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Home , Bullion Mountains, Chemehuevi Mountains, Coxcomb Mountains, Kilbeck Hills, Sheep Hole Mountains, Ward Valley (California)

U.S. DEPARTMENT OF THE INTERIOR MISCELLANEOUS FIELD STUDIES MF–2344 U.S. GEOLOGICAL SURVEY Sheet 1 of 2

116°00´ 45´ 30´ 15´ 115°00´ 34°30´ A 45 34°30´ Qoa 40 Qoa INTRODUCTION steep west stratal dips of early Miocene rocks in the western Calumet Mountains and is suggested also John, B.E., 1981, Reconnaissance study of Mesozoic plutonic rocks in the Mojave Desert region, in L Qpsh ts Ks Tdvc u Qps YXg 75 Qya d Amboy Crater lava flow Kl 35 by the moderate NNE dip of the early Miocene East Bullion dike swarm in the eastern Bullion Moun- Howard, K.A., Carr, M.D., and Miller, D.M., eds., Tectonic framework of the Mojave and Sonoran 25 l 35 80 Ko Geologic map units are described briefly on this map, with the expectation that readers seeking L Td o 14 Xf Ks u w Painted Rock tains. Cross section A–A' interprets extensional structural style between these localities. Gently east- Deserts, California and Arizona: U.S. Geological Survey Open-file Report 81–503, p. 48–50. Jbv? Tab Qpsg Qya 30 detailed descriptions (including contact relations and modal mineral proportions for plutonic units) can d F Qba l a Qpb 153m Pluton dipping extensional faults are exposed in the eastern Sheep Hole and Pinto Mountains and imaged seis- Karish, C.R., Miller, E.L., and Sutter, J.F., 1987, Mesozoic tectonic and magmatic history of the central o Jbv? 80 u 10 Dၤm Ko 70 consult the source geologic maps listed on the index map (fig. 1). Summary modal diagrams are shown w Jbv? l t 45 PMb Ks mically below Ward Valley (Frost and Okaya, 1986). In cross section A–A', I infer a style of concealed Mojave Desert, in Dickinson, W.R. and Klute, M.A., eds., Mesozoic rocks of southern Arizona and F Qoa e 20 Qya here in Figure 2. Geophysical maps and interpretations are available in Simpson and others (1984), Tblc a Jbv? Tdi a u s 25 70 half grabens under the valleys to be consistent with unmigrated industry seismic reflection profiles adjacent areas: Arizona Geological Society Digest, v. 18, p. 15–32. t 12 30 25 Mariano and others (1986), Frost and Okaya (1986), Mariano and Grauch (1988), and Jachens and l Tdv 16 t b 45 60 (D.A. Okaya, unpub. data). Kupfer, D.H., and Bassett, A.M., 1962, Geologic reconnaissance map of part of the southeastern r Ship Mountains 20 ၤt 20 30 Howard (1992). Neumann and Leszcykowski (1993) summarized information on mines and mineral w Td Qya Ko Tc a 307m 20 45 45 a 65 e 35 n Qps 537m Qya Pluton Ks deposits. Discussions and interpretations of the geology are available from the source geologic maps In late Neogene and Quaternary time, strike-slip faults that are part of the eastern California shear Mojave Desert, California: U.S. Geological Survey Mineral Investigations Field Studies Map Tbl s Qoa c Qoa Xf Dၤm 10 50 20 50 t h 5 Kl 40 zone displaced rocks in western parts of the quadrangle (Howard and Miller, 1992; Richard, 1993). MF–205, scale 1:125,000. b 20 80 55 25 and elsewhere, and are briefly summarized here. The map was prepared in 1994. r 15 30 35 65 30 YXg 50 East-striking faults (in the Pinto Mountains) are sinistral, and NW-striking faults are dextral (Dibblee, Lucchitta, Ivo, 1979, Late Cenozoic uplift of the Colorado Plateau and adjacent Colorado River region: a Tdi Qoa 15 Xk Ko Qo n Jsm 40 20 NAMES Qoa c 70 1961, 1967a; Hope, 1966; Jagiello, 1991). Ranges and basins in the quadrangle may owe their forms Tectonophysics, v. 61, p.63–95. h 13 247m 40 Qya Qpb 0 30 40 The map applies new names to structures including the Ivanhoe fault, eastern Bullion dike swarm, 60 25 15 largely to transpression and transtension between the moving and rotating strike-slip fault blocks Luyendyk, B.P., 1991, A model for Neogene crustal rotations, transtension, and transpression in south- 307m t 45 5 Old Woman Pluton Ko Qblc s 30 Amboy Crater lava flow, Ship Mountains pluton, Cleghorn Pass pluton, Sheep Hole Mountains pluton, (Simpson and others, 1984; Jagiello and others, 1992; Jachens and Howard, 1992; Richard, 1993). ern California: Geological Society of America Bulletin, v. 103, p. 1528–1536. ru ts 55 th Qya 50 Ko a Xk and Sheep Hole Pass pluton. I apply pluton names to structural bodies and not necessarily to lithodemes Large rotations are expected between the Pinto and Bullion Mountains based on models of bookshelf Mariano, John, and Grauch, V.J.S., 1988, Aeromagnetic maps of the Colorado River region including D m Xk Qya Tdv 8 ၤ 50 Ks ts or map units, even though they may largely coincide. For example, the Old Woman pluton is an intru- Qpsh faulting and regional paleomagnetic studies (Carter and others, 1987; Luyendyk, 1991; Dokka and the Kingman, Needles, Salton Sea, and El Centro 1° x 2° quadrangles, California, Arizona, and Qya 45 10 897m 25 a sive body consisting of the formally named Old Woman Mountains Granodiorite. Map units newly Travis, 1990; Richard, 1993). However, Jurassic dike swarms in these two ranges have unexpectedly Nevada: U.S. Geological Survey Miscellaneous Field Studies Map MF–2023, 3 sheets, scale 20 20 Tc Km 35 Xk 40 40 named on this map are the Dale Lake Volcanics; Coxcomb Intrusive Suite and its included Sheep Hole similar strikes, a finding that may accord better with small relative rotation (approximately 20°) pre- 1:250,000. 50 70 Jd Tbst Qoa 60 45 60 Pass Granite, Sheep Hole Mountains Granodiorite, and Clarks Pass Granodiorite; Iron Mountains Intru- dicted by Powell's (1993) palinspastic model. Mariano, John, Helferty, M.G., and Gage, T.B., 1986, Bouguer and isostatic residual gravity maps of 80 89 n 30 50 a Qbl 30 Qoa Qy lo 80 n ၤt sive Suite and its included Granite Pass Granite, Danby Lake Granite Gneiss, and Iron Granodiorite A slickensided surface was encountered in drilling of probable Quaternary deposits under Cadiz the Colorado River region, including the Kingman, Needles, Salton Sea, and El Centro 1° x 2° a 50 60 Qoa 10 c Xk Kop Qy Ycm S 50 Gneiss; Chubbuck Porphyry; Bullion Mountains Intrusive Suite and its included Virginia Dale Quartz Lake (Bassett and others, 1959; Howard and Miller, 1992). The presence of this concealed fault sug- quadrangles: U.S. Geological Survey Open-file Report 86–347, scale 1:250,000, 7 sheets. Qoa Qya Xk Qya Monzonite; and Dog Wash Gneiss. Intrusive suites are proposed on this map in order to group together gests that other Quaternary faults could be concealed by the widespread Holocene deposits in Bristol Metzger, D.G., 1968, The Bouse Formation (Pliocene) of the Parker–Blythe–Cibola area, Arizona and Qy ၦm 75 KJpg 80 85 each of a series of lithodemes that appear to be closely related lithologically, spatially, and temporally. Lake, Cadiz, and Danby Lake valleys. Faults exposed in the east and central parts of the quadrangle last California: Geological Survey Research, 1968, U.S.Geological Survey Professional Paper 600–D, Qoa Jd 85 80 50 Qbl 45 Ycm Ycm 9 Ko 60 Ko The underlying concept of an intrusive suite is that all the units