

1. Phonolite in valley of Rio del Piano in the SEHjSE5* 

sec. 4, and NE^NEH: sec. 9, T. 26 N. , R. 25 E. , Tres 

Hermanos Peak quadrangle . 

2. Phonolite from just west of road, 3,214 ft (980 m) 

south of Jimmy Spring in the south central part of 

sec. 31, T. 28 N. , R. 26 E. , Pine Buttes quadrangle. 

(M.H. Staatz, 1985). 

3. Phonolite at quarry in the NE5* sec. 16, T. 26 N. , R. 

27 E., Lawrence Arroyo quadrangle. 

4. Phonolite from top of massive sill, 4,395 ft (1,340 

m) south of Jimmy Spring near the northern border of 

sec. 6, T. 27 N. , R. 26 E. , Pine Buttes quadrangle. 

(M.H. Staatz, 1985).

TABLE 13. Neutron-activation analysis of a sample of green variety 

of the Chico Phonolite, Raton-Springer area, New Mexico

[Elemental compositions in parts per million. See table 12 for description of sample locality. 

"<" indicates element concentration is below the limit of determination, which is the value 

shown; "±" shows the accuracy of the test. Analyst: Carl Orth, Los Alamos National 

Laboratory]

Field No. 80SM29 Sb <0.9 

Lab. No. 925107 La 133 ±2

 Sm 12.3 ±0.4 

Na 74,000 ±700 W <10 

Mg <5,000 Au <0.03 

Al 110,000 ±3,000 Sc 0.71±0.03 

Cl <300 Cr 6 ±1 

K 40,000 ±3,000 Fe 24,600 ±800 

Ca 17,000 ±3,000 Co 1.5 ±0.2 

Ti 1,500 ±400 Zn 90 ±20 

V 53 ±6 Se 6.0 ±0.7 

Mn 1,390 ±10 Rb 131 ±10 

Cu <600 Cs 1.4 ±0.2 

Sr <600 Ce 205 ±9 

I <30 Eu 2.0 ±0.1 

Ba 560 ±90 Tb 0.65±0.10 

Dy 5.7 ±0.4 Yb 3.8 ±0.2 

U 24.86±0.07 Lu 0.55±0.07 

Ga <200 Hf 14 ±1 

As <6 Ta 5.7 ±0.6 

Br <5 Th 72 ±3

yellowish gray or yellowish brown and is slightly platy or 

shaly (fig. 9). 

A less abundant part of the silver-gray phonolite that 

is not so obviously silver gray and does not show the 

curved and deformed alkali feldspar phenocrysts is well 

exposed on Point of Rocks Mesa (Pecks Mesa) and in a 

small area at the south edge of the Tinaja Mountain 

quadrangle. Two thin sections of each of these two 

varieties are described. 

In thin section the silver-gray phonolite is somewhat 

variable in mineral composition. Textures are generally 

porphyritic in trachytic, subtrachytic, or tinguaitic 

groundmasses. Specimen 80SM13, (table 14, analysis 1; 

locality 15 on fig. 6) from Chico in the Point of Rocks 

Mesa quadrangle, is porphyritic and contains the 

following: about 10 percent alkali feldspar phenocrysts as 

large as 5 mm, showing strain extinction and kaolinized 

margins; 4 percent analcime(?) pseudomorphs after 

sodalite(?) phenocrysts as large as 0.4 mm; and sparse 

plagioclase (oligoclase) phenocrysts associated with the 

alkali feldspar. The groundmass is trachytic in texture 

and composed mainly of alkali feldspar, moderate 

amounts of green acmite, and scattered equant nepheline 

in a mesostasis of an unknown isotropic mineral; also 

present are scattered unknown minerals, the most 

prominent of which are interstitial masses that have low 

relief and a birefringence about 0.02.
24 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

FIGURE 9. Near-vertical jointing and platy weathering in silver-gray 

variety of the Chico Phonolite in Tres Hermanos Peak quadrangle in 

the NEV4NWV4 sec. 27, T. 27 N., R. 26 E. Field notebook, 5V4 inches 

(13 cm) wide, gives scale.

A quarry in the NWViNWVi sec. 3, T. 25 N., R. 26 E., 

at the western edge of Point of Rocks Mesa, is in 

relatively coarse phonolite, which lacks the silvery 

sheen. The rock at this locality contains sparse amounts 

of several rather rare minerals, such as the water-soluble 

fluoride villiaumite (Stormer, 1970, 1981), serandite, and 

eudialyte (Hlava and others, 1984). Other rare minerals 

from this locality are described by DeMark (1983, 1984, 

1985), Hlava and others (1985), and Modreski (1985).

In thin section one specimen (80SM40, table 14, 

analysis 5) from this quarry is porphyritic and contains 

the following: about 15 percent stubby phenocrysts of 

alkali feldspar as large as 2 mm, marginally altered; 

10 percent well-formed prisms of acmite as large as 

0.5 mm; 5 percent blocky phenocrysts of nepheline as 

large as 1 mm containing many inclusions; scattered 

colorless square skeletal phenocrysts as large as 0.3 mm 

of an unknown mineral having rather strong positive 

relief, moderate birefringence, and an optic angle of 

about ( + )40°; sparse sodalite(?) phenocrysts associated 

with fibrous zeolite; and scattered masses of an unknown

isotropic mineral as large as 0.5 mm, which are crowded 

with alkali feldspar tablets of the same size as those of 

the groundmass but without the parallel orientation. The 

groundmass is chiefly alkali feldspar tablets in trachytic 

arrangement.

Specimen 80SM5 (table 14, analysis 6; table 15; locality 

14 on figure 6), from the north end of Tinaja Mountain, is 

nonporphyritic and trachytic in texture and contains 

about 70 percent alkali feldspar in aligned laths as large 

as 0.3 mm; 10 percent poorly formed stubby nepheline 

crystals as large as 0.5 mm; 7 percent acmite prisms as 

long as 0.2 mm; about 3 percent of an unknown, colorless, 

nearly isotropic mineral of negative relief; and about 

3 percent of another unknown, colorless mineral of 

moderate birefringence and moderate positive relief.

Phonolite specimen 81SM4 (table 14, analysis 7), from 

the SE^SE1^ sec. 28, T. 28 N., R. 25 E., at the south 

edge of the Tinaja Mountain quadrangle, like the rock at 

the quarry on Point of Rocks Mesa, lacks the customary 

silvery sheen. It is porphyritic and contains about 

35 percent alkali feldspar phenocrysts, which are as large 

as 2.5 mm and have shadowy extinction, and some of 

which have hourglass structure. The groundmass has 

trachytic texture and consists of about 50 percent alkali 

feldspar laths and ragged green acmite-augite(?) crystals 

with amphibole overgrowths; also present are scattered 

felted, brownish, fine-grained intergrowths of high birefringence and moderate relief.

Distinction between the green and silver-gray phonolites is based chiefly on weathering characteristics 

displayed in hand specimens and thin sections, but 

chemically (fig. IE) they appear to be part of a single 

gradational series. Chemical analyses show the silvergray phonolite (table 14) to be generally higher in Si02 

and lower in A1203 than the green phonolite (table 12).

The neutron-activation analysis of silver-gray phonolite on table 15 shows its elemental composition to be 

close to average crustal abundance and indicates a 

crustal source for the silver-gray phonolite.

NEPHELINE SYENITE DIKE ON POINT OF ROCKS MESA

A nepheline syenite dike (the analcime microfoyaite of 

Stobbe, 1949, p. 1081) apparently intrudes the phonolite 

along the east side of Point of Rocks Mesa, forming a 

narrow 200-ft-high ridge called Hogback Butte. In hand 

specimen, the rock is medium gray, is mottled with very 

light gray spots, and appears somewhat fibrous. Microscopically, the rock (specimen number 81SM41, table 16) 

is porphyritic and trachytic in texture and contains about 

20 percent curved, pearly alkali feldspar phenocrysts as 

large as 10 mm that show a faint grill pattern; about 

10 percent veined and pockmarked nepheline as large as 

1.5 mm; some exsolved and some kaolinized plagioclase(?); and sparse titanite crystals. The groundmass
IGNEOUS ROCKS 25 

TABLE 14. Chemical analyses and norms of samples of silver-gray variety of the Chico Phonolite from Raton-Springer area, New Mexico

[Data in weight percent, n.d., not determined]

Field No.---- 

Lab No ------

1

80SM13 

D229693

2

MHS-88-81 

D240838

3 

Stormer (1981) 

villiaumite 

locality

4

81SM44 

D251099

5

80SM40 

D237456

6

80SM5 

D229685

7

81SM4 

D237458

Major oxides

<?i n

A12 0 3 -------

Fe 2 03 ------- 

FeO ---------

MgO ---------

PoO

Na2 0 --------

K

r\

Volatiles 2 --- 

Tio

P P2°5 n -------- 

MnO ---------

Total --

55.6 

20.8 

1.43 

0.28

0.1 

0.78 

10.1 

5.08

2.55 

0.14 

>0.1 

0.26

98.1

58.7 

20.2 

1.91 

0.45

0.31 

1.25 

8.47 

4.68

2.14 

0.27 

0.06 

0.19

98.6

59.5 

19.0 

1 1.84 

1 0.50

0.02 

0.07 

10.00 

4.80

n.d. 

0.20 

0.02 

0.40

96.35

La Roche and others (1980)

R n ..........

R2 ..........

(-1070) 

506 

Phonolite

(-254) 

546 

Trachyphonolite/ 

phonolite.

(-770) 

382 

Phonolite

59.5 

19.8 

1.36 

0.56

0.17 

0.59 

7.76 

4.68

2.97 

0.18 

<0.05 

0.32

97.9

classification

(64) 

460 

Trachyphonolite.

59.8 

19.0 

2.29 

0.28

0.10 

0.77 

9.64 

4.98

1.03 

0.20 

<0.05 

0.63

98.7

(-683) 

464 

Phonolite

60.4 

19.9 

1.58 

0.36

0.10 

0.72 

9.2 

5.30

1.02 

0.14 

<0.10 

0.36

99.1

(-540) 

477 

Phonolite

61.7 

19.6 

1.51 

0.35

0.18 

0.96 

8.25 

5.39

0.81 

0.15 

<0.05 

0.26

99.2

(-132) 

500 

Trachyphonolite.

Normative composition

aK ..........

di-fs -------

ol-fo -------

ol-fa -------

mt ----------

il ..........

ap ----------

31.39 

35.31 

0.00 

0.00

25.46 

4.33 

0.50 

0.54

1.01 

0.26 

0.80 

0.00 

0.00

0.00 

0.00 

0.28 

0.12

28.66 

49.62 

3.40 

0.00

13.35 

0.00 

0.00 

0.17

0.93 

0.80 

0.00 

0.00 

0.00

1.33 

1.06 

0.53 

0.15

29.44 

47.19 

0.00 

0.00

14.36 

5.52 

1.83 

0.00

0.09 

Trace 

0.10 

0.03 

0.99

0.00 

0.00 

0.39 

0.05

29.14 

57.72 

3.08 

0.94

6.21 

0.00 

0.00 

0.00

0.00 

0.00 

0.00 

0.31 

0.16

2.08 

0.00 

0.36 

<0.12

30.11 

42.96 

0.00 

0.00

15.53 

6.78 

0.96 

0.03

1.52 

0.25 

1.39 

0.00 

0.00

0.00 

0.00 

0.39 

0.07

31.92 

44.05 

0.00 

0.00

16.36 

4.49 

0.00 

0.14

1.24 

0.25 

1.07 

0.00 

0.00

0.09 

0.00 

0.27 

0.12

32.37 

52.58 

0.54 

0.00

9.95 

0.00 

0.00 

1.19

0.53 

0.46 

0.00 

0.00 

0.00

1.57 

0.45 

0.29 

0.07

1 Assumed amount. 

2 Probably mainly H2 0 and C0? , calculated assuming all FeO was oxidized to Fe 2 0o during determination of 

loss on ignition.

DESCRIPTION OF SAMPLE LOCALITIES

1. Phonolite at Chico in the SEk sec. 17, T. 26 N., R. 26 E. , 5. Phonolite from quarry in the NW^NWk sec. 3, 

Point of Rocks Mesa quadrangle. T. 25 N. , R. 26 E. , Point of Rocks Mesa 

2. Trachyphonolite/phonolite from north side of Joe Cabin quadrangle.

Arroyo in the SEk sec. 28, T. 27 N. , R. 26 E. , Pine Buttes

quadrangle. (M.H. Staatz, 1986).

Phonolite from quarry in the NW*sNW*s sec. 3, T. 25 N., R.

26 E., Point of Rocks Mesa quadrangle. From quarry that

contains villiaumite (Stormer, 1981).

Trachyphonolite from east wall of valley in the NE^sNE^s

sec. 9, T. 26 N., R. 25 E., Tres Hermanos Peak quadrangle.

Phonolite from north end of Tinaja Mountain 

in the NE*s sec. 14, T. 28 N. , R. 24 E. , from 

a block in the landslide deposit from Tinaja 

Mountain, Tinaja Mountain quadrangle. 

Trachyphonolite that underlies trachyte in 

the SE*sSE*s sec. 28, T. 28 N. , R. 25 E. , 

Tinaja Mountain quadrangle.
26 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

TABLE 15. Neutron-activation analysis of a sample of silver-gray 

variety of the Chico Phonolite from Tinaja Mountain, RatonSpringer area, New Mexico

[Elemental compositions in parts per million. See table 14 for description of sample locality. "<" 

indicates element concentration is below the limit of determination, which is the value

Laboratory]

Field No. 80SM5 Sb 1.1 ±0.2

Lab No. 925104 La 103 +1

 Sm 7.7 ±0.4

Na 67,400 ±700 W <8

Mg 6,000 Au <0.02

Al 99,000 ±3,000 Sc 0.14+0.01

Cl 680 ±100 Cr 16 ±2

K 40,000 ±5,000 Fe 22,800 ±700

Ca <4,000 Co 1.06±0.10

Ti 2,000 Zn 200 ±30

V <20 Se 7.6 ±0.7

Mn 2,870 ±30 Rb 320 ±10

Cu <700 Cs 8.2 ±0.6

Sr <800 Ce 178 +7

I <50 Eu 1.03±0.07

Ba <400 Tb 0.79+0.10

Dy 5.9 ±0.8 Yb 7.8 ±0.2 

U 20.43±0.06 Lu 1.1 ±0.1 

Ga <200 Hf 23 ±2 

As 9 ±2 Ta 7.1 ±0.7 

Br <4 Th 85 ±3

consists of kaolinized alkali feldspar tablets; abundant 

euhedral crystals of acmite as large as 0.6 mm, which are 

zoned and somewhat altered; nepheline as gray, irregularly formed crystals as large as 0.4 mm; a few clear 

parallel plates of plagioclase; mica partly altered to an 

isotropic dusty material; and opaque black material. The 

presence of curved pearly alkali feldspar phenocrysts 

and the similarities in chemical composition (fig. IB, 

fields 14 and 16) suggest that the nepheline syenite bears 

a genetic relationship to the silver-gray phonolite; perhaps it was a feeder dike to the Point of Rocks phonolite 

sill.

OCELLAR ANALCIME PHONOLITE

From Hogeye Mesa in sec. 26 northeastward to sees. 

13 and 24, T. 27 N., R. 26 E., an ocellar analcime 

phonolite crops out. This phonolite is medium gray and 

porphyritic and has a trachytic to intergranular texture. 

In thin section, specimen 81SM17 (no analysis) from 

the SV6SWV4 sec. 13, T. 27 N., R. 26 E., Pine Buttes 

quadrangle, had abundant phenocrysts of colorless, wellformed analcime crystals as large as 1 mm, some 

clustered in groups; many acmite-augite prisms, pleochroic green to greenish-brown, zoned from light-colored 

centers to dark rims, as much as 1 mm in size; a few 

crystals of sphene; and a few crystals of alkali feldspar. 

The groundmass consists mostly of parallel laths of alkali

TABLE 16. Chemical analysis and norm of nepheline syenite dike on 

Point of Rocks Mesa, Raton- Springer area, New Mexico

[Data in weight percent]

Field No.--- 81SM41 La Roche classification

Lab. No.---- D242013 , 000 .

 K]_ --------- \-m)

,_ _ £0 --------- 473 SiOo ------- 60.1 2 .

A^2°3 " - 19.3 syenite.

Fe 0 0o ------ 2.45 *- > Normative composition FeO -------- 0.11

MgO -------- 0.14 or --------- 29.80

2 ne --------- 11.07

K0 0 -------- 4.90 T7 , -, 01 2. wo 1 -------- 1.Z1 

Volatiles 1 -- 1.62 di-wo ------ 0 42

Ti02 ------- 0.20 di-en ------ 0.36

^- j u i 11

Mn0 -------- 0.63 ^ ......... 0 39

Total -- 98.8 ap --------- 0.07

1 Probably mainly ^0 and (X^ , calculated 

assuming all FeO was oxidized to Fe20o during 

determination of loss on ignition.

DESCRIPTION OF SAMPLE LOCALITY

Nepheline syenite dike that cuts(?) gray phonolite 

on Point of Rocks Mesa in SWkSEkSEk sec. 34, T. 

26 N. , R. 26 E. , Point of Rocks Mesa quadrangle.

feldspar and small prisms of acmite in a mesostasis of 

analcime(?) crystals. 

According to Stobbe (1949, p. 1073), the ocellar variety 

has a mode comparable to that of the other phonolites 

considering that analcime and nepheline are measured 

together as feldspathoid content. She found the analcime 

ocelli to be round or oval shaped, and all are bordered by 

aegirine crystals; turbid zeolitic alteration affected some 

analcime crystals. She believed the ocelli to have been 

gas vesicles in a crystallizing magma, which were later 

filled by analcime as a product of the last residual liquid.

MAFIC AND ULTRAMAFIC DIKES AND SILLS 

(INCLUDING LAMPROPHYRIC ROCKS)

Mafic dikes are common from Raton southward to 

beyond Eagle Tail Mesa, but less common in the area of 

the Chico sill complex. An extensive dike swarm just 

south of Eagle Tail Mesa and Tinaja Mountain, trending 

east by southeast, contains more than 20 dikes per mile 

(12 per kilometer) in a belt as much as 3 mi (4.8 km) wide. 

One of the thickest of these is the spectacular Eagle Rock 

dike, 30 ft (9 m) wide where it is cut by Interstate 

Highway 25 about 17 mi (27 km) south of Raton (locality
IGNEOUS ROCKS 27

16 on fig. 6; also fig. 10A). This basanitic dike is composite and has several thin parallel members of varied 

texture.

Several dikes are traceable for as much as 3 mi 

(4.8 km), and one, extending eastward from sec. 16, 

T. 22 N., R. 21 E., to sec. 12, T. 22 N., R. 22 E., can be 

traced for 9 mi (14 km). Most dikes have chilled selvages, 

and sedimentary rocks adjacent to these have been 

baked to hornfels. Because the hornfels is more resistant 

to weathering than either the dike or the enclosing 

normal sedimentary rock, it commonly stands out above 

the ground surface as paired ribs and scattered plates, 

and is easily traced on the ground or on aerial 

photographs. Trenches have been dug in some of the 

dikes, but, except for one that was used for road metal, 

the purpose of the trenching is unknown to us. The dikes 

are dark gray to olive gray or olive black and are 

generally very dense and hard. Most weather to round 

nodules having a friable outer layer, which readily spalls, 

around a core that can be broken only with the hardest 

blows of a hammer.

