DOCSLIB.ORG

Geology of the Northeast Margin of the Salton Trough, Salton Sea, California

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Geology of the Northeast Margin of the Salton Trough, Salton Sea, California ELKANAH A. BABCOCK Department of Geology, University of Alberta, Edmonton 7, Alberta, Canada Geology of the Northeast Margin of the Salton Trough, Salton Sea, California ABSTRACT mately 6,100 m, about 35 km east-southeast of the Salton Sea. Sharp (1967) documented of Mexicali, Baja California (Biehler, 1964; about 24-km right-lateral separation on this The San Andreas fault zone, in the Biehler and others, 1964, p. 132). From the fault. Other important faults of the San Durmid area northeast of the Salton Sea, deepest part of the trough, the irregular Andreas system in the Salton trough are forms the northeast boundary of the Salton basement surface rises to crop out at San the Imperial, Cucapa, Superstition Moun- trough (the landward continuation of the Gorgonio Pass (Fig. 1; Biehler and others, tain, Superstition Hills, and Elsinore faults Gulf of California rift). The zone is 1964, Fig. 6). Recent work suggests that the (Fig- 1). characterized by subparallel faults having Gulf of California and the San Andreas fault The Mecca Hills lie immediately north of both right-lateral and vertical separations. are the result of sea-floor spreading and the Durmid area. Within the Mecca Hills, Stratigraphic offsets indicate at least 1,100 associated transform faulting (Menard, Cenozoic clastic rocks, tightly folded and m of vertical separation on the San Andreas 1960; Hamilton, 1961; Harrison and cut by numerous closely spaced faults of the fault, southwest side downthrown, and Mathur, 1964; Rusnak and Fisher, 1964; San Andreas system, form an anticlinorium. 850-m right-lateral strike-slip separation is Wilson, 1965; Larson and others, 1968). Crystalline basement rocks are exposed in indicated by offset drainage. The eastern margin of the Salton trough is Painted Canyon at the core of the An anticlinal structure southwest of the characterized by a complex of subparallel anticlinorium (Hays, 1957, PI. 2). This study San Andreas fault is probably caused by branches of the San Andreas fault. The zone indicates that the style of deformation in the drape folding over an upfaulted basement of faulting is about 8 to 16 km wide and Mecca Hills continues with little change block or a recently intruded pluton. Small extends from the north end of the Coachella southward into the Durmid area. folds on the southwest flank of the anticline Valley to the Durmid area northeast of the are caused by drag along the San Andreas Salton Sea (Fig. 1). Its trace southeast of the Previous Work fault and gravity sliding. An angular Durmid area is commonly hidden by Little has been published about the discordance of 18° between the Shavers Well Pleistocene lake silts and dune sand. geology of the Durmid area. Dibblee (1954) and Borrego Formations indicates that Evidence of active faulting can be seen, briefly described the sedimentary rocks and tilting adjacent to the San Andreas fault however, southeast of Niland, as offset structure. He assigned the older coarse began prior to Borrego deposition in cultural features and as lineaments on clastic rocks to the Palm Spring Formation Pleistocene time. Folding followed deposi- oblique infrared aerial photographs (Bab- and the younger lacustrine clay and silt to tion of the lacustrine Borrego Formation. cock, 1971). the Borrego lacustrine facies of the Palm Uplift halted, and the area was planed off by The two major faults lying along the Spring Formation and the unconformably erosion. Renewed uplift followed, probably northeast border of the Coachella Valley are overlying Brawley Formation. Dibblee's within the last few thousand years. Key the Banning and Mission Creek faults. data for the Durmid area are summarized on words: structural geology, stratigraphy, San Southward in the Indio Hills, they join to the Salton Sea sheet (see Rogers, 1967). Andreas fault, folds. become the principal fault of the San Andreas fault zone, which is parallel to the STRATIGRAPHY INTRODUCTION AND eastern shore of the Salton Sea (Fig. 1). Sedimentary rocks within the Salton GEOLOGIC Right-lateral displacements have been trough range in age from probable late SETTING measured on faults of the San Andreas zone Pliocene to Holocene. The sediments near The Durmid area (Fig. 1) is an excellent in the Indio Hills (Stotts, 1965) and Mecca the axis of the trough are deltaic sand, silt, location to study structural relations along Hills (Hays, 1957). The total right-lateral and clay deposited by the Colorado River the eastern margin of the Salton trough, a separation on the San Andreas fault in this (Merriam and Bandy, 1965; Muffler and landward continuation of the Gulf of area may be as much as 257 km (Crowell, Doe, 1968). At the margins of the trough California rift. The Salton trough (Fig. 