are in some manner cogenetic and that moved in the early Pleistocene, whereas the Valley Mountain faults in the southwest part of the quad- p. 126–136. Qoa Td ts 65 55 6055 101m Dၤm ၤt they are products of a single fusion episode (Bateman, 1992). Qoa rangle cut deposits assigned to the Holocene (Howard and Miller, 1992). This concentration of young- Miller, C.D., 1989, Potential hazards from future volcanic eruptions in California: U.S. Geological Sur- 75 45 30 est fault activity to the southwest accords with a southwestward increase in seismicity (Goter, 1992). vey Bulletin 1847, 17 p. Jbv? 60 45 Xs GEOLOGIC SUMMARY Jbv 70 Ycm Km Miller, C.F., Howard, K.A., and Hoisch, T.D., 1982, Mesozoic thrusting, metamorphism, and pluton- Ko 40 C 80 PMb 60 The Sheep Hole Mountains quadrangle covers an area of the Mojave Desert characterized by ism, Old Woman-Piute Range, southeastern California, in Frost, E.G. and Martin, D.L, eds., Meso- l e Kcg Qya gh Qya Ko basins and ranges (fig. 3). Alluviated valleys and playas (dry lakes) are as low as 165 m elevation at zoic-Cenozoic tectonic evolution of the Colorado River region, California, Arizona, and Nevada Qpsg Jd Ko REFERENCES CITED o Jbv? Qoa 75 Cadiz Lake playa (see map of major topographic features). The mountain ranges they separate are as Jbv r 45 20 Anderson, J.L., 1988, Core complexes of the Mojave-Sonoran Desert: Conditions of plutonism, myloni- (Anderson-Hamilton volume): San Diego, Cordilleran Publishers, p. 1561–581 Jbv n Qps Qwo Qoa 35 50 50 high as 1490 m elevation, for example in the Old Woman Mountains. Rock units are well exposed P 60 Ko ts tization, and decompression, in Ernst, W.G., ed., Metamorphism and crustal evolution of the west- Miller, C.F., Wooden, J.L., Bennett, V.C., Wright, J.E., Solomon, G.C., and Hurst, R.W., 1990, Petro- Qoa a Qwy Kcg 70 Km Km s Ko 55 owing to low rainfall and sparse vegetation. genesis of the composite peraluminous-metaluminous Old Woman-Piute Range batholith, south- s 85 Qwy ern United States (Rubey volume 7): Englewood Cliffs, New Jersey, Prentice Hall, p. 502–525. Jbpm ts 50 F Qoa 75 80 Ko eastern California; Isotopic constraints, in Anderson, J.L., ed., The nature and origin of Cordilleran a Kccp? 40 Ko Kop PROTEROZOIC ROCKS Bacheller, John, III, 1978, Quaternary geology of the Mojave Desert-Eastern Transverse Ranges boun- u 50 80 Kcg 80 45 35 35 l Kcsh 20 70 70 magmatism: Geological Society of America Memoir 174, p. 99–109. Ja t 40 80 Xk Km Xk Proterozoic rocks are found mostly in the eastern and southwestern parts of the quadrangle. They dary in the vicinity of Twentynine Palms, California: Los Angeles, University of California, M.S. 75 30 40 Miller, D.M., and Howard, 1985, Bedrock geologic map of the Iron Mountains quadrangle, San Bernar- Jbv Qwy 80 75 80 are metamorphosed, and encompass few supracrustal rocks and a variety of plutonic rocks of mostly thesis, 157 pp. 70 85 Qwo dino and Riverside Counties, California: U.S. Geological Survey Miscellaneous Filed Studies Map Tdi 70 70 granitic composition (fig. 2g). Early Proterozoic plutonic and metaplutonic units about 1.7 Ga in age in Barth, A.P., Wooden, J.L., Coleman, D.S., and Fanning, C.M., 2000, Geochronolgy of the Proterozoic Jbv? Jbv? Km 35 MF–1736, scale 1:62,500. ၦm Qoa 60 the Old Woman Mountains and Kilbeck Hills underlie the metamorphosed Cambrian Tapeats Sand- basement of southwesternmost North America, and the origin and evolution of the Mojave crustal 15 Miller, D.M., Howard, K.A., and Anderson, J.L., 1981, Mylonitic gneiss related to emplacement of a Jd 45 30 80 30 province: Tectonics, v. 19, p. 616–629. 40 50 80 40 a 15 stone. Rocks about 1.7 Ga in age are also found in the Pinto Mountains: the Dog Wash Gneiss, which Jbpm 35 ၢs 10 Cretaceous batholith, Iron Mountains, southern California, in Howard, K.A., Carr, M.D., and Qwo Qwy 40 5 65 80 Barth, A.P., Tosdal, R.M., Wooden, J.L., and Howard, K.A., 1997, Triassic plutonism in southern Cali- Jgg Xk 55 intrudes the unit here called the Pinto Gneiss (part) of Miller (1938), and the granite of Joshua Tree, Qoa Kcg 80 Qoa fornia: Southward younging of arc initiation along a truncated continental margin: Tectonics, v. 16, Miller, D.M., eds., Tectonic framework of the Mojave and Sonoran Deserts, California and Ari- 40 Kcg 80 which nonconformably underlies the quartzite of Pinto Mountain. The quartzite of Pinto Mountain Tbv Qya zona: U.S. Geological Survey Open-file Report 81–503, p. 73–75. 80 Jbep Jg 75 could be as old as Early Proterozoic based on Powell's (1982) suggested correlation with the Pinto p. 290–304. Jbv 25 E 55 Jk 55 60 Jc thrust a Jqk n Xk 50 Miller, D.M., Howard, K.A., and John, B.E., 1982, Preliminary geology of the Bristol Lake region, 75 s Qoa 40 15 nlo ၣrb Gneiss (part) of Miller (1938), or it could be as young as Late Proterozoic and Early Cambrian if corre- Bassett, A.M., Kupfer, D.H., and Barstow, F.C., 1959, Core logs from Bristol, Cadiz, and Danby Dry 65 75 80 t 55 ca ts 25 S Qoa r e 40 ၤt 40 5 5 Mojave Desert, California, in Cooper, J.D., compiler, Geologic excursions in the California desert:

r 35 70 o Lakes, San Bernardino County, California: U.S. Geological Survey Bulletin 1045–D, p. 97–138. n Tdv lative with the Stirling Quartzite. Middle Proterozoic plutonic rocks (approximately 1.4 Ga) are recog- Jbv Ks 45 Pk 35 5 Qoa d i Geological Society of America Cordilleran Section, 78th Annual Meeting, Anaheim, Calif., April B Xf 10 Bassett, A.M., and Kupfer, D.H., 1964, A geologic reconnaissance in the southeastern Mojave Desert, Jbe r Jbv 50 Kop 25 80 Km nized in the Calumet and Old Woman Mountains. The gneiss of Dry lakes valley, of Early or Middle d u Qwy 70 70 r l 40 Dၤm 19–21, 1982, p. 91–100. 5 i o k l Qwy Qpsg Qwy California: California Division of Mines and Geology Special Report 83, 43 p. Jbep i Jc c Proterozoic protolithic age, is distinct from other Proterozoic intrusive rocks because it is highly peralu- e o PMb 50 50 40 n Ks Jk Jqk k Fault Xk 25 25 50 40 Miller, W.J., 1938, Pre-Cambrian and associated rocks near Twentynine Palms, California: Geological Jcp s 27 Qya ilbec 50 85 25 40 l minous. Bateman, P.C., 1992, Constitution and genesis of the central part of the Sierra Nevada batholith, Cali- ၦm w Xgn 65 a Tdv K 35 45 30 50 45 Society of America Bulletin, v. 49, p. 417–446. a 85 n Cleghorn Qoa 80 ts Pk 80 50 60 60 30 fornia: U.S. Geological Survey Professional Paper 1483. r 35 o m 35 50 70 Qbr Jbpm 70 ၣrb 15 55 ts i Qya PALEOZOIC ROCKS Miller, W.J., 1944, Geology of the Palm Springs-Blythe strip, Riverside County, California: California 50 ၢs PMb 70 35 s Bishop, C.C., 1964, Needles sheet: California Division of Mines and Geology, Geologic map of Cali- A Jcp Pass Qoa Qy 20 Ko 10 55 ts A' Xk n 40 85 Ko Journal of Mines and Geology, v. 40, p. 11–72. Pluton 55 50 Qoa 40 35 e Paleozoic strata metamorphosed to sillimanite grade are found in the northeastern and central parts fornia, Olaf P. Jenkins edition, scale 1:250,000. 