The ages of the mafic dikes appear to cover a wide 

range through most of the Tertiary. Many dikes cut the 

alkalic rocks of the Chico sill complex, which itself covers 

a wide range of ages. (See section on Chico sill complex.) 

A K-Ar age of the Eagle Rock dike was determined to be 

24.16±1.01 m.y. (table 1). M.J. Aldrich (written commun., 1983) determined a whole-rock K-Ar age of 

15.6±0.7 m.y. for a mafic dike on the north flank of 

the Turkey Mountains (fig. I A), about 2 mi (3.2 km) 

south of the south edge of the Springer 30' x 60' quadrangle (not to be confused with Turkey Mountain of the 

Tres Hermanos Peak quadrangle, shown on fig. IB). The 

dike described by Aldrich is part of a linear dike swarm 

that extends northward into the Springer 30' x 60' 

quadrangle.

Although these mafic dikes and sills have been described as various types of lamprophyres including vogesites, minettes, kersantites, and spessartites (Mertie, 

1922; Stobbe, 1949, p. 1082)-many of them do not fit a 

commonly accepted part of the definition of lamprophyres which states that lamprophyres are porphyritic 

rocks with dominantly ferromagnesian phenocrysts 

(Rock, 1977; Hughes, 1982; Williams and others, 1984; 

Bates and Jackson, 1987). Concerning the dikes in this 

region, Mertie (1922, p. 12) states that some lamprophyres are "coarse grained and others are almost aphanitic. Almost without exception they are nonporphyritic. 

Their fabric is in some places ophitic or diabasic. Most 

commonly, perhaps, it is granular and here or there it is 

intersertal." In view of the varying definitions and 

usages of the term lamprophyre, we generally avoid it 

here; instead, we use the common rock name indicated by 

the bulk chemistry or, lacking that, simply refer to it as

a mafic rock. Many of the nonporphyritic rocks, however, 

do fit other important elements of the definition of 

lamprophyres, particularly in the abundance of hydrous 

minerals (biotite, hornblende, and analcime) and carbonate; these minerals imply a deep-seated parent 

magma of relatively high volatile content (H20, C02) and 

high temperature.

In thin sections the main minerals are plagioclase, 

clinopyroxene, hornblende (in part kaersutitic), and olivine, all in widely varying proportions. Less abundant are 

opaque oxides, biotite, apatite, nepheline, analcime, and 

carbonate minerals.

The Eagle Rock dike appears to be compound that is, 

made up of successive injections of magma. It has the 

chemical composition of a basanite (specimen 80SM25, 

table 17, analysis 3). Grain size varies from fine to coarse 

between different intruded sheets; where it is relatively 

coarse grained (fig. IOB) and the texture is lamprophyric, the corresponding phaneritic term, theralite, might be 

justified. In thin section a specimen has an intersertal 

texture and consists of the following approximate 

proportions: 40 percent plagioclase (labradorite) as much 

as 1.5 mm in length, strongly veined by zeolite(?) and 

feldspathoid(?); 30 percent pale-green clinopyroxene as 

stubby crystals as much as 2 mm long having a positive 

optic angle about (+)50°; 15 percent kaersutitic hornblende in crystals as much as 2 mm in length, pleochroic 

russet brown to pale yellow brown; 8 percent black 

opaque oxide as much as 0.2 mm long; 5 percent palegreen chlorite interstitial to other crystals; 1 percent 

scattered pseudomorphs as much as 0.7 mm long of green 

smectite after olivine(?); 1 percent apatite as thin prisms 

as much as 1 mm long; traces of dark mica as plates and 

irregular crystals associated with the opaque oxide; and 

traces of carbonate. Chemical analyses of the mafic dike 

rocks (table 17) show that Si02 ranges from about 40 to 

43 percent, typical of a variety of mafic rocks. Na20 plus 

K20 ranges from 3.32 to 5.38 percent; CaO ranges from 

about 9 to 15 percent.

Another dike (specimen 81SM14, table 17, analysis 4) 

cut by Interstate Highway 25 about 15% mi (25 km) 

south of Springer, in the Colmor quadrangle, has the 

composition of a trachybasalt, and in some parts is coarse 

enough to be called a syenogabbro. In thin section the 

specimen consists of the following: about 40 percent 

plagioclase (zoned labradorite to oligoclase) in lathes as 

much as 0.8 mm long having interiors strongly laumontitized(?); 35 percent irregular crystals of kaersutitic 

hornblende as long as 1 mm; 10 percent smectite as 

interstitial masses of fronds; 7 percent opaque oxide 

crystals as long as 0.1 mm, many in groups; 6 percent 

pale-green-brown clinopyroxene as long as 0.6 mm, 

many altered and rimmed with hornblende; scattered
28 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

/Dike

Pierre Shale

L.

Pierre Shale

^M^^^Mi^ 'iMHMii
IGNEOUS ROCKS 29

crystals of apatite, commonly in clusters; and a few 

masses of carbonate filling interstices. 

A sample (specimen 81SM2B, table 17, analysis 5) from 

the more southern of a pair of contiguous dikes in the 

center of SVfe sec. 5, T. 28 N., R. 25 E., in the Tinaja 

Mountain quadrangle, has the chemical composition of a 

picritic basanite. In thin section it has equigranular 

(cumulate?) texture, shows some shear fracturing, and 

has the following approximate mineral composition: 

75 percent euhedral clinopyroxene crystals as long as 

0.2 mm, 16 percent euhedral olivine crystals mostly less 

than 0.2 mm long (though a few crystal fragments are 

larger); 2 percent calcic plagioclase laths as much as 

0.1 mm long; 2 percent equant opaque oxide crystals as 

long as 0.05 mm; 3 percent unknown colorless mineral of 

low birefringence and moderate relief in interstitial 

bundles; and 1 percent interstitial chlorite. 

A sample from the northern of the two dikes (81SM2A) 

(same locality as 81SM2B, above) is porphyritic, containing abundant phenocrysts of clinopyroxene and olivine as long as 0.6 mm. The olivine is altered to 

carbonate and smectite. The groundmass is composed of 

plagioclase, altered olivine, clinopyroxene, and opaque 

oxide. A few vugs, as much as 1.5 mm in diameter, are 

filled with analcime(?) and carbonate. 

A specimen (specimen 82SM]) from a sill in the 

extreme northeastern corner of the Eagle Tail Mountain 

quadrangle, in the NWV&SEV&SWVfc sec. 15, T. 29 N. 

R. 24 E., appears to be a monchiquitic lamprophyre. It 

contains abundant stubby phenocrysts of pale-brown 

clinopyroxene as large as 1 mm. The crystals are zoned 

and have an optic angle about ( + )60° in the center and 

( + )40° at the somewhat darker edges. The rock also 

contains abundant brown amphibole phenocrysts, which 

are moderately pleochroic and have an extinction angle 

Z:c of 17°; many olivine phenocrysts as large as 2 mm, 

altered to smectite; and scattered crystals of dark-brown 

mica as large as 0.3 mm. The groundmass is made up of 

interstitial analcime(?), altered sodic plagioclase, many 

opaque oxide grains, and long needles of apatite. 

A dike of ankaratritic composition (specimen 80SM36, 

table 17, analysis 2) forms the crest of Tres Hermanos 

Peak in the southern part of sec. 23, T. 27 N., R. 24 E., 

Tres Hermanos Peak quadrangle. The rock is medium 

dark gray and dense. In thin section it has a porphyritic 

to seriate texture and is composed of the following: about 

21 percent olivine phenocrysts as large as 1.5 mm with 

many broken fragments; 8 percent pale-yellow nepheline

FIGURE 10 (facing page). Eagle Rock dike on east side of Interstate 

Highway 25 in the NEV4 sec. 16, T. 28 N., R. 23 E., Eagle Tail 

Mountain quadrangle. A, View of outcrop showing dike intruding 

lower part of Pierre Shale (Upper Cretaceous). Heat of dike has 

baked adjacent parts of the shale to hornfels. B, Closeup of dike rock 

showing large hornblende crystals.

TABLE 17. Chemical analyses and norms of samples of mafic dike 

rocks from the Raton-Springer area, New Mexico

[Data in weight percent, n.d., not determined]

Sample 1 2 3 4 5 

Field No. VCK 82- 80SM36 80SM25 81SM14 81SM2B 

NM-059 

Lab. No.-- --- D237455 D231890 D242007 D237457

Major oxides

Si02 ---- 40.17 42.2 43.0 43.2 43.3 

A1 2 03 --- 11.92 12.6 17.1 16.8 11.0 

Fe 2 03 --- 4.08 3.15 5.81 6.67 2.70 

FeO ----- 6.34 7.06 6.02 5.88 8.64

MgO ----- 11.74 13.3 4.95 5.58 14.5 

CaO ----- 15.34 11.1 10.8 9.15 11.8

Na2 0 ---- 2.32 3.54 4.02 3.26 2.59

K2 o ----- 1.00 1.84 0.81 1.14 1.0 

H2 0+ ---- 2.45 n.d. n.d. n.d. n.d. 

H2 0~ ---- 0.26 n.d. n.d. n.d. n.d. 

Vols. 1 -- n.d. 1.50 4.49 4.14 1.50 

Ti02 ---- 1.78 2.05 2.05 2.48 1.72 

P2 05 ---- 1.66 0.75 0.35 0.52 0.69 

MnO ----- 0.205 0.17 0.16 0.15 0.18

SrO ----- 0.26 n.d. n.d. n.d. n.d.

Total 99.53 99.3 99.6 99.0 99.6

La Roche and others (1980) classification

#! ...... 1,298 802 887 1,064 1,384

R2 ...... 2,464 2,110 1,740 1,589 2,206

Name ---- Picritic Ankara- Basanite Trachy- Picritic 

ankara- trite. basalt/ basantrite. syeno- ite. 

gabbro .

Normative composition

or ...... o.OO 6.67 5.03 7.10 6.02

ab ------ 0.00 0.00 18.93 26.25 4.31

an ------ 19.84 13.35 27.58 29.35 15.72

lc ------ 4.80 3.49 0.00 0.00 0.00

ne ------ 11.01 16.59 9.13 1.53 9.76

cs ------ 0.21 0.00 0.00 0.00 0.00

di-wo --- 19.66 15.84 11.01 6.23 16.42 

di-en --- 14.79 11.73 7.96 4.98 11.49 

di-fs --- 2.89 2.58 2.04 0.53 3.54 

oi-fo --- 10.86 15.52 3.51 6.77 17.73 

ol-fa --- 2.34 3.76 0.99 0.79 6.02 

mt ------ 6.13 4.67 8.86 10.20 3.99

il ------ 3.50 3.98 4.09 4.97 3.33

ap ------ 4.07 1.82 0.87 1.30 1.66

1Volatiles, probably mainly ^0 and CC>2, calculated 

assuming all FeO was oxidized to Fe20-j during determination of loss on ignition.

DESCRIPTION OF SAMPLE LOCALITIES

1. Picritic ankaratrite dike in the NE^NE^t sec. 24, T. 

31 N., R. 23 E., on the north side of Raton (36°54.7' 

N. , 104°26.5' E.) Raton quadrangle (M.J. Aldrich, Los 

Alamos National Laboratory, unpub. data, 1983). 

2. Ankaratrite from Tres Hermanos Peak, SW^SE1* sec. 23, 

T. 27 N. , R. 24 E. , Tres Hermanos Peak quadrangle. 

3. Basanite dike at Eagle Rock on Interstate Highway 25 

in the NE^NE^t sec. 21, T. 28 N. , R. 23 E. , Eagle Tail 

Mountain quadrangle. 

4. Trachybasalt or syenogabbro dike crossing Interstate 

Highway 25 in the SW^NWk sec. 14, T. 22 N. , R. 21 E. , 

Colmor quadrangle. 

5. Picritic basanite dike in the SWtSE^ sec. 5, T. 28 

N. , R. 25 E. , Tinaja Mountain quadrangle (southern of 

two dikes) .
30 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

t^X^ 'jsi* ' ' I ! <fJ "'

FIGURE 11. Smoky Hill Shale Member of the Niobrara Formation 

brecciated by a lamprophyre dike along a tributary of Tinaja Creek 

in the NE^SW^NE^ sec. 35, T. 28 N., R. 24 E., Tres Hermanos 

Peak quadrangle.

phenocrysts as large as 0.2 mm, some with thin needles 

of clinopyroxene and apatite(?) as inclusions; 5 percent 

poorly formed plagioclase phenocrysts as large as 

0.4 mm; and 4 percent prismatic, pale-dirty-green clinopyroxene phenocrysts as large as 0.2 mm. The groundmass consists of abundant clinopyroxene and nepheline; 

moderate amounts of inclusion-rich plagioclase; scattered 

spots of a cloudy, brown unknown mineral of negative 

relief; and a clear, colorless unknown isotropic mineral of 

positive relief.

Many of the mafic dikes in the region appear to be 

members of a gradational series ranging from simple 

dikes to more forcefully injected bodies, such as diatremes. The intensity of intrusion is illustrated by one 

mafic body, exposed along a tributary of Tinaja Creek in 

the NWVfcNEVfc sec. 35, T. 28 N., R. 24 E., which has 

severely brecciated the Upper Cretaceous Niobrara 

Formation it intrudes. Some of the breccia fragments 

(fig. 11) are more than 1 ft (0.3 m) in length.

DIATREMES

Several diatremes were noted during the reconnaissance mapping of this area, and more could probably

be found with careful search. A small kimberlitic diatreme crops out in a low knoll east of Raton, on the Olen 

Caviness ranch in the NE^NW^SE1^ sec 20, T. 31 N., 

R. 24 E. (locality 17 on fig. 6). Most of the knoll (fig. 12A) 

is occupied by disoriented masses of sedimentary 

sandstone, limestone, claystone and other types that 

range in size from a fraction of an inch to several feet. 

The diatreme is apparently less than 300 ft (90 m) in 

diameter and intrudes the Pierre Shale in the middle of 

the formation at about the faunal level of Didymoceras 

cheyennense, an approximately 72-m.y.-old fauna (Obradovich and Cobban, 1975). Much of the sedimentary rock 

in the neck of the diatreme is brecciated and altered to 

hornfels (fig. 12B), and so the stratigraphic origins of 

most of the fragments are hard to determine. It seems 

probable, however, that they were from the overlying 

Trinidad Sandstone, the Pierre Shale, the underlying 

Niobrara Formation, or an underlying Permian sandstone. One fossiliferous block of limestone from the 

diatreme contained specimens of the pelecypod Inoceramus (Platyceramus) cf. /. cycloides Wegner, which 

traces that block to the Smoky Hill Shale Member of the 

Niobrara Formation (identified by W.A. Cobban, U.S. 

Geological Survey). A radiometric age of the diatreme 

was obtained by the fission-track method on zircon in a 

sandstone block (table 2). The age, 30.1±1.2 m.y., which 

represents the time of resetting resulting from the heat 

of the intrusion (thus the age of emplacement), was 

determined by Mutsumi Miyachi in the laboratory of 

C.W. Naeser, U.S. Geological Survey. A second sample 

of zircon from the same sandstone yielded a fission-track 

age of 25.5+1.3 m.y.

Alien V. Heyl, U.S. Geological Survey, examined with 

a binocular microscope many hand specimens of the 

igneous rock and the breccia from the diatreme and 

concluded that the ultramafic igneous rock was a mica 

peridotite, a common rock type in many diatremes. The 

peridotite contains spheroidal dunite lapilli, which 

formerly were composed of olivine but now are largely 

altered to serpentine (probably antigorite). Phlogopite 

mica occurs in small sheeted aggregates as primary 

fragments in the lapilli and in the groundmass. Minute 

quartz crystals occur in vugs. Opaque minerals include 

diamond-shaped crystals, probably of chromite, and 

smaller square crystals of probable perovskite. Heyl 

noted the apparent absence of several minerals-such as 

garnet, chrome spinel, and chrome diopside that are 

characteristic of many kimberlitic diatremes.

The ultramafic igneous rock (fig. 12C), which is only a 

small part of the diatreme body, can be called a kimberlite. In thin section (specimen 80SM33, tables 18 and 19) 

the rock is porphyritic and includes about 45 percent 

smectite pseudomorphs after olivine phenocrysts, as 

large as 1.5 mm, and scattered pseudomorphs of horn-
IGNEOUS ROCKS 31

FIGURE 12.-Kimberlite diatreme east of Raton in the NEi^NWViSEVi sec. 20, T. 31 N., R. 24 E., Raton quadrangle. A, Low knoll formed by 

the diatreme. B, Closeup of brecciated sedimentary rock in the diatreme. C, Closeup of mica peridotite in the diatreme, containing spheroidal 

dunite lapilli.

blende(?) and mica(?). The groundmass is smectite, 

opaque oxide grains, and masses of a brown, finegrained, undetermined isotropic mineral of high relief 

(garnet?).

A diatreme 2.5 mi (4.0 km) east of Maxwell and north 

of the Pinon Road, in the SEV4 sec. 28, T. 27 N., R. 23 E. 

(symbol Td in southwest corner of fig. 6), crops out as an 

irregularly shaped plug of peridotite about 40 ft (12 m) in 

diameter intruding the calcareous uppermost shale unit 

of the Smoky Hill Shale Member of the Niobrara 

Formation. Anastomosing tongues of peridotite extend 

out into the shale (now hornfels). Internally the structure 

contains chaotic nodules and blocks of fine- and coarsegrained mafic igneous rock and fragments of probable 

Precambrian pegmatite and granitic gneiss. In thin 

section the fine-grained igneous rock (specimen 81SM59, 

table 19) is porphyritic and contains about 15 percent 

olivine phenocrysts as long as 2 mm, partly altered to 

smectite(?), and about 5 percent colorless clinopyroxene 

phenocrysts as large as 0.5 mm having an optic angle of 

about ( + )60°. The groundmass consists of about equal 

parts of clinopyroxene, plagioclase, and alkali feldspar 

and a minor amount of dark mica. A thin section from 

another block (specimen 82SM5) from the same diatreme 

shows euhedral altered olivine, kaersutitic hornblende, 

stubby pale-brown clinopyroxene, equant opaque oxide
32 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

crystals, a few plagioclase crystals, scattered needles of 

apatite, and sparse dark mica, all in an interstitial 

mixture of a dusty isotropic material of strong negative 

relief (zeolite?) and carbonate.

