ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

ls

Qls

Qls

Qls

Qls

Qoal

 STAR

 MOUNTAIN

 PLUTON

 BRUSHY

MOUNTAIN

 PLUTON

SMOKY CREEK

 PLUTON

GOODS CREEK

 PLUTON

WILDWOOD 

 PLUTON

POST CREEK

PLUTON

ROAD

GULCH

PLUTON

SILVER

CREEK

PLUTON

ls

Qls

Ks

Ks

Qoal

Qoal

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls Qls Qls

Qls

Qls

Qls

Qls

Qls Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls Qls

Qls

Qls

Qls

Qls

Qls Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

hgc

hgc Jmsv

hgc

hgc

hwpx

Jmsv

Qal

Qal

Qal

Qal

Ks

Qoal

Qoal

Jmsv

am am

Jg

Jg

Jg

Jg

Jg

Jg

Ksfm

Qal

Jsp

Jsp

Jsp

Jsp

Jsp

Jsp

Jsp

Qal

Qal

Qal

Qal

Qal

Qoal

JPrc

JPrc

JPrc

JPrc

JPrc

JPrc

JPrc JPrc

JPrc

JPrc

JPrc

JPrc

JPrc

JPrc

JPrc

JPrc

JPrc

JPrc

JPrc

JPrc

JPrc

JPrc

hw

rcv

rcv

rcis

ls

rcic

rcic

rcv

rcv

ls

rcic

rcic

rcic

rcic

rcic

rcic

rcv

rcv

rcv

rcic

rcic

rcic

rcic

rcic

rcic

rcic

rcv

rcic

rcic

rcic

rcic

rcv

rcic

rcv

rcv

rcv

rcv

rcv

pd

um

rcp

rcp

rcp

rcp

rcp

rcp

rcp

rcp

rcp

rcv

rcv

rcv

rcv

rcv

rcv

rcv

rcv

rcv rcv

rcv

rcv

rcv

rcv

rcv

rcv

rcv

rcv

rcv

rcv

rcv

rcv

rcv

rcv rcv

rcv

rcv

rcv

rcv

rcv

rcv

rcv

Jmsv

Jmsv

Jmsv

Jmsv

hmsp

ls

JPrc

rcic

Qoal

rcic

pd

um

um

um

um

um

um

um

um

um

um

um

um

um

um

um

pd um

um

um

um

um

um

um

um

um

um

um

um

um

um

um

um um

um

um

um

um

um

um

um

um

um

um

14

15

13

17

18

19

20

21

 1

 2

 4

 3

 6

 9

10

 5

 6 7

 68

11

12

16

22

24

25

26

27

28

29

30

31

23

Au

Cr

Mn

Mn

Mn

Mn

123°15' 123°10' 123°05' 123°00'

123°15'

40°30'

40°25'

40°20'

40°15'

R A T T L E S N A K E

C R E E

K

T E

R

R A N

E

Wildwood pluton

EHT

EASTERN HAYFORK

 TERRANE

 Great

 Valley

sequence

GVs

WJT

P I C K E T T P E A K T E R R A N E 

 W E S T E R N

J U R A S S I C T E R R A N E

WESTERN

HAYFORK

TERRANE

GCp

RCT

GCp?

Wilson Point Fault

Salt Creek Fault

Bear Wallow Fault

South Fork Fault

Post Creek 

 Pluton

 Road 

 Gulch 

Pluton

Silver 

Creek 

Pluton

Smoky Creek 

 Pluton

Brushy Mountain 

 Pluton

Star Mountain 

 Pluton

GENERALIZED TERRANE MAP

The Dubakella Mountain 15' quadrangle includes parts of four generally subparallel northwest-trending terranes 

(the Eastern Hayfork, Western Hayfork, Rattlesnake Creek, and Western Jurassic terranes) that were sequentially 

accreted to North America during Jurassic time to become parts of the Klamath Mountains geologic province. 

Later, during Early Cretaceous time, a fifth terrane (Pickett Peak terrane) was accreted to become part of the 

Coast Ranges geologic province. The Cretaceous Great Valley sequence overlap assemblage, which once 

covered much of the southern Klamath Mountains, remains in the quadrangle as three erosional outliers. 

Abbreviations: EHT, Eastern Hayfork terrane; RCT, Rattlesnake Creek terrane; WJT, Western Jurassic terrane; 

GCp, Goods Creek pluton and related small plutons; and GVs, Great Valley sequence. 

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

only and does not imply endorsement by the U.S. Government.