65 60 50 50 t 50 50 x Qoa 30 45 Kcsh Tcs Qya 30 40 of the quadrangle. In the Kilbeck Hills and Old Woman Mountains the Paleozoic rocks nonconformably Moyle, W.R., Jr., 1961, Data on water wells in the Dale valley area, San Bernardino and Riverside 55 Xf Qya 25 e Qy Brown, W.J., and Rosen, M.R., 1992, The depositional history of several desert basins in the Mojave Tdi 35 35 50 40 65 r Counties, California: California Department of Water Resources Bulletin 91–5, 55 p. Jcp 35 Xgn Ko 10 overlie the Fenner Gneiss of Hazzard and Dosch (1937); in the Old Woman Mountains, they probably Desert: Implications regarding a Death Valley—Colorado River hydrologic connection, in Rey- 20 74 50 15 ts 35 35 e 30 v Qwy Qwy Moyle, W.R., Jr., 1967, Water wells and springs in Bristol, Broadwell, Cadiz, Danby, and Lavic Valleys 45 Jbv? 35 i also overlie the Kilbeck Gneiss although contact relations are obscured by the effects of deformation 55 50 55 0 nolds, R.E., compiler, Old Routes to the Colorado: Redlands, California, San Bernardino County Jbv ts 55 Kop R Jbq ၤt 45 and metamorphism. The Paleozoic rocks form a distinctive lithologic sequence (Stone and others, and vicinity: California Department Water Resources Bulletin 91–14, 17 p. Qo m 45 60 Museum Association Special Publication 92–1, p. 77–82. ၦ 20 o Jbv Jbv 15 Qoa 10 50 30 d Neumann, T.R., and Leszcykowski, Andrew, 1993, Identified mineral resources of the Needles 1 x 2 6 25 60 1983) that allows them to be correlated with Cambrian to Permian marine units deposited on the shal- Calzia, J.P., 1982, Geology of granodiorite in the Coxcomb Mountains, southeastern California, in ° ° Qwy Kcg Kck 40 55 a Kcsh r 45 Qwy low shelf of cratonic North America: the Tapeats Sandstone, Bright Angel Shale, higher Cambrian and quadrangle, California: U. S. Department of the Interior, Bureau of Mines, Mineral Land Assess- 65 40 o Frost, E.G. and Martin, D.L, eds., Mesozoic-Cenozoic tectonic evolution of the Colorado River 40 85 l 30 o Devonian carbonate rocks (including the Bonanza King Formation), Redwall Limestone, Bird Spring ment Open File Report MLA 14–93, 349 p. 60 45 ၢs 45 30 region, California, Arizona, and Nevada (Anderson-Hamilton volume): San Diego, Cordilleran Tdi 50 Kcg 30 Tbv 75 70 C 80 Kcg 65 25 Formation, Hermit Shale, Coconino Sandstone, and Kaibab Limestone (Stone and others, 1983). Parker, R.B., 1963, Recent volcanism at Amboy Crater, San Bernardino County, California: California 30 35 r Publishers, p. 173–181. Qya 60 Jbv? 30 Km 40 30 C 60 Kcgi 85 o Jvh Xk f Qya Division of Mines Special Report 76, 21 p. l Qoa Calzia, J.P., 1991a, Geophysical, lithologic, and water quality data from Bristol Dry Lake, San Bernar- e 40 MESOZOIC ROCKS Qoa 45 5 t g 35 l Powell, R.E., 1981, Geology of the crystalline basement complex, Eastern Transverse Ranges, southern h 75 25 u dino County, California: U.S. Geological Survey Open-file Report 91–263. o q 20 Mesozoic rocks consist of scattered metamorphosed supracrustal rocks and large volumes of bath- Qoa 65 Kccm 80 45 a California: Constraints on regional tectonic interpretation: Pasadena, California, California Insti- r 10 F Calzia, J.P., 1991b, Geophysical, lithologic, and water quality data from Danby Dry Lake, San Bernar- n Xbg Qya 11 50 olithic rocks. The early Mesozoic Buckskin Formation of Reynolds and Spencer (1989), which is corre- Xk y dino County, California: U.S. Geological Survey Open-file Report 91–264. tute of Technology Ph.D. thesis, 441 p. Tdv Xg 152m a Jcp L w lative with the Moenkopi Formation, crops out in the Kilbeck Hills where it overlies the Permian 124m a Qy Powell, R.E., 1982, Crystalline basement terranes in the southern eastern Transverse Ranges, Califor- a Kcsm Calzia, J.P., 1991c, Geophysical, lithologic, and water quality data from Dale Dry Lake, San Bernar- k 25 k Kaibab Limestone. The metasedimentary gneiss of Sheep Hole Mountains is also inferred to represent 30 Sheep Hole 30 a nia, in Cooper, J.D., compiler, Geologic excursions in the Transverse Ranges, southern California: e Qwy 70 e dino County, California: U.S. Geological Survey Open-file Report 91–268. D s r Pass Pluton B early Mesozoic strata, but its contact relations are obscure. Geological Society of America Cordilleran Section 78th Annual Meeting, Anaheim, Calif., April e F 75 Calzia, J.P., 1992, Geology and saline resources of Danby Lake playa, southeastern California, in Rey- l a t 35 80 20 The earliest Phanerozoic intrusion in the quadrangle is the Early Triassic quartz monzonite of a u 20 19–21, 1982, Volume and guide, p. 109–151. Qps l nolds, R.E., compiler, Old Routes to the Colorado: Redlands, California, San Bernardino County, F 60 t 30 80 Xg Twentynine Palms (approximately 240 Ma). This quartz-poor unit (fig. 2f) forms four small bodies in Powell, R.E., 1993, Balanced palinspastic reconstruction of pre-late Cenozoic paleogeology, southern a Jbv Jbq 30 Qwy Qy p. 87–91. u 70 the southwest corner of the quadrangle and is more widepread west of the quadrangle (Rogers, 1961; l 25 California: Geologic and kinematic constraints on evolution of the San Andreas fault system: Geo- t Qya 70 75 Kck Calzia, J.P., DeWitt, Ed, and Nakata, J.K., 1986, U-Th-Pb age and initial strontium isotopic ratios of the Xgn ts 65 Dibblee, 1967b, 1968; Trent, 1984). It records the earliest phase of continental arc magmatism related Qss 30 Coxcomb Granodiorite, and a K-Ar date of olivine basalt from the Coxcomb Mountains, southern logical Society of America Memoir 178, p. 1–105. 80 50 12 to the newly active western margin of North America. Further intrusive magmatism in Jurassic and Cre- 60 California: Isochron/West, no. 47, p. 3–7. Reynolds, R.E., and Reynolds, R.L. 1992, Pleistocene faunas in the Bristol-Danby trough, in Reynolds, Jbv Kcsh 85 Qps taceous time tended to be increasingly more siliceous (fig. 2), and was so voluminous as to displace W 30 Calzia, J.P., and Moore, S.W., 1980 Geophysical, lithologic, and water quality data from Cadiz Dry R.E., compiler, Old Routes to the Colorado: Redlands, California, San Bernardino County e 65 70 s 80 14 22 much pre-existing Proterozoic crust in the quadrangle by Mesozoic batholithic rocks. Museum Association Special Publication 92–2, p. 83-86. t 80 Kccm Qpsh Lake, San Bernardino County, California: U.S. Geological Survey Open-file Report 80–273. 75 C 30 4 Jbq 3 Sheep Hole 75 Kck Numerous Jurassic plutons were emplaced in the western part of the quadrangle. They embrace a Reynolds, S.J., and Spencer, J.E., 1989, Pre-Tertiary rocks and structures in the upper plate of the 40 73 a 30 Xgn Calzia, J.P., and Morton, J.L., 1980, Compilation of isotopic ages within the Needles 1° by 2° quadran- Mountains lu 153m 1 wide range of compositions from gabbro to syenogranite (figs. 2d,e), and also a range of emplacement Jbs m 35 Buckskin detachment fault, west-central Arizona, in Spencer, J.E., and Reynolds, S.J., eds., Geol- 15´ 85 25 30 15´ gle, California and Arizona: U.S. Geological Survey Open-file Report 80–1303, scale 1:250,000. Qo Jvh 65 e 60 45 5 Kcsk depths. Rocks in the Goat Basin and Music Valley plutons in the southwest corner of the quadrangle 35 Pluton t 268m ogy and mineral resources of the Buckskin and Rawhide Mountains, west-central Arizona: Ari- Qya Jcp? 70 25 Kcg 40 Calzia, J.P., Kilburn, J.E., Simpson, R.W., Jr., Allen, C.M., Leszcykowski, A.M., and Causey, J.D., 75 F Qoa Qps Qwy 35 20 a 70 18 contain euhedral epidote suggestive of crystallization at high pressure, and therefore, deep emplace- 80 Kcgp 0 u ၤt 10 zona Geological Survey Bulletin 198, p. 67–102. 