An irregular body about 1,000 ft (305 m) long and 

200 ft (60 m) wide at the faulted Joyce dome (Staatz, 

1986) in the Pine Buttes quadrangle (NW^NW1^ sec. 25, 

T. 27 N., R. 25 E.) has many of the aspects of a diatreme. 

The principal rock is hornblende-rich and contains 

inclusions of Precambrian gneiss, pegmatite, and possible Precambrian quartzite. According to M.H. Staatz 

(written commun., 1981), chemical analysis shows the 

rock is trachyandesite. In thin section a specimen 

(No. 81SM25, table 19) is porphyritic and includes the 

following: about 10 percent green hornblende phenocrysts that are generally less than 2.5 mm across but 

locally form coarse crystal segregations as much as 

7.5 cm in diameter; 5 percent blue-green pseudomorphs 

of smectite after pyroxene(?) as large as 1.5 mm; 

1 percent dark-brown mica crystals as large as 1.2 mm; 

1 percent plagioclase (andesine?) phenocrysts as large as 

1.2 mm with oscillatory zoning; 1 percent opaque oxide 

crystals; and broken crystals of apatite. The groundmass 

is chiefly feathery appearing feldspar and secondary 

carbonate. Other minerals in the groundmass include 

opaque oxides, pyrite, and an unknown yellowish-brown 

mineral of strong birefringence. Vugs are filled with 

quartz and carbonate.

Tables 18 and 19 show spectrographic analyses and 

neutron-activation analyses of the igneous rocks in the 

diatremes. Despite the lesser precision of the spectrographic analyses, both analyses are included because 

each shows some elements not included in the other. 

Table 19 also shows that many elements are more 

abundant in the diatremes than in average crustal rocks. 

These higher abundances suggest that the diatreme 

rocks were derived from the mantle. Elements whose 

concentrations are particularly diagnostic of a mantle 

source are barium, chromium, iridium, magnesium, 

nickel, thorium, titanium, and yttrium.

IGNEOUS ROCKS NEAR CIMARRON, 

NEW MEXICO

The igneous rock exposures in the vicinity of Cimarron 

are separated from the main area of igneous rock 

outcrops east of Interstate Highway 25 by some 40 mi 

(64 km) of sedimentary rock exposures. The geology of 

the area immediately south of Cimarron has been 

mapped by Scott (1986). West of Cimarron is an 

extensive series of felsic sills, and east and south of 

Cimarron are outcrops of syenite sills over an area 2-3 mi 

(3-5 km) wide. Both rock units probably are parts of a 

large intrusive complex. Although syenite sills are found

TABLE l8. Semiq^tantitative six-step spectrographic analyses of 

rocks from diatremes in the Raton-Springer area, New Mexico

[Table lists only the elements detected. Other elements looked for but not detected (and their 

lower limits of determination, in parts per million) are Ag (0.5), As (1,000), Au (20), B 

(20), Bi (10), Cd (50), Eu (100), Ge (10), Hf (100), In (10). Li (100), Pd (2), Pt (50), Re (50), 

Sb (200), Sm (100), Sn (10), Ta (500), Te (2,000), Th (200), Tl (50), U (500), W (100), and 

Zn (300). N=not detected; < = element detected but below the limit of determination, 

which is value shown; =element not looked for. Analyst L.A. Bradley; fluorine by the 

specific ion electrode method by H.G. Neiman and F. NewmanJ

Sample - - 

Field No, 

Lab. No.-

1

80SM33 

D237463

2

81SM25 

D241840

3

81SM59 

D241941

Data in percent

Al --------

Ca --------

Fe --------

K ---------

Mg --------

Na --------

P ---------

Si --------

Ti --------

F ---------

1.

3

7

1.

5

N

7

0.

0.

5

5

15

3

11

5

7

7

3

2

3

0.5

10

0.7

0.14

7

7

7

1

5

1

0

10

1

0

.5

.5

.3

.06

Data in parts per million

Ba ------

Be ------

Ce ------

Co ------

Cr ------

Cu ------

Ga ------

La ------

Mo ------

Nb ------

Nd ------

Ni ------

Pb ------

Sc ------

Sr ------

V -------

Y -------

Yb ------

Zr ------

700

<1

<200

30

700

70

--. ___

100

N

30

70

300

N

15

300

150

20

-__ _-.

70

1,000

2

200

30

70

70

30

70

<3

30

150

30

20

30

500

200

50

3

150

1,500

1.5

200

30

300

70

20

70

5

70

100

200

15

30

700

150

30

...

150

DESCRIPTION OF SAMPLE LOCALITIES

1. Kimberlite diatreme in the NE^NW^SE^ sec. 20, T. 

31 N., R. 24 E., Raton quadrangle.

2. Diatreme at the Joyce faulted dome in the NWsNWs 

sec. 25, T. 27 N., R. 25 E., Pine Buttes 

quadrangle.

3. Diatreme north of the Pinon road in the SE% sec. 

28, T. 27 N., R. 23 E., Loco Arroyo quadrangle.

only east of the escarpment of the Park Plateau (fig. 1), 

rhyodacite sills project northwestward from Tooth of 

Time Ridge into the mountains beyond Elizabethtown 

(fig. 1). Similar rocks also extend northwestward from 

Elizabethtown to the valley of the Rio Grande (P.W. 

Lipman, oral commun., 1982).
IGNEOUS ROCKS 33

TABLE 19. Neutron-activation analyses of rocks from diatremes in 

the Raton-Springer area, New Mexico

[See table 18 for description of sample localities. "<" indicates element concentration is below 

the limit of determination, which is the value shown. Analyst: Carl Orth, Los Alamos 

National Laboratory]

Sample--- 1 2

Field No. 80SM33 81SM25

Lab. No. RB-11 RB-41 RB-98

3 Average

81SM59 crustal

RB-99 abundance

Elemental compositions in percent

Al 

Ca 

Fe 

Mg

3.4

6.9

7.5

11.4

3.6

7.2

7.6

12.3

6.6 

7.0 

7.2 

1.9

7.1 

7.1 

7.1 

4.9

8.1 

3.6 

5 

2.1?

Elemental compositions in parts per million

Ba

Ce

Co

Cr

Cs

Dy

Eu

Hf

K

La

Lu

Mn

Na

Rb

Sc

Sm

Sr

Ta

Th

Ti

U

V

Yb

Zr

1,880

237

65

1,500 

<2 

5.1 

3.3 

4

9,170 

106

0.5

1,600

496

<60

27

10

<330

2.3 

22 

8,290

4.4 

207 

<2.6 

<150

1,900 

245 

<35 

1,170 

<2 

4.8 

3.1 

4

17,200 

113

0.8

1,580

650

<50

25

20

600

2.3 

23 

8,190

4.8 

185 

<3.1 

<150

700 

156 

31 

66 

<2 

11.6 

2.4 

3.6

£15,000 

55

0.5

1,750

25,500

36

22

15

<1,100

1.4 

9.0 

10,950

2.4 

240

3.2 

150

1,815 

132 

48 

390 

2.7 

4.5 

2.0 

2.6

=13,000 

61

0.2 

1,620 

25,360 

<28 

24 

6?

1,500 

2.0 

9.5 

9,850

3.7 

210

3.9 

200

425

60

100

100

3

3.0

1.2

3

26,000

30

0.5

950

28,300

90

22

6

375

2

7.2

4,400

1.8

135

3.4

165

Elemental composition in parts per trillion

Ir 140 220 80 36

RHYODACITE WEST OF CIMARRON

A large sill complex or laccolith(?) of porphyritic 

rhyodacite to dacite crops out southwest of Cimarron and 

west of the Philmont Scout Ranch headquarters (fig. 1). 

This mass is resistant to weathering and forms bold 

monoliths, pinnacles, ridges, and fluted columnar outcrops, such as Tooth of Time Ridge, Cathedral Rock, and 

the Palisades. The sills northwest of Tooth of Time Ridge 

have fairly gentle dips and are intricately interlayered 

with Cretaceous and older sedimentary rocks. The 

sediments intruded by the rhyodacite generally have 

been baked to hornfels near the contacts.

The radiometric age of the rhyodacite was determined 

by Armstrong (1969) to be 33.8 m.y. (34.6 m.y. by the 

new constants) using the K-Ar method on biotite (table

3). On a different sample from Cimarron Canyon l/z mi 

(0.8 km) east of the Palisades (specimen 81SM24; locality 

19 on fig. 1), Mutsumi Miyachi obtained a fission-track 

age of 29.1 ±1.4 m.y. (table 2). The latter age is close to 

that of the quartz latite in the Latir Peak volcanic field, 

about 25 mi (40 km) northwest of Cimarron Canyon 

(fig. 1A). H.H. Mehnert and P.W. Lipman (oral commun., 1982), obtained K-Ar ages ranging from 20 to 

28 m.y. for samples from the Latir Peak field, and they 

suggest that the intrusive body west of Cimarron was 

contemporaneous with the extrusive rocks at Latir Peak.

The rocks west of Cimarron were called porphyritic 

monzonite by Smith and Ray (1943, p. 904) and dacite by 

Wanek (1963), Wanek and others (1964), and Robinson 

and others (1964). The eastern tip of the complex was 

mapped by Simms (1965), who referred to granodiorite 

porphyry intrusives occurring as sills in an elongate 

laccolith. The variety of rock names applied to the mass 

is apparently due in part to variation in size and abundance of phenocrysts and to some variation in composition, as well as to different petrographic nomenclatures used by the authors.

Rhyodacite from the valley of the South Fork Urraca 

Creek (tables 20 and 21) in the NE^SW^ sec. 2, T. 25 

N., R. 18 E., south of Tooth of Time Ridge, is a 

light-gray rock containing abundant large phenocrysts of 

feldspar. A thin section of this rock (specimen 80SM45; 

table 21 contains about 15 percent oligoclase-andesine 

phenocrysts (some laumontitized), many larger than 8 

mm; 5 percent relics of hornblende phenocrysts altered 

to a gold-yellow mineral; 1 percent dark mica partly 

altered to an olive-green mineral with optic angle near 

(-)0° (smectite?); scattered prismatic crystals of apatite 

as large as 0.15 mm; scattered titanite and black opaque 

oxide crystals; and, rarely, rounded and embayed crystals of quartz as large as 10 mm. The groundmass is 

finely holocrystalline and sugary textured and is made up 

of quartz, alkali feldspar, scattered interstitial mica, and 

opaque oxides.

Chemical analysis and neutron activation analysis of 

the rhyodacite (tables 20 and 21) show that it contains 

about 67 percent Si02 . The R1R2 parameters of the 

sample fall well within the rhyodacite field of figure IB. 

The neutron activation analysis (table 21) shows concentrations of elements close to that of average crustal 

abundance; hence the rhyodacite apparently had a source 

in the Earth's crust.

SYENITE AND TRACHYTE SILLS EAST OF CIMARRON

Scattered outcrops of syenite and trachyte sills from 1 

to 6 ft (0.3-1.8 m) thick intrude the Pierre Shale over an 

area of nearly 25 mi2 (64.8 km2) east and south of 

Cimarron. The rock is medium gray to pale yellowish 

brown, aphanitic, and very hard, and weathers light
34 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

TABLE 20. Chemical analysis and norm of rhyodacite west of 

Cimarron, New Mexico

[Data in weight percent]

Field No.--- 81SM24 La Roche classification 

Lab. No.---- D242011

P, /)')'\~J

Major oxides ^ ......... 692

A1 2 03 ------ 16.6 

pe203 - - 1 33 Normative composition

FeO -------- 1.13 0/ ,,

Me0 -------- 0 84 q --"---"- 24.65 6 _' O r --------- 17.73

ab --------- 35.99

Na2 0 ------- 4.14 an ......... 14 50 vrt o qo an -- -- I^.DU K2 o -------- z.yz c .......... 1 49

Volatiles 1 -- 1.72 :; £,*

Tino n 95 hy " en ------ 2 - 15

t> n n i/ hy-fs ------ 0.67 P 2 06 ------- 0.14 J , QR

MnO -------- 0.05 . n n /n il --------- 0.49

Total --- 99.1 ap --------- 0.34

1 Probably mainly H20 and C02 , calculated 

assuming all FeO was oxidized to Fe20 3 during 

determination of loss on ignition.

DESCRIPTION OF SAMPLE LOCALITY

Rhyodacite from outcrop one-half mile (0.8 km) east 

of the Palisades in Cimarron Canyon on U.S. 

Highway 64 , Ute Park quadrangle .

olive gray. In thin sections (specimen 81SM10, from 

SWV4SW1/4 sec. 12, T. 26 N., R. 19 E., on south side of 

New Mexico Highway 58, and specimen 81SM39, from 

NWV&SWVfc sec. 6, T. 26 N., R. 20 E.) the texture is 

jackstraw-like. Alkali feldspar laths as much as 0.4 mm in 

length are abundant in bundles and rosettes. Dark mica 

crystals as long as 0.3 mm are common, along with 

amphibole(?) as slender needles as much as 0.4 mm in 

length, having low birefringence, positive elongation, 

and parallel extinction. Yellow pseudomorphous(?) 

masses as large as 0.3 mm are also present. Quartz is 

scattered throughout the rock as small grains and is also 

associated with carbonate in vugs and veins. Titanite is 

present as an accessory.

TRACHYANDESITE OF MIDDLE PINE BUTTE

A large trachyandesite dome forms the steep-sided 

middle Pine Butte in the northeastern part of the Pine 

Buttes quadrangle. The butte rises 600-800 ft (ISO240 m) above the surrounding area and lies between two 

even higher rhyodacite domes that form the eastern and 

western Pine Buttes. Rock composing middle Pine 

Butte, termed phonolite by Collins (1949, p. 1035), was 

determined by Stormer (1972b) to be a trachyandesite

TABLE 21. Neutron-activation analysis of a sample of rhyodacite 

west of Cimarron, New Mexico

[Elemental compositions in parts per million. "<" indicates element concentration is below the 

limit of determination, which is the value shown; "±" shows the accuracy of the test.

Field No. 80SM45 Sb <0.4 

Lab No. 925108 La 20.7 ±0.4

 Sm 3.4 ±0.2

Na 33,000 ±300 W <5

Mg 3,800 ±800 Au <0.01

Al 84,000 +2,000 Sc 1.96+0.04

Cl <110 Cr 5.1+0.9

K 24,000 +2,000 Fe 17,500 +500

Ca 19,000 +1,000 Co 4.1+0.2

Ti 1,300 +200 Zn 48 +8

V 26 ±3 Se 2.6 ±0.3

Mn 251 +3 Rb 66 +5

Cu <300 Cs 2.3+0.2

Sr 820 +90 Ce 35 +1

I <20 Eu 0.78+0.05

Ba 1,450 +60 Tb 0.22±0.07

Dy <0.8 Yb 0.30±0.07 

U 1.44+0.02 Lu <0.03 

Ga <120 Hf 3.8 ±0.3 

As <3 Ta 0.30±0.08 

Br <2 Th 3.0 ±0.1

DESCRIPTION OF SAMPLE LOCALITY

Rhyodacite from outcrop in the valley of South Fork 

Urraca Creek in the NE^SWk sec. 2, T. 25 N. , R. 

18 E., south of Tooth of Time Ridge, Miami 15- 

minute quadrangle .

(table 22, analysis 1). It is a light-gray porphyritic rock 

showing dark-red oxyhornblende crystals set in a finely 

crystalline groundmass. 

In thin section (specimen 81SM60, table 22, analysis 2) 

the porphyry is subtrachytic and contains about 15 

percent embayed oxyhornblende as large as 2 mm having 

opacite rims, a few dusty pseudopleochroic apatite 

crystals as large as 0.5 mm, and traces of plagioclase. 

The groundmass is composed chiefly of subparallel plates 

of plagioclase (oligoclase?), clinopyroxene prisms, and 

abundant opaque oxides in an alkali feldspar(?) mesostasis; some secondary carbonate is present. 

The chemical analyses and norms (table 22) show that 

the trachyandesite has a low Si02 content and is nearly 

quartz free in the norm. It has a fairly high potassium 

content and about 15.5 percent orthoclase in the norm.

RED MOUNTAIN RHYODACITE

The name "Red Mountain dacites" was given by Collins (1949, p. 1031) to rocks that crop out at Red 

Mountain volcano (fig. 13A) on Johnson Mesa in eastern 

Colfax County and to similar rocks at other volcanoes in
IGNEOUS ROCKS 35

TABLE 22. Chemical analyses and norms of trachyandesite porphyry 

of middle Pine Butte, Raton-Springer area, New Mexico

[Data in weight percent, n.d., not determined!

Sample - - 

Field No. 

Lab No . - -

1 

199

2 

81SM60 

D242015

Major oxides

Si02 ---

A12 03 --

Fe 2 03 --

FeO ----

MgO ----

CaO ----

Na20 ---

K2 0 ----

H20+ ---

H20" ---

Vols. 1 --

Ti02 ---

p r2 n o5 - - _

MnO ----

Total

54.78

17.59

6.06

0.55

2.60

6.35

5.64

2.54

0.88

0.19

n.d.

0.92

0.87

0.16

99.1

55.5

17.7

6.75

0.04

2.36

6.34

5.42

2.65

n.d.

n.d.

0.55

0.88

0.91

0.15

99.3

1 

199

2 

81SM60 

D242015

La Roche classification

Rl -

R2 -

Name

871

1,166

Trachyandesite.

965

1,144

Trachyandesite .

Normative composition

q ---

or - -

ab --

an - -

di-wo 

di-en

hy-en

ol-fo

hm - -

il --

tn --

ap --

0.00

15.30

48.64

15.47

4.34 

3.75

1.23

1.13

6.18

1.53

0.32

2.10

1.34

15.86

46.44

16.35

2.98 

2.57

3.38

0.00

6.84

0.41

1.66

2.18

1 Volatiles, probably mainly H2 0 and C02 , calculated assuming all FeO was oxidized to Fe 2 0o during 

determination of loss on ignition.

DESCRIPTION OF SAMPLE LOCALITIES

1. Trachyandesite from blocks on north slope of middle 

Pine Butte, SUk sec. 3, T. 27 N., R. 26 E., Pine 

Buttes quadrangle. (Sample 199 of Stormer, 1972b, 

tables 1 and 7).

2. Trachyandesite from middle Pine Butte in the SEkSWk 

sec. 3, T. 27 N., R. 26 E., Pine Buttes quadrangle.

the area. Collins' type locality at Red Mountain occurs in 

sees. 22 and 23, T. 31 N., R. 26 E., Colfax County, N. 

Mex. In the classification used here (La Roche and 

others, 1980) the rock at Red Mountain itself plots as 

rhyodacite close to dacite, whereas those at most of the 

other localities sampled are clearly rhyodacite (fig. IB, 

field 23). In addition to the occurrence at Red Mountain 

volcano, this is the chief rock type at Palo Blanco 

Mountain (fig. 135), Pine (Timber) Buttes, Green 

Mountain, Towndrow Peak, Cunningham Butte volcano, 

Raspberry Mountain, and Laughlin Peak (fig. 13C). 

Staatz (1985) gives detailed descriptions of the rhyodacite at Raspberry Mountain and Laughlin Peak.

Diameters of the bases of these volcanoes, excluding 

flanking landslides, range from 0.25 to 1.5 mi (0.4 to 

2.4 km), and the crests range in elevation above the 

surrounding country from 400 to 1,200 ft (120-360 m). 

Gullies channeling the flanks of the volcanoes provide 

access to the least weathered rock. The forms of these 

edifices and the persistent presence of oxyhornblende

and opacite in their rocks, rather than common green 

hornblende, indicate that they are volcanic domes; that 

is, they were extruded slowly as hot but highly viscous 

magma, with time for the hornblende to be roasted to 

oxyhornblende or opacite pseudomorphs.