This map was printed on an electronic plotter directly from digital files. Dimensional 

calibration may vary between electronic plotters and between X and Y directions on the 

same plotter, and paper may change size due to atmospheric conditions; therefore, scale 

and proportions may not be true on plots of this map.

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, 

Denver, CO 80225, 1-888-ASK-USGS

Digital files available at http://pubs.usgs.gov/sim/3149/

Base: U.S. Geological Survey Dubakella Mtn 15-minute 

quadrangle, 1954; polyconic projection

North American Datum 1927.

Reconnaissance Geologic Map of the Dubakella Mountain 15’ Quadrangle, Trinity, Shasta, and Tehama Counties, California

By

William P. Irwin, J. Douglas Yule, Bradford L. Court, Arthur W. Snoke, Laura A. Stern, and William B. Copeland

2011

CONTOUR INTERVAL 100 FEET

DATUM IS MEAN SEA LEVEL

AREA

OF MAP CALIFORNIA

19O

magnetic north

true north

Scientific Investigations Map 3149 U.S. Department of the Interior

U.S. Geological Survey

Geology mapped by W.P. Irwin 1968-1984; 

A.W. Snoke, 1968; J.D. Yule and B.L. Court, 

1983; and L.A. Stern and W.B. Copeland, 1984. 

GIS database and digital cartography by W.P. 

Irwin and C.M. Wentworth, 2010.

Edited by Theresa Iki

Manuscript approved for publication January 21, 2011

 Contact, showing dip; dashed where approximately 

 located

 Fault, showing dip; dashed where approximately located; 

 teeth on upper plate where thrust

Small fold, showing plunge of axis where known

Attitude of inclined bedding

 Inclined Vertical

 Attitude of foliation

 Inclined Vertical 

 Attitude of joints 

50

30

40

20

30

 Inclined Horizontal

 Attitude of cleavage

MAP SYMBOLS

10

15

Fossil locality

30

 Mineral prospect—

Au, gold; Cr, chromite; Mn, manganese 

Au

40°15'

123°15' 123°10' 123°05'

40°30'

40°25'

40°20'

123°15' 123°10' 123°05' 123°00'

 40°30'

123°00'

40°15'

40°20'

40°25'

R. 12 W. R. 11 W. R. 10 W.

T. 28 N.

T. 31 N.

R. 12 W. R. 11 W. R. 10 W.

T. 31 N.

T. 30 N.

T. 29 N.

T.29 N.

T. 30 N.

T. 28 N.

 Table 1. Fossil localities in the Dubakella Mountain 15' quadrangle

Map Sample Lithology* Fossils Age Reference

 No. No. 

1 20-82 C Radiolarians Late Triassic (Late Norian) C.D. Blome, written 

 to Early Jurassic (Hettangian) commun., 1982 

2 76-80 C Radiolarians Late Triassic (late Karnian Irwin and others, 1982

 to late middle Norian)

3 7-81 L Fusulinids late Permian Nestell and others, 1981

 (Tethyan fauna)

4 27-81 C Radiolarians Mesozoic Irwin and others, 1982

5 84-77 L Fusulinids late Permian Nestell and others, 1981

 (Tethyan fauna)

6 42-83 C Radiolarians Mesozoic C.D. Blome, written

 commun.,1983

7 D702 L Ammonite late Permian Irwin and Galanis, 1976 

 83-77 L Fusulinids late Permian

 (Tethyan fauna)

8 82-77 C Radiolarians Triassic or Jurassic Irwin and others, 1982

9 30-73 L Fusulinids and late Permian Irwin and Galanis, 1976

 foraminifers (Tethyan? fauna)

 29-68 L do. do. do.

 7-61 L do. do. do.

10 80-77 C Radiolarians Triassic Irwin and others, 1982

 C Conodonts Middle or Late Triassic Irwin and others, 1983

11 21-76 C Radiolarians Late Triassic (Karnian or Norian) Irwin and others, 1982

12 37-76 C Radiolarians Triassic or Jurassic do.

13 39-76 C do. do. do.

14 8-77 C do. do. do.

15 38-83 C do. Mesozoic C.D. Blome, written

 commun., 1983

16 47-84 C do. Late Triassic (Norian) C.D. Blome, written

 commun., 1984

17 40-76 C do. Early or Middle Jurassic Irwin and others, 1982

 46-84 C do. Early Jurassic C.D. Blome, written 

 commun., 1984

18 43-77 C do. Mesozoic(?) do.

