Coso Peak Quadrangle

117¡ 45' 00'' 36¡ 15' 00'' 117¡ 37' 30'' Qya 36¡ 15' 00'' † Tbu EXPLANATION Tbup

Tbu Tbu Jjfb Jjf COVER UNITS MAP SYMBOLS

Jjf Tbu Jjf Jcc

Qya Younger Alluvium* Boundary of Quaternary rhyolite within coeval pyroclastic de posits; tick marks face toward eruptive center

Tbu 85 Jjfb Qoa Older Alluvium* 62 Quaternary Boundary of probable landslide; tick marks localized along b ase of 43 slide block and face toward structural top 72

Jcc Tcp Coso Formation, air-fall pumice*

Tc Coso Formation, fanglomerate* Approximate structural limit of tectonic breccia; tick marks localized Tbu along brecciated side of contact mv-j Jcc Jjfb Qoa mv-j Tbup Basalt of Upper Centennial Flat, pyroclastic*

Fault contact; solid (known), dashed (approximate), dotted ( inferred), Tbu Basalt of Upper Centennial Flat* queried where conjectural. Ball and bar on down-dropped side of normal fault. Teeth on upper plate of thrust fault.

Qoa Tbpp Basalt of Petroglyph Canyon, pyroclastic*

Ductile shear (mylonite) zone Tbp Basalt of Petroglyph Canyon*

Qya

Jcc Tertiary

Basalt of Coso Peak, pyroclastic cs Tbcp * Kg Intrusive or depositional contact; solid (known), dashed (ap proximate), Kg short dash with query (inferred) Tbc Basalt of Coso Peak*

cs Jecg cs,m Tap Andesite, pyroclastic* Tbc 77 Jcc

Ta Andesite*

50 Qya 59 Td Dacite* Jcc 80 cs

79 Fold axis; syncline, anticline, doubly-plunging syncline Qya 64 80 Tbc Tbc BASEMENT UNITS Tbc 63 Strike and dip of bedding plane; inclined cs,m,q

Jmci 52 70 Kdc—Coso Dike Swarm {Alkali-feldspar Granite} [88.3±0.1 Ma] Jmci 81 Strike and dip of flow foliation; inclined, vertical 49 Tbc Tbc Kg Kg Undifferentiated Granitoid Rocks Kg Qya 44 13 74 Strike and dip of fault plane; inclined, w/ down-dip lineati on, 58 32 Cretaceous w/ horizontal lineation, w/ oblique lineation, subhorizontal Tbc Kdg—Granitic Dikes lineation Jmci Tbc JKdi—Independence Dike Swarm (red: felsic, green: mafic–inte rmediate) [166±1 to ~119 Ma] Jmci 80 Strike and dip of fracture cleavage; inclined, vertical

Tbc 28 36 36 Tbcp Jjfb Joshua Flat Pluton, border facies {Quartz Monzonite} to {Gra nite} 58 34 Strike and dip of joint plane; inclined, vertical Tbc Jjf Joshua Flat Pluton {Quartz Monzonite} to {Granite} Tbc 33 cs,m Tbc 35 21 Strike and dip of foliation/compositional layering; inclined , 60 48 vertical, w/ down-dip lineation, w/ horizontal lineation, 59 81 17 w/ oblique lineation Jmci cs,m Mixed Complex, intermediate component {Quartz Monzodiorite} to {Diorite} [151±1 Ma] Qya Tbcp 63 Qya Kdc 51 Jecg Locality of sample used for radiometric age determination.

Tbcp Jurassic Jsp Silver Peak Pluton {Quartz Monzonite} to {Granite} [158±1 Ma ] Kg 63 Tbc 75 Tbp Tbc Jcc Crystal Canyon Pluton, coarse-grained {Alkali-feldspar Quart z Syenite}

