oi/*VT Vidal California ancl Arizona Q,)Ef.atO6tCAX SURVEY PRGrE'S&IO-H'&I. PAiPXB 143 e&tec n Godp&raM&n -w%1k me &$. fifmkiar A Contribution to the Structural History of the Vidal-Parker Region, California and Arizona By W. J. CARR U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1430 Prepared in cooperation with the U.S. Nuclear Regulatory Commission A report concerning stratigraphy, structure, and geophysics of a region within the eastern Mojave Desert and Mojave-Sonoran structural-physiographic belt, wherein tectonic activity has occurred at a very low rate since late Miocene time. Important structural activity of Tertiary age culminated and concluded in a major regional episode of detachment faulting UNITED STATES GOVERNMENT PRINTING OFFICE, WASHINGTON : 1991 U.S. DEPARTMENT OF THE INTERIOR MANUEL LUJAN, JR., Secretary U.S. GEOLOGICAL SURVEY Dallas L. Peck, Director Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government Library of Congress Cataloging in Publication Data Carr, Wilfred James, 1926- A contribution to the structural history of the Vidal-Parker region. California and Arizona. (U.S. Geological Survey professional paper ; 1430) Bibliography: p. Supt. of docs, no.: I 19.16:1430 1. Geology California Vidal Region. 2. Geology Arizona Parker Region. 3. Geology, Structural. I. U.S. Nuclear Regulatory Commission. II. Series. QE90.V53C37 1990 557.94'9 85-600261 For sale by the Books and Open-File Reports Section, U.S. Geological Survey, Federal Center, Box 25425, Denver, CO 80225 CONTENTS Page Abstract ........................................... 1 Stratigraphic history Continued Introduction ....................................... 2 Tertiary volcanic and sedimentary rocks Continued Purpose of investigation .......................... 2 Sedimentary rocks Continued Methods of study ................................ 2 Bouse Formation ......................... 17 Acknowledgments ............................... 3 Correlation with surrounding areas .......... 18 Physiography and the Mojave-Sonoran Belt ............. 4 Tertiary and Quaternary deposits .................. 19 Stratigraphic history ................................ 4 Colorado River deposits .......................... 19 Metamorphic, intrusive, and sedimentary rocks ...... 4 Alluvial deposits ................................ 19 Mesozoic, Paleozoic, and older(?) rocks ........... 4 Age of the alluvial units .......................... 19 Rocks at the east foot of the Riverside Mountains 4 Structure and tectonics of the Vidal-Parker area and surround­ Rocks of probable late Paleozoic age ......... 5 ing region ........................................ 21 Possible structural significance of changes in General setting .................................. 21 character in the upper Paleozoic rocks ...... 6 Geophysics ..................................... 22 Lower plate gneisses ...................... 6 Seismology .................................. 22 Mesozoic(?) rocks .......................... 8 Magnetics ................................... 23 Granite gneiss ............................ 8 Gravity ..................................... 24 Metamorphic rocks intruded by dikes and sills 9 Level line, by D. D. Dickey ....................... 25 Granite and gneissic granite ................ 9 Structures in pre-Tertiary rocks .................... 26 Tertiary volcanic and sedimentary rocks ............ 9 Tertiary structures .............................. 28 Volcanic rocks ............................... 12 Stratigraphic-structural record ................. 29 Andesite lavas ........................... 12 Middle Miocene unconformity .................. 29 Rhyodacite lavas ......................... 12 Whipple Mountains detachment fault ........... 30 Basaltic rocks ............................ 12 Regional implications ...................... 31 Trachytic rocks in the Buckskin Mountains ... 13 Origin of Whipple Mountains detachment fault Peach Springs Tuff of Young and Brennan (1974) 13 and regional extension ................... 33 Sedimentary rocks ........................... 15 Early end of faulting ......................... 35 Breccias ................................. 15 Pliocene-Pleistocene tectonics ............... 35 Conglomerate, sandstone, siltstone, and limestone 15 Summary of structural history ................. 37 Fanglomerate of Osborne Wash ............. 16 References cited .................................... 