That at least some explosive activity accompanied the 

extrusion of the domes is indicated by the local 

occurrences of pumiceous pyroclastic deposits, such as in 

the lahar (mudflow; Tl on fig. 6) on the north flank of 

Laughlin Peak, which extends downslope to the north 

and northeast for almost 4 mi (6 km). The lahar contains 

blocks of pumice as large as 6 ft (1.8 m) across (fig. 14). 

The pumice has a subparallel flowage texture. This 

deposit is pinkish gray to medium gray and is unsorted; 

blocks of pumice, vitrophyre, and banded rhyodacite are 

not in contact with each other but apparently moved in a 

suspension of fine sand- and silt-sized vitrophyre during 

transport. The lahar is at least 25 ft (7.6 m) thick. Along 

a circling road south of Laughlin Peak, an unmapped 

stratified pumiceous deposit containing vitrophyre and 

pumice lumps and glass shards apparently is a water-laid 

tuff. Artifacts composed of vitrophyre show that local 

Indian tribes used this deposit as a source of stone for 

tools.

A K-Ar age of the hornblende in a probably weathered 

rhyodacite at Cunningham Butte was determined by 

Stormer (1972a) as 8.2+0.8 m.y. (8.40±0.8 m.y. based on 

new decay constants). In the present study the hornblende of a less weathered sample of rock from a quarry 

in the dike at the west end of Cunningham Butte was 

dated as 6.9±1.0 m.y. and 7.6±1.1 m.y. (table 1). Four 

other K-Ar ages on hornblendes from three of the domes 

(table 1) range from 6.43±0.67 to 7.6±1.1 m.y., giving a 

mean of 7.01 m.y. K-Ar ages determined on plagioclase 

in the same rocks showed greater scatter and were 

generally younger. A K-Ar age of hornblende from a 

large block of pumice in the lahar deposit at Laughlin 

Peak (specimen 80SM37, table 1) was determined to be 

6.90±0.80 m.y., similar to the hornblende ages of the 

domes and the dike. One measured K-Ar age of the 

plagioclase, 21.79±2.22 m.y., is anomalously old, 

possibly due to contamination of the pumice by old 

detrital feldspar. A K-Ar age of 8.1 ±0.6 m.y. on hornblende was reported by Staatz (1985, p. E17) from a 

sample on the northeast part of Raspberry Mountain in 

sec. 18, T. 27 N., R. 26 E., Colfax County, N. Mex. He 

reported another age of 7.7±0.5 m.y. for a sample from 

the knoll at the north end of southwest Pine Buttes dome 

(Staatz, 1986).

The rhyodacite ranges from gray to orange pink or 

pale red, is generally nonvesicular, and has textures 

variously porphyritic or seriate. Phenocrysts are plagioclase and hornblende (in most cases oxyhornblende) in a 

hyalocrystalline, pilotaxitic, or totally glassy ground-
36 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

FIGURE 13. Volcanoes consisting of Red Mountain Rhyodacite in the Raton-Springer area. 

A, Red Mountain from the northwest, the type locality. Mountain lies in the EV6 sec. 22 and the WV6 sec. 23, T. 31 N., R. 26 E., Dale Mountain

quadrangle. 

B, Palo Blanco Mountain from the north. Mountain lies in sees. 8, 9, 16, and 17, T. 27 N., R. 27 E., Palo Blanco Mountain quadrangle. East

(left) side has steeply tilted sedimentary beds. 

C, Laughlin Peak from the north, showing deep erosion into pumiceous laharic deposits on flank of cone. Mountain is in sees. 28, 29, 32, and

33, T. 28 N., R. 26 E., Mesa Larga and Pine Buttes quadrangles. Outcrop of Dakota Sandstone (Upper Cretaceous) is at crest of mountain

(M. H. Staatz, oral commun., 1980).
IGNEOUS ROCKS 37

!*& £. , :^^--^<v.<> ^S^-r.jSt?-i-^'--..«i*#«> «*- .>-^s ***

^^iS«:rft«ia, i -,^<;^^ J

FIGURE 14. Pumiceous rhyodacitic lahar on north flank of Laughlin Peak in the SEVi sec. 19, T. 28 N., R. 26 E., Mesa Larga quadrangle. 

A, Wide view showing large blocks of pumice. B, Closeup of lahar, showing smaller clasts. Hat is approximately 12 inches (30 cm) across.

mass. The rock ranges from a red and gray, fluidally 

banded variety having as much as 85 percent glassy 

groundmass (at Laughlin Peak and Green Mountain) to a 

crystal-rich porphyry having little more than 30 percent 

glassy or finely crystalline groundmass. The rapid 

quenching during eruption of the glassy phases prevented the conversion of the hornblende to oxyhornblende and preserved the common green hornblende. 

Green hornblende is also preserved in dikes of rhyodacite, such as that trending northwestward from Cunningham Butte. In the dikes, the confining pressure 

during intrusion of the magma would have prevented 

breakdown of the hydroxyl-bearing minerals.

Mertie (1922, p. 10) gave the modal composition of 

rhyodacite lava from Towndrow Peak as 21 percent 

feldspar, 10 percent basaltic hornblende (oxyhornblende), 2 percent magnetite (opaque oxide), and 67 

percent glass. Stobbe (1949, p. 1068) gave the modal 

composition of the dacite at Red Mountain as 28.7 

percent plagioclase, 9.7 percent hornblende, 4.4 percent 

magnetite, and 57.2 percent glass.

In thin section, specimen 80SM6 from the west end of 

Towndrow Peak (table 23, analysis 1; locality 10 on fig. 6) 

is porphyritic to seriate in texture and contains about 

30 percent plagioclase (oligoclase-andesine) phenocrysts 

as large as 1.5 mm, 10 percent oxyhornblende phenocrysts as long as 2 mm (extinction angle Z:c=2°), and 

sparse stubby crystals of apatite. The groundmass consists mainly of glass containing microlitic needles of 

opaque oxide (pseudomorphs of hornblende microlites?).

Specimen 80SM12 (table 23, analysis 60) from Palo 

Blanco Mountain is porphyritic and contains about 

35 percent plagioclase phenocrysts as large as 1.4 mm, 

15 percent oxyhornblende phenocrysts as long as

0.5 mm, 5 percent opaque oxide crystals as large as 

0.05 mm, and a few crystals of corroded oxybiotite. The 

groundmass is isotropic and has strong negative relief 

(glass?).

Specimen 80SM3 (table 23, analysis 13) from Green 

Mountain is porphyritic and contains about 12 percent 

plagioclase phenocrysts of two types: (a) clear euhedral 

crystals of andesine as large as 0.3 mm and (b) internally 

corroded crystals as large as 1 mm with clear rims. It 

also includes 3 percent prismatic oxyhornblende phenocrysts as large as 0.2 mm, some in clots having opacite 

rims. The groundmass has hyalocrystalline texture, is 

composed of plagioclase glass(?) and small amounts of 

oxyhornblende and opaque oxide, is inhomogeneous, is 

both clear and cloudy brown (buff in reflected light), and 

contains rusty colored hornblende crystals.

Specimen 80SM37 (table 23, analysis 12; also table 1; 

locality 13 on fig. 6), from a vesicular, glassy pumice 

block in the lahar on the north side of Laughlin Peak, is 

porphyritic and contains about 3 percent strongly zoned 

plagioclase (andesine) phenocrysts and 2 percent olivegreen hornblende as large as 0.4 mm. Its trachytic 

groundmass is about one-half plagioclase tablets and 

one-half glass (or cristobalite?) containing a few hornblende needles and opaque oxide grains.

Specimen 80SM18 (table 23, analysis 3; locality 11 on 

fig. 6), from a quarry in a dike that trends northwestward from Cunningham Butte, is porphyritic and 

contains about 5 percent prismatic green hornblende as 

long as 1 mm and 3 percent stubby plagioclase (andesinelabradorite) phenocrysts as large as 0.7 mm. Its groundmass is pilotaxitic in texture, and about one-half is 

plagioclase (oligoclase-andesine) and the rest opaque
VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

TABLE 23. Chemical analyses and norms of Red Mountain

[Data in weight percent.

Field No. 

Lab No. 

Si02 

A1 203 

Fe 2°3 

FeO 

MgO 

Na 2 0 -

K20 

H2 0~ 

Volatiles 1 

rrij f\

MnO 

rr»

Total

 n 1

R2

q

ab 

hy-fs 

mt -~ 

il 

tn 

ap -

1 

80SM6 

D229686

65.2 

16.1 

3.62 

0.08 

1.9 

4.24 

4.4 

2.28 

n.d. 

n.d. 

1.36 

0.47 

0.3 

0.05 

.n.d.

100.0

2,142 

864 

Dacite/ 

rhyodacite.

20.44 

13.66 

37.74 

17.68 

0.00 

0.00 

0.21 

0.18 

4.61 

0.00 

0.00 

3.67 

0.28 

0.81 

0.00 

0.72 

0.00

2 

(From Stobbe, 

1949)

66.01 

14.57 

4.16 

n.d. 

0.20 

3.71 

5.24 

2.34 

n.d. 

n.d. 

n.d. 

n.d. 

n.d. 

n.d. 

n.d.

96.23

La Roche

1,958 

720 

Dacite/ 

rhyodacite.

21.08 

14.37 

46.08 

9.69 

0.00 

3.34 

0.60 

0.52 

0.00 

0.00 

0.00 

4.32 

0.00 

0.00 

0.00 

0.00 

0.00

3

80SM18 

D231887

Major

66.9 

15.60 

1.82 

1.01 

1.28 

3.96 

4.50 

2.38 

n.d. 

n.d. 

1.06 

0.37 

0.23 

0.02 

n.d.

99.1

and others

4 

277

oxides

67.04 

15.6 

1.84 

0.89 

1.29 

3.96 

4.61 

2.36 

1.34 

0.38 

n.d. 

0.43 

0.21 

0.04 

n.d.

99.99

5

MHS-16-81 

D240836

67.2 

15.4 

2.87 

0.24 

1.24 

3.18 

3.96 

2.80 

n.d. 

n.d. 

2.03 

0.38 

0.22 

0.05 

n.d.

99.6

6 

80SM12 

D229692

67.7 

15.2 

2.90 

0.09 

1.2 

3.13 

4.1 

2.99 

n.d. 

n.d. 

1.55 

0.36 

0.2 

0.04 

n.d.

99.5

7 

MHS-94-80 

D229972

67.8 

15.1 

2.31 

0.20 

1.2 

3.09 

3.6 

3.01 

2.23 

0.45 

n.d. 

0.32 

0.2 

0.04 

0.09

99.6

(1980) classification

2,237 2,203 

800 797 

Rhyodacite/ Rhyodacite/ 

dacite. dacite.

Normative

22.92 

14.34 

38.82 

15.64 

0.00 

0.00 

1.19 

1.03 

2.22 

0.00 

2.29 

0.27 

0.72 

0.00 

0.00 

0.56 

0.00

composition

22.49 

14.19 

39.69 

15.16 

0.00 

0.00 

1.43 

1.24 

2.03 

0.00 

1.78 

0.64 

0.83 

0.00 

0.00 

0.51 

0.00

2,297 

705 

Rhyodacite

26.05 

16.96 

34.35 

14.70 

0.61 

0.00 

0.00 

0.00 

3.17 

0.00 

0.00 

2.94 

0.63 

0.00 

0.06 

0.53 

0.00

2,282 

696 

Rhyodacite

25.00 

18.04 

35.43 

14.52 

0.01 

0.00 

0.00 

0.00 

3.05 

0.00 

0.00 

2.96 

0.28 

0.00 

0.22 

0.48 

0.00

2,482 

692 

Rhyodacite

28.61 

18.34 

31.41 

13.87 

1.02 

0.00 

0.00 

0.00 

3.08 

0.00 

0.00 

2.38 

0.52 

0.00 

0.05 

0.49 

0.21

Probably mainly H20 and C02 , calculated assuming all FeO was oxidized to Fe 203 during determination of

DESCRIPTION OF SAMPLE LOCALITIES

Rhyodacite/dacite from the west end of Towndrow 

Peak in the NWiSEi sec. 22, T. 31 N., R. 25 E., 

Yankee quadrangle.

Dacite/rhyodacite from Cunningham Butte in sec. 

36, T. 30 N., R. 24 E., Hunter Mesa quadrangle 

(Stobbe, 1949, p. 1067).

Rhyodacite from quarry in dike trending northwestward from Cunningham Butte in the SW| sec. 

25, T. 30 N., R. 24 E., Hunter Mesa quadrangle. 

Rhyodacite from quarry in dike west of Cunninghan 

Butte in the north center of sec. 31, T. 30 N. ,

R. 24 E., Hunter Mesa quadrangle (sample 277 of

Stormer, 1972b, figure 2 and table 5).

Rhyodacite from top of western Pine Butte in the

SWiSWi sec. 10, T. 27 N., R. 26 E., Pine Buttes

quadrangle (Staatz, 1985).

Rhyodacite from Palo Blanco Mountain in the

SWiSEi sec. 17, T. 27 N., R. 27 E., Palo Blanco

Mountain quadrangle.

Rhyodacite from southeast flank of eastern Pine

(Timber) Buttes in the SEiSEi sec. 11, T. 27 N.,

R. 26 E., Pine Buttes quadrangle (Staatz, 1985).
IGNEOUS ROCKS 39

Rhyodacite samples from Raton-Springer area, New Mexico

n.d., not determined]

69.7 

15.0 

0.83 

0.83 

0.55 

2.49 

4.13 

3.13 

n.d. 

n.d. 

2.64 

0.20 

0.07 

0.02 

n.d.

99.6

70.6 

15.4 

1.43 

0.21 

0.61 

2.50 

4.6 

2.86 

n.d. 

n.d. 

1.34

0 

<0

17

1

0.04 

n.d.

99.85

70.9 

15.6 

1.40 

0.36 

0.1 

1.90 

4.0 

2.64 

1.06 

0.22 

n.d. 

0.21 

<0.2 

<0.02 

0.01

98.4

Sample 8 9 10 11 12 13 14

Field No. M-15 MHS-67-80 MHS-93-80 MHS-74-80 80SM37 80SM3 MHS-119-80

Lab No. D229966 D229971 D229970 D231895 D229683 D229973

	Major oxides

Si02 67.98 68.0 68.1 69.0

A1 2°3 15 ' 53 15 - 1 15 ' 7 16 '°

Fe 203 2.68 2.30 2.11 1.50

FeO 0.18 0.39 0.88 0.43

MgO 1.47 1.1 1.3 0.3

CaO 3.39 3.20 3.34 2.47

Na20 4.53 4.0 4.0 3.7

K2 0 3.00 2.94 2.68 2.83

H2 0+ 1.05 1.36 1.25 2.28

H2 0~ 0.11 0.23 0.28 0.55

Volatiles 1 n.d. n.d. n.d. n.d.

Ti02 0.34 0.33 0.38 0.22

P2°5 °' 33 °' 2 °' 2 <°- 1

MnO 0.04 0.05 0.05 <0.02

C02 n.d. 0.11 0.08 0.02

Total 100.63 99.3 100.4 99.3

	La Roche and others (1980) classification

RI 2>126 2,367 2,397 2,592 2,405 2,360 2,675 

R2 736 700 729 600 590 601 523 

Name Rhyodacite/ Rhyodacite Rhyodacite Rhyodacite Rhyodacite/ Rhyodacite/ Rhyodacite/ 

	dacite. rhyolite. rhyolite. rhyolite.

	Normative composition

q 22.06 26.45 26.58 32.10 28.36 27.32 34.30

or 17.82 17.78 16.02 17.34 19.08 17.15 16.06

ab 38.53 34.63 34.25 32.45 36.04 39.51 34.85

an 13.25 14.20 14.93 12.57 12.27 11.93 9.64

c 0.00 0.26 0.82 2.49 0.47 0.44 2.79

wol 0.00 0.00 0.00 0.00 0.00 0.00 0.00

di-wo 0.48 0.00 0.00 0.00 0.00 0.00 0.00

di-en 0.42 0.00 0.00 0.00 0.00 0.00 0.00

hy-en 3.26 2.80 3.28 0.77 1.41 1.54 0.26

Hy-fs 0.00 0.00 0.00 0.00 0.56 0.00 0.00

mt 0.00 0.47 1.92 0.78 1.24 0.32 0.57

hm 2.69 2.03 0.81 1.02 0.00 1.23 1.05

il 0.47 0.64 0.73 0.43 0.39 0.33 0.41

tn 0.23 0.00 0.00 0.00 0.00 0.00 0.00

ru 0.00 0.00 0.00 0.00 0.00 0.00 0.00

ap 0.79 0.48 0.48 0.00 0.17 0.24 0.00

cc 0.00 0.26 0.18 0.05 0.00 0.00 0.02

loss on ignition.

DESCRIPTION OF SAMPLE LOCALITIES

10.

11,

Rhyodacite from Red Mountain in center of Wi 

sec. 23, T. 31 N., R. 26 E., Dale Mountain 

quadrangle (sample M-15 of Mertie, 1922, p. 11). 12. 

Rhyodacite from steep northeast flank of Raspberry Mountain in NWiNEiNEi sec. 18, T. 27 N., 

R. 26 E., Pine Buttes quadrangle (Staatz, 1985). 13. 

Rhyodacite from lower south flank of Palo Blanco 

Mountain in the SW^SEi sec. 17, T. 27 N., R. 27 

E., Palo Blanco quadrangle (Staatz, 1985). 14. 

Rhyodacite tuff from north side of county road 

A-8, 951 ft (290 m) northeast of ranch house in

the SEl sec. 5, T. 27 N. , R. 26 E., Pine Buttes

quadrangle (Staatz, 1985).

Rhyodacite glassy block in pumiceous lahar on

north flank of Laughlin Peak in the NW|SEi sec.

19, T. 28 N., R. 26 E., Mesa Larga quadrangle.

Rhyodacite from Green Mountain in the NW^NWi

sec. 23, T. 29 N., R. 25 E., Tinaja Mountain

quadrangle.

Rhyodacite/rhyolite from peak 8632 on southwest

flank of Laughlin Peak in NEi sec. 32, T. 27 N.,

R. 26 E., Pine Buttes quadrangle (Staatz, 1985).
40 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

oxide grains in an extremely fine mesostasis of tridymite(?) and glass(?); carbonate occurs rarely.

The rhyodacite unit includes the most siliceous rock 

type in the area, and normative quartz ranges from 20 to 

34 percent (table 23). All of the samples contain very 

little Fe203 . FeO, and MgO, and as a result have only 

small amounts of iron oxide and ferromagnesian minerals 

in their norms.

Neutron activation analysis of a sample from the unit 

(table 24; specimen 80SM12) shows an elemental comTABLE 24. Neutron-activation analysis of a sample of Red Mountain 

Rhyodacite, Raton-Springer area, New Mexico

[Elemental compositions in parts per million. See table 23 for description of sample locality. "<" 

indicates element concentration is below the limit of determination, which is the value 

shown; "±" shows the accuracy of the test. Analyst: Carl Orth, Los Alamos National 

Laboratory]

Field No. 