1), an 1962). these fine-grained sediments interfinger with isostatically compensated depression caused Relatively high seismicity characterizes locally derived coarse-grained detritus. by thinning of the crust, contains a the San Jacinto fault zone which enters the Formations recognized within the Dur- maximum sediment thickness of approxi- Salton trough through Borrego Valley west mid area by the author include the lacustrine Geological Society of America Bulletin, v. 85, p. 321—332, 9 figs., March 1974 321 Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/3/321/3432965/i0016-7606-85-3-321.pdf by guest on 02 October 2021 Figure 1. Index map of the Saltón trough, California Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/3/321/3432965/i0016-7606-85-3-321.pdf by guest on 02 October 2021 SALTON TROUGH, SALTON SEA, CALIFORNIA 323 Fault „»^ Fault located approximately " Fault existance uncertain Approximate axial trace of Durmid Anticline Generalized strike and dip of bedding linilllllll Generalized outline of Durmid Hill Scale in kilometers J 2 3 Figure 2. Sketch map of tectonic elements in the Durmid area. Borrego Formation named by Tarbet and is predominantly coarse-grained arkose and Borrego Formation Holman (1944, p. 1781) and the coarse- arkosic conglomerate, containing cobbles of grained Shavers Well Formation, defined by coarse-grained plutonic rock derived from The Borrego Formation crops out in the Hays (1957). the eastern side of the Chocolate Mountains Durmid area between the San Andreas fault or from ranges east of the Orocopia and the Salton Sea and on the plain Shavers Well Formation Mountains (Fig. 1), where similar rocks are northeast of Durmid Hill (Figs. 2 and 5). exposed today. Coarse-grained sandstone Exposed in the Durmid area is a The Shavers Well Formation, of late with interbeds of pebble conglomerate and 1,475-m-thick section which has been Pliocene or early Pleistocene age, crops out siltstone make up the upper 330 m of the Sea divided into six informal units (Fig. 4). Units northeast of the San Andreas fault at the Bat View Member. 1 and 2, the lowermost, crop out near Salt Caves Buttes (Figs. 2 and 5). The section Finer grained than the Sea View Member, Creek, northeast of the San Andreas fault; exposed at the Bat Caves Buttes is the Skeleton Canyon Member consists of and units 3, 4, 5, and 6 crop out at the south approximately 765 m thick (Fig. 3); but the medium- to coarse-grained sandstone in the end of Durmid Hill (Figs. 2 and 5). The base of the formation is not exposed, and the lower half and mostly fine-grained sand- complete Borrego section is not exposed in upper surface is eroded. On the basis of stone and siltstone in the upper half of the the Durmid area because the contact lithologic similarities, the lower 550 m of the member. Conglomerate beds in the top 15 m between units 2 and 3 is covered. formation was assigned to the Sea View of the Shavers Well Formation contain Based on faunal evidence, the Borrego Member and the upper 215 m was assigned pebbles of Orocopia schist which indicates Formation is a brackish water lacustrine to the Skeleton Canyon Member of Hays uplift of the Orocopia Mountains, and deposit of Pleistocene age (Tarbet and (1957). possibly the Chocolate Mountains, when Holman, 1944, p. 1782). Mineralogical The lower 220 m of the Sea View Member these sediments were being deposited. analyses of samples of the Borrego Forma- Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/85/3/321/3432965/i0016-7606-85-3-321.pdf by guest on 02 October 2021 324 E. A. BABCOCK sand and coarse, bouldery alluvium on the alluvial fans near the mountains. -5 E Description Depositional History unconformify meters- Depositional events in the Durmid area are summa rized below. During late Pliocene or early Pleistocene time, sediments carried Tan, medium-to fine-grained quartz into the area were mostly coarse clastics sandstones, which contain lenses of derived from ranges east of the Chocolate 220+3 granitic conglomerate, interbedded with grey end olive-cobred laminated and Orocopia Mountains, indicating that siltstones. these areas were exposed and shedding coarse detritus at: that time. Near the end of Shavers Well deposition, uplift of :he - -600 Orocopia Mountains is indicated by :he presence of clasts of Orocopia schist in the Shavers Well Formation. Prior to deposition of the Borrego Formation, beds of the LU Shavers Well Formation were tilted and eroded, creating an erosional surface upon Tan, medium-to coarse-grained sandstones. which the Borrego lacustrine sediments were u Granitic pebble conglomerate in lenses. deposited. During deposition of the Borrego OC o Beds '5-25-meters thick. Extensively trough Formation, the Salton trough probably had < I— 330+3 cross bedded. Coarse - grained sandstones a configuration similar to that of today. The oo II® - -400 are arkosic M edium-grained sandstones trough underwent repeated periods of I— are quartzose.
