U. S. DEPARTMENT OF THE INTERIOR 

U.S. GEOLOGICAL SURVEY

Mineral-resource and Environmental Geochemistry

of the Coconino National Forest, 

Coconino, Gila, and Yavapai Counties, Arizona

by 

Maurice A. Chaffee and Harley D. King

U.S. Geological Survey

Mineral Resource Surveys

Box 25046, Federal Center, MS 973

Denver, Colorado 80225

Open-File Report 98-112

This report is preliminary and has not been reviewed for conformity with U.S. Geological 

Survey editorial standards and stratigraphic nomenclature. Any use of trade names is for 

descriptive purposes only and does not imply endorsement by the USGS.
CONTENTS

Page

EXECUTIVE SUMMARY ................... 1

INTRODUCTION ...................... 2

GEOLOGIC SUMMARY .................... 2

MINERAL OCCURRENCES .................. 4

SAMPLE COLLECTION AND PREPARATION ............ 6

Rock Samples ..................... 6

Stream-sediment Samples ................. 6

USGS Stream-sediment Samples ............. 8

NURE Stream-sediment Samples ............. 8

CHEMICAL ANALYSIS .................... 8

EVALUATION OF THE DATA SETS ............... 11

GEOCHEMICAL MAPS .................... 11

Rock Samples ..................... 11

USGS Stream-sediment Samples ............... 18

NURE Stream-sediment Samples ............... 20

ENVIRONMENTAL GEOCHEMISTRY .............. 22

Surficial Environmental Geochemistry ............. 22

Subsurface Environmental Geochemistry ............ 23

CONCLUSIONS AND RECOMMENDATIONS ............ 24

ACKNOWLEDGMENTS .................... 25

REFERENCES CITED .................... 26

ILLUSTRATIONS

Figure 1. Map showing locations of selected geographic features in the

Coconino National Forest, Arizona ........... 3

2. Site locality map for 291 USGS rock samples, Coconino National

Forest, Arizona .................. 7

3. Site locality map for 449 USGS stream-sediment samples, Coconino

National Forest, Arizona ............... 9

4. Site Locality map for 662 NURE stream-sediment samples, Coconino

National Forest, Arizona ............... 10

5. Distribution of anomalous silver in rock samples, Coconino National

Forest, Arizona .................. 30

6. Distribution of anomalous arsenic in rock samples, Coconino National

Forest, Arizona .................. 31

7. Distribution of anomalous gold in rock samples, Coconino National

Forest, Arizona .................. 32

8. Distribution of anomalous cadmium in rock samples, Coconino

National Forest, Arizona ............... 33

ii
Page 

Figure 9. Distribution of anomalous copper in rock samples, Coconino National

Forest, Arizona .................. 34

10. Distribution of anomalous molybdenum in rock samples, Coconino

National Forest, Arizona ............... 35

11. Distribution of anomalous lead in rock samples, Coconino National

Forest, Arizona .................. 36

12. Distribution of anomalous antimony in rock samples, Coconino

National Forest, Arizona ............... 37

13. Distribution of anomalous uranium in rock samples, Coconino

National Forest, Arizona ............... 38

14. Distribution of anomalous zinc in rock samples, Coconino National

Forest, Arizona .................. 39

15. Distribution of anomalous silver in USGS stream-sediment samples,

Coconino National Forest, Arizona ........... 40

16. Distribution of anomalous arsenic in USGS stream-sediment samples,

Coconino National Forest, Arizona ........... 41

17. Distribution of anomalous gold in USGS stream-sediment samples,

Coconino National Forest, Arizona ........... 42

18. Distribution of anomalous cadmium in USGS stream-sediment

samples, Coconino National Forest, Arizona ........ 43

19. Distribution of anomalous copper in USGS stream-sediment samples,

Coconino National Forest, Arizona ........... 44

20. Distribution of anomalous molybdenum in USGS stream-sediment

samples, Coconino National Forest, Arizona ........ 45

21. Distribution of anomalous lead in USGS stream-sediment samples,

Coconino National Forest, Arizona ........... 46

22. Distribution of anomalous antimony in USGS stream-sediment

samples, Coconino National Forest, Arizona ........ 47

23. Distribution of anomalous uranium in USGS stream-sediment samples,

Coconino National Forest, Arizona ........... 48

24. Distribution of anomalous zinc in USGS stream-sediment samples,

Coconino National Forest, Arizona ........... 49

25. Distribution of anomalous silver in NURE stream-sediment samples,

Coconino National Forest, Arizona ........... 50

26. Distribution of anomalous arsenic in NURE stream-sediment samples,

Coconino National Forest, Arizona ........... 51

27. Distribution of anomalous gold in NURE stream-sediment samples,

Coconino National Forest, Arizona ........... 52

28. Distribution of anomalous cadmium in NURE stream-sediment

samples, Coconino National Forest, Arizona ........ 53

29. Distribution of anomalous copper in NURE stream-sediment samples,

Coconino National Forest, Arizona ........... 54

iii
Page 

Figure 30. Distribution of anomalous molybdenum in MURE stream-sediment

samples, Coconino National Forest, Arizona ........ 55

31. Distribution of anomalous lead in NURE stream-sediment samples,

Coconino National Forest, Arizona ........... 56

32. Distribution of anomalous antimony in NURE stream-sediment

samples, Coconino National Forest, Arizona ........ 57

33. Distribution of anomalous tin in NURE stream-sediment samples,

Coconino National Forest, Arizona ........... 58

34. Distribution of anomalous uranium in NURE stream-sediment

samples, Coconino National Forest, Arizona ........ 59

35. Distribution of anomalous zinc in NURE stream-sediment samples,

Coconino National Forest, Arizona ........... 60

TABLES

Table 1. Summary statistics for analyses for 37 elements in 291 samples of

rock, Coconino National Forest, Arizona ......... 12

2. Summary statistics for analyses for 37 elements in 449 samples of

USGS stream sediment, Coconino National Forest, Arizona ... 13

3. Summary statistics for analyses for 39 elements in 662 samples of

NURE stream sediment, Coconino National Forest, Arizona ... 14

IV
EXECUTIVE SUMMARY

This report describes geochemical studies conducted by the United States Geological 

Survey in the Coconino National Forest, Coconino, Gila, and Yavapai Counties, northern 

Arizona. This report is based on analyses of rock and stream-sediment samples that were 

analyzed for 41 different elements. The distributions and abundances of these elements 

provide information that is useful (1) for understanding geologic environments in the forest 

area that are known to contain, or may contain, mineral deposits, and (2) for determining the 

mineral resource potential of the forest. In addition, the analytical information identifies areas 

with possible chemically-related environmental problems. The information contained in this 

report should thus be useful for decision-making purposes regarding land use in the forest.

Many anomalies were identified in a variety of lithologic environments. However, 

most of these anomalies are weak and deemed to be only the upper parts of the ranges of 

background values for the elements and environments in question.

Significant anomalies in surficial materials include the following:

1. Those related to past mining for manganese in the Long Valley area, near Glints 

Well, where samples are anomalous for as many as 16 elements (Ag, As, Au, Ba, Be, Cd, Co, 

Cu, Mo, Ni, Pb, Sb, Sr, V, W, and(or) Zn);

2. Those related to past mining and smelting, as well as to natural concentrations, in 

the Verde River Valley, where samples are anomalous for as many as 12 elements (Ag, As, 

Au, Cd, Cu, Mo, Pb, Sb, Sn, U (and by association, Rn), and(or) Zn); and

3. Those related to scattered, minor exposures in the Supai Formation in the Fossil 

Creek area (and possibly to exposures of this unit elsewhere) that are anomalous for as many 

as 10 elements (Ag, As, Au, Cd, Cu, Mo, Pb, U (and by association, Rn), and(or) Zn).

Other areas with possibly significant anomalies are described in the report; however, 

their relation to as-yet undefined mineral resources, and(or) their impact on the environment, 

is not clear.

Although surface and ground waters were not studied for this report, it is important to 

note that both surface and (particularly) ground waters may be contaminated by many of the 

elements listed above. Of particular concern is the potential for anomalous radon in soils and 

well waters in the Verde Valley. Although not as yet known to be a problem, another 

potential concern for ground water contamination may exist in areas where silicified or cherty 

lenses in the Kaibab Formation have been penetrated in a given well. Samples from these 

zones were found to contain anomalies of as many as 10 elements (Ag, As, Cd, Cu, Mo, Pb, 

Sb, U (and by association, Rn), and(or) Zn).
INTRODUCTION

This report describes geochemical studies conducted by the United States Geological 

Survey in the Coconino National Forest (the study area), Coconino, Gila, and Yavapai 

Counties, northern Arizona (Fig. 1). The distributions and abundances of elements provide 

essential information that is useful for determining favorable geologic environments for 

mineral deposits in the study area and therefore for identifying its mineral resource potential. 

In addition, the analytical information can be used to identify possible chemically-related 

environmental problems.

This report is based on analyses for 291 samples of rock and 449 samples of stream 

sediment collected in 1993 and 1994 by the United States Geological Survey (USGS) and 662 

samples of stream sediment collected in the 1970's for the United States Department of 

Energy-sponsored National Uranium Resource Evaluation (NURE) program and re-analyzed 

for this report. Oil and gas resources have not been identified or evaluated for this report; 

only metallic mineral resources, and environments related to metallic resources, are discussed 

here. A separate report covering non-metallic resources has been published by the USGS 

(Bliss, 1997).

The climate in the Coconino National Forest has an important relationship to the 

physical and chemical mobility and dispersion of elements. Topographic relief in the forest is 

more than 10,000 feet. The highest point is Humphrey's Peak (elev. 12,633 ft.), just north of 

Flagstaff. The lowest point (elev. about 2550 ft.) is at the junction of Fossil Creek and the 

Verde River, on the extreme southern tip of the forest. Major vegetation life zones range 

from the Lower Sonoran Desert Zone to the Arctic-Alpine Zone, with most of the forest found 

in the Upper Sonoran and Transition Zones.

Because of the extreme range in elevations in the forest, precipitation and 

temperatures vary widely. Data in Sellers (1960) for weather stations in the forest show a 

yearly mean precipitation of 22.56 inches at the highest station (Fort Valley, 7 miles northwest 

of Flagstaff, at an elevation of 7347 ft.) and a yearly mean of 17.27 inches at the lowest 

station (Childs, near the extreme southern tip of the forest, at an elevation of 2650 ft.). Yearly 

mean maximum and minimum temperatures are 59.2°F and 26.3°F for the Fort Valley station 

and 80.9°F and 47.3°F for the station at Childs (Sellers, 1960). No data were presented for 

more extreme elevations in the San Francisco Peaks area, but a contoured map of yearly 

precipitation in Sellers (1960) shows amounts in excess of 25 inches in the high parts of that 

area, just to the north of the Fort Valley Station. Evaporation tends to be much higher in 

areas of the forest at lower elevations because of higher year-round temperatures.