Lab. No.

Na

Mg

Al

Cl

K

Ca

Ti

V

Mn

Cu

Sr

I

Ba

Dy

U

Ga

As

Br

80SM12 

925106

31,400

9,400

81,000

230

22,000

21,000

2,600

40

422

<300

900

<20

1,390

2.0

±300

±1 , 000

±2 , 000

±50

±2,000

±2,000

±200

±3

±5

±100

±60

±0.3

2.7510.02

<120

<3

<2

Sb

La

Sm

W

Au

Sc

Cr

Fe

Co

Zn

Se

Rb

Ce

Eu

Tb

Yb

Lu

Hf

Ta

Th

<0,

30.

3,

<5

<0.

4.

15

22,700

7

<5

2

34

44

0

<0.

0,

0,

2

1

7,

.4

.9 ±0.6

.0 ±0.1

.01

,38±0.09

±2

±700

.2 ±0.3

.2 ±0.4

±5

±2

.75±0.06

.2

.9 ±0.1

.10±0.02

.9 ±0.3

.6 ±0.2

.3 ±0.3

position similar to average crustal abundance as listed by 

Carl Orth in table 19. The high amount of barium 

possibly is the result of enrichment from local 

sedimentary rocks.

MAFIC FELDSPATHOIDAL ROCKS

The mafic feldspathoidal rocks are chiefly flows, but 

also include cinder cones and plugs. They are predominantly basanitic, although some are nephelinitic and 

tephritic. The rocks called nepheline basalt and hauyne 

basalt by Stobbe (1949, p. 1060) are nephelinite and 

hauyne basanite in the chemical classification of La 

Roche and others (1980). The mafic feldspathoidal rocks 

crop out over a broad area from near Raton eastward to 

Capulin, just east of the map area. They comprise both 

old flows on high mesas, such as Johnson Mesa, as much 

as 1,200 ft (360 mm) above modern drainage, and young 

flows only a few hundred feet above the drainage. Dale 

Mountain on Johnson Mesa (fig. 15) is a shield volcano of 

gently sloping basanite flows. In outcrop, the lavas are 

medium light gray to dark gray, finely crystalline to 

aphanitic, dense, hard, and slightly vesicular, and they 

weather spheroidally (fig. 16). Many vesicles are filled 

with calcite. Phenocrysts are not obvious in hand 

specimen.

Although the feldspathoidal character of many of the 

rocks is not readily apparent even in thin section, it 

shows up in the normative minerals and also becomes 

apparent on sawed surfaces treated with phosphoric acid 

and stained with methylene blue (Shand, 1939). 

Inasmuch as this test for feldspathoidal content was not 

made on all the mafic extrusives, some feldspathoidal 

flows and their cinder cones may be included with the 

basalt on the geologic map (fig. 6).

FIGURE 15. Dale Mountain, a shield volcano of basanite in the NEV4 sec. 17, T. 31 N., R. 26 E., Dale Mountain quadrangle.
IGNEOUS ROCKS 41

.^^^^f^afe v-r, F*.\J < ' . . ; : +-.'* ** 

 W* " -<« ,- * ^- i -A, «

FIGURE 16. Spheroidal weathering and vesicles in basanite (specimen 

80SM44) in roadcut on north side of New Mexico Highway 12 near 

Manco Burro Pass in the NWViSEVaNWVa sec. 10, T. 31 N., 

R. 25 E., Yankee quadrangle. Most vesicles are filled with calcite. 

Long dimension of boulder is 2 ft (0.6 m).

The basanite cinder cones are steep-flanked hills 

composed of scoria, bombs, lapilli, and ash. Many cones 

have breached craters. Most of the cinder cones are in 

the Robinson Peak quadrangle, and Robinson Peak itself 

and Jose Butte were the vents for many basanite flows. 

Erosion has removed some cinder cones and exposed the 

central conduits as conical knobs. Two of these crop out 

in the SWVi sec. 32, T. 27 N., R. 25 E., and in the 

NWVUSfWVi sec. 3, T. 26 N., R. 24 E.

Ages of the basanite flows (table 1, numbers 6, 7, 8, 

and 9) range from late Miocene to at least the end of 

Pliocene time and probably into Pleistocene time in the 

Robinson Peak quadrangle. A K-Ar age on plagioclase 

from the basanite on Johnson Mesa near Manco Burro 

Pass was determined as 7.2 ±0.3 m.y. by Stormer (1972a) 

(7.38 by the new decay constants, table 3); our specimen 

from the same locality yielded an age of 8.19±0.31 m.y. 

(specimen 80SM44, table 1).

In thin section, most of the mafic feldspathoidal rocks 

have porphyritic textures and intersertal, pilotaxitic or 

hyalopilitic groundmasses. Only basanites were found in 

the present study, but nephelinites and ankaratrites 

have been described by other workers (Mertie, 1922; 

Aoki, 1967, table 1; Stobbe, 1949; Stormer, 1972b). The

basanites contain phenocrysts of olivine and clinopyroxene; some also contain plagioclase and opaque oxide. 

Where groundmasses are coarse enough for the recognition of minerals, clinopyroxene, plagioclase, opaque 

oxide, and, in some samples, nepheline are seen. Sparse 

xenocrysts of quartz with pyroxene coronas are seen in 

some specimens. As to the nephelinites, according to 

Stormer (1972b, p. 3302) the olivine nephelinite contains 

phenocrysts of nepheline or hauyne in addition to those of 

olivine and augite. The groundmass is fine grained and 

consists of augite accompanied by either nepheline or 

plagioclase. In addition, Stobbe (1949, p. 1062) noted the 

presence of quartz xenocrysts in some specimens.

Among the samples collected in this study, a basanite 

(specimen 80SM7, table 25, analysis 5) contains about 10 

percent olivine phenocrysts as large as 0.5 mm, many 

with dark rims; 3 percent clinopyroxene phenocrysts as 

large as 0.4 mm, some zoned and with mottled cores; and 

about 5 percent quartz xenocrysts, as large as 0.7 mm in 

diameter, having reaction coronas. Its groundmass is 

inhomogeneous and fine grained and is composed of 

about equal amounts of yellow-brown clinopyroxene 

prisms and equant opaque oxide grains, small amounts of 

intersertal nepheline(?), scattered clumps of an unknown 

material having radiating needles of high positive relief 

and low birefringence, and an unknown colorless isotropic material of negative relief.

Specimen 80SM8, a basanite from sec. 6, T. 30 N., 

R. 28 E. (table 25, analysis 6; locality 6 on fig. 6), is 

porphyritic and contains about 30 percent olivine phenocrysts as large as 0.6 mm showing yellow alteration along 

fractures; 3 percent clinopyroxene phenocrysts as large 

as 0.8 mm, mostly in groups; and sparse quartz xenocrysts having coronas of fine pyroxene and opaque oxide. 

The groundmass has a finely intersertal texture and is 

composed of about equal amounts of clinopyroxene, 

plagioclase, and opaque oxide.

Specimen 80SM21, a basanite from a quarry in the 

NWV4 sec. 16, T. 31 N., R. 26 E. (table 25, analysis 7; 

locality 8 on fig. 6) is porphyritic and contains about 

30 percent olivine phenocrysts as large as 0.6 mm; 

20 percent yellow clinopyroxene phenocrysts; and 

10 percent plagioclase (labradorite) phenocryst tablets as 

large as 0.8 mm. The groundmass is a dense, nearly 

opaque glass and an opaque oxide. About 10 percent of 

the rock is vesicles lined with a material of high relief, 

white in reflected light.

Specimen 80SM44, a basanite from a roadcut in the 

NWV4 sec. 10, T. 31 N., R. 25 E. (table 25, analysis 8; 

locality 9 on fig. 6) is porphyritic and contains about 

20 percent brown-green clinopyroxene phenocrysts as 

large as 0.6 mm, showing hourglass zoning and an optic 

angle of about (+ )45°; 10 percent olivine phenocrysts as 

large as 0.6 mm with iddingsitized rims; and scattered
42 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

TABLE 25. Chemical analyses and norms of mafic

[Data in weight percent.

Field No. 

Lid U IN O .

1 

1

2 

1861

3 

B-15

4 

116

5

80SM7

6 

80SM8

Major oxides

O-f /~\

Al n

Fe 2°3 

FeO 

MgO 

Na20 

K20 - - 

Hn""

Volatiles 1 

MnO 

Total 

36.74 

13.70 

10.85 

1.75 

7.65 

14.37 

4.68 

1.90 

1.42 

1.35 

n.d.

1

O Q 

* O J

2.87 

0.24

99.35

40.66 

12.76 

8.91 

2.89 

9.27 

13.17 

4.22 

1.71 

1.07 

0.20 

n.d. 

2.10 

1.99 

0.24

99.19

40.72 

15.03 

5.52 

6.86 

8.29 

13.95 

4.01 

2.34 

0.32 

0.12 

n.d. 

0.99 

1.75 

0.18

100.08

41.31 

13.91 

5.49 

6.77 

8.32 

12.35 

4.66 

1.46 

1.03 

0.09 

n.d. 

1.99 

1.97 

0.29

99.64

42.1 

12.9 

7.12 

4.21 

8.74 

12.9 

3.4 

0.77 

n.d. 

n.d. 

3.38 

1.92 

1.9 

0.20

99.5

44.2 

13.9 

4.14 

8.42 

9.91 

11.4 

3.2 

1.12 

n.d. 

n.d. 

0.98 

1.79 

1.1 

0.20

100.4

La Roche and others (1980) classification

pRl

2

(

^ tc.

2,230 

Olivine

nephelinite.

458 

2,141 

Ankaratrite/ 

nephelinite.

387 

2,199 

Ankaratrite/ 

nephelinite.

381 

2,016 

Nephelinite

1,078 

2,076 

Basanite

1,158 

1,977 

Basanite

Normative composition

ab -

1C .

di-fs -

ol-fo -

ol-fa -

\_ o

il -

ap 

0.00

0.00

11.14

9.12

O O O 1

15.94

13.77

0.00

4.17

0.00

1.60

1.16

10.43 

3.6

7.04

10.31 

2.01 

11.04 

0.00 

18.65 

17.68 

15.28 

0.00 

5.80 

0.00 

0.00 

4.09 

6.27 

4.07 

4.81

0.00 

0.00 

16.16 

10.88 

18.45 

15.15 

10.49 

3.42 

7.17 

2.58 

1.71 

8.03 

0.00 

1.89 

4.16

8.75 

5.00 

12.90 

0.00 

18.95 

15.10 

10.98 

2.73 

7.03 

1.93 

0.00 

8.07 

0.00 

3.83 

4.73

4.73 

16.84 

18.35 

0.00 

7.07 

14.71 

12.72 

0.00 

6.93 

0.00 

0.00 

8.99 

1.19 

3.79 

4.68

6.66 

13.14 

20.37 

0.00 

7.63 

12.22 

8.18 

3.13 

11.66 

4.92 

0.00 

6.04 

0.00 

3.42 

2.62

Probably mainly 1^0 and C02» calculated assuming all FeO was oxidized to 

of loss on ignition.

DESCRIPTION OF SAMPLE LOCALITIES

during determination

Oxidized olivine nephelinite from Johnson 

Mesa 15 mi (24 km) east of Raton, probably 

from quarry on Dale Mountain in the SW^NWi 

sec. 16, T. 31 N., R. 26 E., Dale Mountain 

quadrangle (Aoki, 1967, table 1). 

Ankaratrite-nephelinite flow from Robinson 

Peak, near northeast corner sec. 9, T. 29 

N., R. 27 E., from flow forming low mesa 

northwest and west of King Ranch headquarters, Robinson Peak quadrangle (sample 

1861 of Stormer, 1972b, tables 1 and 7).

Ankaratrite/nephelinite from flow near Yankee, probably from SEi sec. 12, T. 31 N., R. 24 E., Yankee 

quadrangle (sample B-15 of Mertie, 1922, p. 11). 

Nephelinite from flow near Yankee, center of sec. 14, 

T. 31 N. , R. 24 E., from outlying remnant of flow at 

top of hill just east of Chicorica Creek, Yankee quadrangle (sample 116 of Stormer, 1972b, tables 1 and 7), 

Basanite from SWiNWiNEi sec. 8, T. 29 N. , R. 27 E., 

Robinson Peak quadrangle.

Basanite from NW|NWi sec. 6, T. 30 N., R. 28 E., 

Robinson Peak quadrangle.
IGNEOUS ROCKS 43

feldspathoidal rocks from Raton-Springer area, New Mexico

n.d., not determined]

Sample - 

Field No. 

Lab No. 

7 

80SM21 

D231888

8 

80SM44 

D231897

9 

380

10 

80SM38 

D231896

11 

80SM39 

D229694

12 

117

13 

80SM23 

D229690

14 

110

Major oxides

O -J /"v

A1 2 03 

T?o n * e 2°3

FeO ----- 

MgO 

\_,eiU . 

Na 2 0 

V K2 f\0 - 

Hfv"

n^O 

Volatiles 1 

rp f\

P2°5

Total 

p Rl

R2 

Name -

44.2 

14.7 

6.05 

4.90 

9.71 

11.0 

3.11 

1.48 

n.d. 

n.d. 

0.56 

1.84 

1.20 

0.20

99.0

1,171 

1,968 

Basanite

44.5 

14.2 

5.09 

5.32 

8.24 

11.3 

3.37 

1.36 

n.d. 

n.d. 

3.09 

2.01 

1.05 

0.17

99.7

La

1,126 

1,902 

Basanite

44.54 

14.73 

6.40 

4.68 

9.67 

10.89 

3.27 

1.43 

0.63 

0.14 

n.d. 

1.93 

1.16 

0.18

99.65

Roche and

1,137 

1,943 

Basanite

45.4 

14.8 

6.50 

3.20 

8.93 

10.5 

3.26 

1.70 

n.d. 

n.d. 

1.30 

1.75 

1.21 

0.15

98.7

others (1980)

46.0 

14.6 

3.50 

6.90 

8.27 

11.2 

3.8 

1.55 

n.d. 

n.d. 

1.18 

1.59 

1.2 

0.19

100.0

46.03 

14.78 

5.32 

5.19 

7.91 

9.47 

3.86 

1.37 

2.43 

0.49 

n.d. 

1.90 

0.99 

0.18

99.92

46.6 

14.9 

6.70 

2.90 

8.17 

10.6 

4.2 

1.34 

n.d. 

n.d. 

0.90 

1.74 

1.3 

0.16

99.5

47.03 

16.88 

6.89 

3.78 

5.50 

9.05 

4.69 

1.80 

0.57 

0.12 

n.d. 

1.90 

1.23 

0.17

99.61

classification

1,187 1,031 

1,880 1,895 

Basanite Basanite

1,055 

1,705 

Alkali basalt/ 

basanite.

1,009 

1,839 

Basanite

724 

1,580 

Tephrite

Normative composition

ab 

di-fs 

ol-fo 

ol-fa 

l~ O

mt - 

11 

ap _________

8.88 

16.57 

22.12 

0.00 

5.50 

10.58 

8.78 

0.48 

11.06 

0.67 

0.00 

8.91 

0.00 

3.55 

2.89

8.31 

18.02 

20.28 

0.00 

6.22 

12.78 

10.09 

1.26 

7.81 

1.07 

0.00 

7.63 

0.00 

3.95 

2.57

8.54 

17.80 

21.52 

0.00 

5.51 

10.62 

9.05 

0.17 

10.72 

0.22 

0.00 

9.38 

0.00 

3.70 

2.78

10.31 

20.97 

21.27 

0.00 

3.97 

10.05 

8.68 

0.00 

9.90 

0.00 

0.00 

5.88 

2.61 

3.41 

2.94

9.26 

16.34 

18.41 

0.00 

8.77 

12.47 

8.44 

3.07 

8.69 

3.49 

0.00 

5.13 

0.00 

3.05 

2.87

8.34 

26.32 

19.53 

0.00 

3.97 

9.27 

7.35 

0.87 

9.07 

1.18 

0.00 

7.95 

0.00 

3.72 

2.42

8.02 

24.39 

18.08 

0.00 

6.30 

11.11 

9.60 

0.00 

7.72 

0.00 

0.00 

4.89 

3.42 

3.35 

3.12

10.75 

28.40 

19.89 

0.00 

6.34 

7.24 

6.26 

0.00 

5.31 

0.00 

0.00 

7.30 

1.92 

3.65 

2.94

DESCRIPTION OF SAMPLE LOCALITIES

10.

Basanite from quarry on Dale Mountain, in the 11, 

SW{NWi sec. 16, T. 31 N., R. 26 E., Dale Mountain 

quadrangle. 12, 

Basanite from Johnson Mesa in road cut in the 

SE|NWi sec. 10, T. 31 N., R. 25 E., Yankee 

quadrangle. Same locality as sample 117 of Stormer 

(1972b, tables 1 and 7). 13, 

Basanite from quarry at Dale Mountain in SW|NW{ 

sec. 16, T. 31 N., R. 26 E., Dale Mountain quadran- 14, 

gle (Sample 380 of Stormer, 1972b, tables 1 and 7). 

Basanite from the NWJNEi sec. 20, T. 29 N., R. 28 

E., Capulin quadrangle, Union County.

Basanite from SWiNW{ sec. 13, T. 26 N., R. 25 

E., Point of Rocks Mesa quadrangle. 

Alkali basalt/basanite from northwestern part 

of Johnson Mesa in a road cut in NW| sec. 10, 

T. 31 N., R. 25 E., Yankee quadrangle (sample 

117 of Stormer, 1972b, tables 1 and 7). 

Basanite from a quarry in the SW^-NWi- sec. 23, 

T. 29 N., R. 27 E., Kiowa quadrangle. 

Tephrite from mesa south of buildings at El 

Rancho Grande in the SW{ sec. 28, T. 27 N., 

R. 26 E., Pine Buttes quadrangle (sample 110 

of Stormer, 1972b, tables 1 and 7).
44 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

plagioclase phenocrysts as large as 0.5 mm. The groundmass has an intersertal texture and is composed of 

plagioclase, opaque oxide, iddingsitized olivine, clinopyroxene, and an unknown interstitial material of negative 

relief and low birefringence. The specimen also has 

scattered carbonate vesicle fillings.

Specimen 80SM38, a basanite from the NEVi sec. 20, 

T. 29 N., R. 28 E., in Union County just outside the 

mapped area (table 25, analysis 10), is porphyritic and 

contains about 15 percent cloudy, pale-greenish-yellow 

clinopyroxene in stubby phenocrysts as large as 0.3 mm 

and in aggregates; 10 percent poorly formed olivine 

phenocrysts as large as 0.5 mm; and, rarely, platy 

plagioclase phenocrysts as large as 0.3 mm. The groundmass is composed of abundant clinopyroxene and opaque 

oxide and moderate amounts of plagioclase and feldspathoids(?). One feldspathoid is of low birefringence and 

low positive relief (nepheline?), and another is isotropic 

and has strong negative relief. Scattered vesicles have 

irregular shapes.