Load more

Recommended publications
  • Investigating Earthquake Hazards in the Northern Salton Trough, Southern California, Using Data from the Salton Seismic Imaging Project (SSIP)
    Investigating Earthquake Hazards in the Northern Salton Trough, Southern California, Using Data from the Salton Seismic Imaging Project (SSIP) G. S. Fuis1, J. A. Hole2, J. M. Stock3, N. W. Driscoll4, G. M. Kent5, A. J. Harding4, A. Kell5, M. R. Goldman1, E. J. Rose1, R. D. Catchings1, M. J. Rymer1, V. E. Langenheim1, D. S. Scheirer1, N. D. Athens1, J. M. Tarnowski6 Refraction Models Line 6 Line 7 Abstract 1 U.S. Geological Survey (USGS), Earthquake Science Center (ESC), Menlo Park, CA. The southernmost San Andreas fault (SAF) system, in the northern Salton Trough (Salton Sea and Coachella Valley), is considered likely to produce a large-magnitude, damaging earthquake in the 2 Virginia Polytechnic Institute and State University, near future. The geometry of the SAF and the velocity and geometry of adjacent sedimentary Dept. Geosciences, Blacksburg, VA basins will strongly influence energy radiation and strong ground shaking during a future rupture. The Salton Seismic Imaging Project (SSIP) was undertaken, in part, to provide more accurate infor- 3 California Institute of Technology, Seismological mation on the SAF and basins in this region. Laboratory 252-21, Pasadena, CA. We report preliminary results from modeling four seismic profiles (Lines 4-7) that cross the Salton 4 Scripps Institution of Oceanography, La Jolla, CA. Trough in this region. Lines 4 to 6 terminate on the SW in the Peninsular Ranges, underlain by Meso- From high-res zoic batholithic rocks, and terminate on the NE in or near the Little San Bernardino or Orocopia active-source seismic - 5 Nevada Seismological Laboratory, University of From 1986 North Palm ? modeling 8 km SE PC and Mz igneous Mountains, underlain by Precambrian and Mesozoic igneous and metamorphic rocks.
    [Show full text]
  • GEOPHYSICAL STUDY of the SALTON TROUGH of Soutllern CALIFORNIA
    GEOPHYSICAL STUDY OF THE SALTON TROUGH OF SOUTllERN CALIFORNIA Thesis by Shawn Biehler In Partial Fulfillment of the Requirements For the Degree of Doctor of Philosophy California Institute of Technology Pasadena. California 1964 (Su bm i t t ed Ma Y 7, l 964) PLEASE NOTE: Figures are not original copy. 11 These pages tend to "curl • Very small print on several. Filmed in the best possible way. UNIVERSITY MICROFILMS, INC. i i ACKNOWLEDGMENTS The author gratefully acknowledges Frank Press and Clarence R. Allen for their advice and suggestions through­ out this entire study. Robert L. Kovach kindly made avail­ able all of this Qravity and seismic data in the Colorado Delta region. G. P. Woo11ard supplied regional gravity maps of southern California and Arizona. Martin F. Kane made available his terrain correction program. c. w. Jenn­ ings released prel imlnary field maps of the San Bernardino ct11u Ni::eule::> quad1-angles. c. E. Co1-bato supplied information on the gravimeter calibration loop. The oil companies of California supplied helpful infor­ mation on thelr wells and released somA QAnphysical data. The Standard Oil Company of California supplied a grant-In- a l d for the s e i sm i c f i e l d work • I am i ndebt e d to Drs Luc i en La Coste of La Coste and Romberg for supplying the underwater gravimeter, and to Aerial Control, Inc. and Paclf ic Air Industries for the use of their Tellurometers. A.Ibrahim and L. Teng assisted with the seismic field program. am especially indebted to Elaine E.