GEOLOGIC SUMMARY

The Coconino National Forest lies mostly within the Colorado Plateau Physiographic 

Province. Smaller parts on the southern edge of the forest are in the Transition Zone between 

the Colorado Plateau and Basin and Range Provinces. The Mogollon Rim, a distinct 

topographic feature occurring where the relatively flat surface of the Colorado Plateau is 

terminated regionally southward by steep cliffs, is generally considered to represent the 

southern boundary of the Colorado Plateau Physiographic Province.
112° 00' 111° 45' 111° 30'

35° 30' -

35° 15'-

35° 00' -

34° 45' -

34° 30' -

Sunset / 

Crater N. M. Phoenix 

ARIZONA

Kendnck Peak

Mormon Lake

Cottonwood

 Road

'---' Stream **

 Approximate boundary 

of Coconino National ,$> 

Forest /

X Area of mines or prospects

A Smelter sites

Figure l.-Maps showing location of Coconino National Forest and geographic features in and 

near the forest.
North of the Mogollon Rim, rock exposures in the study area consist of a nearly flatlying sequence of upper Paleozoic sedimentary rocks, including the Coconino Sandstone, 

Toroweap Formation, and Kaibab Formation, all of Permian age (see, for example, Billingsley 

and others, 1988; Ulrich and others, 1984; Weir and others, 1989). Locally, this sequence is 

overlain by beds of the Triassic Moenkopi and Chinle Formations. Extensive areas of Tertiary 

and Quaternary volcanic flows and volcaniclastic rocks, varying from felsic to mafic 

compositions, cover the Paleozoic sedimentary sequence. The San Francisco Peaks region 

north of Flagstaff includes the majority of the Quaternary volcanic rocks; the Tertiary volcanic 

rocks are generally west and south of Flagstaff (Ulrich and others, 1984). In the area just 

north of the Mogollon Rim, Tertiary conglomerates representing channel deposits are locally 

present (Weir and others, 1989; 1994).

South of the Mogollon Rim, cliffs contain exposures of generally flat-lying 

sedimentary rocks that range in age from Pennsylvanian to Permian (Karlstrom and others, 

1983; Weir and others, 1989). In the Verde Valley and adjacent hills, on the west border of 

the forest (Fig. 1), carbonate-dominant to clastic-dominant lake-bed and alluvial deposits of the 

Tertiary Verde Formation are widespread. Locally, these rocks are interbedded with, or 

overlain by, volcanic flows of predominantly basaltic composition (Karlstrom and others, 

1983; Weir and others, 1989). Tertiary volcanic rocks of intermediate composition and a 

small area containing Precambrian schist and Paleozoic sedimentary rocks are present locally 

in the extreme southwestern part of the forest (G.B. Haxel, written communication, 1997).

Unconsolidated sediments of Quaternary age are also found in most stream channels in 

the forest.

MINERAL OCCURRENCES

Several types of mineral deposits have been recognized in the Coconino National 

Forest. The two most important of these are manganese and uranium deposits. Secondary 

manganese oxide ores have been mined in the past from several localities in the Long Valley 

manganese district, in the southern part of the study area, just north of the Mogollon Rim 

(Farnham and Stewart, 1958; Lane, 1992; Weir and others, 1994). The most significant of 

these deposits is at the site of the Last Chance mine, northwest of Glints Well (Fig. 1). Most 

of these deposits occur as irregular bodies in the Kaibab Formation; however, similar 

mineralization also occurs locally in Tertiary gravels and in the Moenkopi Formation (Weir 

and others, 1994). The origin of these deposits is not completely understood. In many 

localities in the forest, small (about 1-mm diameter) manganese oxide nodules are present in 

abundance in washes and low swales on the surface of basalt flows, indicating that manganese 

oxides are forming as part of the weathering of these basalts. Weir and others (1994) suggest 

that the manganese deposits have formed on Tertiary erosional surfaces. We speculate that 

manganese and other metals have been carried in solution in ground waters through relatively 

permeable, near-surface horizons in the Tertiary gravels, and in the Kaibab and Moenkopi 

Formations, and deposited locally in these rocks to form the manganese oxide deposits. All 

known manganese deposits occur within about 60 feet of the surface (Farnham and Stewart, 

1958); thus, the maximum potential depth of these deposits is not known. No deposits of this 

type are currently being mined.
Secondary uranium minerals, locally accompanied by arsenic and(or) molybdenum, 

occur in scattered localities in the Verde Formation, a sequence of Tertiary lake-bed deposits 

found in the Verde Valley, in the southwestern part of the study area (Duncan and Spencer, 

1993; Lane, 1992) (Fig. 1). Numerous prospects are present within the forest; however, no 

significant deposits have been found and no mining of uranium has occurred. The source(s) of 

these three elements is not known. They were probably leached from uranium-rich rocks, 

such as some of the Tertiary volcanic rocks or strata within the Supai Formation, carried in 

solution in ground waters, and then redeposited in various localities in the lake beds of the 

Verde Formation.

To the north, east, and west of the Coconino National Forest, chiefly in the Kaibab 

National Forest and the Navajo Indian Reservation, uranium- and copper-rich collapse breccia 

pipes have been recognized in many localities along the south side of the Grand Canyon 

(Sutphhi and Wenrich, 1989). No deposits of this type are known to exist in the Coconino 

National Forest. However, such deposits might be present but covered by younger volcanic 

flows.

Uranium is also known to occur widely in the Colorado Plateau in fluvial deposits in 

the Shinarump Member of the Chinle Formation. One small exposure of this unit crops out in 

the extreme northwest boundary of the forest and contains weakly to moderately anomalous 

arsenic, gold, molybdenum, lead, and(or) uranium. No mining has occurred in this locality.

Karlstrom and others (1983) describe unusual silver anomalies in the Coconino 

Sandstone "about 20 mi south of the Rattlesnake Roadless Area" (no location given). Silver 

concentrations have been found in this unit and in the Kaibab Formation hi the West Clear 

Creek Roadless Area (Ulrich and Bielski, 1983). However, details of these occurrences were 

not given. These anomalous samples may be from the locality referred to by Karlstrom and 

others (1983). Anomalous silver has been identified during the present study in streamsediment samples from several localities in the southeastern part of the Coconino National 

Forest containing outcrop of Coconino Sandstone. The source(s) of the silver (and locally As, 

Au, Cd, U, and Zn) is not known but may have originally been the Precambrian highlands 

thought to have existed to the south of the forest (Ulrich and Bielski, 1983). Although 

Karlstrom and others (1983) report silver concentrations of 6 to 9 ppm, the concentration 

levels of this element determined for this present study of the Coconino National Forest are all 

much lower, and thus not economic, making such occurrences of academic interest only.

Secondary copper and uranium occurrences have been reported in several horizons in 

the Supai Formation in the Fossil Springs Roadless Area (Peirce and others, 1977; Weir and 

others, 1983). Other anomalous elements have been reported in coal beds from this area and 

include Ag, As, B, Ba, Bi, Cd, Co, Mo, Nd, Ni, and Y (C. W. Holmes, written 

communication, 1993). The source(s) of these elements is not known. No mining has been 

done there and the occurrences are deemed to be subeconomic.

Hydrothermally altered Tertiary volcanic rocks were recognized during this study in 

the vicinity of the Childs power plant, near Verde Hot Springs, in the extreme southern part of 

the study area (Fig. 1); however, no mining has been done in this area, either. In the extreme 

northwestern part of the forest, near Slate Mountain (Fig. 1), a contact zone between a small
Tertiary rhyolite intrusion and Paleozoic carbonate sedimentary rocks has been reported to 

contain skarn-type base-metal occurrences (Lockrem, 1983; quoted in Bliss, 1997).

Gold has been reported to occur in scattered localities in areas of volcanic cinders in 

the San Francisco Volcanic Field, north of Flagstaff (Lane, 1992). The nature of these 

occurrences has not been described. Analyses of samples of cinders from many localities in 

the forest failed to identify any meaningful gold resources (Lane, 1992).

SAMPLE COLLECTION AND PREPARATION

Rock Samples

Two types of rock samples were collected. The first type included samples of 

material deemed to be representative of the general area of a given sample site. These samples 

were not obviously altered and were collected in order to provide baseline chemical 

information about various rock types and localities in the study area. All rock samples of this 

type consisted of composited chips collected from several outcrops. Before crushing, the rock 

chips were trimmed to remove any obviously weathered surface material.

The second type of rock sample consisted of untrimmed grab samples from mine 

dumps or prospect pits or of trimmed, composited outcrop samples of visibly altered (usually 

silicified and iron-stained) material. These samples were collected to provide information on 

the elements associated with known manganese or uranium mineral deposits in the study area.

The rock data set consists of 291 samples, all collected by the USGS. The data set 

includes 132 new samples collected from 125 sites plus 159 previously collected samples that 

were re-analyzed for the present study. These older samples were originally collected for the 

Arnold Mesa (Wolfe, 1983), Fossil Springs (Beard and Weir, 1984; Weir and others, 1983), 

Strawberry Crater (Wolfe and Hahn, 1982), West Clear Creek (Ulrich, 1983), and Rattlesnake 

and Wet Beaver (Gerstel and others, 1983) Roadless Area studies conducted for the U.S. 

Forest Service. These samples may have been single grab samples or samples composited 

from several different outcrops. We could not verify the details of collection for these older 

samples. All sites for rock samples are shown on figure 2.

Stream-sediment Samples

Stream-sediment samples consist of unconsolidated material deemed to represent a 

composite of all rock material cropping out in the basin upstream from each sample site. The 

chemistry of these samples represents a sum of (1) a mixture of the chemistries of all types of 

rock eroded from outcrops throughout the drainage basin, including rocks that have been 

enriched naturally as a result of the formation of mineral deposits, and (2) the chemistries of 

materials introduced to a given drainage as a result of human activities, such as mining, 

timbering, road building, and recreation.

Within a given drainage basin, the specific source or sources for the concentrations of 

any given element in a stream-sediment sample may or may not be known. In contrast, the 

source of the rock sample taken from an outcrop is obviously known but its chemistry is 

normally only representative of a very small area.
112° 00' 111° 45' 111° so- 15' 111° DO30'

35° 15'

35° GO340 45'

34° 30'

0 5

I I I 

20 25 30 km

Figure 2. Site locality map for 291 USGS rock samples, Coconino National Forest, Arizona. 

Open circles locate sample sites.