Specimen 80SM39, a basanite from the NWVi sec. 13, 

T. 26 N., R. 25 E., Point of Rocks Mesa quadrangle 

(table 25, analysis 11; locality 7 on fig. 6) has a porphyritic texture and contains about 20 percent stubby paleyellow-green clinopyroxene phenocrysts as large as 

0.3 mm; 15 percent well-formed olivine phenocrysts as 

large as 2.5 mm and rimmed orange brown; and 5 percent 

opaque oxide crystals as large as 0.2 mm that are in part 

included in the olivine and clinopyroxene phenocrysts. 

The groundmass is composed of abundant clinopyroxene 

and opaque oxide and many plagioclase tablets. Sparse 

xenocrysts of quartz with coronas are present. Vesicles 

are lined with carbonate and acmite(?).

Specimen 80SM23, a basanite from a quarry in the 

NWVi sec. 23, T. 29 N., R. 27 E., Kiowa quadrangle 

(table 25, analysis 13) is porphyritic and contains about 

10 percent olivine phenocrysts as large as 0.2 mm; 

10 percent zoned pale-yellow-green clinopyroxene phenocrysts as large as 0.3 mm (rarely 1 mm); 5 percent 

equant opaque oxide phenocrysts as large as 0.5 mm; and 

about 5 percent quartz, hornblende (opacite) xenocrysts, 

and aggregates. The groundmass is a pilotaxitic mat of 

clinopyroxene prisms, plagioclase laths, opaque oxide, 

and scattered carbonate.

Chemical analyses and norms of the mafic feldspathoidal rocks (table 25) show considerable variation. 

None of the norms include quartz, although Si02 ranges 

in abundance from 36.74 to 47.03 percent, and xenocrystic quartz is present in a few samples. The relation 

between the high CaO content and the low K20 and Na20 

contents is also expressed in the norms as a high anorthite content and low orthoclase and albite contents.

TABLE 26. Neutron-activation analysis of a sample of basanite from 

near Folsom, New Mexico

[Elemental compositions in parts per million. See table 25 for description of sample locality. 

"<" indicates element concentration is below the limit of determination, which is the value 

shown; "±" shows the accuracy of the test. Analyst: Carl Orth, Los Alamos National 

Laboratory]

Field No. 80SM8 

Lab. No. 925105

Na

Mg

Al

Cl

K

Ca

Ti

V

Mn

Cu

Sr

I

Ba

Dy

U

Ga

As

Br

26,000

60,000

75,000

720

<5,000

82,000

8,800

254

1,680

<400

1,300

<30

840

4.

2.

<100

<4

<3

±300

±2,000

±2 , 000

±60

±4 , 000

±400

±9

±20

±200

±70

.5 ±0.4

,95+0.02

Sb

La

Sm

W

Au

Sc

Cr

Fe

Co

Zn

Se

Rb

Cs

Ce

Eu

Tb

Yb

Lu

Hf

Ta

Th

<0,

93

9,

<7

<0.

27.

350

99,000

57

180

<2

<20

<0.

148

2.

1.

2.

0.

4.

2.

11.

.6

±1

.4 ±0.4

.02

.6 ±0.5

±30

±3,000

±2

±30

,8

±5

,7 ±0.1

0 ±0.1

9 ±0.2

33±0.04

1 ±0.4

6 ±0.3

9 ±0.5

Neutron activation analysis of a young basanite 

(80SM8) shows that five elements, barium, chromium, 

magnesium, thorium, and titanium, regarded by Carl 

Orth (written commun., 1983) to be diagnostic of mantle 

origin, exceed average crustal abundance and suggest to 

us a probable upper mantle origin. (See discussion and 

conclusions.) Basanite from the mafic feldspathoidal 

rocks is shown in table 26.

BASALTIC TO LATIANDESITIC 

EFFUSIVE ROCKS

The basaltic and latiandesitic rocks of the RatonSpringer area range in age from Pliocene to Holocene, 

overlapping the ages of some of the mafic feldspathoidal 

lavas. They form dark lava flows, most of which issued 

from vents now marked by steep-sided (30°) cinder 

cones. (The Raton I°x2° quadrangle contains 96 such 

cones, of which 66 are in the eastern part under 

consideration here.) A few vents lack prominent cinder 

cones (fig. 17), either because the easily eroded cinders 

have been removed or because relatively little pyroclastic material was erupted; these vents are surrounded by 

gently sloping lava flows, forming low shield volcanoes 

and mesas. Exposures of dikes are few. One crops out 

near the northeast corner of the map area but is not 

shown on figure 6; it extends for 9 mi (14.5 km) northeastward into Colorado and locally is 10 ft (3 m) thick and 

has well-developed columnar jointing (fig. 18).
IGNEOUS ROCKS 45

FIGURE 17. Volcanic vent at south edge of Juan Torres Mesa, revealed in cross section by erosion. Vent lies just north of the TO Ranch

headquarters in the SEV4 sec. 22, T. 30 N., R. 25 E., Hunter Mesa quadrangle.

FIGURE 18. Olivine basalt dike with joints perpendicular to its walls in the SW1/iSW1/4 sec. 14, T. 35 S., R. 60 W., Trinchera Pass quadrangle.
46 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

Individual flow sheets may represent separate 

eruptions or merely separate surges of magma in the 

same eruptive episode. Flows generally are disconformable with the underlying and overlying flows, from which 

they are commonly separated by scoria, reddened zones, 

and ash. Under the lowermost flow of a series, a layer of 

basaltic ash and lapilli, locally more than 6 ft (1.8 m) 

thick, may lie between the flow itself and the gravel floor 

of a former valley.

Several approaches have been used in the past for 

subdividing these rocks. Mertie (1922) and Collins (1949, 

p. 1025-1026) divided them according to relative age 

estimated on the basis of degree of weathering and depth 

of dissection. Collins (1949), without distinguishing 

between basaltic and feldspathoidal lavas, assigned them 

to "Raton" (oldest), "Clayton" (intermediate), and 

"Capulin" (youngest) lavas. Stormer (1972b) set apart 

the mafic feldspathoidal lavas as a separate group 

overlapping in age with the basaltic rocks. He noted that 

the rate of dissection in the western part of the area was 

markedly greater than in the eastern part, owing to the 

Canadian River and its tributaries, and divided the 

basaltic rocks into only two groups: "Raton-Clayton" 

(older) and "Capulin" (younger). His "Raton-Clayton" 

group consisted mainly of alkali basalts that have a 

holocrystalline groundmass and contain only large olivine 

crystals as phenocrysts. His "Capulin" group consisted of 

those basalts that contain resorbed and cloudy plagioclase phenocrysts in addition to large olivine phenocrysts 

and that have a fine-grained, commonly clouded glassy 

groundmass.

Here we will follow an arrangement similar to those 

proposed by Mertie (1922) and by Collins (1949). These 

units, as given in figures 5 and 6, are the Raton (oldest), 

Clayton (intermediate), and Capulin (youngest). Based 

on comparative physiographic studies in this area and in 

adjacent areas to the north (Levings, 1951; Pillmore and 

Scott, 1976), rough allowance has been made here for 

rates of dissection that are less in the poorly drained 

eastern part of the area than in the western part. As an 

example, the basanite flow in the SW^NW1/^ sec. 23, 

T. 29 N., R. 27 E., on Melon Mesa in eastern Colfax 

County, might appear to be very young, judged merely 

on its topographic position a few tens of feet above 

stream level. Overlying this flow, however, is a welldeveloped calcrete layer, apparently equivalent to the 

prominent calcrete soil horizon on the Ogallala Formation of Miocene age, which could make this flow as old as 

3-6 m.y. It has been assigned here as age-equivalent to 

the Raton Basalt. Another flow of basaltic composition in 

the NW*/4 sec. 34, T. 27 N., R. 27 E., lies at stream level; 

however, it also has a well-developed calcrete layer on 

it; therefore we consider it contemporaneous with the 

Clayton Basalt.

TABLE 27. Heights of basaltic and latitic flows above major nearby 

streams or valley floors in the Raton-Springer area, New Mexico

[Age correlations by Collins (1949) and by usj

Map 

No. 1 Location Feet Meters

Raton Basalt (Tb on fig. 19)

1

2

3

4

5

6

7

8

9

10

11

12

13

Barela (Barilla) Mesa ----------

Bartlett Mesa ------------------

Horse Mesa ---------------------

Johnson Mesa (west end) --------

Hunter Mesa --------------------

Upper Juan Torres (Meloche) Mesa

Chavez Mesa --------------------

Kelleher Mesa ------------------

Dry Mesa -----------------------

Buckhorn Mesa ------------------

Johnson Mesa (southeastern part)

Mesa Larga ---------------------

Kiowa Mesa2 --------------------

1,200

1,200

1,200

1,200

1,200

1,200

1,100

1,100

1,000

600

600

600

500

366

366

366

366

366

366

335

335

305

180

180

180

150

Clayton Basalt (Qcb on fig. 19)

14

15

16

17

18

19

20

21

22

23

24

25

26

Lower Juan Torres (Meloche) Mesa

Eagle Tail Mountain ------------

Griego Mesa --------------------

Black Mesa ---------------------

Dwyer Mesa ---------------------

Blosser Mesa -------------------

Tinaja Mesa --------------------

Flows near Cunningham Butte

Troyburg Mesa ------------------

Loco Mesa ----------------------

Flow in NEk Lawrence Arroyo

quadrangle 3 ------------------

Flow in NWk Lawrence Arroyo

quadrangle 3 ------------------

Round Mesa (Not Round Mesa of

Collins, 1949) ---------------

550

400

400

300

300

300

300

240

200

200

200

200

200

165

120

120

90

90

90

90

72

60

60

60

60

60

1 0n figure 19.

2 Assignment to the Raton Basalt is uncertain.

3 Not shown on figure 19.

Table 27, on the other hand, shows the heights above 

modern valley floors of some of the more westerly 

basaltic flows. Those assigned to Raton Basalt age, for 

instance, range in heights from 500 to 1,200 ft (150 to 366 

m) above valley floors. Several high-standing flows 

assigned by Stormer (1972b) to his "Capulin" group 

among them those of Eagle Tail, Tinaja, Dwyer, and 

Blosser Mesas (fig. 6) are here deemed equivalent to 

the Clayton Basalt. The few radiometric ages determined for the Raton, Clayton, and Capulin rocks in the 

present study (table 1) and those taken from the 

literature (table 3) range from about 4 m.y. to somewhat 

less than 8,000 years (Baldwin and Muehlberger, 1959, 

p. 129). Thus far no alkali basalt has been found to be as 

old as the 8.2-m.y. age of the basanite flow near Manco
IGNEOUS ROCKS 47

Burro Pass on the north edge of Johnson Mesa (locality 9, 

table 1 and fig. 6). To establish the limits of each age unit 

and to identify the lava flows contained in each would 

require a much more detailed field and laboratory study.

In addition to measuring the heights of the Raton, 

Clayton, and Capulin flows above modern drainage, we 

have also attempted to infer the drainage system of the 

area near Raton during late Tertiary and early 

Quaternary time. Reconstructed paleovalleys of Raton 

Basalt, Clayton Basalt, and Quaternary ages are drawn 

on a map of the northern part of the Raton-Springer area 

(fig. 19). The areas encompassed by the Raton and 

Clayton paleovalleys were delimited by using K-Ar ages 

of rocks and heights of the mesas above present valley 

floors. The heights shown in table 27 can be used by the 

reader to assess the validity of the paleovalleys shown on 

figure 19. Notice that there are no topographically low 

(Clayton) surfaces within the bounds of the Raton paleovalley and conversely no high (Raton) surfaces within the 

limits of the Clayton surface. The Raton paleovalley 

obviously was much wider before the creation of the 

Clayton paleovalley; indeed we saw no preserved valley 

wall on either the north or south flank of the ancient 

Raton paleovalley, surely owing to later erosion when 

streams cut downward to a new Clayton valley.

The mid-Pleistocene paleovalley is shown only by a line 

which marks the approximate center of a buried valley 

that extends toward Capulin. The subsurface expression 

of this valley was located by drilling and described to us 

by ranchers living west of Capulin. We have shown no 

Capulin paleovalleys on figure 19 because the Capulin 

flows (Qb on fig. 6) still occupy the valleys and therefore 

are easy to recognize. The Capulin paleovalleys are 

essentially the same as the present drainage system.

The radiometric ages of the dated Raton, Clayton, and 

Capulin basaltic and latitic rocks range from about 4 m.y. 

to somewhat less than 8,000 years (Baldwin and Muehlberger, 1959, p. 129). Thus far, no olivine basalt has been 

dated that is as old as the 8.2±0.3 m.y. basanite flow 

near Manco Burro Pass, although the oldest flow on 

Fishers Peak Mesa (Fishers Peak quadrangle, Colorado), just north of Raton, could be older than 4.0 m.y.

Five samples of the basaltic-latiandesitic rocks were 

analyzed for K-Ar age. An alkali basalt from Mesa Larga 

(80SM31, table 1; locality 5 on fig. 6) shows an age of 

3.95±0.19 m.y., which is very close to the age of 3.5±0.2 

m.y. obtained by Stormer (1972a) (3.59±0.2 m.y. by the 

new decay constants) for the olivine basalt on Bartlett 

Mesa north of Raton (table 3). Both of these flows are 

included here as the Raton Basalt. The four other 

basaltic to latiandesitic flows dated by us (table 1) range 

from 1.27 to 0.66 m.y. and are included here as the 

Clayton Basalt.

RATON BASALT

Raton Basalt caps the highest and longest mesas in the 

area. Many sheets of lava are included in the unit, but 

their vents are generally no longer marked by cinder 

cones. Collins (1949) named the Raton after Raton Mesa 

in Colorado, considered here to be the type area. Most of 

the analyzed specimens of the Raton Basalt flows and 

cinder cones are olivine basalts and alkali basalts; a few 

are trachybasalts and latibasalts. In hand specimen the 

rocks are medium gray to black, very hard, and in part 

vesicular. Some have a silvery sheen on a fresh break, 

apparently owing to fine diktytaxitic texture. They are 

visibly porphyritic, typically having only olivine phenocrysts, though some flows include phenocrysts or xenocrysts of other minerals. Altered phenocrysts of olivine 

appear as red or brown specks.

Rocks of the Raton examined in thin section are 

porphyritic and contain phenocrysts of one or more of 

these minerals: olivine, plagioclase, clinopyroxene, apatite, and opaque oxides. Some samples also have xenocrysts of hornblende (opacite). Specimen 80SM31 (table 

28, analysis 1; locality 5 on fig. 6), an alkali basalt from 

Mesa Larga, is porphyritic and contains 10 percent 

stubby olivine phenocrysts as large as 2 mm, rimmed 

with orange-brown iddingsite alteration, and scattered 

opaque oxide. The groundmass is intergranular in texture and composed of abundant stubby clinopyroxene 

crystals and plagioclase (labradorite) plates, and many 

olivine and opaque oxide crystals.

Specimen 80SM11 (table 28, analysis 10), a trachybasalt/alkali basalt from the SWVi sec. 30, T. 28 N., 

R. 27 E., Kiowa quadrangle, is porphyritic and contains 

about 10 percent plagioclase (andesine?) phenocrysts as 

thin laths ranging from 0.3 mm down to groundmass size; 

5 percent hornblende (opacite) ghosts as long as 1 mm; 

3 percent equant opaque oxide crystals; traces of palegreen-yellow clinopyroxene phenocrysts as large as 

0.6 mm; and apatite. The groundmass is somewhat 

vesicular, has subtrachytic texture, and is composed of 

plagioclase, clinopyroxene(?), and opaque oxide.

Specimen 81SM6 (table 28, analysis 11), a trachybasalt/alkali basalt from the middle of sec. 36, T. 27 N., 

R. 26 E., Pine Buttes quadrangle, is porphyritic and 

contains about 10 percent altered hornblende (now opacite) phenocrysts as long as 0.4 mm; 5 percent clear 

pale-yellow clinopyroxene phenocrysts as long as 

1.5 mm; and scattered dusty apatite as large as 0.2 mm. 

The groundmass has a trachytic texture, consists mainly 

of plagioclase (labradorite?), and has lesser amounts of 

clinopyroxene and opaque oxide crystals in alkali feldspar(?). Also present are a few fine-grained xenoliths.
48 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

TABLE 28. Chemical analyses and norms of samples ofRaton Basalt from the Raton-Springer

[Data in weight percent, n.d., not determined]

Sample - - 

Field No. 

Lab No . - -

Si02 ---- 

A1 2 0 3 --- 

Fe 2 0 3 --- 

FeO ----- 

MgO -----

CaO ----- 

Na2 0 ---- 

Kn

H2 0+ ---- 

H20" ----

Volatiles 1 

Ti02 ----

P2°5 - 

MnO -----

co2 -----

Total

RI P ------

R2 ------ 

Name - - - -

q -------

=K ------

di-wo --- 

di-en --- 

di-fs ---

hy-en --- 

hy-fs --- 

ol-fo --- 

ol-fa --- 

mt ------

il ------

ap ------

1

80SM31 

D231894

45.4 

13.8 

5.35 

6.07 

11.0

9.76 

2.95 

1.34 

n.d. 

n.d.

1.00 

1.82 

0.83 

0.17 

n.d.

99.5

1,321 

1,870 

Olivine 

alkali 

basalt.

0.00 

8.04 

20.59 

20.76 

0.00

2.57 

9.55 

7.42 

1.09

0.00 

0.00 

14.28 

2.32 

7.87

0.00 

3.51 

2.00 

0.00

2 

MHS-88-80 

D229969

45.6 

15.1 

7.00 

5.20 

6.86

11.4 

3.1 

1.06 

1.79 

0.20

n.d. 

1.45 

1.1 

0.18 

0.12

100.2

1,334 

1,859 

Basalt

0.00 

6.38 

25.94 

24.59 

0.00

0.42 

10.39 

8.35 

0.83

0.00 

0.00 

6.34 

0.70 

10.33

0.00 

2.80 

2.65 

0.28

3 

81SM11 

D237462

46.2 

15.1 

3.91 

7.91 

9.18

10.3 

3.01 

0.99 

n.d. 

n.d.

1.14 

1.52 

0.61 

0.19 

n.d.

100.1

La Roche

1,419 

1,852 

Alkali 

basalt.

0.00 

5.91 

21.43 

25.03 

0.00

2.34 

9.43 

6.25 

2.50

0.00 

0.00 

11.81 

5.20 

5.73

0.00 

2.92 

1.46 

0.00

4 

MHS-68-82 

D246866

Major

46.2 

17.0 

7.27 

3.54 

4.80

9.40 

3.73 

1.82 

n.d. 

n.d.

2.22 

1.86 

1.33 

0.18 

n.d.

99.4

and others

994 

1,580 

Trachybasalt.

Normative

0.00 

11.06 

30.34 

24.97 

0.00

1.16 

5.87 

5.08 

0.00

0.00 

0.00 

5.06 

0.00 

6.80

2.79 

3.63 

3.24 

0.00

5 

293

oxides

48.82 

15.34 

3.28 

7.94 

7.44

9.28 

3.45 

0.90 

0.64 

0.06

n.d. 

1.59 

0.42 

0.18 

n.d.