37 ILLUSTRATIONS [Plates are in pocket] PLATE Geologic and structural unit map of the Vidal-Parker region, California-Arizona. Generalized regional geologic and structural unit map and Bouguer gravity map of part of southeastern California and western Arizona. Generalized regional geologic and structural unit map and residual aeromagnetic map of part of southeastern Califor­ nia and western Arizona Tectonic map of Vidal-Parker region, California and Arizona. Generalized topography of part of southeastern California and western Arizona. Page FIGURE Index map of the eastern Mojave Desert ...................................... 3 Map of the basins and ranges of Arizona, Utah, Nevada, and southeastern California 5 Map showing postulated area! distribution of Permian rocks at localities in western Arizona, southern Nevada, and southeastern California .......................................................................... 7 Composite diagrammatic columnar sections of Tertiary rocks in the Vidal-Parker region ...................... 11 Distribution of the Peach Springs Tuff of Young and Brennan ........................................... 14 6. Relation of Tertiary and Quaternary deposits between the Whipple Mountains and Colorado River in the vicinity of Parker, Ariz. 20 in IV CONTENTS FIGURE 7. Seismic stations in the eastern Mojave Desert, 1974-77 ................................................. 22 8. Map and profile along part of the Colorado River aqueduct showing elevation differences between surveys in 1931 and 1975 ......................................................................................... 26 9. Section through the eastern Whipple Mountains showing configuration of the Whipple Mountains detachment fault 28 10. Structure contour sketch map of the Whipple Mountains detachment fault ................................. 32 TABLES TABLE 1. Potassium-argon dates on granitic rocks in Vidal-Parker region ........................................... 9 2. Age of Tertiary volcanic rocks in Vidal-Parker region ................................................... 10 3. Petrographic comparison of the phenocrysts of Peach Springs Tuff of the Vidal-Parker region with those of the type area in northwestern Arizona .................................................................... 15 4. Comparison of ash beds in sand of the Bouse Formation and in fanglomerate of Osborne Wash ............... 17 5. Faults and photo lineaments in old alluvium of the Vidal-Parker region .................................... 36 A CONTRIBUTION TO THE STRUCTURAL HISTORY OF THE VIDAL-PARKER REGION, CALIFORNIA AND ARIZONA By W. J. GARR ABSTRACT Geologic investigations in the area of the lower Colorado River trachybasalts or basaltic andesites. A small center in the Buckskin Valley have provided some new information that permits an integra­ Mountains erupted trachytes and trachyandesites with peralkaline tion of part of the geologic history for western Arizona and affinities. southeastern California. The studies, aimed principally at evaluating Peach Springs Tuff of Young and Brennan (1974), an important ash- the recency of faulting in the eastern Mojave Desert, were done in flow tuff stratigraphic marker, has been found at several localities support of geologic evaluation of the region for proposed nuclear power in the Vidal-Parker region. A map of the known localities of the tuff generating facilities. shows a predominant northeast-southwest distribution, with a possible Several maps are presented, including l:125,000-scale geologic map, source southwest of Kingman, Ariz. and regional compilations of geology, gravity, and aeromagnetics at Sedimentary material, ranging from megabreccia to lacustrine 1:500,000. limestone, dominates the Tertiary section in most areas. Megabrec­ Physiography, geology, and geophysics combine to delineate a cias consist of metamorphic and locally identifiable late Paleozoic northwest-trending zone about 100 km wide, here named the Mojave- rocks. In some areas a prominent unconformity separates volcanic Sonoran Belt. This structural-physiographic feature can be viewed as rocks and breccias consisting of granitic and metamorphic rocks from a southeastward extension of the Walker Lane Belt of western Nevada overlying thin-bedded sandstone, siltstone, and limestone. Rocks of Precambrian, Permian, Cretaceous, Miocene, Pliocene, and A unit of detrital material called the fanglomerate of Osborne Wash, Quaternary age have been identified in the Vidal-Parker region. All overlies with sharp unconformity the highly disturbed older Tertiary the pre-Tertiary rocks have undergone varying degrees of metamor- volcanic and sedimentary rocks. On the basis of dates on intercalated phism. Although some rocks in the Riverside Mountains are probably lavas, this unit ranges in age from about 13 to 5 m.y. Precambrian, some evidence suggests that most of the rocks previous­ The Bouse Formation, a late Miocene and Pliocene estuarine deposit, ly mapped in the Vidal-Parker region as Precambrian may be Paleozoic