7
It is important to note that the chemistry of stream-sediment samples largely reflects 

the chemistry of materials at or near the present erosion surface. Thus, a mineral deposit not 

exposed at the surface will not normally be detected by the geochemical sampling procedure 

used for this study. Samples that are found to be strongly anomalous for one or more of the 

elements considered to be related to mineral deposits in the study area probably reflect nearsurface mineralization. In contrast, samples that are found to be weakly anomalous for 

mineral deposit-related elements may reflect (1) material eroded from near-surface, 

mineralized rock that has been diluted by barren sediment, (2) the upper, weak manifestations 

of a deep-seated mineral deposit that is not truly exposed at the surface, or (3) normal but 

relatively high background concentrations in one lithology as compared to another.

USGS Stream-sediment Samples

Two stream-sediment data sets have been evaluated for this report. The first set of 

stream-sediment samples, collected by the USGS, consisted of bulk sediment from 449 sites 

representing first-order (unbranched) and second-order (below the junction of two first-order) 

streams as defined on l:24,000-scale topographic maps (Fig. 3). The bulk stream sediment 

for each sample was composited from material collected from several locations within a 30- 

meter radius of each site plotted on figure 3. The bulk sample was sieved and a <0.17-mm 

(minus-80-mesh) fraction was saved for analysis.

NUKE Stream-sediment Samples

The second stream-sediment data set includes new analyses for 662 samples of <0.15- 

mm (minus- 100-mesh) stream sediment collected during the 1970's from the Flagstaff, 

Holbrook, and Prescott 1° x 2° quadrangles for the NURE program (Clark, 1979; Cook and 

Fay, 1982; Thayer and Cook, 1980). Our examination of the locations of sites for these 

samples on topographic bases, as well as our study of photographs of the sites taken by the 

sample collectors, indicate that many of these samples, particularly those collected in the 

Flagstaff quadrangle, are from the upper reaches of stream channels. As a result, these 

samples represent drainage basins that are very limited in size. The rest of the samples 

represent larger basins and are therefore more typical of the type of stream-sediment samples 

collected by the USGS. The sites for the NURE samples are shown on figure 4.

CHEMICAL ANALYSIS

All samples were analyzed by several different methods for a total of 53 elements. 

These 53 include 41 different elements plus other repeated elements. The samples were 

analyzed for 40 elements (Ag, Al, As, Au, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Eu, Fe, Ga, 

Ho, K, La, Li, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pb, Sc, Sn, Sr, Ta, Th, Ti, U, V, Y, Yb, 

and Zn) by a hot-acid extraction followed by inductively coupled plasma-atomic emission 

spectrometry (ICP-AES) (Briggs, 1990) and for 10 elements (Ag, As, Au, Bi, Cd, Cu, Mo, 

Pb, Sb, and Zn) using a partial-extraction ICP-AES method (ICP-P) (Motooka, 1990). The 

samples were also analyzed for uranium and thorium by instrumental neutron activation
112° 00' 111 0 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

15

I I I

20 25 30 km

Figure 3. Site locality map for 449 USGS stream-sediment samples, Coconino National Forest, 

Arizona. Open circles locate sample sites.
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

20.mi

. ?. T . T .20 i'

~TlIIIr

0 5 10 15 20 25 30km 

______I__________________ I

Figure 4. Site locality map for 662 NURE stream-sediment samples, Coconino National 

Forest, Arizona. Open circles locate sample sites.

10
analysis (INAA) (McKown and Knight, 1990), and for gold by graphite-furnace atomicabsorption spectrophotometry (AA) (O'Leary and Meier, 1990). Further details of the sample 

preparation and analysis for these samples, as well as a complete listing of the analyses for the 

samples, have been published elsewhere (Chaffee and others, 1996). Additionally, sample 

locations in that report allow the interested reader to locate sites in more detail than is possible 

on the maps in this report.

EVALUATION OF THE DATA SETS

Of the original 53 elements determined by the various analytical methods, 11 

determined by ICP-AES (Ag, As, Au, Bi, Cd, Ho, Mo, Sn, Ta, Th, and U) and five elements 

determined by ICP-P (Au, Bi, Cu, Pb, and Zn) were deleted from the rock and USGS streamsediment data sets either (1) because a given element had two or fewer reported values above 

its lower limit of determination (an unqualified value) for the method used, or (2) because a 

given element was determined by more than one method and the alternate method contained 

fewer censored values (a value below the lower limit of determination). With fewer censored 

values, the ranges of values were commonly greater for the analytical technique chosen for 

most of these elements, making selection of a threshold value easier. For similar reasons, 

analyses for 10 elements determined by ICP-AES (Ag, As, Au, Bi, Cd, Mo, Ho, Ta, Th, and 

U) and four determined by ICP-P (Au, Cu, Pb, and Zn) in the NURE stream-sediment data set 

were not considered further. Information on the remaining elements for each sample type is 

summarized in tables 1-3.

Threshold values are shown on each geochemical map. The values were not 

statistically calculated but were instead determined after first examining histograms showing 

the distributions of the ranges of reported values for each element and sample medium and 

then evaluating locations of sites for anomalous samples with reference to the local geology. 

Threshold values were then adjusted where necessary to better fit the known geology.

GEOCHEMICAL MAPS

Rock Samples

A diverse group of lithologies are present in the Coconino National Forest, and the 

normal expected ranges of concentrations of many elements vary with rock type. For 

example, one finds relatively higher background concentrations of the elements associated with 

dark minerals (such as Co, Cr, Fe, Mg, Mn, Ni, and V) commonly found in andesites and 

basalts as compared to dark-mineral-poor carbonate rocks and felsic volcanic rocks. 

Concentrations of calcium and magnesium are usually much higher in carbonate-rich rocks, 

such as those in the Kaibab Formation, than in the igneous rocks found in the forest area. 

Lithologies that are dominantly sandstone, such as the Tapeats Formation and the Coconino 

Sandstone, are chiefly composed of silicon and normally contain very low concentrations of 

most other major elements, as well as low concentrations of most trace elements.

Because of these chemically different lithologies, the anomalous range of 

concentrations, based on one population for all samples, typically represent the high end of a 

background range rather than additions of elements as a result of mineralization.

11
TABLE 1. SUMMARY STATISTICS FOR ANALYSES OF 37 ELEMENTS IN 291 SAMPLES OF 

ROCK, COCONINO NATIONAL FOREST, ARIZONA

[All values in ppm unless % shown after element symbol. N=not detected at the lower limit of determination 

shown in parentheses. L=detected but in a concentration less that the lower limit of determination shown in 

parentheses. Mean values based on unqualified values only. "P" following element symboI=ICP partial analysis; 

"NA"=neutron-activation analysis; "AA"=atomic-absorption analysis; no letters, ICP-AES analysis]

Element

Ag-P1 - 2

Al (%)

As-P1 - 2

Au-AA1 - 3

Ba

Be

Ca (%)

Cd-P1 - 2

Ce

Co

Cr

Cu

Eu

Fe (%)

Ga

K(%)

La

Li

Mg (%)

Mn

Mo-P1 - 2

Na (%)

Nb

Nd

Ni

P(%)

Pb

Sb-P1 - 2

Sc

Sr

Th-NA1

Ti (%)

U-NA1

V

Y

Yb

Zn

Range

Minimum

N(0.067)

0.07

N(l.O)

L(0.002)

8

L(l.)

0.01

N(0.050)

L(4.)

L(l.)

L(l.)

L(l.)

L(2.)

0.05

L(4.)

0.03

L(2.)

L(2.)

0.02

6

N(0.10)

L(0.005)

L(4.)

L(4.)

L(2.)

L(0.005)

L(4.)

N(l.O)

L(2.)

10

L(l.OO)

L(0.005)

L(0.14)

L(2.)

L(2.)

L(l.)

L(2.)

of values

Maximum

1.90

9.90

2200

0.034

17,000

35

39

40

250

920

2700

186,000

4

39

25

5.0

150

370

12

328,000

1100

4.1

110

110

810

0.71

1900

17

83

2100

49.9

1.90

158

1000

64

6

2800

Geometric

mean

0.32

3.18

5.9

0.004

320

1.5

3.54

0.18

35

13

35

20

2.6

1.7

15

0.74

20

11

1.4

410

0.54

0.44

25

22

24

0.076

11

4.0

12

250

6.6

0.17

1.78

52

13

1.7

39

Number

unqualified

25

291

87

30

291

168

291

119

268

260

278

282

28

291

202

291

278

290

285

291

260

284

188

232

267

283

157

10

207

291

188

286

281

286

250

187

287

Percent

unqualified

9

100

30

10

100

58

100

41

92

89

96

97

10

100

69

100

96

99

98

100

90

98

65

80

92

97

54

3

71

100

65

98

97

98

86

64

99

'Lower limits vary. Lowest reported value shown. 

2Only 288 samples analyzed for Ag, As, Cd, Mo, and Sb. 

3Only 290 samples analyzed for Au.

12
TABLE 2. SUMMARY STATISTICS FOR ANALYSES OF 37 ELEMENTS IN 449 SAMPLES OF USGS 

STREAM SEDIMENT, COCONINO NATIONAL FOREST, ARIZONA

[All values in ppm unless % shown after element symbol. N=not detected at the lower limit of determination shown in 

parentheses. L=detected but in a concentration less that the lower limit of determination shown in parentheses. Mean values 

based on unqualified values only. "P" following element symbol=ICP partial analysis; "NA"=neutron-activation analysis; 

"AA"=atomic-absorption analysis; no letters, ICP-AES analysis]

Element

Ag-P1

Al (%)

As-P1

Au-AA2

Ba

Be

Ca (%)

Cd-P1

Ce

Co

Cr

Cu

Eu

Fe (%)

Ga

K(%)

La

Li

Mg(%)

Mn

Mo-P1

Na (%)

Nb

Nd

Ni

P(%)

Pb

Sb-P1

Sc

Sr

Th-NA 1 - 2

Ti (%)

U-NA2

V

Y

Yb

Zn

Range

Minimum

N(0.045)

0.47

N(l.O)

L(0.002)

39

L(l.)

0.04

N(0.050)

6

L(l.)

6

2

L(2.)

0.23

L(4.)

L(0.10)

4

3

0.06

38

N(0.10)

0.01

L(4.)

L(4.)

3

0.005

L(4.)

N(0.60)

L(2.)

19

L(0.97)

0.03

0.39

7

2

L(l.)

6

of values

Maximum

0.52

9.10

46

0.046

1900

6

18

2.20

400

270

1400

160

2

12

32

2.3

120

220

6.10

11,000

6.6

3.3

88

68

400

0.31

59

1.4

120

1700

31.2

2.10

7.59

370

30

3

200

Geometric

mean

0.15

3.39

3.4

0.003

370

1.5

1.52

0.20

41

15

94

20

2

2.4

10

0.88

22

15

1.01

530

0.51

0.33

16

18

41

0.052

11

1.2

9

140

5.5

0.27

1.64

63

11

1.5

45

Number

unqualified

13

449

230

62

449

232

449

324

449

448

449

449

6

449

372

448

449

449

449

449

408

449

286

441

449

449

441

6

398

449

403

449

440

449

449

272

449

Percent

unqualified

3

100

51

14

100

52

100

72

100

99

100

100

1

100

83

99

100

100

100

100

91

100

64

98

100

100

98

1

89

100

92

100

100

100

100

61

100

'Lower limits vary. Lowest reported value shown. 