19 49-83 C do. Late Triassic or Early Jurassic C.D. Blome, written

 commun., 1983

20 75-83 C do. Mesozoic do.

21 40-83 C do. do. do.

22 57-83 C do. Early Jurassic do.

23 54-83 C do. Mesozoic (Late Triassic?) do.

24 53-83 C do. Late Triassic or Early Jurassic do.

25 33-68 L Corals Triassic(?) Irwin and Galanis, 1976 

26 52-83 C Radiolarians Late Triassic C.D. Blome, written

 commun., 1983

27 D705 L Ammonites Late Triassic (Karnian) Silberling and Irwin, 1962

 3-61

28 51-83 C Radiolarians Triassic to Middle Jurassic C.D. Blome, written 

 commun., 1983

29 37-68 L Conodonts Late Triassic Irwin and others, 1983

30 46-83 C Radiolarians Late Triassic C.D. Blome, written

 commun., 1983

31 1-61 L Fusulinids late Paleozoic Irwin and Galanis, 1976

 *Abbreviations: C, chert; L, limestone

?

Qal Qls

Ks

Psv

Psv

Psv

Psv

ls

Qoal

Early Cretaceous

Late Jurassic

Middle Jurassic

Early Jurassic

Ksfm

Jg

Jmsv hgc

Jsp

hw

rcis rcic rcp

hwpx

hmsp

rcv

JPrc

ls

am

Qal Qls

Ks

Psv

Psv

Psv

Psv

ls

Qoal

Early Cretaceous

Late Jurassic

Middle Jurassic

Early Jurassic

Ksfm

Jg

Jmsv hgc

Jsp

hw

rcis rcic rcp pd

hwpx

hmsp

ls

rcv

JPrc

ls

am

um

CORRELATION OF MAP UNITS

UNCONSOLIDATED DEPOSITS

BEDROCK

GREAT VALLEY OVERLAP SEQUENCE

Major unconformity Early Cretaceous (~136 Ma)

TECTONOSTRATIGRAPHIC TERRANES

 Western

 Hayfork

 Eastern

 Hayfork

Rattlesnake

 Creek

Lower Cretaceous

 (Hauterivian)

Holocene and

(or) Pleistocene QUATERNARY

CRETACEOUS

JURASSIC

TRIASSIC

PERMIAN

Pickett

 Peak

Western

Jurassic

CRETACEOUS

hw

hwpx

rcp

Ks

Qoal

Qls

Qal

Psv

ls

Jg

hgc

Jmsv

rcis

rcic

Ksfm

JPrc

ls

am

rcv

Jsp

hmsp

ls

um

pd

Younger alluvium (Holocene and (or) Pleistocene)—Unconsolidated sand

 and gravel in modern stream channels and on associated low terraces

Landslide deposits (Holocene and (or) Pleistocene)—Landsliding is particularly 

 prominent in the Rattlesnake Creek terrane and is minimal in the Western 

 Hayfork terrane. Most landslide deposits on the northeast slope of South Fork 

 Mountain are not shown, although downslope movement resulting from mass 

 wasting is widespread

BEDROCK

GREAT VALLEY OVERLAP ASSEMBLAGE

Great Valley sequence (Lower Cretaceous)—Well-bedded and indurated mudstone, 

 sandstone and conglomerate that occur as erosional remnants overlying Eastern 

 Hayfork and other pre-Cretaceous terranes with high angular unconformity. 

 Patch at western boundary of quadrangle is part of Glade Creek outlier, which in the 

 adjoining Pickett Peak 15’ quadrangle (Irwin and others, 1974) contains Valanginian 

 fossils and shows an upward transition from nonmarine to marine deposition (Jones and 

 Irwin, 1971). Outlier at northern boundary of quadrangle is mainly conglomerate and 

 coarse sandstone; exposure is especially poor in southern part of that outlier. Fossils have 

 not been found in the Great Valley sequence in this quadrangle. The outliers are 

 depositional although largely bounded by steep faults 

TECTONOSTRATIGRAPHIC TERRANES

DESCRIPTION OF MAP UNITS

Mélange (Early Jurassic? to Permian)—Includes mafic volcaniclastic rocks, 

 thin-bedded chert, argillite, pillow basalt, tuff, sandstone, limestone (ls, where 

 shown), serpentinite (hmsp), and minor amounts of mica schist and amphibolite. 