    [Show full text]
  • 2008 Trough to Trough
    Trough to trough The Colorado River and the Salton Sea Robert E. Reynolds, editor The Salton Sea, 1906 Trough to trough—the field trip guide Robert E. Reynolds, George T. Jefferson, and David K. Lynch Proceedings of the 2008 Desert Symposium Robert E. Reynolds, compiler California State University, Desert Studies Consortium and LSA Associates, Inc. April 2008 Front cover: Cibola Wash. R.E. Reynolds photograph. Back cover: the Bouse Guys on the hunt for ancient lakes. From left: Keith Howard, USGS emeritus; Robert Reynolds, LSA Associates; Phil Pearthree, Arizona Geological Survey; and Daniel Malmon, USGS. Photo courtesy Keith Howard. 2 2008 Desert Symposium Table of Contents Trough to trough: the 2009 Desert Symposium Field Trip ....................................................................................5 Robert E. Reynolds The vegetation of the Mojave and Colorado deserts .....................................................................................................................31 Leah Gardner Southern California vanadate occurrences and vanadium minerals .....................................................................................39 Paul M. Adams The Iron Hat (Ironclad) ore deposits, Marble Mountains, San Bernardino County, California ..................................44 Bruce W. Bridenbecker Possible Bouse Formation in the Bristol Lake basin, California ................................................................................................48 Robert E. Reynolds, David M. Miller, and Jordon Bright Review
    [Show full text]
  • Southern Exposures
    Searching for the Pliocene: Southern Exposures Robert E. Reynolds, editor California State University Desert Studies Center The 2012 Desert Research Symposium April 2012 Table of contents Searching for the Pliocene: Field trip guide to the southern exposures Field trip day 1 ���������������������������������������������������������������������������������������������������������������������������������������������� 5 Robert E. Reynolds, editor Field trip day 2 �������������������������������������������������������������������������������������������������������������������������������������������� 19 George T. Jefferson, David Lynch, L. K. Murray, and R. E. Reynolds Basin thickness variations at the junction of the Eastern California Shear Zone and the San Bernardino Mountains, California: how thick could the Pliocene section be? ��������������������������������������������������������������� 31 Victoria Langenheim, Tammy L. Surko, Phillip A. Armstrong, Jonathan C. Matti The morphology and anatomy of a Miocene long-runout landslide, Old Dad Mountain, California: implications for rock avalanche mechanics �������������������������������������������������������������������������������������������������� 38 Kim M. Bishop The discovery of the California Blue Mine ��������������������������������������������������������������������������������������������������� 44 Rick Kennedy Geomorphic evolution of the Morongo Valley, California ���������������������������������������������������������������������������� 45 Frank Jordan, Jr. New records
    [Show full text]
  • The Salton Sea Scientific Drilling Project, California, U
    THE SALTON SEA SCIENTIFIC DRILLING PROJECT, CALIFORNIA, U. S. A.: AN INVESTIGATION OF ,A HIGH-TEMPERATURE GEOTHERMAL SYSTEM IN SEDIMENTARY ROCKS ELDERS, W. A., Institute of Geophysics and Planetary Physics, University of California, Riverside, CA 92521 U. S. A. SASS, J. H., U. S. Geological Survey, Office of Earthquakes, Volcanoes & Engineering, Tectonophysics Branch, 2255 N. Gemini Drive, Flagstaff, AZ 86001 INTRODUCTION In March 1986, a research borehole, called the "State 2-14", reached a depth of 3.22 km in the Salton Sea Geothermal System (SSGS), on the delta of the Colorado River, in Southern California (Figure 1). This was part of the Salton Sea Scientific Drilling Project (SSSDP), the first major (Le., multi-million U. S. dollar) research drilling project in the Continental Scientific Drilling Program of tne U. S. A. The principal goals of the SSSDP were to investi­ gate the physical and chemical processes going on in a high-temperature, high-salinity, hydrothermal system. The borehole encountered temperatures of up to 355°C and p'roduced metal­ rich, alkali chloride brines containing 25 weight per cent of total dissolved solids. The rocks penetrated exhibit a progressive transition from unconsolidated lacustrine and deltaic sediments to hornfelses, with lower amphibolite facies mineralogy, accompanied by pervasive copper, lead, &inc, and iron ore mineral. The SSSDP included an intensive program of rock and fluid sampling, flow testing, and downhole logging and scientific measurement (Elders and Sass, 1988). The pur­ pose of this paper is to -describe briefly the background of the project and the drilling and testing of the borehole, and to summari&e some of the important scientific results.