40 Qo l 1983, Mineral resource potential map of the Coxcomb Mountains Wilderness Study Area (CDCA- 80 t ment. Aluminous hornblende compositions in an unspecified Jurassic dike rock in the Kilbeck Hills Qoa 65 80 Kcsk Richard, S.M., 1993, Palinspastic reconstruction of southeastern California and southwestern Arizona Jbv 0 75 Kcsm 70 Dၤm 328), San Bernardino and Riverside Counties, California: U.S. Geological Survey Miscellaneous 70 30 35 80 also suggest moderately high-pressure emplacement (corresponding to depths of approximately 16 km; Qo Qo Qoa Qpsh Field Studies Map MF–1603–A, scale 1:62,500. for the middle Miocene: Tectonics, v. 12, p. 830–854. Jbq Jbs 70 Jbq 52 70 13 Foster and others, 1992). Shallow mesozonal or hypabyssal emplacement is indicated for other plutons 50 45 Qya Rogers, J.J.W., 1961, Igneous and metamorphic rocks of the western portion of Joshua Tree National 85 8 Carl, B.S., Miller, C.F., and Foster, D.A., 1991, Western Old Woman Mountains shear zone; Evidence Jl 40 20 such as the Cleghorn Pass pluton and Ship Mountains pluton. The Jurassic Dale Lake Volcanics appear Jvh 15 for late ductile extension in the Cordilleran orogenic belt: Geology, v. 19, p. 893–896. Monument: California Division of Mines Special Report 68, 26 p. Jbv 40 27 80 Kcsm? 50 Qoa 30 Kia Jvh 35 60 50 ၦm 55 8 25 to represent eruptive products associated with the voluminous Bullion Mountains Intrusive Suite. This 55 20 Rosen, M.R., 1989, Sedimentologic, geochemical, and hydrologic evolution of an intracontinental, 12 20 55 60 25 15 5 Carter, J.N., Luyendyk, B.P., and Terres, R.R., 1987, Neogene clockwise rotation of the eastern Trans- Qoa 85 65 65 75 45 Xgn 35 30 Kid 6 Jurassic suite (approximately 160 Ma) encompasses rock units most of which contain lavender alkali Qoa 70 45 70 45 25 7 18 181m verse Ranges, California, suggested by paleomagnetic data: Geological Society of America Bulle- closed-basin playa (Bristol Dry Lake, CA): A model for playa development and its implications Qy 20 30 8 Kcg 55 Tvm Tg 44 Kcsh 80 30 25 15 15 137m feldspar; representative modal compositions are indicated in Figure 2d. Swarms of mafic dikes and 65 ၢs 55 Qss 5 tin, v. 98, p. 199–206. for paleoclimate: University of Texas, Austin, Ph.D. dissertation, 266 p. 7 45 Kcg 50 12 8 Qwo 25 75 Qya YXd Xgn 30 Kcg 17 granite prophyry dikes in the western part of the quadrangle are probably part of the Late Jurassic Inde- Rosen, M.R., 1991, Sedimentologic and geochemical constraints on the hydrogeologic evolution of Jbv 85 30 10 60 55 Qya 6 Qoa 2 Chen, J.H., and Moore, J.G., 1979, Late Jurassic Independence dike swarm in eastern California; Geol- 60 Jggd 20 35 80 17 pendence dike swarm described by Chen and Moore (1979), Karish and others (1987), and James Jbv Qbr ၢs 65 13 Bristol Dry Lake Basin, California, USA: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 35 70 Kid 8 4 24 ogy, v. 7, p. 129–133. 50 85 60 25 Qoa 7 2 140m Ja 50 55 40 75 20 I (1989). 84, p. 229–257. Jggd 55 70 80 Jgrg ro Davis, G.A., and Lister, G.S., 1988, Detachment faulting in continental extension: Perspectives from 80 45 65 50 70 Qy 9 Kia Nonmarine deposition in the Jurassic(?) and Cretaceous is represented by the McCoy Mountains Qya 45 50 60 9 n Qya Rosen, M.R., and Warren, J.K., 1990, The origin and significance of groundwater-seepage gypsum Jbv 60 5 M the southwestern U.S. Cordillera: Geological Society of America Special Paper 218, p. 133–159. 40 60 Formation of Miller (1944), present in the Coxcomb Mountains in the south-central part of the quadran- Jbv 20 65 50 4 10 o from Bristol Dry Lake, California, USA: Sedimentology, v. 37, p. 983–996. 10 80 Kcg 16 u Dibblee, T.W., Jr., 1961, Evidence of strike-slip movement on northwest-trending faults in Mojave Des- 30 0 16 n Qps gle. This unit was intruded and metamorphosed by Late Cretaceous plutons. Qya 50 0 t Silver, L.T., and Anderson, T.H., 1974, Possible left-lateral early to middle Mesozoic disruption of the Qoa S 45 60 Qwo a 3 ert, California, in Geological Survey Research 1961: U.S. Geological Survey Professional Paper h 60 65 14 15 i Qpsg Late Cretaceous (approximately 70 Ma) plutonic rocks dominate the eastern two-thirds of the e 40 10 n southwestern North American craton margin: Geological Society of America Abstracts with Pro- e Kcpg C 17 10 s 424-B, p. 197–199. p 85 Kcg Jgg a 154m 0 40 l 50 2 quadrangle, forming parts of two coeval and similar batholiths. The Old Woman-Piute Range batholith grams, v. 6, p. 955–956. H Kcg u Kii F Qwy Dibblee, T.W., Jr., 1967a, Evidence of major lateral displacement on the Pinto Mountain fault, south- o 40 m Jgrg 19 a l 50 80 15 Qya Qya (Miller and others, 1990) crops out in the northeast part of the quadrangle and farther north in the Old e 85 e 8 15 u Silver, L.T., and McKinney, C.R., 1963, U-Pb isotopic age studies of a Precambrian granite, Marble F 60 t 45 45 l B' eastern California: Geological Society of America Abstracts for 1967, Special Paper 115, p. 322. a 4 Kccl ts 2 3 t Woman Mountains and Piute Mountains (fig. 2c). It consists chiefly of metaluminous granodiorite and E u Jbv 40 65 8 Mountains, San Bernardino County, California [abs.]: Geological Society of America Special a lt 75 Qya Kcgp 8 0 Qoa Dibblee, T.W., Jr., 1967b, Geologic map of the Joshua Tree quadrangle, San Bernardino and Riverside s 75 Kcg F 0 peraluminous granite described by Miller, Howard, and Hoisch (1982), Miller and others (1990), and W t Jg 56 44 Paper 73, p. 65. V 65 a Kid Counties, California: U.S. Geological Survey Miscellaneous Geologic Investigations Map I–516, e Kcg u Qoa Qoa s a 65 Jgrg 15 Foster and others (1989, 1992). Hornblende compositions suggest that the granodiorite was emplaced at l 74 l Simpson, R.W., Bracken, R.E., and Stierman, D.J., 1984, Aeromagnetic, Bouguer gravity, and interpre- t l 5 t 15 Qwo scale 1:62,500. V e y 26 Jh 40 0 Qy 12 estimated pressures corresponding to depths of approximately 15–19 km (Foster and others, 1992). The a 35 85 9 2 11 18 tation maps of the Sheep Hole-Cadiz Wilderness Study Area (CDCA–305), San Bernardino 29 Qya l 35 6 Dibblee, T.W., Jr., 1968, Geologic map of the Twentynine Palms quadrangle, San Bernardino and Riv- l 55 Qwy 12 5 Cadiz Valley batholith underlies much of the central part of the quadrangle and areas south of the quad- e M112m 45 Kccl 7 0 8 10 County, California: U.S. Geological Survey Miscellaneous Field Studies Map 1615–B, 4 sheets, y 25 Kcg 15 16 8 12 Tbg 8 Qoa erside Counties, California: U.S. Geological Survey Miscellaneous Geologic Investigations Map 107m o Qoa 35 Kcg 50 7 Kii 5 10 5 u 18 36 60 20 Kid rangle (John, 1981). It encompasses granite and granodiorite here divided into two intrusive suites scale 1:62,500. M n 0 4 20 28 t 60 45 Qoa I–561, scale 1:62,500. 