2Only 440 samples analyzed for Au, Th, and U.

13
TABLE 3. SUMMARY STATISTICS FOR ANALYSES OF 39 ELEMENTS IN 662 SAMPLES OF NURE 

STREAM SEDIMENT, COCONINO NATIONAL FOREST, ARIZONA

[All values in ppm unless % shown after element symbol. N=not detected at the lower limit of determination shown in 

parentheses. L=detected but in a concentration less that the lower limit of determination shown in parentheses. G=detected 

but in a concentration greater than the upper limit of determination shown in parentheses. Mean values based on unqualified 

values only. "P" following element symbol=ICP partial analysis; "NA"=neutron-activation analysis; "AA"=atomicabsorption analysis; no letters, ICP-AES analysis]

Element

Ag-P1

Al (%)

As-P1

Au-AA1

Ba

Be

Bi-P1

Ca (%)

Cd-P1

Ce

Co

Cr

Cu

Eu

Fe (%)

Ga

K(%)

La

Li

Mg (%)

Mn

Mo-P1

Na (%)

Nb

Nd

Ni

P(%)

Pb

Sb-P1

Sc

Sn

Sr

Th-NA1 - 3

Ti (%)

U-NA3

V

Y

Yb

Zn

Range

Minimum

N(0.067)

1.10

N(l.O)

L(0.002)

73

L(l.)

L(l.)

0.07

N(0.050)

10

1

7

1

L(2.)

0.29

L(4.)

0.29

6

4

0.09

50

N(0.10)

0.03

L(4.)

5

2

0.008

L(4.)

N(l.O)

L(2.)

L(5.)

24

L(1.40)

0.04

L(0.086)

9

3

L(l.)

11

of values

Maximum

0.68

9.50

110

0.04

2700

9

4.1

16

13

870

67

990

1000

2

17

27

3.2

470

110

G(5.00)

3000

20

3.0

70

360

300

0.37

300

25

43

21

2200

270

1.70

14.6

510

130

19

520

Geometric

mean

0.13

4.66

3.0

0.004

310

1.3

2.5

1.64

0.22

50

16

95

26

2

3.0

12

1.3

29

20

0.95

605

0.51

0.54

15

24

36

0.064

16

1.8

9.4

8.3

190

7.6

0.39

2.45

77

15

1.6

59

Number

unqualified

39

662

535

48

662

496

3

662

611

662

662

662

662

4

662

630

662

662

662

661

662

648

662

607

662

662

662

660

16

648

13

662

625

662

638

662

662

593

662

Percent

unqualified

6

100

81

7

100

75

0.5

100

92

100

100

100

100

0.6

100

95

100

100

100

99

100

98

100

92

100

100

100

99

2

98

2

100

98

100

99

100

100

90

100

'Lower limits vary. Lowest reported value shown. 

2Only 661 samples analyzed for Au. 

3Only 639 samples analyzed for Th, and U.

14
The distributions of anomalous concentrations of 10 elements (Ag, As, Au, Cd, Cu, 

Mo, Pb, Sb, U, and Zn) in rock samples are shown on figures 5 to 14, at the back of this 

report. Small open circles on each map show the approximate locations of samples with 

concentrations less than the threshold value shown on the map. Larger, filled circles show the 

approximate locations of samples with concentrations greater than or equal to the threshold 

value shown. The letters A to H on each map refer to sites or clusters of sites for each of the 

selected lithologic environments described below under ENVIRONMENTS A to I. For each 

site or cluster of sites, all of the described elements are not necessarily anomalous for all 

samples. Readers are referred to the data report (Chaffee and others, 1996) for more specific 

information for each site.

ENVIRONMENT A. Sites labeled "A" on the maps represent samples collected from 

two outcrops of the Shinarump Member of the Chinle Formation, a known favorable host for 

uranium deposits in many areas of the Colorado Plateau. The only outcrops of this unit in the 

study area are found at the extreme northern boundary of the forest. Anomalous elements 

(with single anomalous values or ranges of anomalous values in parentheses) include As (6.9- 

65 ppm) (Fig. 6), Au (0.034 ppm) (Fig. 7), Mo (3.1-4.0 ppm) (Fig. 10), Pb (32 ppm) (Fig. 

11), and U (7.50 ppm) (Fig. 13). With the possible exception of gold, all of these elements 

are known to be associated with uranium deposits found elsewhere in this lithologic 

environment (Rose, Hawkes and Webb, 1979). As compared to rocks of similar lithology 

elsewhere in the forest, the concentration ranges for arsenic and molybdenum at this location 

are moderately anomalous; those for the other elements are only weakly anomalous. The gold 

value is low and is not deemed to represent a potential gold resource.

ENVIRONMENT B. Sites labeled "B" on the maps include samples from outcrops of 

felsic to intermediate volcanic rocks that range in composition from rhyolite to dacite. These 

sites are found in the northwestern and southwestern parts of the forest. Samples from a few 

sites in these areas exhibit hydrothermally altered rocks; however, the highest concentrations 

of the selected elements are not necessarily in the most obviously altered rocks, mainly 

because weathering processes have caused some elements in altered samples to be leached at 

the surface. Anomalous elements include Ag (0.11-0.91 ppm) (Fig. 5), As (5.2-17 ppm) (Fig. 

6), Au (0.01 ppm) (Fig. 7), Cu (100-330 ppm) (Fig. 9), Mo (2.2-4.5 ppm) (Fig. 10), Pb (25- 

27 ppm) (Fig. 11), Sb (2.2 ppm) (Fig. 12), U (5.27-9.45 ppm) (Fig. 13), and Zn (100-240 

ppm) (Fig. 14). The ranges for most of these elements (except for lead and possibly uranium) 

are at least moderately anomalous as compared to normally expected background ranges for 

lithologies of these compositions. The associations, if any, of these anomalies with possible 

metallic mineral deposits is not known.

ENVIRONMENT C. Sites labeled "C"' on the maps include samples of the Verde 

Formation. This unit crops out along both sides of the Verde Valley. This formation locally 

contains anomalous concentrations of As (7.3-66 ppm) (Fig. 6), Mo (3.3 ppm) (Fig. 10), and 

U (5.52-63 ppm) (Fig. 13). When compared to concentration ranges in rocks of similar 

composition found elsewhere, these ranges indicate that these three elements are moderately 

enriched in the Verde Formation, at least locally. Rock samples analyzed by Lane (1992) also 

contain anomalous arsenic and uranium, plus antimony, but not molybdenum. As noted

15
above, enrichment of these elements in the Verde Formation is thought to have resulted from 

their deposition from metal-rich ground waters.

ENVIRONMENT D. Sites labeled "D" on the maps include samples that are most 

commonly from silicified and(or) cherty limestone or dolomitic limestone beds of the Kaibab 

Formation. Several sites are for samples that were chiefly composed of sandstone. Exposures 

of this formation are scattered throughout the forest. Samples from these sites contain 

anomalous concentrations of one or more of the elements Ag (0.34-1.1 ppm) (Fig. 5), As (4.7- 

93 ppm) (Fig. 6), Au (0.008 ppm) (Fig. 7), Cd (0.42-5.2 ppm) (Fig. 8), Mo (2.4-7.3 ppm) 

(Fig. 10), Pb (28-1900 ppm) (Fig. 11), Sb (3-17 ppm) (Fig. 12), U (5.16-6.62 ppm) (Fig. 13), 

and Zn (120-220 ppm) (Fig. 14). Most of these elements were found to be most highly 

concentrated in the siliceous zones or in chert nodules and not in the carbonate-rich layers. As 

compared to the typical abundances of these elements in limestone or dolomite layers in the 

Kaibab Formation, the levels listed above are moderately to strongly anomalous for all of the 

elements except gold and uranium, which are only weakly anomalous. The reason for these 

unusual concentrations is not understood. They may represent contributions of elements from 

volcanism occurring in the region at the time of deposition of the carbonate rocks or might 

represent deposition from circulating ground waters at a later time.

ENVIRONMENT E. Sites labeled "E" on the maps consist of three samples of 

manganese oxide "ore" collected from abandoned mines or prospects located north of Glints 

Well (Fig. 1). Elements associated with these samples include Ag (0.39-1.9 ppm) (Fig. 5), As 

(120-2200 ppm) (Fig. 6), Au (0.012 ppm) (Fig. 7), Cd (0.47-2.5 ppm) (Fig. 8), Cu (97-480 

ppm) (Fig. 9), Mo (3.5-1100 ppm) (Fig. 10), Pb (61 ppm) (Fig. 11), Sb (2.5-3.6 ppm) (Fig. 

12), and Zn (550-750 ppm) (Fig. 14). Many of these element ranges are clearly strongly 

anomalous. It is probable that these elements were carried in metal-rich ground waters and 

adsorbed onto manganese (and possibly iron) oxides as they were deposited in a natural 

process commonly called manganese scavenging (Chao and Theobald, 1976; Rose and others, 

1979). Many elements are known to be naturally enriched by this process. Other elements 

enriched in the manganese deposits in the study area (but not discussed here) include Ba, Be, 

Bi, Co, Fe, Hg, Ni, Sr, Tl, V, and W (Chaffee and others, 1996; Lane, 1992; Ulrich and 

Bielski, 1983). If there were deposits of manganese in the forest that could be mined 

economically (not presently the case), then it might be worth recovering at least some of these 

associated elements as by-products.

ENVIRONMENT F. The sites labeled "F" on the maps include samples from shale, 

limestone, or calcareous sandstone beds in the Supai Formation, found mainly in the 

southwestern part of the forest. Some of these samples were collected to determine elements 

associated with local zones of outcropping, visible secondary copper minerals and(or) 

anomalous radioactivity in the Fossil Springs Roadless Area (Peirce and others, 1977; Weir 

and others, 1983). The samples contained anomalous concentrations of one or more of the 

elements Ag (1.2 ppm) (Fig. 5), As (9.2 ppm) (Fig. 6), Cd (40 ppm) (Fig. 8), Cu (170- 

190,000 ppm) (Fig. 9), Mo (3.7-8.7 ppm) (Fig. 10), Pb (32-47 ppm) (Fig. 11), U (5.0-158 

ppm) (Fig. 13), and Zn (120-2800 ppm) (Fig. 14). With the possible exception of lead, these 

elements are moderately to strongly enriched locally in the zones containing visible copper

16
minerals and(or) anomalous radioactivity. As previously noted, the source(s) of the anomalous 

elements is not known.