    [Show full text]
  • Geological Society of America Bulletin
    Downloaded from gsabulletin.gsapubs.org on January 15, 2014 Geological Society of America Bulletin Oceanic magmatism in sedimentary basins of the northern Gulf of California rift Axel K. Schmitt, Arturo Martín, Bodo Weber, Daniel F. Stockli, Haibo Zou and Chuan-Chou Shen Geological Society of America Bulletin 2013;125, no. 11-12;1833-1850 doi: 10.1130/B30787.1 Email alerting services click www.gsapubs.org/cgi/alerts to receive free e-mail alerts when new articles cite this article Subscribe click www.gsapubs.org/subscriptions/ to subscribe to Geological Society of America Bulletin Permission request click http://www.geosociety.org/pubs/copyrt.htm#gsa to contact GSA Copyright not claimed on content prepared wholly by U.S. government employees within scope of their employment. Individual scientists are hereby granted permission, without fees or further requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in subsequent works and to make unlimited copies of items in GSA's journals for noncommercial use in classrooms to further education and science. This file may not be posted to any Web site, but authors may post the abstracts only of their articles on their own or their organization's Web site providing the posting includes a reference to the article's full citation. GSA provides this and other forums for the presentation of diverse opinions and positions by scientists worldwide, regardless of their race, citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflect official positions of the Society. Notes © 2013 Geological Society of America Downloaded from gsabulletin.gsapubs.org on January 15, 2014 Oceanic magmatism in sedimentary basins of the northern Gulf of California rift Axel K.
    [Show full text]
  • Imperial Irrigation District Final EIS/EIR
    Final Environmental Impact Report/ Environmental Impact Statement Imperial Irrigation District Water Conservation and Transfer Project VOLUME 2 of 6 (Section 3.3—Section 9.23) See Volume 1 for Table of Contents Prepared for Bureau of Reclamation Imperial Irrigation District October 2002 155 Grand Avenue Suite 1000 Oakland, CA 94612 SECTION 3.3 Geology and Soils 3.3 GEOLOGY AND SOILS 3.3 Geology and Soils 3.3.1 Introduction and Summary Table 3.3-1 summarizes the geology and soils impacts for the Proposed Project and Alternatives. TABLE 3.3-1 Summary of Geology and Soils Impacts1 Alternative 2: 130 KAFY Proposed Project: On-farm Irrigation Alternative 3: 300 KAFY System 230 KAFY Alternative 4: All Conservation Alternative 1: Improvements All Conservation 300 KAFY Measures No Project Only Measures Fallowing Only LOWER COLORADO RIVER No impacts. Continuation of No impacts. No impacts. No impacts. existing conditions. IID WATER SERVICE AREA AND AAC GS-1: Soil erosion Continuation of A2-GS-1: Soil A3-GS-1: Soil A4-GS-1: Soil from construction existing conditions. erosion from erosion from erosion from of conservation construction of construction of fallowing: Less measures: Less conservation conservation than significant than significant measures: Less measures: Less impact with impact. than significant than significant mitigation. impact. impact. GS-2: Soil erosion Continuation of No impact. A3-GS-2: Soil No impact. from operation of existing conditions. erosion from conservation operation of measures: Less conservation than significant measures: Less impact. than significant impact. GS-3: Reduction Continuation of A2-GS-2: A3-GS-3: No impact. of soil erosion existing conditions.