99.34

6 

2

48.87 

15.75 

3.28 

8.29 

7.35

9.26 

3.53 

0.85 

0.55 

0.19

n.d. 

1.13 

0.50 

0.15 

n.d.

99.70

7 

80SM24 

D231889

49.1 

16.5 

4.37 

6.51 

7.28

9.47 

3.32 

0.88 

n.d. 

n.d.

0.86 

1.54 

0.40 

0.16 

n.d.

100.4

8 

L-515

49.73 

15.46 

3.32 

8.14 

7.20

9.63 

3.30 

0.87 

0.32 

0.16

n.d. 

1.59 

0.42 

0.13 

n.d.

100.27

9 

3

49.74 

14.98 

7.42 

4.68 

5.79

8.43 

3.59 

1.25 

1.40 

0.46

n.d. 

1.15 

0.53 

0.18 

n.d.

99.60

(1980) classification

1,488 

1,673 

Alkali 

basalt.

composition

0.00 

5.39 

29.59 

24.03 

0.00

0.00 

8.29 

5.14 

2.66

2.42 

1.25 

7.86 

4.48 

4.82

0.00 

3.06 

1.01 

0.00

1,468 

1,672 

Olivine 

alkali 

basalt.

0.00 

5.07 

30.18 

24.87 

0.00

0.00 

7.61 

4.53 

2.70

1.48 

0.88 

8.75 

5.76 

4.80

0.00 

2.17 

1.20 

0.00

1,550 

1,691 

Olivine 

basalt.

0.00 

5.22 

28.22 

27.64 

0.00

0.00 

7.07 

4.86 

1.64

6.05 

2.03 

5.12 

1.90 

6.36

0.00 

2.94 

0.95 

0.00

1,321 

1,689 

Olivine 

basalt.

0.00 

5.15 

27.98 

24.85 

0.00

0.00 

8.46 

5.16 

2.83

5.52 

3.03 

5.10 

3.08 

4.82

0.00 

3.03 

1.00 

0.00

1,334 

1,496 

Olivine alkali 

basalt/latibasalt .

2.25 

7.56 

31.07 

21.55 

0.00

0.00 

7.38 

6.09 

0.38

8.66 

0.54 

0.00 

0.00 

11.00

0.00 

2.23 

1.28 

0.00

1 Probably mainly H2 0 and C02 , calculated assuming all FeO was oxidized to Fe 2 0 3 during determination of

Chemical analyses and norms of the rocks of the Raton 

Basalt (table 28) show a broad range in composition, 

including alkali basalt, olivine basalt, latibasalt, and 

trachybasalt. The analyzed basalts contain from 45.4 to 

51.68 percent Si02 , but most have no normative quartz.

CLAYTON BASALT

The Clayton Basalt includes olivine basalt, trachybasalt, trachyandesite, and latiandesite. Collins (1949) 

named the Clayton after outcrops in the area he called
IGNEOUS ROCKS 49

area, New Mexico

Sample -- 10 11 12 

Field No. 80SM11 81SM6 L-512 

Lab No.-- D229691 D237460

Major oxides

Si02 ---- 50.4 50.4 51.68 

A1 2 03 --- 17.2 15.9 15.05 

Fe 2 03 --- 5.65 5.48 5.22 

FeO ----- 2.61 2.60 5.64

MgO ----- 3.8 5.08 5.63 

r^n ----- Q9s Q i T. R ^n

Na2 0 ---- 4.6 4.65 3.75 

Kn i 01 o ^ f\ ^ IQ

H2 0+ ---- n.d. n.d. 0.62 

H2 0" ---- n.d. n.d. 0.72

Volatiles 1 1.98 1.10 n.d. 

Ti02 ---- 1.08 1.26 1.54

P2°5 """ 1 ' 2 1 ' 46 °- 45 

MnO ----- 0.17 0.15 0.12

Total 99.9 99.3 100.11

La Roche and others (1980) classification

RI ------ 1,037 980 1,468

R2 ------ 1,518 1,551 1,471 

Name ---- Trachybasalt/ Trachybasalt/ Latibasalt/ 

alkali alkali andesibasalt. basalt. basalt.

Normative composition

q ------- 0.00 0.00 1.88 

or ------ 11.52 12.63 8.31

ab ------ 37.40 36.01 32.12

an ------ 21.08 16.59 20.37

c ------- 0.00 0.00 0.00

ne ------ 1.27 2.18 0.00

di-wo --- 7.42 8.26 7.65 

di-en --- 6.41 7.14 5.50 

di-fs --- 0.00 0.00 1.46

hy-en --- 0.00 0.00 8.69 

hy-fs --- 0.00 0.00 2.31 

ol-fo --- 2.28 4.02 0.00 

ol-fa --- 0.00 0.00 0.00 

mt ------ 5.96 5.31 7.66

hm ------ 1.66 1.91 0.00

il ------ 2.09 2.43 2.96

ap ------ 2.90 3.52 1.08 

cc ------ 0.00 0.00 0.00

loss on ignition.

the Folsom-Clayton Mesa near Clayton, N. Mex. We 

consider a widespread basalt flow on the mesa surmounted by Mount Clayton to be the type area. The 

physiographic positions of the flows (table 27), about 100

DESCRIPTION OF SAMPLE LOCALITIES

1. Olivine Alkali basalt from Mesa Larga in the 

SWkSWk sec. 34, T. 29 N. , R. 26 E. , Mesa Larga 

quadrangle . 

2. Basalt from 100 m north of county road A-8 

between two drainages of Tinaja Creek in the 

NWkSE>i sec. 5, T. 27 N. , R. 26 E. , Pine Buttes 

quadrangle (Staatz, 1985). 

3. Alkali basalt from the SWkSEk sec. 9, T. 21 N. , 

R. 28 E. , Valencia Spring quadrangle, south of 

the Raton- Springer area. 

4. Trachybasalt on top of bluff south side of Joe 

Cabin Arroyo , directly south of El Rancho Grande 

in the SWkSEkSEk sec. 27, T. 27 N. , R. 26 E. , 

Pine Buttes quadrangle (Staatz, 1985). 

5. Alkali basalt from Bartlett Mesa, 36°51'32" N. , 

104°24'55" W., probably from road in NEkNWk sec. 

8, T. 31 N., R. 24 E. , Raton quadrangle (sample 

293 of Stormer, 1972b, tables 1 and 7). 

6. Olivine alkali basalt from Bartlett Mesa, 

probably from same locality as sample 5 above 

(Aoki, 1967, table 1), Raton quadrangle. 

7. Olivine basalt that overlies red zone in road 

cut just south of Wagon Mound in the SWkSEk sec. 

33, T. 21 N., R. 21 E. , Wagon Mound quadrangle. 

Collected by C.L. Pillmore. 

8. Olivine basalt from the south rim of Barela Mesa 

at the mouth (source?) of Chicorica Creek, 

Yankee quadrangle (sample L-515 of Mertie, 1922, 

p. 11). 

9. Olivine alkali basalt/latibasalt from Little 

Mesa, probably in the NEk sec. 3, T. 31 N. , R. 

25 E., Yankee quadrangle (Aoki, 1967, table 1). 

10. Olivine trachybasalt/basalt from the SWk sec. 

30, T. 28 N., R. 27 E. , Kiowa quadrangle. 

11. Trachybasalt/alkali basalt from landslide 

deposit near middle of sec. 36, T. 27 N. , R. 26 

E. , Pine Buttes quadrangle. 

12. Olivine latibasalt/andesibasalt from the east 

rim of Barela Mesa near Yankee, Yankee quadrangle (sample L-512 of Mertie, 1922, p. 11).

to 400 ft (30 to 120 m) above major drainage, suggest 

ages between 2.0 and 0.5 m.y. K-Ar ages determined on 

four Clayton rocks (table 1, analyses 1^4) range from 

1.27±.71 m.y. to 0.66±.12 m.y. From geomorphic 

evidence we infer an age range of 2 to 0.5 m.y. The 

conical cinder cones of ash, cinders, and bombs are much 

better preserved and less modified by erosion than are 

the cones of the Raton Basalt. 

In hand specimen, the Clayton rocks are black to 

medium gray, fine to medium grained, porphyritic, and 

mostly dense. The Clayton flows are more scoriaceous 

than the Raton flows. Some have a silvery sheen. Some 

have obvious flow structure and the lava commonly 

shows well-formed to crudely formed columnar joints. 

Some flows contain xenoliths, the most common of which 

are rhyodacite.
50 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

104°00'

R23 f; R24E R25E R26F R27 E

10 MILES

5 10 

EXPLANATION

I 

15 KILOMETERS

Clayton Basalt

Raton Basalt

Mafic feldspathoidal rocks

22 Measurement locality listed in table 27

 Line of approximate equal elevation

 ^- Approximate position of ancient stream

FIGURE 19. Inferred paleovalleys of late Tertiary and Quaternary age near Raton, N. Mex. Stream positions shown represent the times of 

the Raton Basalt and mafic feldspathoidal rocks (8.2-3.0 m.y.), the Clayton Basalt (2.0-0.5 m.y.), the ancestral Canadian River and 

tributary (1.4-0.6 m.y.), the eastward channel toward Capulin (700,000 years and later), and the present channel of the Canadian River 

(commencing about 120,000-130,000 years ago). The lines of approximate equal elevation (dashed) also show the inferred shapes and slopes 

of the valley floors.
IGNEOUS ROCKS 51

Microscopic examination of four samples of basalt and 

latiandesite of the Clayton shows them to be more 

phenocryst rich than the Raton Basalt. Phenocrysts 

include olivine, augite, plagioclase, and, less commonly, 

orthopyroxene and oxyhornblende. Xenocrysts of quartz 

and feldspar are sporadically present. Some flows 

contain no obvious phenocrysts.

Specimen 80SM1 (table 29, analysis 1; locality 1 on 

fig. 6), from an olivine basalt flow containing scattered 

large xenoliths of rhyodacite, is porphyritic and contains 

about 15 percent olivine phenocrysts as large as 1.6 mm, 

5 percent clinopyroxene (augite) phenocrysts as large as 

0.4 mm, some in clots as large as 1 mm, and 3 percent 

plagioclase (labradorite) phenocrysts as large as 0.4 mm. 

The groundmass is intergranular in texture and is 

composed of plagioclase tablets, stubby clinopyroxene 

crystals, opaque oxide crystals, and sparse quartz xenocrysts.

Specimen 80SM4 (table 29, analysis 3; table 30), a 

basalt from a road cut at the east end of Eagle Tail 

Mountain, is porphyritic and composed of the following: 

about 15 percent plagioclase (labradorite) phenocrysts as 

large as 1 mm; 10 percent clinopyroxene phenocrysts as 

large as 0.2 mm, commonly in groups; and 5 percent 

olivine phenocrysts as large as 1.2 mm. The groundmass 

has an intergranular texture and consists of much plagioclase and lesser amounts of clinopyroxene and opaque 

oxide.

Specimen 80SM2 (table 29, analysis 5; locality 3 on 

fig. 6), a trachybasalt from Juan Torres Mesa in the 

Johnson Park quadrangle, is porphyritic and contains 

about 10 percent olivine phenocrysts as large as 2 mm, 

10 percent clinopyroxene phenocrysts as large as 

1.5 mm, and scattered plagioclase (labradorite) phenocrysts in tablets as large as 1 mm. Its groundmass is 

inhomogeneous, has an intersertal texture, and is composed of plagioclase, clinopyroxene, and opaque oxide in 

varying proportions. Also present are scattered xenocrysts of strongly fritted alkali feldspar with labradorite 

overgrowths, and quartz with coronas of clinopyroxene.

Specimen 80SM15 (table 29, analysis 9; locality 2 on 

fig. 6), a latite/trachyandesite from the NWV4 sec. 15, 

T. 26 N., R. 27 E., Lawrence Arroyo quadrangle, is 

vesicular, has a trachytic to pilotaxitic texture, and is 

composed of the following: about 45 percent plagioclase 

tablets as large as 0.1 mm, 35 percent interstitial alkali 

feldspar, 15 percent opaque oxide grains, 5 percent of an 

unknown, red, nearly opaque mineral as tiny platelets, 

and scattered opacite pseudomorphs after hornblende.

Specimen 80SM16 (table 29, analysis 10; locality 4 on 

fig. 6), a latiandesite from the southeastern flow of Las 

Mesetas, Lawrence Arroyo quadrangle, has a seriate 

texture and is composed of the following: about 65 

percent plagioclase (andesine) as large as 1.5 mm,

15 percent pleochroic pale-green to pale-brown orthopyroxene crystals as large as 0.4 mm, 7 percent strongly 

opacitized oxyhornblende crystals, 7 percent clinopyroxene as large as 0.6 mm, 6 percent fine opaque oxide 

grains, and sparse titanite and sphene crystals.

Chemical analyses and norms of the Clayton Basalt 

(table 29) show that almost all of the rocks are higher in 

Si02 than rocks of the Raton Basalt. In addition, a few of 

the rocks have quartz in their norms. CaO exceeds 

combined Na20 and K20 in the less silicic, more mafic 

rocks of the Clayton, whereas in the more silicic, less 

mafic rocks the Na20 and K20 together are nearly equal 

in abundance to CaO. As a result the normative anorthite 

of the more mafic group greatly exceeds normative 

orthoclase, but in the less mafic rocks these two are 

roughly equal.

The result of a neutron activation analysis (table 30) of 

specimen 80SM4 shows that amounts of 23 elements 

exceed average crustal abundance, including 5 of the 

most diagnostic elements. We infer that the source of 

this specimen, and possibly of the Clayton unit, was the 

lower crust.

CAPULIN BASALT

The Capulin Basalt is widespread in the eastern part of 

the Raton-Springer area, cropping out as flows and 

cinder cones along Trinchera Creek just south of the 

Colorado-New Mexico border, at the confluence of 

Cherry Creek and the Dry Cimarron River, and in the 

valleys east and west of Dry Mesa. To the south it caps 

Loco Mesa and forms Horseshoe Crater (fig. 20A) and 

The Crater (Twin Craters) southwest of Pine Buttes. To 

the east of the map area it forms Capulin Mountain 

(fig. 205) and other nearby vents and flows. Collins 

(1949) named the Capulin after the cone and flows of 

Capulin Mountain. We consider the type area to occur in 

sec. 4, T. 29 N., R. 28 E., Union County, N. Mex.

The flows of this group, where not mantled by ash, 

generally are only sparsely vegetated, have rough clinkery and spinose surfaces, and commonly have tumuli on 

their surfaces. The steep-flanked cones (fig. 205) range 

in height from a few hundred feet to 1,500 ft (450 m) and 

are composed of ash (fig. 21), scoria, bombs, and blocks in 

various states of induration. Mertie (1922, p. 11) 

observed that Capulin volcanism, compared to the Raton 

and Clayton episodes, was characterized by greater 

development of central eruption and by more explosive 

activity, which produced a greater abundance of pyroclastics and more vesicular lava.

The rocks of the Capulin Basalt are strikingly inhomogeneous, even within a single thin section. Sample 

analyses (table 31) show that they range from andesibasaltic to latibasaltic, but some alkali basalts have also
52 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

TABLE 29. Chemical analyses and norms of samples of Clayton Basalt from the Raton-Springer area, New Mexico

[Data in weight percent, n.d., not determined]

Sample

Field No.

Lab No.

Si02 

A120 3 

Fe 2°3 

FeO - 

MgO 

CaO 

Na2 0 

K20 

H2 0+ 

H2 0~ 

Vols. 1 

Ti02 

P2 05 

MnO 

co2 

Total

RI 

DR2

Name 

q - -

or 

ab 

an 

c 

ne 

di-wo 

di-en 

di-fs 

hy-en 

hy-fs 

ol-fo 

ol-fa 

mt 

hm 

il 

ap 

cc 

1

80SM1

D229681

50.0

14.6

2.06

7.50

9.97

9.45

3.2

1.26

n.d.

n.d.

0.84

1.29

0.50

0.16

n.d.

100.8

1 ,593

1,777

Olivine

basalt.

0.00

7.44

27.07

21.75

0.00 

0.00

9.13

6.00

2.48

0.83

0.34

12.61

5.73

2.99

0.00

2.45

1.18

0.00

2

147

 

51.00

15.68

1.71

7.75

6.33

9.39

3.75

1.33

0.32

0.04

n.d.

1.40

0.63

0.18

n.d.

99.51

1,468

1

£ Q C

,0 JO

Basalt

0.00

7.92

31.99

22.20

0.00 

0.00

8.61

4.88

3.36

1.72

1.18

6.51

4.94

2.50

0.00

2.68

1.50

0.00

3

80SM4

D229684

51.4

15.8

1.90

7.40

6.22

9.36

3.6

1.36

n.d.

n.d.

0.83

1.32

0.61

0.15

n.d.

100.0

1 ,538

1,619

Olivine

basalt

0.00

8.11

30.72

23.13

0.00 

0.00

8.22

4.74

3.10

4.70

3.07

4.33

3.12

2.78

0.00

2.53

1.46

0.00

4

332

 

52.67

17.75

5.26

2.79

3.72

7.14

5.08

1.97

0.42

0.05

n.d.

1.22

1.06

0.13

n.d.

99.26

La Roche

1,011

1,307

Trachybasalt

0.00

11.78

43.49

20.04

0.00 

0.00

3.67

3.17

0.00

4.87

0.00

0.94

0.00

5.95

1.22

2.34

2.54

0.00

5

80SM2

D229682

Major

53.4

17.8

4.64

3.32

3.7

7.22

5.0

2.05

n.d.

n.d.

0.45

1.17

1.2

0.13

n.d.

100.1

and others

1,063

1,304

Olivine

trachybasalt.

Normative

0.32

12.15

42.44

20.13

0.00 

0.00

3.31

2.73

0.17

6.51

0.40

0.00

0.00

6.75

0.00

2.23

2.85

0.00

6

L-542

 

oxides

53.52

17.88

4.21

3.51

3.90

7.36

5.19

2.39

0.00

0.15

n.d.

1.14

1.26

0.11

n.d.

100.62

(1980) clas

927

1,325

Augite

trachybasalt.

composition

0.00

14.05

43.32

18.33

0.00 

0.20

4.09

3.21

0.43

0.00

0.00

4.52

0.66

6.07

0.00

2.15

2.97

0.00

7

L-541

 

54.08

21.87

5.22

0.88

2.69

5.53

5.46

2.88

0.00

0.16

n.d.

0.98

0.91

0.09

n.d.

100.75

sif ication

805

1 147

Augite

trachyandesite.

0.00

16.91

45.91

21.35

1 QQ

1 . OO

0.00

0.00

0.00

0.00

0.04

0.00

4.63

0.00

0.29

4.99

1.85

2.14

0.00

8

279

 

55.54

15.33

1.54

5.58

5.87

6.53

4.08

2.42

0.41

0.08

n.d.

1.18

0.51

0.14

n.d.

99.21

1 474

1 ,302

Latibasalt/

latiandesite.

O

f Q

.00

14.48

34.96

16.58

0.00 

0.00

5.37

3.36

1.68

11.44

5.70

0.00

0.00

2.26

0.00

2.27

1.22

0.00

9

80SM15

D229695

56.0

17.9

5.30

1.82

2.80

6.06

5.10

2.32

n.d.

n.d.