ENVIRONMENT G. Samples from sites labeled "G" on the maps are from massive 

sandstone exposures of the Toroweap Formation or the Coconino Sandstone that crop out in 

scattered sites in this lithologic environment, most of which are in the southern part of the 

forest. Samples from these sites contain anomalous concentrations of one or more of the 

elements Ag (0.22-1.4 ppm) (Fig. 5), As (5.1-580 ppm) (Fig. 6), Au (0.022 ppm) (Fig. 7), Cd 

(0.42 ppm) (Fig. 8), U (5.01-5.72 ppm) (Fig. 13), and Zn (170 ppm) (Fig. 14). These 

concentration levels are deemed to be weakly to moderately anomalous for a rock lithology 

that normally contains very low levels of these selected elements. As noted previously, 

weakly anomalous silver has been identified elsewhere in this lithologic environment 

(Karlstrom and others, 1983; Ulrich and Bielski, 1983). These new analyses suggest that the 

anomalous silver may be accompanied locally by anomalous concentrations of other elements. 

The source(s) of these elements is not known. Ulrich and Bielski (1983) suggest that the silver 

(and thus, by analogy, the other elements listed above) may have come from the Precambrian 

highlands that are thought to have existed to the south of the forest.

ENVIRONMENT H. Sites labeled with the letter "H" on the maps identify samples 

from outcrops of mafic volcanic rocks, mainly basalt flows. A few samples are of cinders or 

tuffs of similar chemical composition. These sites are mostly in the southern part of the 

forest. Anomalous elements include Ag (0.11-1.2 ppm) (Fig. 5), As (6.9-31 ppm) (Fig. 6), 

Cu (81-110 ppm) (Fig. 9), Mo (3.0 ppm) (Fig. 10), U (5.1 ppm) (Fig. 13), and Zn (130-140 

ppm) (Fig. 14). These ranges of values are thought to only represent the high end of the 

background ranges for the respective elements, with the highest concentrations generally 

associated with high levels of iron and(or) manganese. Two samples of weathered material 

from a cinder quarry (site labeled "HQ" on figures 11 (Pb) and 12 (Sb)) yielded very strongly 

anomalous concentrations of Pb (1700 ppm) and Sb (2.6-13 ppm). No other mafic volcanic 

rock samples contained anomalous concentrations of these two (and only these two) elements. 

Because this locality has been used extensively for a target range, it seems likely that the 

concentrations of these two metals are the result of contamination.

ENVIRONMENT I. Samples labeled "I" on the maps were all collected from 

outcrops of Tertiary gravels. These samples include: (1) one containing anomalous As (5.2 

ppm) (Fig. 6) and Sb (1.6 ppm) (Fig. 12) in Precambrian clasts in gravels collected from the 

Fossil Springs Roadless Area, in the southern part of the forest (site labeled "H") ; (2) one 

containing anomalous Sb (2.5 ppm) (Fig. 12) in a granite clast in conglomerate collected from 

the West Clear Creek Roadless Area (site labeled "12"); and (3) one containing anomalous As 

(8.2 ppm) (Fig. 6) and Cd (0.45 ppm) (Fig. 8) in a sample of gravel collected northeast of 

Glints Well (site labeled "13"). All of these anomalies are considered to be weak. The sources 

of the elements in these samples of transported material is not known but may have been the 

Precambrian highlands that are thought to have existed to the south of the forest (Ulrich and 

Bielski, 1983).

17
USGS Stream-sediment Samples

The distributions of anomalies for 10 elements in USGS stream-sediment samples are 

shown on figures 15 to 24, in the back of this report. These anomalies are also classified into 

sites or clusters of sites with common lithologic environments, which are listed below as 

ENVIRONMENTS A to I.

ENVIRONMENT A. Sites labeled "A" on the maps identify anomalous sediment 

samples whose dominant source material is mafic volcanic rocks, chiefly basalt flows. Minor 

amounts of sediment derived from the Kaibab Formation, Coconino Sandstone, Tapeats 

Formation, and(or) the Supai Formation may also be present. These anomalies are scattered 

throughout the study area. Most of these samples are only anomalous for one or two of the 

elements in the suite. These elements include (with single anomalous value or range of 

anomalous values in parentheses) Ag (0.088-0.3 ppm) (Fig. 15), As (4.2-30 ppm) (Fig. 16), 

Au (0.008 ppm) (Fig. 17), Cd (0.40-2.0 ppm) (Fig. 18), Cu (71-160 ppm) (Fig. 19), Mo (6.6 

ppm) (Fig. 20), Pb (25-42 ppm) (Fig. 21), Sb (0.9-7.5 ppm) (Fig. 22), U (5.75 ppm) (Fig. 

23), and Zn (120-200 ppm) (Fig. 24). All of these anomalies are considered to represent 

simply the upper part of the normal background ranges for weathered mafic rocks, with some 

enhancement of concentrations caused by the iron- and(or) manganese-scavenging process.

ENVIRONMENT B. Sites labeled "B" on the maps identify samples from stream 

channels with sediment that is predominantly composed of felsic volcanic rocks. These sites 

are scattered throughout the study area. Anomalous elements found in this environment 

include As (9.7-11 ppm) (Fig. 16), Cd (0.55 ppm) (Fig. 18), Mo (2.4-2.8 ppm) (Fig. 20), Pb 

(59 ppm) (Fig. 21), Sb (1.4 ppm) (Fig. 22), U (4.09-7.59 ppm) (Fig. 23), and Zn (120-190 

ppm) (Fig. 24). All of these anomalies are relatively weak and are thought to represent only 

the high end of the normal background ranges for the respective elements.

ENVIRONMENT C. Sites labeled "C" on the maps identify samples with anomalous 

concentrations from stream channels in which the sediment is mostly composed of material 

from the Kaibab Formation. This material mostly includes carbonate-rich fragments 

commonly accompanied by silicified and(or) cherty fragments that may include iron and(or) 

manganese oxides. These sites are found near Flagstaff and in the southern part of the forest.

Anomalous elements in this environment include As (4.3-19 ppm) (Fig. 16), Cd (0.66- 

2.2 ppm) (Fig. 18), Mo (2.5-4.0 ppm) (Fig. 20), U (4.16-4.67 ppm) (Fig. 23), and Zn (130 

ppm) (Fig. 24). All of these anomalies are deemed to represent relatively high but normal 

concentrations for the lithologies present. As was noted for the rock samples from this 

lithologic environment, anomalies for these elements in sediment seem to be associated with 

material from silicified and(or) cherty horizons. The origins for these unusual concentrations 

is not understood. They may represent contributions of elements from volcanism occurring in 

the region at the time of deposition of the carbonate rocks or might represent deposition from 

ground waters.

ENVIRONMENT D. Sites labeled "D" on the maps identify localities where the 

sample material is composed of an approximately equal mixture of mafic volcanic rocks 

(mostly basalts) and the carbonate-rich Kaibab Formation, two chemically contrasting 

lithologies. These sites are mostly in the central third of the forest. Anomalous elements 

include Ag (0.52 ppm) (Fig. 15), As (6.0-46 ppm) (Fig. 16), Au (0.012 ppm) (Fig. 17), Cd

18
(0.44-0.87 ppm) (Fig. 18), Cu (79 ppm) (Fig. 19), Mo (2.5-3.7 ppm) (Fig. 20), and U (4.06 

ppm) (Fig. 23). None of the samples in this lithologic environment is anomalous for more 

than two of these elements. All of the anomalies are deemed to be related to high but normal 

concentration levels for the lithologies present.

ENVIRONMENT E. Four samples of sediment derived chiefly from Coconino 

Sandstone and collected in the extreme southeastern part of the study area, comprise lithologic 

environment E. These samples contain weakly anomalous Ag (0.087-0.18 ppm) (Fig. 15) but 

are not anomalous for any of the other elements studied. As noted previously, the presence of 

anomalous silver has been reported for this lithologic environment elsewhere in the region 

(Karlstrom and others, 1983; Ulrich and Bielski, 1983). This weakly anomalous silver does 

not indicate a significant mineral resource and is thus only of academic interest. Weakly 

anomalous arsenic (5.9 ppm) was identified in one sample that was collected during evaluation 

of the Wet Beaver Roadless Area (Ulrich and others, 1983) in a side canyon draining outcrops 

of Coconino Sandstone, in the upper part of Wet Beaver Creek (Fig. 16). This arsenic 

anomaly is not accompanied by anomalous concentrations of any of the other elements studied, 

and is thus thought to represent only a high background concentration.

ENVIRONMENT F. One sample originally collected for the Fossil Springs Roadless 

Area (sample number FC61S; Chaffee and others, 1996) was from a drainage basin 

characterized as containing mostly Paleozoic sedimentary rocks, chiefly the Supai Formation 

(Weir and others, 1983). This sample contained 140 ppm copper (Fig. 19). As noted 

previously, locally high copper contents were measured in rock samples from the Supai 

Formation in this general area. Anomalies for copper were previously determined by Weir 

and others (1983) in rock, stream-sediment, and panned heavy-mineral-concentrate samples 

from the area. The source of the copper has not been identified.

ENVIRONMENT G. Sites labeled "G" on the maps are found along the Verde River 

Valley and identify anomalies that are composed predominantly of material from the Verde 

Formation, which consists mostly of clastic- and carbonate-rich lake-bed sediments. Rock 

samples collected from this lithologic environment were found to be locally anomalous in 

arsenic, molybdenum, and(or) uranium. Stream sediments derived from this unit also contain 

anomalous arsenic (6.2-17 ppm) (Fig. 16) and uranium (4.93 ppm) (Fig. 23). Several samples 

collected along the Verde Valley also exhibit weak anomalies for either gold (0.008 ppm) (Fig. 

17) or cadmium (0.41-0.59 ppm) (Fig. 18). These weakly anomalous concentrations of gold 

and cadmium are thought to result from contamination from past prospecting, mining, and(or) 

smelting in the upper Verde River Valley (Fig. 1) and not from metal-enriched deposits in the 

Verde Formation.

ENVIRONMENT H. Samples with anomalies labeled "H" are from the extreme 

northwestern part of the study area and are located on the maps for lead (25 ppm) (Fig. 21) 

and uranium (5.45 ppm) (Fig. 23). These samples are of sediment derived chiefly from the 

Shinarump Member of the Chinle Formation, a known source of uranium deposits in other 

parts of the Colorado Plateau region. The relatively low concentrations in the samples from 

this area, along with the similar low concentrations of these elements in rock samples from the 

same area, suggest that any exposed concentrations of uranium in the area are not significant.