    [Show full text]
  • Bombay Beach Swarm Triggering Probabilities for Larger Earthquakes (On the San Andreas and Elsewhere)
    The 2016 Bombay Beach Swarm Triggering Probabilities for Larger Earthquakes (on the San Andreas and Elsewhere) Morgan Page USGS Pasadena The Basics of Earthquake Forecasting The Statistical Seismologist’s Approach M 104 ≥ Gutenberg-Richter Magnitude Scaling 102 Earthquakes in California, 1984-2011 b=1 100 -2 Number of earthquakes per year 10 345678 Magnitude (M) The Basics of Earthquake Forecasting The Statistical Seismologist’s Approach M 104 ≥ Gutenberg-Richter Magnitude Scaling 102 Earthquakes in California, 1984-2011 b=1 103 100 Omori Decay of 102 -2 Number of earthquakes per year 10 345678 Aftershock 101 Magnitude (M) Rate aftershock rate Daily 100 10-1 10-2 10-1 100 101 Time since Mainshock (days) The Basics of Earthquake Forecasting The Statistical Seismologist’s Approach M 104 ≥ Gutenberg-Richter Magnitude Scaling 102 Earthquakes in California, 1984-2011 b=1 103 100 Omori Decay of 102 -2 Number of earthquakes per year 10 345678 Aftershock 101 Magnitude (M) Rate aftershock rate Daily 100 10-1 10-2 10-1 100 101 Big earthquakes trigger more aftershocks Time since Mainshock (days) The Basics of Earthquake Forecasting The Statistical Seismologist’s Approach M 104 ≥ Gutenberg-Richter Magnitude Scaling 102 Earthquakes in California, 1984-2011 b=1 103 100 Omori Decay of 102 -2 Number of earthquakes per year 10 345678 Aftershock 101 Magnitude (M) Rate aftershock rate Daily 100 10-1 10-2 10-1 100 101 Big earthquakes trigger more aftershocks Time since Mainshock (days) Aftershock rates decay with distance from the mainshock The Basics of
    [Show full text]
  • Earthquake of the Week -‐ Spring 2016 Suggested Reading List (B
    Earthquake of the Week - Spring 2016 Suggested Reading list (B. Romanowicz) Chaves and Schwartz (2016) Monitoring transient changes within overpressured regions of subduction zones using ambient seismic noise, Science Advances, 8 Jan 2016 Hardebeck, J. (2015) Stress orientations in subduction zones and the strength of subduction megathrust faults, Science,349, 11 sept 2015 Galetzka et al. (2015) Slip pulse and resonance of the Kathmandu basin during the 2015 Gorkha earthquake, Nepal, Science, 349, 1091-1095, 4 sept issue. Gerya et al. (2015) Plate tectonics on the Earth triggered by plume-induced subduction initiation, Nature, 527, 22-225. Hicks and Rietbock (2015) Seismic slip on an upper-plate normal fault during a large subduction megathrust rupture Natgeo, 8, - pp955 - 960 Shillington et al. (2015) Link between plate fabric, hydration and subduction zone seismicity in Alaska -Natgeo, 8, pp961 - 964 Ikari et al. (2015) Spectrum of slip behaviour in Tohoku fault zone samples at plate tectonic slip rates -Natgeo, 8, pp870 - 874 Viesca and Garagash (2015) Ubiquitous weakening of faults due to thermal pressurization - Natgeo 8, pp875 - 879 Avouac et al. (2015) Lower edge of locked Main Himalayan Thrust unzipped by the 2015 Gorkha earthquake -Natgeo 8, pp708 - 711 together with: Bilham (2015) Seismology: Raising Kathmandu - Natgeo 8, pp582 - 584 Arculus et al. (2015) A record of spontaneous subduction initiation in the Izu–Bonin– Mariana arc - Natgeo 8, pp728 - 733 Herrendorfer et al. (2015) arthquake supercycle in subduction zones controlled by the width of the seismogenic zone - Natgeo 8, pp471 - 474 Martinez-Garzon et al. (2015) Scaling of maximum observed magnitudes with geometrical and stress properties of strike-slip faults, GRL, 42,10,230–10,238 Sandanbata et al.