 Chert contains Late Triassic and Jurassic(?) radiolarians, and Middle or Late 

 Triassic conodonts (fossil locality nos. 2, 4, 8, 9, 10; table 1); limestone yielded 

 a Late Permian ammonite and a Late Permian Tethyan fusulinid fauna (fossil 

 locality nos. 3, 5, 7, 9; table 1). Unit structurally overlies the Hayfork Bally Meta-

 andesite along Wilson Point Fault and is equivalent to the eastern Hayfork terrane 

 of Wright (1982). Upper age of unit is constrained by Lower Cretaceous strata of 

 the Great Valley sequence that unconformably overlie unit at south end of Klamath

 Mountains province 

Hayfork Bally Meta-andesite (Middle Jurassic)—Mafic volcanogenic rocks that 

 range from crystal tuff and tuff breccia to coarse breccia. Commonly characterized

 by euhedral augite and plagioclase phenocrysts in a light- to dark-green

 groundmass. Commonly well bedded and locally includes interlayers of thin-bedded

 chert and dark argillite. Unit is equivalent to the lower unit of the Hayfork terrane

 of Irwin (1974, 2010), and to the western Hayfork terrane of Wright (1982). Age 

 is herein considered Middle Jurassic on the basis of a probable cogenetic relation 

 with the Ironside Mountain batholith (about 170 Ma; Lanphere and others, 1968; 

 Wright, 1981) that intrudes the meta-andesite just north of the map area. Unit thought 

 to be entirely marine and probably represents an island-arc deposit. Limestone 

 body (ls) and chert (fossil locality no. 1; table 1), 1.5 km southeast of Natural Bridge, 

 may be a small thrust outlier of the Eastern Hayfork terrane

Older alluvium (Pleistocene or older(?))—Weakly consolidated nonmarine

 sand and gravel. Generally on ridge crests high above modern streams;

 associated with remnants of old land surfaces

 

Western Hayfork Terrane

Eastern Hayfork Terrane

Rattlesnake Creek Terrane

Wildwood Pluton (Middle Jurassic)—Dominantly medium- to coarse-grained 

 biotite-pyroxene diorite; includes gabbroic and other facies where undivided

 and pyroxenite (hwpx) where divided; intrudes only the Hayfork Bally Meta-

 andesite (Jmsv); presumably Middle Jurassic in age based on petrologic similarity

 to isotopically dated Ironside Mountain batholith

Goods Creek Pluton (Middle? Jurassic)—Mainly medium-grained hornblende-

 biotite-quartz diorite. Same pattern used for small dioritic and gabbroic intrusive 

 bodies situated along Shasta-Trinity County boundary and on Dead Horse Ridge

 and for probable exposures of Oliphant Creek pluton of Wright (1981) 

Plutonic complex (Early Jurassic and (or) LateTriassic)—Medium- to coarse-grained rocks that range

 from gabbro to quartz diorite; includes Star Mountain, Brushy Mountain, Silver Creek, Smoky Creek,

 Road Gulch, and Post Creek plutons. U-Pb isotopic analysis of zircon from six localities of the quartz

 diorite in the Rattlesnake Creek terrane, mostly beyond the boundary of the Dubakella Mountain

 quadrangle, yielded ages of 193 Ma to 207 Ma (see Wright, 1981). Contact relations with adjacent units 

 are unclear and may be faults

Serpentinite (age uncertain)—Dominantly serpentinized peridotite, but includes greenstone, rodingite and other 

 metasomatized rocks of uncertain origin, volcanic rocks, chert, and limestone (ls, where divided). Locally

 gradational with unit pd and other units of JPrc 

Blocky peridotite (age uncertain)—Dominantly tectonized harzburgite; moderately serpentinized; character-

 ized by bold, blocky outcrops; locally includes nearly unserpentinized dunite; grades into unit um

 Western Jurassic Terrane

Galice (?) Formation (Late Jurassic)—Mildly slaty to phyllitic argillite, graywacke, and stretched-pebble 

 conglomerate; unfossiliferous in this quadrangle; kink folds common; unit presumably correlative with 

 the Late Jurassic (Oxfordian and Kimmeridgian) Galice Formation of southwestern Oregon; isotopic age 

 of metamorphic overprint is about 150 Ma (Lanphere and others, 1978)

Serpentinite (Late? Jurassic)—Occurs as tectonic slices along the South Fork Fault; may be related to the 

 Josephine ophiolite of Harper (1980), which is exposed farther north along the western margin of 

 the Klamath Mountains, rather than to nearby serpentinite (um) of the Rattlesnake Creek terrane 

 Pickett Peak Terrane

South Fork Mountain Schist (Early Cretaceous)—Mostly fine-grained quartz-albite-muscovite-chlorite schist 

 with sparse lawsonite; the schist contains abundant large lenticular segregations and veinlets of coarse quartz.