19
ENVIRONMENT I. Several sites just north of Glints Well, in the southeastern part 

of the forest (Fig. 1), identify samples collected downstream from inactive manganese mines 

or prospects. These samples are in drainage basins containing outcrops of the Kaibab 

Formation. Anomalies for Ag (0.17 ppm) (Fig. 15), As (8.6-46 ppm) (Fig. 16), Cd (0.65-1.1 

ppm) (Fig 18), and Mo (3.2-5.9 ppm) (Fig. 20) were detected. As noted under rock samples, 

manganese "ores" from this area often contain anomalous concentrations of other elements. 

All of these anomalies are deemed to be the direct result of elements enriched by the ironand(or) manganese-scavenging process and therefore do not identify hydrothermal mineral 

deposits.

NURE Stream-sediment Samples

As noted earlier, most of the samples collected from drainage channels in the forest 

for the NURE program are from the upper reaches of drainage basins. As such, these samples 

represent material that has not been transported for very long distances and may thus more 

closely approximate soil samples than true stream-sediment samples.

The anomalous distributions of 11 elements (Ag, As, Au, Cd, Cu, Mo, Pb, Sb, Sn, U, 

and Zn) in NURE stream-sediment samples are shown on figures 25 to 35, in the back of this 

report. The anomalies shown on these figures are classified into areas of common lithologic 

environments that are listed below as ENVIRONMENTS A to G.

ENVIRONMENT A. Sites labeled "A" on the maps identify anomalous sediment 

samples whose dominant source material is mafic volcanic rocks, chiefly basalt flows. These 

areas are scattered throughout the forest. Anomalous elements (with single anomalous values 

or ranges of anomalous values in parentheses) include Ag (0.10-0.11 ppm) (Fig. 25), As (5.0- 

6.1 ppm) (Fig. 26), Au (0.008-0.04 ppm) (Fig. 27), Cd (0.50-3.90 ppm) (Fig. 28), Cu (70-87 

ppm) (Fig. 29), Mo (1.6 ppm) (Fig. 30), Pb (32-51 ppm) (Fig. 31), Sn (5 ppm) (Fig. 33), U 

(4.49-5.43 ppm) (Fig. 34), and Zn (120-190 ppm) (Fig. 35). With the possible exception of 

tin, all of these concentrations are deemed to represent the upper part of the normal 

background ranges for each of these elements in this lithologic environment. Some of the high 

values for elements such as cadmium, molybdenum, and zinc may be the result of the 

enriching effects of manganese and(or) iron scavenging. The anomalous tin value is in a 

sample collected in basaltic cinder deposits in the vicinity of Kendrick Peak (Fig. 1), an area 

of Quaternary rhyelites (Ulrich and others, 1984). Thus, the tin value may indicate a 

contribution to this chiefly basaltic sediment sample of material from these rhyolites. The tin 

is therefore considered to be within its normal background range.

ENVIRONMENT B. The sites labeled "B" on the maps indicate localities where the 

sediment is composed mostly of felsic to intermediate volcanic rocks chiefly related to dacite 

flows in the San Francisco Peaks region just north of Flagstaff or to rhyolite flows near 

Kendrick Peak, near the western boundary of the forest. Elements identified as anomalous in 

this lithologic environment include Cd (0.54-1.91 ppm) (Fig. 28), Mo (1.3-2.2 ppm) (Fig. 

30), Pb (32-39 ppm) (Fig. 31), Sn (6-10 ppm) (Fig 33), and U (4.40-11.3 ppm) (Fig. 34). All 

of these values are deemed to represent normal values at the upper end of background ranges 

for the respective elements in this lithologic environment.

20
ENVIRONMENT C. The sites labeled "C" on the maps identify localities where the 

sediment is composed mostly of carbonate-rich fragments in the Kaibab Formation that may 

include silicified and(or) cherty fragments. Manganese-oxide coatings have been observed 

locally on sediment grains in the vicinity of these localities. For NURE samples, these 

anomalies are found mostly in the southeastern part of the forest but are also present in 

scattered localities east of Flagstaff and along the eastern and western boundaries of the forest. 

Anomalies identified include Ag (0.11-0.14 ppm) (Fig. 25), As (5.4-82 ppm) (Fig. 26), Cd 

(0.53-3.2 ppm) (Fig. 28), Mo (1.3-8.5 ppm) (Fig. 30), Pb (30 ppm) (Fig. 31), U (4.41-6.35 

ppm) (Fig. 34), and Zn (140 ppm) (Fig. 35). All of these anomalies are deemed to represent 

relatively high but normal background concentrations. As noted previously, the reasons for 

some of these relatively high concentrations, especially for arsenic, cadmium, molybdenum, 

lead, and uranium, is not understood but may represent contributions of these elements from 

volcanism occurring in the region at the time of deposition of the carbonate rocks or 

contributions caused by deposition of the elements from circulating ground waters.

ENVIRONMENT D. Sites labeled "D" on the maps identify localities where the 

sample materials are thought to be composed of an approximately equal mixture of mafic 

volcanic rocks (chiefly basalts) and the carbonate-rich Kaibab Formation, two chemically 

contrasting lithologies. These areas are mostly located in the west-central part of the forest, 

south and west of Flagstaff but are also present in other localities scattered throughout the 

forest. Anomalous elements include Ag (0.11-0.68 ppm) (Fig. 25), As (5.8-7.6 ppm) (Fig. 

26), Cd (0.51-2.40 ppm) (Fig. 28), Cu (73-160 ppm) (Fig. 29), Mo (3.0 ppm) (Fig. 30), Pb 

(40-54 ppm) (Fig. 31), and Zn (180 ppm) (Fig. 35). All of these anomalies are thought to 

represent the normal, upper range of background values for the lithologies present.

ENVIRONMENT E. Two samples of sediment derived chiefly from Coconino 

Sandstone were collected in the extreme southeastern part of the forest. As was the case for 

some of the USGS stream-sediment samples collected in this same environment (Fig. 15), 

these two samples contained weakly anomalous silver (0.11-0.17 ppm) (Fig. 25). In addition, 

one of the two samples also contained weakly anomalous molybdenum (1.5 ppm) (Fig. 30). 

As noted previously, the source(s) of these elements in this usually metal-barren sandstone is 

not known but may be the Precambrian highlands thought to have existed to the south of the 

forest (Ulrich and Bielski, 1983). The concentrations are of academic interest only and do not 

represent hydrothermal mineralization processes.

ENVIRONMENT F. Sites labeled "F" are from localities containing mixed clastic and 

carbonate Paleozoic sediments, with the Supai Formation (mostly sandstones and siltstones) 

being the dominant unit. These few areas are found in the west central part of the study area. 

Anomalous elements include As (6.3 ppm) (Fig. 26), Au (0.009 ppm) (Fig. 27), and Pb (31-37 

ppm) (Fig. 31). All of these concentrations are deemed to be in the upper parts of the ranges 

of background concentrations for the respective elements.

ENVIRONMENT G. Sites labeled "G" on the maps are found in the Verde River 

Valley and identify anomalous samples composed of material derived from the Verde 

Formation, which has been previously described, and also derived from a variety of rock types 

exposed to the west of the Verde River (and outside of the forest), that are not present within 

the forest and are not further discussed here. The chemistry for samples collected outside of

21
Coconino National Forest was added to the data set to provide context to the zone bounding 

the forest. The element concentrations for most of the samples labeled "G" are based on the 

cumulative effects of natural concentrations added to those caused by mining and smelter 

contamination in the general area of the Verde River Valley (Fig. 1). Anomalous elements 

identified in samples from areas labeled "G" include Ag (0.11-0.62 ppm) (Fig. 25), As (5.2- 

110 ppm) (Fig. 26), Au (0.008-0.016 ppm) (Fig. 27), Cd (0.59-8.0 ppm) (Fig. 28), Cu (87- 

580 ppm) (Fig. 29), Mo (1.3-20 ppm) (Fig. 30), Pb (30-300 ppm) (Fig. 31), Sb (1.6 ppm-8.2 

ppm), (Fig. 32), Sn (5-11 ppm) (Fig. 33), U (4.40-14.8 ppm) (Fig. 34), and Zn (120-520 

ppm) (Fig. 35).

ENVIRONMENTAL GEOCHEMISTRY

The geochemical data for both rock and stream-sediment samples provide some 

guidance as to possible environmental concerns related to dispersion of potentially toxic 

elements in the Coconino National Forest. Potential environmental problems are discussed 

below for two environments: the surficial environment and the subsurface environment.

Surficial Environmental Geochemistry

Based on the chemistry of surficial materials, four areas in or near the Coconino 

National Forest are potentially of environmental concern. In the Long Valley area, near Glints 

Well, in the southern part of the forest (Fig. 1), manganese oxide ores have been mined in the 

past. Other prospects for manganese are known in the same general area (Farnham and 

Stewart, 1958). Analyses of samples of ores, described earlier, indicate that strongly 

anomalous concentrations of as many as nine elements (Ag, As, Au, Cd, Cu, Mo, Pb, Sb, and 

Zn) are present, as well as 11 other elements not discussed here (Ba, Be, Bi, Co, Fe, Hg, Ni, 

Sr, Tl, V, and W). Samples of stream sediment collected about two miles or less downstream 

from the abandoned mines are also enriched in many of the elements analyzed for this report. 

Sample data from the West Clear Creek Roadless Area study (Ulrich, 1983) indicate that 

chemical anomalies related to the manganese mining drop to background ranges at a distance 

downstream from the old workings of between two and nine miles, suggesting that the effects 

of dispersion of ore-related elements downstream from the mines are limited.

Other manganese prospects examined for this study were found to be limited in 

exposure. In addition, most are not located in or near any major drainage channel, so that 

potential mechanical or chemical dispersion from these prospects is limited. Consequently, 

these minor areas of manganese deposits are probably not an environmental concern.

It is also important to note that these secondary manganese deposits do not contain any 

sulfide minerals; consequently, any water draining such deposits will not be acidic.

The second area of environmental concern related to surficial materials is along the 

western boundary of the forest, where beds of the Verde Formation crop out. As previously 

noted, localized areas in the Verde Formation are known to contain weakly to moderately 

anomalous concentrations of arsenic, molybdenum, and(or) uranium. Radon, a daughter 

product of uranium, was not measured for this report; however, significant concentrations of 

this gas have been found in the Camp Verde-Middle Verde area (Duncan and Spencer, 1993) 

and might be present elsewhere in the rocks and soils in and near the Verde Valley. Thus,

22
caution is advised regarding constructing any enclosed structures on outcrops or shallowly 

covered areas of the Verde Formation that may present a potential radon hazard. Again, 

sulfide minerals have not been identified in the Verde Formation, so surface waters draining 

this formation will not be acidic.

As noted earlier, many of the MURE stream-sediment samples were collected from 

channels representing very small watersheds. Samples from such areas often tend to have 

more characteristics of residual-soil samples, which are composed of very local material, than 

of stream-sediment samples, which are commonly composed of actively migrating material. 