24 117m a 60 4 closely similar in composition and age, the Iron Mountains Intrusive Suite (fig. 2b) and the Coxcomb o i Kcg ts n 15 25 Smith, P.B., 1960, Fossil foraminifera from the southeastern California deserts: U.S. Geological Survey 103m u 363m Dokka, R.K., 1989, The Mojave extensional belt of southern California: Tectonics, v. 8, p. 363–390. n F Jbv 5 33 15 Intrusive Suite (fig. 2a). By means of geobarometric study, Anderson (1988) concluded that intrusion of 344m a 0 26 Professional Paper 400, p. B278–B279. t u 30 6 30 Dokka, R.K., and Travis, C.J., 1990, Late Cenozoic strike-slip faulting in the Mojave Desert, Califor- 27 a 23 l 13 20 70 Kid i t 50 25 rocks in the Iron Mountains Intrusive Suite was shallow, at an estimated pressure corresponding to n 6 8 31 60 35 35 ts Smith, P.B., 1970, New evidence for a Pliocene marine embayment along the lower Colorado River Qwy 21 10 35 Kii nia: Tectonics, v. 9, p. 311–340. F 105m 0 130m Jgdg 15 60 45 35 approximately 6–8 km depth. The Cretaceous rocks have been further discussed by Miller and others a Qwy Kcgi Qoa 42 42 65 25 area, California and Arizona: Geological Society of America Bulletin, v. 81, p. 1421–1420. u 17 Kcgp 65 Kccl 32 2 4 0 80 16 Evans, J.R., 1964, Xenotime mineralization in the southern Music Valley area, Riverside County, Cali- l 12 17 22 (1981), Miller, Howard, and John (1982), Calzia (1982), and Calzia and others (1986). t 45 26 21 14 12 15 Qoa fornia: California Division of Mines and Geology Special Report 79, 24 p. Spencer, J.E., and Patchett, P.J., 1997, Sr isotope evidence for a lacustrine origin for the upper Miocene 133m 50 40 Kcg 66 20 ts Qwy 18 26 CENOZOIC ROCKS AND DEPOSITS Foster, D.A., Harrison, D.T.M., and Miller, C.F., 1989, Age, inheritance, and uplift history of the Old to Pliocene Bouse Formation, lower Colorado River trough, and implications for timing of Colo- 15 12 Qoa ၢs Jggd 20 Tdi 7 rado Plateau uplift: Geological Society of America Bulletin, v. 109, p. 767–778. Qya 55 20 55 Qoa 29 Qoa Early Miocene basalt, dacite, and clastic units in the western part of the quadrangle form the strati- Woman-Piute batholith, California, and implications for K-feldspar age spectra: Journal of Geol- Jg 22 Stone, Paul, Howard, K.A., and Hamilton, Warren, 1983, Correlation of metamorphosed Paleozoic Qpsh Kid 72 28 graphically lowest Tertiary deposits. Regional relations indicate that they are associated with an episode ogy, v. 97, p. 232–243. M 16 22 Kig e Qss Qya q 30 72 31 4 40 39 strata of the southeastern Mojave Desert region, California and Arizona: Geological Society of sq 70 80 30 of tectonic extension. Early Miocene dacitic intrusions include a laccolith in the Iron Mountains, a sub- Foster, D.A., Miller, C.F., Harrison, T.M., and Hoisch, T.D., 1992, Ar/ Ar thermochronology and ui 73 80 te 70 70 38 America Bulletin, v. 94, p. 1135–1147. 42 L Qy 40 Kcg Qya 42 volcanic stock intruded into a dacitic volcanic carapace at Lead Mountain, and the eastern Bullion dike thermobarometry of metamorphism, plutonism, and tectonic denudation in the Old Woman Moun- a Qya 85 75 28 28 Qoa ke Qo Qy 19 ts 9 Streckeisen, A.L., 1973, Plutonic rocks classification and nomenclature recommended by the IUGS F Qoa Qoa Kcgp Kcg swarm. tains area, California: Geological Society of America Bulletin, v. 104, p. 176–191. 18 a Qwy 45 ul 115m 20 Qya 16 t ts Foster, D.A., Miller, D.S., and Miller, C.F., 1991, Tertiary extension in the Old Woman Mountains area, Subcommsion on the Systematics of Igneous Rocks: Geotimes, v. 18, no. 10, p. 26–30. 1 21 22 Qya Kccl Younger Neogene deposits include Miocene and (or) Pliocene conglomerate and gravel units in the Dog Wash Old Dale F Jpqm Kig Sugiura, Ray, and Sabins, Floyd, 1980, The evaluation of 3-cm-wavelength radar for mapping surface P 126m 116m ault 60 28 10 west part of the quadrangle. Sedimentary breccia of Miocene and (or) Pliocene age occurs in several California: Evidence from apatite fission track analysis: Tectonics, v. 10, p. 875–886. into Fau 38 Qo Qwy 24 M Qo lt 45 Jd Qwy deposits in the Bristol Lake/Granite Mountain area, Mojave Desert, California, in Radar geology: o Qo Qch Jbv patches isolated from its source materials and may represent landslides associated with strike-slip fault- Frost, E.G., and Okaya, D.A., 1986, Application of seismic reflection profiles to tectonic analysis in u 10 28 65 An assessment; Report of the Radar Geology Workshop, Snowmass, Colorado, July 16–20, 1979: Qoa nt 12 8 ing. The basalt of Deadman Lake volcanic field in the northwest corner of the quadrangle and rocks of mineral exploration, in Beatty, B. and Wilkinson, P.A.K., eds., Frontiers in geology and ore depos- ain F 30 40 Tbg 70 25 aul Qwy 19 Kccp 85 Jbqm 65 70 70 National Aeronautics and Space Administration, Jet Propulsion Laboratory Publication 80–61, p. t Qya 70 the remainder of the Deadman Lake volcanic field west of the quadrangle are assigned a late Pliocene its of Arizona and the Southwest: Arizona Geological Society Digest, v. 16, p. 137–152. Jbv 20 Qya 50 50 Qoa 10 Qch 122m 30 Qoa age based on correlation with basalt at Dish Hill north of the quadrangle, which was dated as 2 Ma Gerber, M.E., Miller, C.F., and Wooden, J.L., 1995, Plutonism at the eastern edge of the Cordilleran 439–456. Qo Qya 55 80 Kcgp Qbr Qya 20 60 Qwy Tchakerian, V.P., 1989, Late Quaternary aeolian geomorphology of the Dale Lake sand sheet, southern 30 T 2 Qwy 65 Kid 0 (Wilshire and Nielson-Pike, 1986). Two Quaternary basalt flows lie nearby, the basalt of Lead Moun- Jurassic magmatic belt, Mojave Desert, California, in Miller, D.M. and Busby, C., eds., Jurassic Qss w Qss Kccp 20 20 Tb Xp 42 75 en 5 Qya 75 ts Mojave Desert, California: Physical Geography, v. 12, p. 347–369. ty 45 H 40 Tb 28 Qoa tain and the younger basalt of Amboy. tectonics of the Cordillera: Geological Society America Special Paper 299, p. 351–374. n Xag um Kcg 45 27 55 Qoa i 23 Tchakerian, V.P., 1992, Aeolian geomorphology of the Dale Lake sand sheet, in Reynolds, R.E., com- Xsg n Qya bu Qya Qy Basin deposits beneath the present valleys have been explored by scores of shallow drill holes and Glazner, A.F., Farmer, G.L., Hughes, W.T., Wooden, J.L., and Pickthorn, William, 1991, Contamination 80 e g D 45 27 Kig Xdw M Qy Qoa r Kccl piler, Old Routes to the Colorado: Redlands, California, San Bernardino County Museum Associa- 70 50 45 o Jcp? Jd y 80 by 29 holes deeper than 100 m (table 1). Smith (1960, 1970) described faunal assemblages characteris- of basaltic magma by mafic crust at Amboy and Pisgah Craters, Mojave Desert, California: Journal Tg 80 P 70 u Kcgp a Jbv n 7 tion Special Publication 92–2, p. 46–49. l ta L 35 Qya tic of brackish water, recovered from depth under Cadiz and Danby Lakes, which form a basis for cor- of Geophysical Research, v. 96, p. 13,673–13,692. m in 80 a 5 66 80 65 Xbg Qoa F 50 k 20 15 Kig Thompson, D.G., 1929, The Mohave Desert region, California: U.S. Geological Survey Water Supply 70 55 s 60 Qoa a Jl 80 e 40 15 66 Goter, S.K., 1992, Southern California earthquakes: U.S. Geological Survey Open-file Report 92–533, 5 50 u KJpg s Kcg 170m relating the subsurface sediments containing them with the Bouse Formation. This Pliocene unit is 70 lt Jcp? Kcg 25 0 41 25 0 0 55 40 M ၠpm? 15 0 3 Kigm Paper 578, 759 p. Kwt 75 F 35 28 20 60 30 0 50 exposed east of the quadrangle and was deposited in lakes and (or) an estuarine proto-gulf of California scale 1:375,000. 