Late Cenozoic geology and lacustrine history of Searles Valley, Inyo and San Bernardino Counties, California

Abstract

Cataloging-in-publication data are on file with the Library of Congress (URL http://www.loc.gov/). FRONT COVER False-color satellite image (Landsat Thematic Mapper) of Searles Valley, California. North is at the top. The valley is flanked by the Slate Range on the east and the Argus Range and Spangler Hills on the west. The linear feature trending east-northeast from southwest corner of image is the Garlock Fault. Scale: widest part of valley near middle of Searles Lake is 15 km; vertical dark line north of lake is 1,800-m-long airport runway. Image is a band-ratio composite, in which blue indicates Fe 3+ in the reflecting material, green indicates Fe 2+ , and red reflects clay, CO 3 , and vegetation. Yellow is produced by mixtures of red and green. Searles Lake (left center) is largely magenta and dark blue, colors caused by differing mixtures of Fe 3+-bearing clays and CO 3 (straight lines on the lake surface are roads and evaporating-pond dikes). Alluvial fan surfaces east and north of the lake are mostly green because of the abundance of Fe 2+ in detritus from metamorphic rocks from the Slate Range (note erosional shorelines northeast of lake and curved offshore bars north of lake); fans west and south are also green but have areas of blue (more Fe 3+-bearing volcanic rocks and desert varnish) and red (CO 3-and clay-rich lacustrine sediments). Orange bands on the flanks of the Argus Range and Spangler Hills are caused by the impure CO 3 in massive tufa deposits near the highest lake shoreline (carbonate bedrock in mountain areas in northeast part of image also shows orange hues). Photograph courtesy of Ronald Blom, Jet Propulsion Laboratory,

Ancient vicariance and recent dispersal of springsnails (Hydrobiidae: Pyrgulopsis) in the Death Valley system, California-Nevada

“…Our finding that the single lineage endemic to Owens Valley (A) is not closely related to Amargosa River lineages suggests that the occasional late Quaternary overflow of Lake Panamint (which formed the terminus of the pluvial Owens River drainage) into Death Valley (Smith, 1976) did not result in genetic exchange between Amargosa and Owens River springsnail faunas. Our results indicate that the clade composed of the Owens Valley lineage (A) and a western California species (P. taylori) diverged from an Amargosa River lineage (I) as early as 2.8 Ma (Table 2), which well preceded this brief interval of basin integration.…”

Geologic Map of the Northern Lava Mountains and Summit Range, San Bernardino County, California

“…There are locally white, fine-grained layers that appear to be lacustrine deposits. Smith (2009) from what had previously been mapped as Christmas Canyon Fm. (Smith, 1964).…”

“…The basalt boulder conglomerate has been deformed into a broad east-northeast plunging anticline with gently dipping limbs. The source for the basalt clasts is interpreted to be from basalt lava flows capping the mesas of the Black Hills, southeast of the study area (Smith, 2009;this study). This source interpretation is based on the relatively unique fresh appearance of the basalt clasts, compared to other basalts in the area.…”

“…Christmas Canyon Formation (middle Pleistocene) [Smith 1964; redefined by Smith, 2009; redefined herein] Smith (2009) estimated ages of this formation to be 0.30 to 1.3 Ma.…”

Long Valley Caldera Lake and reincision of Owens River Gorge

“…Because drillhole data (Fournier, 1989) indicate no evidence of unconformity or dessication within (all but the basal 10 m of) the 700-m section of lake sediments, we infer that the caldera lake persisted for about 600,000 years before its demise in MIS 6. Owens Lake and Searles Lake, downstream from Long Valley Lake along the Owens River drainage system, each have extended drillcore records of alternating hydrologically open and closed Pleistocene conditions, but both were shown to have been fresh and intensely overflowing during the interval 170-120 ka (Bradbury, 1997;Smith and others, 1997;Smith, 2009). Regional evidence is thus consistent with inference of overflow at Long Valley in MIS 6.…”