Tcp Qya Tbc Jcc Crystal Canyon Pluton, fine-grained {Alkali-feldspar Quartz Syenite} 67 Jecg Kg Kg Tbc Tbcp Tbcp Tbc Jecg Intrusive Complex of Eastern Coso Range, granitic rocks [>16 6 Ma] Tbc Tbc Tbp Kg Tbp Tbc Kg Qya Tbc Tbc Tbc 23 Tbc mv-j Metavolcanic Rocks of north of Joshua Flat; felsicÐintermedi ate, porphyritic and pyroclastic Tbc 19 Tbp Tbc 54 q Tbc 51 Kg 54 Tbc Tbc 71 31 cs 29 61 PzÐMz cs, etc. Metamorphic Rocks of Uncertain Age (see Chapter One for deta ils) 54 26 30 64 m 50 43 68 39 25 49 40 20 Tbc 35 49 42 Jecg 15 37 74 Tbp Tbp 48 Kdg Kg Units listed represent only the geologic column for this qua drangle. The geologic column for the entire Coso Range, incl uding description of the radiometric ages cited here, is lis ted within the text 26 † 73 51 67 file on this CD. Units highlighted with an asterisk ( *) were defined and described by Duffield & Bacon (1981). Map symbols shown represent the complete set of symbols used in this study. Some 38 of those illustrated may not be relevant to the geology of this particular quadrangle. Tc 51 47 78 53 66 Jecg 73 Jecg Tcp Tbp 47 Tbp 53 Tbp 56 Jecg Tbc 81 35 46 Jsp Jecg 79 Jsp Qya 41 51 Kg Kg Tbpp 64 Tbp Tbp 77 63 38 64 Jecg

Tbp Tap Tbp Jecg Jecg Tap Qya Jsp

Kg Tbp Jsp Qya Jecg 46 Tbp Tap Ta Jsp

Tbp Jecg Jecg

Ta Ta Tbp Ta Qya Td Td Tbp 79 80 Jsp Ta Tap Ta Ta 70 36¡ 07' 30'' 73 117¡ 45' 00'' 36¡ 07' 30'' 117¡ 37' 30''

GEOLOGIC MAP OF THE COSO PEAK 7.5' QUADRANGLE;

118¡ 00' W 117¡ 45' W 117¡ 30' W INYO COUNTY, CALIFORNIA

Talc Vermillion Centennial City Canyon Canyon Darwin Hills Total map area of Whitmarsh (see reference map) includes som e contacts and unit labels A Compilation by Richard S. Whitmarsh established by Stinson (1977) and Duffield & Bacon (1981). C ontacts within the Cenozoic 36¡ 15' N 1997 cover sequence either copied or adapted from Duffield & Baco n (1981). Structural data and Upper Haiwee Coso China Centennial contacts within the pre-Cenozoic basement complex, except wi thin unit Mzb, established Reservoirs Peak Gardens Flat by Whitmarsh 1994-1996. References Cited: Coso Cactus Petroglyph Louisiana ArcInfo¨ coverage Junction Peak Canyon Butte Duffield, W.A. and Bacon, C.R. 1981. Geologic map of the Cos o volcanic field and adjacent areas, B Inyo County, California. U.S.G.S., Miscellaneous Investigat ions Series, Map I-1200. 36¡ 00' N Stinson, M.C. 1977. Geologic map and sections of the Keeler 15-minute quadrangle, Inyo County,

Mountain California. California Division of Mines and Geology, Map S heet 38. Little Volcano Airport Springs Lake Peak Lake Canyon SCALE 1:24,000 CONTOUR INTERVAL 20 feet A. Stinson (1977): dotted outline Magnetic North B. Duffield & Bacon (1981): dash-dotted outline UTM Grid North (about 15¡ east) Ninemile White Burro 0 1 2 3 Pearsonville Canyon Hills Canyon Geographic North 35¡ 45' N Kilometers (about 0.5¡ east) Reference map with 7.5 minute quadrangle boundaries. Red lin e delineates 0 1 2 boundary of ArcInfo¨ coverage compiled by Whitmarsh during 1994-1997 at the University of Kansas: Department of Geology: Structur al geology and GIS laboratory. Shaded areas (A and B) encompass portions of earlier Miles geological maps containing contacts that have been included in this compilation. Bold black line highlights the locality and boundary of this quadrangle. Topographic base: COSO PEAK 7.5' QUADRANGLE (USGS, PROVISION AL EDITION 1982)