60 o 35 23 a 45 45 45 25 55 50 u 30 Qya Jcp? u 70 Trent, D.D., 1984, Geology of the Joshua Tree National Monument, Riverside and San Bernardino Xp 35 Qoa 35 Kid 35 Greeley, Ronald, and Iverson, J.D., 1978, A field guide to Amboy lava flow, San Bernardino County, 30 30 n 45 Jbv lt Qoa 75 (Metzger, 1968; Lucchitta, 1979; Spencer and Patchett, 1997). Below Bristol Lake, Rosen (1989) found 5 45 t Qwy 35 60 20 Jgdg 55 15 Xd Xdw a 23 Counties: California Geology, v. 37, n. 4, p. 75–86. 35 70 i 0 that cored sediments indicative of persistent playa environments are interbedded with six tephra layers California, in Greeley, Ronald, Womer, M.B., Papson, R.P., and Spudis, P.D., eds., Aeolian fea- n Kf Jbv Jcp? 25 5 Xd 80 85 Kf Qoa 69 50 Kigd Ver Plank, W.E., 1958, Salt in California: California Division of Mines Bulletin 175, 168 p. 25 30 30 Jvh Jvh Kcg 25 35 50 50 72 as old as 3.7 Ma. This indicates that playa environments rather than lacustrine environments have pre- tures of southern California: A comparative planetary geology guidebook: National Aeronautics F Jcp? 62 5 Jcp? Kcgp 20 50 48 Jbv 25 Wilshire, H.G., and Nielson-Pike, J.E., 1986, Upper-mantle xenoliths in alkaline basalt, Dish Hill, Cali- 50 Xdw a 35 Tbg vailed at the sites of the dry lakes since Pliocene time. and Space Administration, and Tempe, Arizona, Arizona State University Department of Geology 35 u Xbg Kcgp l Jd Qya Jcp? Qya Jbqm Kcgp fornia, in Ehlig, P.L., compiler, Guidebook Southern California field trips; Mojave Desert xenolith 20 Xp 45 t Jbv 24 Playa deposits occupy the surface of four large dry lakes in the quadrangle, as well as five smaller and Center for Meteorite Studies, p. 23–52. 20 Jvh 7 40 35 35 Jdl Jdl Qwy Kig 85 suites—Malapai Hill and Dish Hill, Peninsular Ranges batholith, and Geology and hydrology of Xdw Qoa 44 80 basins. Evaporite deposits in the larger playas have provided major resources of brine and salt (Ver Gundry, R.R., 1992, Saline mineral extraction from southern Mojave Desert playas of California, in 35 30 Xbg Qy 45 25 Jbv Jbv Catalina Island, Southern California: Geological Society of America Cordilleran Section 82nd 1515 ၣt 45 35 Jd Plank, 1958; Calzia, 1992; Gundry, 1992). Quaternary alluvial units intervene between the playas and Reynolds, R.E., compiler, Old routes to the Colorado: Redlands, Calif., San Bernardino County 60 25 Qwy Qwy 55 73 Museum Association Special Publication 92–2, p. 65–70. Annual Meeting, Los Angeles, California, March 25–28, 1986, p. 9–11. 33 50 Jcp? Qo Kigd the ranges and include wide expanses of Holocene alluvium. Late Pleistocene faunas were described by 85 Qya 11 Qoa Wooden, J.L., and Miller, D.M., 1990, Chronologic and isotopic framework for Early Proterozoic crus- 31 Xp Ivanhoe 75 30 Reynolds and Reynolds (1992). Perched or dissected old Pleistocene alluvium and associated sandstone Hazlett, R.W., 1992, Some thoughts on the development of Amboy Crater, in Reynolds, R.E., compiler, 20 10 Fau Jdl Xs Jd Qoa Qoa lt 65 Kig 70 tal evolution in the eastern Mojave Desert region, SE California: Journal of Geophysical Research, Xdw Qya Qwy Qo 49 and breccia crop out adjacent to range fronts and along faults; a Rancholabrean vertebrate faunal Old Routes to the Colorado: Redlands, California, San Bernardino County Museum Association Xbg 89 Jdl 60 5 Jbqm 75 Qwy Jgdg v. 95, p. 20,133-20,146. 38 30 Jd Jcp? Jvh Qya assemblage (Jefferson, 1992) and an ash bed correlated with the 0.7-Ma Bishop Tuff (Bacheller, 1978) Special Publication 92–1, p. 71–73. Xd Jbv Qoa Wooden, J.L., Powell, R.E., Howard, K.A., and Tosdal, R.M., 1991, Eagle Mountains 30' x 60' quadran- Jgb 48 10 Qya Jdl have been described from the southwest corner of the quadrangle. Windblown sand reworked from allu- Hazzard, J.C., and Dosch, E.K., 1937, Archean rocks in the Piute and Old Woman Mountains, San Ber- 5 35 Qoa 55 40 Qya Qya Qy t 47 Qy 30 Jbq 30 Qya gle, southern California: II Isotopic and chronologic studies: Geological Society of America ၣ 15 80 Jbv 12 45 vial and playa deposits forms extensive dune fields and sand sheets in the basins and locally climbs nardino County, California [abs.]: Geological Society of America Proceedings 1936, p. 309. Jd 35 60 Xp 30 74 65 Jbq Granite Pass Pluton Abstracts with Programs, v. 23, no. 5, p. A478. 60 Jg 60 70 Jcp? onto the highlands. Windblown sand near Dale Lake has been tentatively dated as 5 to 60 ka in age Hope, R.A., 1966, Geology and structural setting of the eastern Transverse Ranges, southern California: Xag 65 60 Jbv Jbq a Qy 35 35 35 ၠp 45 Qy Jdl Qya Los Angeles, University of California, Ph.D. thesis, 158 p. Wright, J.E., Howard, K.A, and Anderson, J.L., 1987, Isotopic systematics of zircons from Late Creta- Qoa Jd ၠpm Qo Jbv Jvh (Tchakerian, 1992). Many of the dune fields are active. 50 45 Jh Qoa 88 Kcc Qoa ceous intrusive rocks, southeastern California [abs.]: Implications for a vertically stratified crustal 70 50 1 Jbv Qoa Jdl Horringa, E.D., 1989, Rocks and structural evolution of the northern Kilbeck Hills, San Bernardino 25 0 45 25 52 40 Qoa B 65 45 80 Qy column: Geological Society of America Abstracts with Programs, v. 19, p. 898. Jd 0 70 ၠp STRUCTURAL EVOLUTION County, California: San Jose, California, San Jose State University, M.S. thesis, 180 p. 55 45 70 Qwy KJm Qya 50 lgt 40 80 60 75 55 45 Qoa 80 80 Qoa The Early Proterozoic Ivanpah orogeny associated with plutonism produced pervasive foliation Howard, K.A., 1993, Cenozoic stratigraphy of the Lead Mountain and Valley Mountain areas, eastern 2 40 Xdw 75 50 Jbv Jbq Jh Qoa Jgdg Qo 22 60 27 Xjt Qya Jvh Kcc Qwy Qoa and mineral assemblages of high amphibolite to granulite facies in nearby regions (Wooden and Miller, Bullion Mountains, Calif., in Sherrod, D.R. and Nielson, J.E., eds., Tertiary stratigraphy of highly 70 40 50 80 Qoa Qya 44 Kid? 35 80 55 Qoa Qoa Qya Kig 1990; Foster and others, 1992). The details of this orogeny are obscure within the quadrangle, but much extended terranes, California, Arizona, and Nevada: U.S. Geological Survey Bulletin 2053, p. 70 Jgb 4 ၣt Qo Jbq 45 75 60 Kid? 60 Qoa Jcp? Jgdg 80 Jgb 70 Jbv Xjt Qoa Qoa 35 30 of the fabric and mineral assemblages in the exposed Proterozoic rocks likely date from this era. Early 123–126. Goat Basin Xp 80 70 Qya Jdl 80 35 70 80 Qoa Qy Qy Qy Jbq 72 55 60 Proterozoic events in the San Bernardino Mountains area a few tens of kilometers west of the quadran- Howard, K.A., and Allen, C.M., 1988, Geologic map of the southern part of the Dale Lake 15-minute Pluton 40 Jg 45 Jbq Qoa Qy 85 Jgdg Xs Xgn Table 1. Drill holes (wells and test wells) deeper than 100 m. [Numerous shallower