Although we have not conducted any soil surveys for this report, the high concentrations of 

many of the selected elements in the MURE samples suggest a widespread, smelter-related soil 

contamination problem one that probably exists both on private lands and on forest lands. 

Our observation is corroborated by Nash and others (1996), who suggested that soil 

contamination related to smelters in the Verde River area (Fig. 1) is probably widespread in 

the Verde River Valley north and east of Clarkdale.

The third area of concern is in the Fossil Springs Roadless Area, where minor 

amounts of sulfide minerals have been reported to occur locally in outcrops of the Supai 

Formation in association with secondary copper minerals, as well as with various other 

minerals containing the suite of elements determined for this study (Peirce and others, 1977; 

Ulrich and Bielski, 1983). Waters leaching these sulfide-rich areas may become acidic. 

However, it seems unlikely that these waters would remain acidic for any significant distance 

below the sulfide-rich outcrops because of (1) strongly oxidizing conditions and (2) the 

presence of carbonate-rich material that would rapidly neutralize any acid present.

The last area of possible concern is in the vicinity of Slate Mountain, in the 

northwestern part of the forest (Fig. 1). Oxidized base-metal minerals, which probably have 

unoxidized, sulfide-phase analogs at depth, have been reported from this area (Lockrem, 1983; 

quoted in Bliss, 1997). The locality was not further examined for this study. Low 

topographic relief in the area, together with relatively low precipitation, have created only a 

very poorly integrated stream network. As a result, any downstream movement of base-metal 

sulfides that may exist would be minimal. Thus, the production of acidic waters in the 

immediate area is not deemed to be a significant environmental concern.

Subsurface Environmental Geochemistry

Under the right combination of physical and chemical conditions, many elements can 

migrate in solution in ground water. As a result, the siting of wells in some areas of the 

forest, whether for domestic or agricultural purposes, must be evaluated carefully, and the 

chemistry of well waters should be monitored.

Within the Coconino National Forest, an area of primary concern for ground water is 

that underlain by the Verde Formation, west of Sedona and extending along the Verde Valley. 

No water analyses were determined for this study, but the potential exists for toxic levels of 

elements such as arsenic, molybdenum, and(or) uranium (as well as radon) in waters from 

wells drilled in the Verde Formation.

Although no uranium-rich collapse-type breccia-pipe deposits (which contain 

significant volumes of sulfide minerals) have been identified in the forest (Sutphin and

23
Wenrich, 1989), this type of mineral deposit might still be present at shallow depths under a 

veneer of volcanic rocks or alluvium, particularly in the northern part of the forest. Deep 

wells penetrating such a deposit could produce acidic water containing significant levels of 

potentially toxic elements such as As, Cd, Cu, Mo, Pb, Rn, U, and Zn.

Another potential ground water-related environmental problem could occur over major 

parts of the forest. Samples of both rock and stream sediment containing silicified and(or) 

cherty material in the Kaibab Formation have been found to contain anomalous concentrations 

of as many as nine of the elements determined for this report (Ag, As, Cd, Cu, Mo, Pb, Sb, 

U, and Zn). The origin and extent of these zones is not known but may be widespread in 

areas where the Kaibab Formation is present, either at the surface or in the subsurface. No 

sulfide minerals are known to be associated with these mineralized zones. The mobility, if 

any, of these elements in the Kaibab aquifers has also not been established but is not thought 

to be significant. Nevertheless, a slight potential exists for the presence of toxic levels of 

these elements in waters from wells drilled anywhere the Kaibab Formation occurs.

CONCLUSIONS AND RECOMMENDATIONS

Only a few localities in Coconino National Forest contain significant anomalies for 

one or more of the selected elements discussed for this report. As a consequence, only limited 

areas in the forest can be identified as having: (1) any potential for metallic mineral deposits or 

(2) potential environmental problems.

The most significant area, for both mineral resources and environmental concerns, is 

the region along the Verde River Valley. Although uranium anomalies are widespread, past 

studies indicate that the potential resources for uranium in this region are small. In this area, 

relatively high concentrations of a number of elements in surficial materials identify 

contamination related to past mining and smelting, which occurred on the west side of the 

Verde River, outside of the forest (Fig. 1). In addition, uranium prospects are present in a 

few localities in the Verde Formation, both along, and just east of, the Verde River Valley. 

Rock samples analyzed for the present study indicate that relatively low but anomalous levels 

of arsenic and(or) molybdenum may accompany the uranium. Although concentrations of 

radon were not measured for this study, a potential exists for the presence of this element in 

areas enriched in uranium. Wells drawing ground water from this region may also contain 

potentially hazardous concentrations of uranium, radon, and(or) other elements. We are not 

aware of any study of such well waters and recommend that well waters be analyzed, 

especially if used for domestic purposes.

As noted above, soils in the area from the Verde River Valley eastward for an 

unknown distance have been contaminated with a number of potentially toxic elements 

deposited from smelter effluent. The extent of this contamination was not determined for this 

study. Detailed soil surveys for this purpose are recommended.

We also caution that, although no problem is now known to exist, a potential 

environmental problem may exist in well waters coming from some aquifers in the Kaibab 

Formation, as anomalous concentrations of a number of potentially toxic elements were found 

in silicified zones in that formation. The locations and extents of these silicified zones are not 

known. No sulfide minerals were identified in the samples of rock collected from these zones

24
for this study; thus, the mobility of the elements of concern is probably limited. Again, 

analyses of well waters were not done for this study but would seem to be a prudent 

recommendation if a given well is expected to penetrate any silica-rich zones in the Kaibab 

Formation.

Samples of manganese from deposits in the Long Valley area, near Glints Well in the 

southern part of the forest, were found to contain significant concentrations of as many as 13 

of the elements determined for this study. However, downstream dispersion of these elements 

probably does not extend more than a few miles below old mine workings. The lack of any 

sulfide minerals in these deposits indicates that no acid is generated upon weathering of these 

deposits. Past studies suggest that the potential resources for manganese are small.

The minor exposures of sulfide minerals in Fossil Creek Canyon do not constitute a 

significant acid-generating source. Based on our evaluation of the data gathered for this 

report, other potential sources of concentrations of metallic minerals are not thought to be 

significant enough in terms of grade, tonnage, or sulfide content, to identify significant 

mineral resources or to produce potential environmental problems.

A concern has been registered in the past by Forest Service officials that claims are 

being filed for gold in the forest in localities where geologic conditions suggest that gold 

deposits are not likely to occur. We note that very few gold values above the lower limit of 

determination (0.002 ppm) were found in the samples analyzed for this report. Our 

observations are corroborated by the regional sampling and analysis for gold described by 

Lane (1992). The lack of any meaningful gold concentrations in the samples collected within 

the forest suggests that this element is probably not enriched to the level of a potential resource 

anywhere in the forest and, in any case--with the exception of several NURE samples included 

in the NURE data set but collected from outside the forest in the Verde River Valley-is not 

associated with any known type of mineral deposit or alteration phase sampled in the study 

area.

ACKNOWLEDGMENTS

Many people have assisted us in this project. Help provided by the Coconino National 

Forest personnel, Flagstaff, Arizona, is appreciated. We thank P.M. Theodorakos, USGS, 

Denver, Colorado, for assistance in preparing the samples for analysis and G.B. Haxel and 

J.D. Hendricks of the USGS office in Flagstaff, Arizona, for guidance in the field.

25
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Yavapai, Gila, and Coconino Counties, Arizona: U.S. Geological Survey Open-File Report 

84-340, 8 p.

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486, 262 p.

Briggs, P.H., 1990, Elemental analysis of geologic materials by inductively coupled plasmaatomic emission spectrometry, in Arbogast, B.F., Quality assurance manual for the 

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Roushey, B.H., 1996, Analytical results for rock and stream-sediment samples, Coconino 

National Forest, Coconino, Gila, and Yavapai Counties, Arizona: U.S. Geological Survey 

Open-File Report 96-282-A, 160 p., and 96-282-B, diskette.

Chao, T.T., and Theobald, P.K., Jr., 1976, the significance of secondary iron and manganese 

oxides in geochemical exploration: Economic Geology, v. 71, no. 8, p. 1560-1569.

Clark, R.J., 1979, Hydrogeochemical and stream sediment reconnaissance basic data report 

for the Prescott NTMS quadrangle, Arizona: U.S. Department of Energy Report GJBX2(79), 19 p., appendices, microfiches.

Cook, J.R., and Fay, W.M., 1982, Data report: Western United States: U.S. Department of 

Energy Report GJBX-132(82), 33 p., microfiches.

Duncan, J.T., and Spencer, J.E., 1993, Uranium-bearing rocks in Verde Valley, Yavapai 

County, and implications for indoor-radon gas, in Spencer, I.E., ed., Radon in Arizona: 

Arizona Geol. Society Bulletin 199, 96 p.

Farnham, L.L., and Stewart, L.A., 1958, Manganese deposits of western Arizona: U.S. 

Bureau of Mines Circular 7843, 87 p.

26
Gerstel, W.J., Day, G.W., and McDanal, S.K., 1983, Analytical results for 178 streamsediment, 98 heavy-mineral-concentrate, and 11 water samples, Rattlesnake and Wet 

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Open-File Report 83-339, 156 p., 2 sheets, scale 1:24,000.

Karlstrom, T.N.V., Billingsley, G.H., and McColly, Robert, 1983, Mineral resource potential 

and geologic map of the Rattlesnake Roadless Area, Coconino and Yavapai Counties, 

Arizona: U.S. Geological Survey Miscellaneous Field Studies Map MF-1567-A, 1 sheet, 

scale 1:24,000 (includes 9-page interpretive pamphlet).

Lane, M.E., 1992, Mineral resource appraisal of the Coconino National Forest, Arizona: U.S. 

Bureau of Mines Mineral Land Assessment Open File Report MLA 11-92, 62 p., 2 

appendices, 3 plates, scale 1:126,720.

/ 

Lockrem, T.M., 1983, Geology and emplacement of the Slate Mountain volcano-laccolith,

Coconino County, Arizona: Flagstaff, Northern Arizona University Master's thesis, 103 p.

McKown, D.M., and Knight, R.J., 1990, Determination of uranium and thorium in geologic 

materials by delayed neutron counting, in Arbogast, B.F., Quality assurance manual for 

the Branch of Geochemistry, U.S. Geological Survey: U.S. Geological Survey Open-File 

Report 90-688, 183 p.

Motooka, J.M., 1990, Organometallic halide extraction applied to the analysis of geologic 

materials for 10 elements by inductively coupled-atomic emission spectrometry, in 

Arbogast, B.F., Quality assurance manual for the Branch of Geochemistry, U.S. 

Geological Survey: U.S. Geological Survey Open-File Report 90-688, 183 p.