 Unit locally includes the Chinquapin Metabasalt Member (not shown separately), which consists of fine-grained

 albite-chlorite-actinolite-epidote gneiss with local crossite-rich layers; also includes rare metachert. Age of 

 protolith is Late Jurassic(?) and Early Cretaceous(?); Early Cretaceous age of metamorphism is based on

 isotopic ages of about 120 Ma (Lanphere and others, 1978) 

 

 

Mélange (Jurassic to Permian)—Sheared and dislocated bodies of pillow basalt and other 

 mafic volcanic rocks, thin-bedded chert, argillite, serpentinite and related metasomatized 

 rocks (um, where divided), limestone (ls, where divided), and amphibolite (am, 

 where divided). Areas of dominantly mafic volcanic rocks (rcv, where divided) are 

 indicated by v pattern. Chert yielded Late Triassic to Early Jurassic and rarely to Middle

 Jurassic radiolarians (See table 1). A few limestone bodies yielded Triassic(?) corals 

 (fossil locality no. 25; table 1), late Paleozoic fusulinids (fossil locality no. 31; table 1), 

 and Late Triassic ammonites (fossil locality no. 27; table 1)

Areas of clastic sedimentary rock that are mildly slaty to phyllitic and may be 

correlative with the Galice(?) Formation (Jg)

Intrusive complex (Jurassic or Triassic)—Areas of dikes and other shallow, irregularly 

 shaped bodies intruding extrusive volcanic rocks equivalent to units rcv and rcis; 

 intrusive rocks dominantly leucocratic, but range from gabbro to granite; at least in part

 correlative with the Tule Creek Granite Complex of the Pickett Peak 15’ quadrangle 

 (Irwin and others, 1974); time of intrusion is probably Late Triassic or Early Jurassic

Intermediate to silicic volcanic rocks (Jurassic or Triassic)—Fine-grained, commonly 

 leucocratic volcanic rocks; locally includes dikes and other shallow intrusions that 

 may be equivalent to unit rcic, and minor mafic volcanic rocks

UNCONSOLIDATED DEPOSITS REFERENCES CITED

Harper, G.D., 1980, The Josephine ophiolite—remains of a Late Jurassic marginal basin in 

 northwestern California: Geology, v. 8, no. 7, p. 333-337.

Irwin, W.P., 1974, Reconnaissance geologic map of the Hayfork quadrangle, Trinity County, 

 California: U.S. Geological Survey, Miscellaneous Field Studies Map MF-576, scale 

 1:62,500.

Irwin, W.P., 2010, Reconnaissance geologic map of the Hayfork 15' quadrangle, Trinity 

 County, California: U.S. Geological Survey Scientific Investigations Map 3119, map

 scale 1:50,000, [http://pubs.usgs.gov/sim/3119].

Irwin, W.P., and Galanis, S.P., Jr., 1976, Map showing limestone and related fossil localities in 

 the Klamath Mountains province, California and Oregon: U.S. Geological Survey 

 Miscellaneous Field Studies Map MF-749, scale 1:500,000.

Irwin, W.P., Jones, D.L., and Blome, C.D., 1982, Map showing sampled radiolarian localities in 

 the western Paleozoic and Triassic belt, Klamath Mountains, California: U.S. Geologi

 cal Survey Miscellaneous Field Studies Map MF-1399, scale 1:250,000.

Irwin, W.P., Wardlaw, B.R., and Kaplan, T.A., 1983, Conodonts of the western Paleozoic and 

 Triassic belt, Klamath Mountains, California and Oregon: Journal of Paleontology, v. 

 57, no. 5, p. 1,030-1,039.

Irwin, W.P., Wolfe, E.W., Blake, M.C., Jr., and Cunningham, C.G., Jr., 1974, Geologic map of 

 the Pickett Peak quadrangle, Trinity County, California: U.S. Geological Survey 

 Geological Quadrangle Map GQ-1111, scale 1:62,500.

Irwin, W.P., Yule, J.D., Court, B.L., Snoke, A.W., Stern, L.A., and Copeland, W.B., 1985, 

 Reconnaissance geologic map of the Dubakella Mountain quadrangle, Trinity, Shasta, 

 and Tehema Counties, California: U.S. Geological Survey Miscellaneous Field Studies 

 Map MF-1808, scale 1:62,500.