drill holes are 40 Xp 18 Music Jm Jbq Qoa Qya 55 Xsg 58 5 Jdl a 32 Jgdg 65 65 20 85 Qya 34°00´ 34 Valley Pluton 73 50 Jbv Jbv Qya Qoa ts 30 Qo 34°00´ gle were discussed by Barth and others (2000). quadrangle, San Bernardino and Riverside Counties, California: U.S. Geological Survey Open-file described by Thompson (1929), Moyle (1961, 1967), Calzia and Moore (1980), Rosen (1989), and 30 116°00´ 45´ 30´ 15´ 115°00´ Following Proterozoic erosion, marine Cambrian sandstone and younger Paleozoic strata were report, 17 p., map scale 1:62,500. Calzia (1991a,b,c)] deposited unconformably over Proterozoic plutonic and metamorphic rocks. Crustal stability prevailed Howard, K.A., Bacheller, John, Fitzgibbon, T.T., Powell, R.E., and Allen, C.M., in press a, Geologic Base from U.S. Geological Survey, Sheep Hole Mts., 1985 13° SCALE 1:100 000 Digital cartography by Geoff Phelps until the earliest Triassic when plutonism began in the west, followed by pre-Jurassic metamorphism map of the Valley Mountain 15-minute quadrangle, San Bernardino and Riverside Counties, Cali- Map No. Well Area Depth (m) Well log Universal Transverse Mercator projection H 1 021 345678 MILES Standard cartography by Darlene A. Ryan and Kathryn Nimz and ductile deformation of the Permian or Triassic intrusions and surrounding rocks in the Pinto Moun- fornia: U.S. Geological Survey Open-File Report 95–548, scale 1:62,500. T

R O tains. Howard, K.A., Jagiello, K.J., Fitzgibbon, T.T., and John, B.E., in press b, Geologic map of the Lead N Edited by Jan L. Zigler 1 Danby 1 Danby Lake 268 Bassett and others (1959)

IC 1 012356789 4 10 KILOMETERS CALIF Manuscript approved for publication September 19, 2000 Jurassic volcanic rocks and elongate plutons in the western and southern parts of the quadrangle Mountain 15-minute quadrangle, San Bernardino County, California: U.S. Geological Survey ET 2 Danby 2 Danby Lake 140 Bassett and others (1959) N form part of a long NW–SE belt of Jurassic igneous rocks in the southwestern Cordillera. Where the Open-file report 95–552, scale 1:62,500. G TRUE NORTH A 3 Dan 1 Danby Lake 154 Calzia (1991b) M CONTOUR INTERVAL 50 METERS belt narrows just southeast of the quadrangle could be a place to look for disruption related to a Jurassic Howard, K.A., and John, B.E., 1984, Geologic map of the Sheep Hole-Cadiz Wilderness Study Area APPROXIMATE MEAN 4 Dan 2 Danby Lake 153 Calzia (1991b) DECLINATION, 2001 QUADRANGLE LOCATION sinistral Mojave-Sonora megashear postulated by Silver and Anderson (1974). Cretaceous intrusions (CDCA-305), San Bernardino County, California: U.S. Geological Survey Miscellaneous Field obscure the critical eastern part of the Jurassic igneous belt. Studies Map MF–1615–A, scale 1:62,500. 5 Ward 2 Danby Lake 181 Thompson (1929, p. 709) The N to NNW strike of Jurassic dike swarms that are present in mountain ranges in the southwest Howard, K.A., and John, B.E., 1987, Crustal extension along a rooted system of imbricate low-angle 6 Ward 3 Danby Lake 137 Moyle (1967, p. D-2) part of the quadrangle suggest that they were emplaced during approximately E–W or ENE–WSW faults: Colorado River extensional corridor, California and Arizona, in Coward, M.P., Dewey, J.F., A BULLION MOUNTAINS CALUMET MOUNTAINS CADIZ VALLEY KILBECK HILLS OLD WOMAN MOUNTAINS W A R D VA LLEY A' 7 1S/18E-13L1 S. of Danby Lake 170 Moyle (1967, p. D-1) extension in the Late Jurassic. Their original orientation is less certain because the ranges in which they and Hancock, P.L., eds., Continental Extensional tectonics: Geological Society of London Special METERS KILOMETERS 8 Mojave 1 E. of Ship Mts. 897 Howard and others (1989a) CLEGHORN PASS FAULT ZONE CLEGHORN LAKES EASTERN BULLION DIKE SWARM occur may have been rotated during Neogene events (Carter and others, 1987). Publication No. 28, p. 299–311. FAULT Qo ၢs In the northeastern part of the quadrangle, a regionally developed Mesozoic ductile fault (tectonic Howard, K.A., and Miller, D.M., 1992, Late Cenozoic faulting at the boundary between the Mojave and 9 Archer 1 SE of Ship Mts. 101 Thompson (1929, p. 698) Jbv Jcp Qya Qbr Jbe Jbep Kcsh ၦm Ko 1000 Qo Jbv Jbpm Tdi Kcg Qya Kcsh ၣb ts ts 1 10 Cadiz 1 Cadiz Lake 152 Bassett and others (1959) Qo Qoa Dၤm SCANLON THRUST Xk ts slide in the sense of Hutton, 1979), the Scanlon thrust, places an inverted sequence of early Paleozoic Sonoran blocks: Bristol Lake area, California, in Richard, S.M., ed., Deformation associated with Tcs Ks PMb AULT Xk Kop Tdv Kcg Pk KILBECK F Qo Jgp Qo Xgn Qo Qpsh Qo Xf Qo strata and their Proterozoic basement over younger Paleozoic and Triassic rocks (Miller, Howard, and the Neogene eastern California shear zone, southeastern California and southwestern Arizona: 11 CAD-1 Cadiz Lake 124 Calzia and Moore (1980) ts SEA LEVEL Tdd UNEXPOSED NEOGENE DEPOSITS ၤt Dၤm ၤt Ko Ko SEA LEVEL Hoisch, 1982; Howard and others, 1987). Present evidence suggests that the upper plate moved west. Redlands, Calif., San Bernardino County Museums Special Publication 92–1, p. 37–47. 12 Bristol 1 Bristol Lake 307 Bassett and others (1959) UNE NEOGENE DEPOSITS Xf ၤt Km UNEXPOSED NEOGENE DEPOSITS Jbpm Tdd XPOSE D Xk? Km Tdv Tcs ၦm ts ts The lower plate Paleozoic and Triassic rocks in turn are internally sliced and folded (Horringa, 1989) Howard, K.A., Horringa, E.D., Miller, D.M., and Stone, Paul, 1989a, Geologic map of the eastern parts Jmd Kcg Km BREAKA 13 Bristol 2 Bristol Lake 307 Bassett and others (1959) PMb Xk? W A and ductilely faulted down over highly strained tectonic schist derived from Proterozoic protoliths. I use of the Cadiz Lake and Cadiz Valley 15-minute quadrangles, San Bernardino and Riverside Coun- ၦm Tdv Kcg? ၣb Y FAUKop? –1000 Kcsh Kcg LT –1 14 BR-1 Bristol Lake 153 Calzia (1991a) Jgp Jdu Tdd Tdd Kcg? PMb ts Kck Kck? Kop? the term "tectonic schist" in the sense of Hutton (1979) to describe highly foliated rocks in a zone of ties, California: U.S. Geological Survey Miscellaneous Field Studies Map MF–2086, scale Tdd Kcg ? Ko 15 BR-2 Bristol Lake 247 Calzia (1991a) Jmd Kcg? Kcg? Kck? Km Xgn? high strain. The lower tectonic slide (ductile fault), here termed the Kilbeck fault, attenuates crustal sec- 1:62,500. Kcgp ? Kcg? Kck? Kck PROTEROZOIC ROCKS? Tdd Tdd Xk? Km tion and so may be a lag fault. Relative and absolute timing of the two major tectonic slides and associ- Howard, K.A., John, B.E., and Miller, C.F., 1987, Metamorphic core complexes, Mesozoic ductile 16 CAES 2 Bristol Lake 537 Rosen (1989) –2000 –2 PROTEROZOIC ROCKS? 