Nash, J.T., Miller, W.R., McHugh, J.B., and Meier, A.L., 1996, Geochemical

characterization of mining districts and mining-related contamination in the Prescott 

National Forest area, Yavapai County, Arizona: a preliminary assessment of environmental 

effects: U.S. Geological Survey Open-File Report 96-687, 80 p.

O'Leary, R.M., and Meier, A.L., 1990, Determination of gold in samples of rock, soil, 

stream sediment, and heavy-mineral concentrate by flame and graphite furnace atomic 

absorption spectrophotometry following dissolution by HBr-Br2 , in Arbogast, B.F., 

Quality assurance manual for the Branch of Geochemistry, U.S. Geological Survey: 

U.S. Geological Survey Open-File Report 90-688, 183 p.

Peirce, H.W., Jones, Niles, and Rogers, Ralph, 1977, A survey of uranium favorability of 

Paleozoic rocks in the Mogollon rim and slope region east central Arizona: Arizona 

Bureau of Geology and Mineral Technology Circular 19, 71 p.

27
Rose, A.W., Hawkes, H.E., and Webb, J.S., 1979, Geochemistry in Mineral Exploration 

(2nd. ed.): New York, Academic Press, 657 p.

Sellers, W.D., ed., 1960, Arizona Climate: Tucson, University of Arizona Press, 60 p. (Plus 

about 300 pages of climate data).

Sutphin, H.B., and Wenrich, K.B., 1989, Map of locations of collapse-breccia pipes in the 

Grand Canyon region of Arizona: U.S. Geological Survey Open-File Report 89-550, 1 

plate, scale 1:250,000.

Thayer, P.A., and Cook, J.R., 1980, Hydrogeochemical and stream sediment reconnaissance 

data report (abbreviated) for the Flagstaff 1° x 2° NTMS area: Department of Energy 

Report GJBX-137(81), 16 p., appendices.

Ulrich, G.E., 1983, Geochemical data for the West Clear Creek Roadless Area, Yavapai and 

Coconino Counties, Arizona: U.S. Geological Survey Open-File Report 83-165, 9 p.

Ulrich, G.E., and Bielski, A.M., 1983, Mineral resource potential map of the West Clear 

Creek Roadless Area, Yavapai and Coconino Counties, Arizona: U.S. Geological Survey 

Miscellaneous Field Studies Map MF-1555-A, 1 sheet, scale 1:24,000 (includes 9-page 

interpretive pamphlet).

Ulrich, G.E., Bielski, A.M., and Bywaters, J.S., 1983, Mineral resource potential and

geology of the Wet Beaver Roadless Area, Coconino and Yavapai Counties, Arizona: U.S. 

Geological Survey Miscellaneous Field Studies Map MF-1558-A, 1 sheet, scale 1:24,000 

(includes 5-page interpretive pamphlet).

Ulrich, G.E., Billingsley, G.H., Hereford, Richard, Wolfe, E.W., Nealey, L.D., and Sutton, 

R.L., 1984, Map showing geology, structure, and uranium deposits of the Flagstaff 1° x 

2° quadrangle, Arizona: U.S. Geological Survey Miscellaneous Investigation Series Map 

1-1446, 2 sheets, scale 1:250,000.

Weir, G.W., Beard, L.S., and Ellis, C.E., 1983, Mineral resource potential of the Fossil 

Springs Roadless Area, Yavapai, Gila, and Coconino counties, Arizona: U.S. Geological 

Survey Miscellaneous Field Studies Map MF-1568-A, 1 sheet, scale 1:24,000 (includes 

interpretive pamphlet).

Weir, G.W., Ulrich, G.E., and Nealey, L.D., 1989, Geologic map of the Sedona 30' x 60' 

quadrangle, Yavapai and Coconino Counties, Arizona: U.S. Geological Survey 

Miscellaneous Investigations Series Map 1-1896, 1 sheet, scale 1:100,000.

28
Weir, G.W., Ulrich, G.E., and Nealey, L.D., 1994, Geologic map of the Long Valley 

quadrangle, Coconino County, Arizona: U.S. Geological Survey Geologic Quadrangle 

Map GQ-1735, scale 1:24,000.

Wolfe, E.W., 1983, Geochemical map of the Arnold Mesa Roadless Area, Yavapai, County, 

Arizona: U.S. Geological Survey Miscellaneous Field Studies Map MF-1577-C, 1 sheet, 

scale 1:24,000.

Wolfe, E.W., and Hahn, D.A., 1982, Geology and geochemical analyses of the Strawberry 

Crater area, Coconino County, Arizona: U.S. Geological Survey Miscellaneous Field 

Studies Map MF-1394-A, 1 sheet, scale 1:24,000.

29
112° 00' 111M51

111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

AgZO.IOppm

. 1IIII , . .

0 5 10 15 20 25 30km

Figure 5. Distribution of anomalous silver in rock samples, Coconino National Forest, 

Arizona. See text for explanation of symbols.

30
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

As I I I I I I > 4.5 ppm

Figure 6. Distribution of anomalous arsenic in rock samples, Coconino National Forest, 

Arizona. See text for explanation of symbols.

31
112° OD- 111° so- ur 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Au > 0.008 ppm I I I I I

Figure 7. Distribution of anomalous gold in rock samples, Coconino National Forest, Arizona. 

See text for explanation of symbols.

32
112° 00' 111° 30' 

 I 

111° 15' 

 I 

111° 00' 

 i 

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Cd £ 0.40 ppm

Figure 8. Distribution of anomalous cadmium in rock samples, Coconino National Forest, 

Arizona. See text for explanation of symbols.

33
112° 00' 111 0 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

10 15 20 mi

Cu > 80 ppm

Figure 9. Distribution of anomalous copper in rock samples, Coconino National Forest, 

Arizona. See text for explanation of symbols.

34
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

10 15 20mi

Mo>2.0ppm i i r i i r

0 5 10 15 20 25 30km

Figure 10. Distribution of anomalous molybdenum in rock samples, Coconino National 

Forest, Arizona. See text for explanation of symbols.

35
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Pb £ 25 ppm 0 5

I I I 

20 25 30 km

Figure 11. Distribution of anomalous lead in rock samples, Coconino National Forest, 

Arizona. See text for explanation of symbols.

36
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Sb > 1.5 ppm

Figure 12. Distribution of anomalous antimony in rock samples, Coconino National Forest, 

Arizona. See text for explanation of symbols.

37
112° 00' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

U > 5.0 ppm

Figure 13. Distribution of anomalous uranium in rock samples, Coconino National Forest, 

Arizona. See text for explanation of symbols.

38
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Zn £ 100 ppm 10 15 20 25 30km

Figure 14. Distribution of anomalous zinc in rock samples, Coconino National Forest, 

Arizona. See text for explanation of symbols.

39
112° 00' 111° 45' 111° 30' 

 I 

111° 15' 

 I 

111 0 00' 

 i 

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

10 15 20mi

Ag > 0.08 ppm i i i i \ r

0 5 10 15 20 25 30km

Figure 15. Distribution of anomalous silver in USGS stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

40
112° 00' 111° 30' 111° 15' 111° DO30'

35° 15'

35° 00'

34° 45'

34° 30'

4.0 pp/n

Figure 16. Distribution of anomalous arsenic in USGS stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

41
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

0.008 ppm

Figure 17. Distribution of anomalous gold in USGS stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

42
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

15 20 mi

Cd Z 0.40 ppm

\ I i i r

5 10 15 20 25 30km

Figure 18. Distribution of anomalous cadmium in USGS stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

43
112° 00' 111° so- ur 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34°

? T

1.5 20.mi

Cu ^ 70 ppm

I I I I \ F 

0 5 10 15 20 25 30km

Figure 19. Distribution of anomalous copper in USGS stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

44
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

f T

20 mi

Mo £ 2.4 ppm

I 1 I I I I

0 5 10 15 20 25 30km

Figure 20. Distribution of anomalous molybdenum in USGS stream-sediment samples, 

Coconino National Forest, Arizona. See text for explanation of symbols.

45
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Pb > 25 ppm

Figure 21. Distribution of anomalous lead in USGS stream sediment-samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

46
112° 00' 111 0 45' 111° 30' 111° 15' nroo1

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Sb£0.9ppm

Figure 22. Distribution of anomalous antimony in USGS stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

47
112° DO- 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

U Z 4.0 ppm

Figure 23. Distribution of anomalous uranium in USGS stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

48
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Zn > 120 ppm

Figure 24. Distribution of anomalous zinc in USGS stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

49
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Ag>0.10 ppm

. . , .

lIIII

0 5 10 15 20 25 30km 

______I___________________I

Figure 25. Distribution of anomalous silver in NURE stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

50
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

As > 5.0 ppm i i i i i r

5 10 15 20 25 30km 

I___________________I

Figure 26. Distribution of anomalous arsenic in NURE stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

51
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Au £ 0.008 ppm

Figure 27. Distribution of anomalous gold in NURE stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

52
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Cd>0.50ppm i i i i i r

5 10 15 20 25 30km

Figure 28. Distribution of anomalous cadmium in NURE stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

53
35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

112° 00' 

 I 

111° 45' 111° 30' 111° 15' 

 l 

111° 00' 

 \ 

Cu £ 70 ppm I I I I I i

0 5 10 15 20 25 30km

Figure 29. Distribution of anomalous copper in NURE stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

54
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Mo > 1.3 ppm

Figure 30. Distribution of anomalous molybdenum in NURE stream-sediment samples, 

Coconino National Forest, Arizona. See text for explanation of symbols.

55
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

0 I*

! T 1

1.5 20.mi

Pb > 30 ppm I I I I I I

0 5 10 15 20 25 30km 

______I___________________I

Figure 31. Distribution of anomalous lead in NURE stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

56
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

? T T

20.mi

Sb > 1.5 ppm

. , ,

r~ r i i r

5 10 15 20 25 30km 

I __________ I

Figure 32. Distribution of anomalous antimony in NURE stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

57
112° 00' 111° 45' 111° 30' 111° 15' uroo1

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Sn>5 ppm

5 10 15 20,mi

~TITIIT 

0 5 10 15 20 25 30km 

______I___________________I

Figure 33. Distribution of anomalous tin in NURE stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

58
112° OD- 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

U £ 4.40 ppm

Figure 34. Distribution of anomalous uranium in NURE stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

59
112° 00' 111° 45' 111° 30' 111° 15' 111° 00'

35° 30'

35° 15'

35° 00'

34° 45'

34° 30'

Zn > 120 ppm

20.mi

. ? . . 1 l° . ? .2°i' 

Tl I I I I

5 10 15 20 25 30km 

I___________________l_

Figure 35. Distribution of anomalous zinc in NURE stream-sediment samples, Coconino 

National Forest, Arizona. See text for explanation of symbols.

60