Jones, D.L., and Irwin, W.P., 1971, Structural implications of an offset Early Cretaceous 

 shoreline in northern California: Geological Society of America Bulletin, v. 82, no. 4, p. 

 815-822.

Lanphere, M.A., Blake, M.C., Jr., and Irwin, W.P., 1978, Early Cretaceous metamorphic age of 

 the South Fork Mountain Schist in the northern Coast Ranges of California: American 

 Journal of Science, v. 278, no. 6, p. 798-815.

Lanphere, M.A., Irwin, W.P., and Hotz, P.E., 1968, Isotopic age of the Nevadan orogeny and 

 older plutonic and metamorphic events in the Klamath Mountains, California: Geologi

 cal Society of America Bulletin, v. 79, no. 8, p. 1,027-1,052.

Nestell, M.K. Irwin, W.P., and Albers, J.P., 1981, Late Permian (early Djulfian) Foraminifera 

 from the southern Klamath Mountains, California: Geological Society of America 

 Abstracts with Programs, v. 12, no. 7, p. 519.

Silberling, N.J., and Irwin, W.P., 1962, Triassic fossils from the southern Klamath Mountains, 

 California: U.S. Geological Survey Professional Paper 450-B, p. B60-B61.

Wright, J.E., 1981, Geology and U-Pb geochronology of the western Paleozoic and Triassic 

 subprovince, Klamath Mountains, northern California: Santa Barbara, Calif., University 

 of California, Ph.D. dissertation, 300 p. 

Wright, J.E., 1982, Permo-Triassic accretionary subduction complex, southwestern Klamath 

 Mountains, northern California: Journal of Geophysical Research, v. 87, no. B5, p. 

 3,805-3,818.

 SYNOPSIS

The Dubakella Mountain 15' quadrangle is located just south of the Hayfork quadrangle and just 

east of the Pickett Peak quadrangle. It spans a sequence of four northwest-trending tectonostratigraphic terranes of the Klamath Mountains geologic province that includes, from east to west, 

the Eastern Hayfork, Western Hayfork, Rattlesnake Creek, and Western Jurassic terranes, as 

well as, in the southwest corner of the quadrangle, part of a fifth terrane, the Pickett Peak 

terrane of the Coast Ranges geologic province (see Generalized Terrane Map). 

 The Eastern Hayfork terrane is a broken formation and mélange of volcanic and sedimentary 

rocks that include blocks of limestone and chert. The limestone contains late Permian microfossils of Tethyan faunal affinity. The chert contains radiolarians of Mesozoic age, mostly Triassic, 

but none clearly Jurassic.

 The Western Hayfork terrane is an andesitic volcanic arc that consists mainly of agglomerate, tuff, argillite, and chert, and includes the Wildwood pluton. That pluton is related to the 

Middle Jurassic (about 170 Ma) Ironside Mountain batholith that is widely exposed farther 

north beyond the Dubakella Mountain quadrangle.

 The Rattlesnake Creek terrane is a highly disrupted ophiolitic mélange of probable Late 

Triassic or Early Jurassic age. Although mainly ophiolitic, the mélange includes blocks of 

plutonic rocks (about 200 Ma) of uncertain genetic relation. Some scattered areas of wellbedded mildly slaty detrital rocks of the mélange appear similar to Galice Formation (unit Jg) 

and may be inliers of the nearby Western Jurassic terrane.

 The Western Jurassic terrane consists mainly of slaty to phyllitic argillite, graywacke, and 

stretched-pebble conglomerate and is correlative with the Late Jurassic Galice Formation of 

southwestern Oregon.

 The Pickett Peak terrane, the most westerly of the succession of terranes of the Dubakella 

Mountain quadrangle, is mostly fine-grained schist that includes the blueschist facies mineral 

lawsonite and is of Early Cretaceous (about 120 Ma) metamorphic age.

 Remnants of the Great Valley sequence of dominantly Cretaceous marine sedimentary strata, 

which once covered much of the southern fringe of the Klamath Mountains, are present at three 

places in the Dubakella Mountain quadrangle.

 Mineral production in the quadrangle has included small amounts of gold, chromite, and 

manganese.

 This map of the Dubakella Mountain 15' quadrangle is a digital rendition of U.S. Geological 

Survey Miscellaneous Field Studies Map MF-1808 (Irwin and others, 1985), with various 

improvements and additions.