    [Show full text]
  • The Salton Trough Rift MICHAEL A
    I Par 76 SUCMA Spec . Pug . 95-1 The Salton Trough Rift MICHAEL A . McKIBBEN Department of Earth Sciences, University of Callfomw, Riverside CA 92521 ABSTRACT The Salton Trough rift is manifested geomorphically as the Imperial Valley in southern California and the Mexicali Valley in northern Baja California. These valleys are major areas for agriculture, game fish, and waterfowl migration and management . Major nonrenewable resources include metallic minerals (primarily gold) and industrial minerals (primarily gypsum and aggregate) . Two of the world's largest liquid-dominated geothermal energy fields are located in the rifts the Salton Sea field in California and the Cerro Prieto field in Mexico. The Salton Trough is an active continental rift, underlain by a fragmented oceanic ridge spreading system into which has been deposited the delta of the Colorado River . Deposition of the delta has significantly influenced the character of mineralization in the rift. The combination of magmatic heat sources, thick porous sediments, tectonic activity, and saline lakes has provided a unique environment for the accumulation and movement of metalliferous hydrothermal brines. TECTONIC EVOLUTION OF THE GULF OF CALIFORNIA AND SALTON TROUGH SSGF S,ilicn Sea Geothermal =lad The Salton Trough (Fig. 1) is located within a unique tectonic CPGF Cerro Prieto Gealhermaa Field I transition zone between the divergent tectonics of the East Pacific SAF Son Andreas Froult `y s SJF Son :ocrnto FJUIf Rise (which dominate the Gulf of California) and the strike-slip a CPF Cerro zrieto '7ult tectonics of the San Andreas fault system (which dominate tE :r,co EF Elsinore Four. California) (Fig.
    [Show full text]
  • Geology of the Salton Trough
    Geology of the Salton Trough edited by David L. Alles Western Washington University e-mail: [email protected] Last Updated 2011-10-28 Note: In PDF format most of the images in this web paper can be enlarged for greater detail. 1 Introduction Geologists call the area that roughly includes the Coachella and Imperial Valleys of southern California, and the western half of the Mexicali Valley and the Colorado River delta in Mexico, the Salton Trough. This region of southern California and northwestern Mexico is an area of intense geological activity. The Salton Trough is a complex transition zone between the right-lateral motion of the San Andreas transform fault system, and the northwestward progressing spreading ridge complex of the Gulf of California segment of the Eastern Pacific Rise. The East Pacific Rise is a tectonic spreading center between the Pacific and North American plates that has jumped inland from the Pacific coast and captured a portion of the North American plate. This captured sliver of land includes all of central and southern California west of the San Andreas fault, and all of the Baja Peninsula including the northern portion of Baja California east to the delta of the Colorado River. As the East Pacific Rise separated this land mass from the North American plate it formed the Gulf of California. Spreading faster at its southern end, it has formed a long narrow wedge between the mainland of Mexico and the Baja Peninsula. The northern tip of this tectonic wedge ends on dry land at San Gorgonio Pass near Palm Springs, California.
    [Show full text]
  • SALTON TROUGH PROVINCE (016) by Charles E
    SALTON TROUGH PROVINCE (016) By Charles E. Barker INTRODUCTION The Salton Trough Province is defined as the Neogene basin existing east of the igneous-metamorphic complex that forms the Peninsular Ranges of Southern California and west of the San Andreas Fault in the vicinity of the Salton Sea. The north and northwest terminus of the trough is formed by the igneous and metamorphic rocks of the Transverse Range at San Gorgonio Pass. The trough widens from its northern terminus to a maximum of 46 mi at its southern end in the Gulf of California, some 115 mi away. The trough reaches a maximum depth of 21,000 ft near the Mexican border. Province 16 has a roughly triangular shape some 100 mi long and about 60 mi wide at the Mexico border, an area of about 4500 sq mi. The Salton Trough extends into Mexico and the Gulf of California, but this portion of the tough is not assessed. The Salton Trough is considered a landward extension of the Gulf of California tectonic zone and is the result of active rifting of the continental crust (Elders and others, 1972). The portion of this rift valley in the United States has been filled by predominantly continental sediments derived from the Colorado River delta from the north and by detritus from the adjacent Peninsular and Transverse Ranges from the west and northwest. The oldest potential source rock in the Salton Trough is the upper Miocene to Pliocene Imperial Formation, which is composed of marine sediments deposited in shallow water resulting from a transgression of the Gulf of California.
    [Show full text]