1524 meters = 5000 feet (Quaternary fault) ated fabrics remain uncertain, but they are cut by the Old Woman pluton and other Late Cretaceous thrusts, and Cenozoic detachments: Old Woman Mountains-Chemehuevi Mountains transect, Cali- 17 Dale Dry Lake 1 Dale Lake 133 Calzia (1991c) Quaternary Thin surficial deposits are not shown Western Old Woman Mountains shear zone formed during early Tertiary batholithic rocks. fornia and Arizona, in Davis, G.H., and VandenDolder, E.M., eds., Geologic diversity of Arizona faults 18 1N/12-20D4 Dale Lake 363 Moyle (1961, p. 34) shear zone or latest Cretaceous unroofing Tectonic schist also formed at lower structural levels as envelopes that separate subhorizontal and its margins: Excursions to choice areas: Arizona Bureau of Geology and Mineral Technology 19 1S/12-3Q1 S. of Dale Lake 122 Moyle (1961), no log tonguelike sheet intrusions of the Old Woman pluton from its Proterozoic host, the Kilbeck Gneiss. The Geological Survey Branch Special Paper 5, p. 365–382. Kilbeck Gneiss shows evidence of ultrametamorphism and partial melting during the Late Cretaceous Howard, K.A., Miller, D.M., and John, B.E., 1982, Regional character of mylonitic gneiss in the Cadiz 20 1N/10-36P1 W. of Dale Lake 116 Moyle (1961, p. 32) events (Miller, Howard, and Hoisch, 1982; Howard and others, 1989b). Valley area, southeastern California, in Frost, E.G. and Martin, D.L, eds., Mesozoic-Cenozoic tec- 21 1N/10-34Q2 W. of Dale Lake 115 Moyle (1961), no log B MUSIC VALLEY PINTO MOUNTAINS SHEEP HOLE MOUNTAINS CADIZ VALLEY IRON MOUNTAINS DANBY LAKE B' The Cretaceous Cadiz Valley batholith was intruded as plutons elongated chiefly NW–SE, as were tonic evolution of the Colorado River region, California, Arizona, and Nevada (Anderson-Hamil- 22 1N/10-34Q1 W. of Dale Lake 126 Moyle (1961, p. 32) GOAT BASIN TWENTYNINE PALMS HUMBUG SHEEP HOLE DRY LAKES CALUMET METERS KILOMETERS the Jurassic plutons. Intrusion recrystallized and foliated a western aureole approximately 2–3 km wide ton volume): San Diego, Cordilleran Publishers, p. 441–447. 23 1N/10-22J1 W. of Dale Lake 105 Moyle (1961), no log PLUTON Xdw Xbg MOUNTAIN FAULT MOUNTAIN FAULT ZONE FAULT FAULT in older rocks. In the southeast part of the batholith in the Iron Mountains, early-intruded parts of the Howard, K.A., Stone, Paul, and Miller, C.F., 1989b, Geologic map of the Milligan 15-minute quadran- 24 1N/10-21F1 W. of Dale Lake 344 Moyle (1961), no log Xdw Jgb Jd Xag Xp Xp Xd FAULT Unexposed Qoa ၣt lgt Jbv batholith, together with intervening screens of Proterozoic rocks that became tectonic schist, were gle, San Bernardino County, California: U.S. Geological Survey Miscellaneous Field Studies Map 1000 Jd ZONE Jd Kcf neogene ts Qoa Kii 1 25 1N/10-15R1 W. of Dale Lake 117 Moyle (1961, p. 31) Xdw Qoa Jcp? Jcp? Kccp Kcg Qoa Tbg Kcg Kii Tbg mylonitized throughout a thickness exceeding 1.3 km in a subhorizontal roof zone above younger unde- MF–2072, scale 1:62,500. Qo Qoa Jbv Jvh Qo Jdl Qy Jbv Qwy Qo Qoa deposits Kid Kid Jmd Qya Kccl Qoa Kid Tbd Qpsg 26 1N/10-14K1 W. of Dale Lake 112 Moyle (1961), no log Qo KJpg Qo Qoa ts Qoa Qpsh Qps Qoa formed parts of the batholith (Miller and others, 1981; Miller and Howard, 1985). Sense of shear in Hutton, D.H.W., 1979, Tectonic slides: A review and reappraisal: Earth Science Reviews, v. 15, p. Jmd Qo Jdu Qo Ja ts SEA LEVEL Jmd Jl Jbqm ts SEA LEVEL mylonitized Cretaceous granite (Danby Lake Granite Gneiss), where measured, is top to the ENE. 151–172. 27 1N/9-24L1 W. of Dale Lake 130 Moyle (1961), no log Jmd Jmd Jbv ts UNEXPOSED NEOGENE DEPOSITS Qo Miller and others (1981) suggested a possible diapiric model to explain this synplutonic deformation in Jachens, R.C., and Howard, K.A., 1992, Bristol Lake basin—A deep sedimentary basin along the Bris- Jmd Xbg Xd Jgdg ts 28 1N/9-24A1 W. of Dale Lake 103 Moyle (1961, p. 31) Xdw Jgp Jgdg Jmd Xjt Jgp Kcg the Iron Mountains. More locally developed mylonitic rocks exhibiting a similar NE strike of lineation tol-Danby trough, Mojave Desert, in Reynolds, R.E., compiler, Old Routes to the Colorado: Red- 29 1N/9-13K1 W. of Dale Lake 107 Moyle (1961), no log –1000 Kcgp ? –1 Xp Kig Kig Tbd B R are found to the west in Cadiz Valley, the northern Coxcomb Mountains, and the Sheep Hole Mountains lands, California, San Bernardino County Museum Association Special Publication 92–2, p. Xbg Jmd Jmd Jgdg E A Kii? Jgp Jgdg K A W Jgp A Y Xsg Xdw Xjt ? Jbqm ? Kid F A (Howard and others, 1982). 57–59. Jd Xd Kigm U LT –2000 –2 To the north in the Old Woman Mountains, local Late Cretaceous mylonitization immediately fol- Jagiello, K.J., 1991, Determination of horizontal separation on late Cenozoic strike-slip faults in the 1524 meters = 5000 feet lowed plutonism and was associated with extensional unroofing and rapid cooling (Foster and others, central Mojave Desert, southern California: Los Angeles, University of California at Los Angeles, Thin surficial deposits are not shown 1991, 1992). The mylonitic fabrics record shear down to the west off the west flank of the range (West- Ph.D. dissertation, 293 p., map scale 1:62,500. ern Old Woman Mountains shear zone of Carl and others (1991) near the northern quadrangle border), Jagiello, Keith, Christie, J.M., and Blom, R.M., 1992, Horizontal separation of major late Cenozoic and shear down to the ESE off the southeast flank of the range (Howard and others, 1989b). strike-slip faults in the Twentynine Palms region, Mojave Desert, California, in Richard, S.M., ed., This map was printed on an electronic plotter directly from digital files. Dimensional Deformation associated with the Neogene eastern California shear zone, southeastern California calibration may vary between electronic plotters and between X and Y directions on the Aplitic dikes and mineralized joints that cut mylonitized Cretaceous rocks in several ranges are same plotter, and paper may change size due to atmospheric conditions; therefore, GEOLOGIC MAP OF THE SHEEP HOLE MOUNTAINS 30' x 60' QUADRANGLE, SAN BERNARDINO AND RIVERSIDE COUNTIES, CALIFORNIA dated as latest Cretaceous or earliest Tertiary in age (Howard and others, 1982; Miller and Howard, and southwestern Arizona: Redlands, California, San Bernardino County Museum Special Publi- scale and proportions may not be true on plots of this map. 1985). They mostly strike northwest, indicating NE–SW orientation of least principal stress at the end cation 92–1, p. 48–53. For sale by U.S. Geological Survey, Map Distribution, Box 25286, Federal Center, of plutonism. James, E.W., 1989, Southern extension of the Independence dike swarm of eastern California: Geology, Denver, CO 80225, 1–888–ASK–USGS By Following denudation in the early Tertiary, the onset of volcanism in the early Miocene coincided v. 17, p. 587–590. This publication also includes digital versions of the map sheets, which are available Jefferson, G.T., 1992, Pleistocene fossil vertebrates from Twentynine Palms, California, in Reynolds, on the World Wide Web at: Keith A. Howard with major tectonic extension in the Mojave Desert. Evidence for this extension is best displayed in http://geopubs.wr.usgs.gov/map-mf/mf2344 areas east and west of the quadrangle (for example, Davis and Lister, 1988; Howard and John, 1987; R.E., compiler, Old Routes to the Colorado: Redlands, California, San Bernardino County Any use of trade, product, or firm names is for descriptive purposes only and does not 2002 Dokka, 1989). In the quadrangle, westward downtilting associated with the extension is recorded by Museum Association Special Publication 92–2, p. 43–45. imply endorsement by the U.S. Government.