0.69

0.95

0.93

0.12

n.d.

100.0

1,169

1 1 1Q 1,1 JO

Latite/

trachyandesite.

4.00

13.80

43.44

19.22

0.00 

0.00

2.06

1.78

0.00

5.24

0.00

0.00

0.00

3.53

2.90

1.82

2.22

0.00

10

80SM16

D229696

58.8

17.0

2.35

3.40

2.5

5.28

4.3

2.86

n.d.

n.d.

1.44

1.00

0.71

0.08

n.d.

99.7

1,546

1,025

Latiandesite.

9.32

17.19

37.01

18.96

0.00 

0.00

1.24

0.80

0.36

5.53

2.49

0.00

0.00

3.47

0.00

1.93

1.71

0.00

Volatiles, probably mainly H20 and C02 , calculated assuming all FeO was oxidized to Fe 2 0g during 

determination of loss on ignition.
DISCUSSION AND CONCLUSIONS 53

DESCRIPTION OF SAMPLE LOCALITIES FOR TABLE 29

1. Olivine basalt that contains hornblende

rhyodacite inclusions in the NWiSE5* sec. 31, T. 

30 N. , R. 25 E., Hunter Mesa quadrangle.

2. Basalt from west flank of Eagle Tail Mountain, 

36°41'12" N., 104°28'12" W., probably in the SW< 

sec. 2, T. 28 N. , R. 23 E., Eagle Tail Mountain 

quadrangle (sample 147 of Stormer, 1972b, tables 

1 and 7).

3. Olivine basalt from east end of Eagle Tail Mountain in a road cut in the NE corner sec. 16, T. 

28 N., R. 24 E., Eagle Tail Mountain quadrangle.

4. Trachybasalt from east Juan Torres Mesa (locally 

called "Meloche Mesa") in the NW< sec. 25, T. 30 

N. , R. 25 E., Johnson Park quadrangle, from 

thick flow forming the lower eastern part of 

mesa (sample 332 of Stormer, 1972b, tables 1 and 

7). Nearly the same locality as samples 5 and 6.

5. Olivine trachybasalt from Juan Torres Mesa in 

the SEINE'4 sec. 26, T. 30 N. , R. 25 E. , Johnson 

Park quadrangle. Nearly the same locality and 

composition as samples 4 and 6.

6. Augite trachybasalt from Juan Torres Mesa,

probably in the NW< sec. 25, T. 30 N., R., 25 E., 

Johnson Park quadrangle. Nearly the same 

locality as samples 4 and 5 (sample L-542 of 

Mertie, 1922, p. 11).

7. Augite trachyandesite from western, higher part 

of Juan Torres Mesa, probably in the Wh sec. 23, 

T. 30 N., R. 25 E., Hunter Mesa quadrangle 

(sample L-541 of Mertie, 1922, p. 11).

8. Latibasalt/latiandesite from flow forming rim of 

mesa south of Blosser Gap in the SWiSEk sec. 25, 

T. 29 N., R. 24 E., Tinaja Mountain quadrangle 

(sample 279 of Stormer, 1972b, tables 1 and 7).

9. Latite/trachyandesite from 200 ft (60 m) above 

drainage in the NWk sec. 15, T. 26 N., R. 27 E., 

Lawrence Arroyo quadrangle.

10. Latiandesite from northeast of road at southeastern flow of Las Mesetas near the center of 

NE*< sec. 33, T. 26 N. , R. 27 E. , Lawrence Arroyo 

quadrangle.

been described. A xenocrystic andesibasalt lava was 

described by Aoki (1967; see table 31, this report) from 

the south base of Capulin Mountain, about 2 mi east of 

the map area. Phenocrysts consist of olivine (about 

2 percent), augite (0.5 percent), and rarely hypersthene. 

The olivine is euhedral, as large as 2 mm, and the 

phenocrysts include tiny crystals of picotite. The augite 

is euhedral to subhedral and ranges to 0.8 mm in length. 

The hypersthene, as large as 0.5 mm, has overgrowths of 

augite. The groundmass is holocrystalline and consists of 

plagioclase, augite, olivine, and opaque oxide. Xenocrysts are quartz (3.1 percent) and feldspar (0.3 percent). 

The quartz grains are less than 2 mm in diameter and 

have reaction rims of augite, some with brown glass. The 

feldspar xenocrysts are rounded and have glassy cores 

and thin overgrowths of calcic plagioclase.

TABLE 30. Neutron-activation analysis of a sample of olivine basalt 

of the Clay ton Basalt from Eagle Tail Mountain, New Mexico

[Elemental compositions in parts per million. See table 29 for description of sample locality. 

"<" indicates element concentration is below the limit of determination, which is the value 

shown; "±" shows the accuracy of the test. Analyst: Carl Orth, Los Alamos National 

Laboratory]

Field No. 80SM4 

Lab. No. 925103

Na

Mg 

Al

Cl

K

Ca

Ti

V

Mn

Cu

Sr

I

Ba

Dy 

U

Ga

As

Br

27,600

39,000 

83,000

<200

12 , 000

63,000

8,400

175

1,260

<300

1,100

<20

690

5. 

2.

<200

<4

<3

±300

±2,000 

±2,000

±2 , 000

±3,000

±400

±6

±10

±200

±60

.0 ±0.3 

. 00±0 . 02

Sb

La

Sm

W

Au

Sc

Cr

Fe

Co

Zn

Se

Rb

Cs

Ce

Eu

Tb

Yb

Lu

Hf

Ta

Th

<0.

59.

7.

<7

<0.

22.

160

73,000

37

<10

<2

<20

<0.

92

1.

1.

2.

0.

3.

1.

7.

5

6+0.8

3 ±0.2

02

1 ±0.4

±10

±2 , 000

±1

9

±4

65±0.10

2 ±0.2

8 ±0.2

28±0.04

2 ±0.3

6 ±0.2

6 ±0.3

Another specimen (85RW5) from the chilled rind of the 

same flow is subtly banded. In thin section one set of 

bands has normal calcic plagioclase, olivine, and clinopyroxene phenocrysts along with xenocrystic quartz, 

internally melted alkali feldspar with plagioclase overgrowths, and a few pseudomorphs of clinopyroxene after 

hornblende(?), all set in a matrix of dark-brown, dusty 

glass. The other set of bands is lighter in color and has 

sparse phenocrysts of calcic plagioclase, olivine, and 

clinopyroxene, but a greater abundance of the felsic 

xenocrysts than the first set of bands, all set in a matrix 

of clear, pale-brown glass that has abundant well-formed 

microphenocrysts of plagioclase, olivine, and clinopyroxene. These microphenocrysts apparently were new 

growths in the liquid just before it was chilled to a glass.

DISCUSSION AND CONCLUSIONS

Study of the Chico sill complex and other igneous rocks 

of the Raton-Springer area was reconnaissance in scope, 

inasmuch as it was subsidiary to making a geologic map 

of the entire Raton I°x2° quadrangle. As the eastern half 

of the quadrangle was mapped, samples were gathered of 

all major igneous rocks for use in determining composition, rock names, age, the origin and relationships of 

the rocks to each other, and the physiographic and 

structural history during and after emplacement. 

Because our intent was to produce a geologic map and
54 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

JSff^TfJ

»^?**^f

FIGURE 20. Cinder cones of Capulin Basalt in the Raton-Springer area. A, Horseshoe Crater, in the SEV4 sec. 2, T. 28 N., R. 27 E., Kiowa 

quadrangle. B, Capulin Mountain, the type area, just east of the main study area, 2.5 mi (4 km) north of the town of Capulin, Folsom 

quadrangle. Photograph B by R. D. Miller, U.S. Geological Survey.

show what kinds of rocks crop out in the Raton-Springer 

area, we have not done a detailed petrogenetic study. 

The following summary, however, relates some of the 

pertinent results.

The Chico sill complex includes phonolite, phonotephrite, trachyte, trachyandesite, and other alkalic rocks, 

ranging in age from Oligocene to Miocene, which have 

been intruded between layers of Cretaceous sandstone,

limestone, and shale to produce some 1,000 ft (305 m) of 

structural relief. Judging from the relatively low values 

of Ba, Cr, Mg, Th, and Ti shown by the neutron 

activation analyses, the source of the magmas of all these 

rock types was apparently in the lower crust.

Sills of the Slagle Trachyte are a part of the Chico sill 

complex and contributed to the general structural 

doming of the area. The green, silver-gray, and ocellar
DISCUSSION AND CONCLUSIONS 55

FIGURE 21. Stratified basaltic ash and volcaniclastics in roadcut on east flank of Capulin Mountain volcano just east of study area. "Field

assistant" on left is about 3 ft (1 m) high.

analcime varieties of the Chico Phonolite were assigned 

separate map units by Scott, recognizing however that 

they are closely related. From the plot of the chemical 

analyses on figure IB (fields 12 and 14), it is apparent 

that the green and silver-gray phonolite units form a 

gradational series, the green phonolite being the lowsilica part. In addition, the nepheline syenite dike on the 

Point of Rocks Mesa (field 16) plots within the field of the 

silver-gray phonolite and might well have been a feeder 

to the system of sills.

Also during this span of Oligocene through Miocene 

time, kimberlite diatremes were intruded into the sedimentary rocks. Inasmuch as the diatremes are inconspicuous in outcrop, some may well have been overlooked 

in the present reconnaissance. On the basis of their 

relatively high values of Ba, Cr, Ir, Mg, and Ti, the 

sources of the diatremes appear to have been in the 

upper mantle.

In a study of the mafic feldspathoidal lavas in Union 

County and parts of eastern Colfax County, Phelps and 

others (1983) concluded that the magmas of most of these 

lavas originated as primary melts in the upper mantle, 

which itself had been metasomatically enriched. A 

comparison of major oxide analyses of mafic feldspathoidal lavas from Union County (Phelps and others, 

1983, table 1) and Colfax County (table 25 of this report), 

shows that the nephelinites and ankaratrites of Union 

County are consistently higher in CaO and MgO than 

those of Colfax County, whereas the basanites of the two 

areas do not show significant differences in this respect.

These relations between the mafic feldspathoidal lavas 

of the two counties are clearly brought out in figure 22, 

a section of the diagram of La Roche and others (1980), in 

which the R2 parameters (6Ca+2Mg + Al) serve to 

distinguish the nephelinites and ankaratrites of Union 

County from those of Colfax County, possibly an 

indication of compositional differences between the 

materials of the respective source regions of these upper 

mantle melts. In contrast, the plots of the basanites 

of the two counties overlap, and they are separated 

from the plots of the ankaratrites and nephelinites by 

an appreciable gap in the R: parameter values 

[4Si-ll(Na + K)-2(Fe + Ti)], suggesting that the basanites form a separate igneous series. (See also fig. IB, 

fields 25 and 28.)

Among the basaltic to latiandesitic rocks, as grouped 

in the present study, there is a progressive increase in 

silica and a less regular increase in potash content from
56 VOLCANIC AND SUBVOLCANIC ROCKS OF RATON-SPRINGER AREA, NEW MEXICO

TABLE

Sample 

Field 

Lab No

31. Chemical analyses and norms of samples of Capulin 

Basalt from the Raton-Springer area, New Mexico

[Data in weight percent, n.d., not determined]

1

0 o /

No.--- MHS-69-82 L-571-A 111 8 

...... D246867

Major oxides

C -5 /~\

A1 2 03 

Fe 2 03 

FeO --

MgO -- 

CaO --

Na 2 0 - 

17 r\

H c\ 

14 n~

------ 51.8 53.27 55.04 55.54

------ 16.4 15.43 15.62 15.40

------ 3.20 2.43 1.57 0.91

------ 6.30 6.50 5.93 7.74

------ 4.60 6.16 5.62 5.45

------ 7.34 8.18 7.23 7.07

------ 3.71 3.51 3.91 3.95

------ 1.90 1.71 1.96 2.05

------ n.d. 0.62 0.80 0.39

,-, A r\ r\r\ nil n m

Volatiles 1 -- 1.67 n.d. n.d. n.d. 

fiO 1 RQ 1 in 110 i r>r>

P

r\

MnO --

Total

------ 0.77 0.50 0.43 0.40

------ 0.18 0.12 0.13 0.14

------ 99.46 99.73 99.54 100.11

La Roche and others (1980) classification

r>

r>

------ 1,380 1,631 1,594 1,553

1

11Q 1 /Q*7 1 Ififi 1 TOO

basalt. basalt. basalt.

Normative composition

q ----

oK ...

di-wo 

di-en 

di-fs 

hy-en 

hy-fs 

mt ---

11 ...

ap

------ 1.46 0.83 1.55 0.15

------ 11.48 10.19 11.74 12.15

------ 32.09 29.96 33.54 33.53

------ 22.98 21.48 19.54 18.30

3

Qf\ r -jc c Q1 c rj£

2 00 /. i ~7 T "; } i r\~i

1 TO 0 1 Q 1 QO O 11

------ 9.43 11.30 10.66 10.55

5

/1 C ^ Q n ^ Q Q Q *3 C

------ 4.74 3.55 2.31 1.32

------ 0.00 0.00 0.00 0.00

------ 3.09 2.49 2.29 1.91

------ 1.86 1.19 1.03 0.95

C/3

z 

o

5

y

_i _i

^ 

z

tr 

Fl

ol 

ta 

cP

ss 

m

X(

af 

re 

si 

tf

gl 

p( 

cr 

it

X(

t?

2500 

1 Probably mainly H2 0 and C02 , calculated assuming 

all FeO was oxidized to FejOs during determination of 

loss on ignition.

DESCRIPTION OF SAMPLE LOCALITIES

1. Latibasalt flow correlated with the Capulin Basalt 

on east side of county road north of Hogeye Mesa and 

south of the eastern Pine Butte in SW^SEk sec. 14, 

T. 27 N., R. 26 E., Pine Buttes quadrangle (Staatz, 

1985).

2. Olivine andesibasalt from Capulin Mountain, possibly 

from sees. 6 or 7, T. 29 N., R. 28 E., Folsom 

quadrangle, Union County, east of map area (sample 

L-571(a) of Mertie, 1922, p. 11).

3. Andesibasalt from flow from Capulin Mountain volcano 

in road cut on north side of U.S. Highway 64 in the 

center of Sh sec. 16, T. 29 N., R. 28 E., Capulin 

quadrangle, east of the map area (sample 111 of 

Stormer, 1972b, tables 1 and 7).

4. Andesibasalt from flow from Capulin Mountain volcano 

in road cut on north side of U.S. Highway 64 in the 

center of Sh sec. 16, T. 29 N., R. 28 E., Capulin 

quadrangle, east of map area (Aoki, 1967, table 1).

2000 

1500-500 0 500 1000 

Ft-,, IN MILLICATIONS

1500

FIGURE 22. Comparison of the major element compositions of the 

mafic feldspathoidal lavas of Colfax County (table 25 of this study) 

with those of Union County, adjacent on the east (Phelps and others, 

1983, table 1), as plotted on the diagram of La Roche and others 

(1980).

older to younger (from the alkali basalt of the Raton, 

table 28; through the basalt, latiandesite, and trachyandesite of the Clayton, table 29; and into the latibasalt and andesibasalt of the Capulin, table 31). Under the 

microscope the Clayton rocks contain scattered reacted 

xenocrysts of feldspar and quartz. The xenocrysts 

appear to be even more abundant in the few Capulin 

rocks examined in this study, and the groundmasses are 

subtly inhomogeneous both in hand specimen and under 

the microscope, having variable grain sizes and being 

glassy in places. Stormer (1972b, p. 3306) considered the 

possibility that these features might be the result of 

crustal contamination of Raton-like magma, but rejected 

it because of the apparent lack of potassium-bearing 

xenoliths to account for the increase in potash through 

the groups. Actually, some scattered felsic xenoliths 

were noted during the mapping for the present study, 

and the plagioclase phenocrysts with clouded interiors 

(the resorbed plagioclase phenocrysts of Stormer, 1972b, 

p. 3303) match well the attributes of alkali-feldspar 

xenocrysts caught in basaltic magmas. Xenocrysts in 

that situation first undergo internal melting, then 

acquire overgrowths of calcic plagioclase (Knopf, 1938; 

Wilcox, 1944). Progressive assimilation of these alkali 

feldspars, along with the reacting quartz xenocrysts, 

could have produced the observed chemical characters of 

these rocks.

Support for the probability of significant contamination is also found in the strontium isotope study by 

Jones and others (1974, fig. 1) on the suite of specimens 

collected from the rocks of the region by Stormer (1972a, 

b). Of this suite, three specimens one from Stormer's 

"Raton-Clayton" group and the two from his "Capulin"
REFERENCES CITED 57

group show anomalously high Sr87/Sr86 ratios, which 

are interpreted by Jones and others (1974) as indicating 

crustal contamination.

If these various rock types (trachybasalt, latibasalt, 

andesibasalt, trachyandesite, and latiandesite) of the 

"Clayton" and "Capulin" groups have been derived by 

contamination of Raton-related magmas, there must 

have been a wide variety of compositions among the 

contaminants. Such a scatter of the plots of the R1R2 

diagram (fig. 75, fields 28, 29, and 31) could conceivably 

result from the assimilation of differing proportions of 

alkali feldspar and quartz, and the proportions of these 

components could vary widely in the common sedimentary and felsic volcanic rocks of the crust contacted 

by the magmas as they rose.

Assignment of formation names to the mafic eruptive 

rocks on the basis of relative ages within early Pliocene 

to Holocene time has been complicated by the setting 

aside of the mafic feldspathoidal lavas as a separate 

group, even though the ages of some overlap with those 

of the Raton and Clayton basaltic lavas. As noted above 

in the discussion of the mafic feldspathoidal lavas as 

plotted on figure 75, the basanites plot in a group away 

from the nephelinites and ankaratrites and very close to 

some of the alkali basalts of the Raton. This juxtaposition 

raises the possibility that the alkali basalts are closely 

related to the basanites, possibly derived from common 

parent magmas, and that the basanites might more 

logically be grouped with the alkali basalts as an age unit.

The results of the present reconnaissance have pointed 

to a number of interesting aspects of the igneous rocks in 

the study area and to logical directions for further 

investigations. The new radiometric age determinations 

of the igneous rocks enable a better understanding of 

their geologic history and structural development. The 

new chemical analyses of the igneous rocks, in conjunction with their plots on the R^R^ diagram of La 

Roche and others (1980), outline several probable 

igneous magmatic events and invite more thorough 

investigations for their interpretations. The geologic 

maps of the Springer quadrangle (Scott, 1986) and the 

Raton quadrangle (Scott and Pillmore, 1989) accurately 

show the placement of all major rock units and should 

facilitate future detailed mapping and petrographic 

study. The above accomplishments, despite their reconnaissance nature, provide an excellent springboard for 

solution of the many important research problems that 

remain. We emphasize that a satisfactory understanding 

of the magmatic development and volcanic history within 

the Pliocene to Holocene time span, however, does not 

seem attainable without extensive integrated field work, 

petrography, petrochemistry, isotopic geochemistry, 

and more radiometric age determinations.

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