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Research about California, Nevada

Source-linked reports with geographic coverage including California, Nevada.

At least 343 records · Page 19Linked to original sources
USGS1970

Deuterium content of snow cores from Sierra Nevada area

The relative deuterium content was measured on 37 snow cores collected in April 1969 in the Sierra Nevada. The deuterium content varies inversely with altitude of collection (approximately 40 per mil per 1000 meters) but is unrelated to latitude. The altitude relationship is particularly well defined west of the crest of the range but is not well defined east of the crest. However, samples from east of the crest tend to be depleted by about 10 to 15 per mil relative to samples collected at the same elevation west of the crest. We propose that the deuterium content of snow cores, collected so as to include the total winter's precipitation, can be used as a climatic indicator to compare the climate of one winter with that of another.

California, Nevada↗
USGS1968

Cenozoic volcanism and sedimentation, silver peak region, western Nevada and adjacent California

Cenozoic deposits of the Silver Peak region, western Nevada, and adjacent California consist principally of continental sedimentary and pyroclastic rocks of the Esmeralda Formation and lavas and tuffs of the Silver Peak volcanic center. The sedimentary rocks comprise several thick sequences of tuffaceous volcanic sandstone and siltstone and interbedded air-fall tuff. These rocks were deposited in basins that coincide in a general way with the present valleys. Thick wedges of conglomerate and sandstone occur along the basin margins and reflect source areas. Most of the sedimentary rocks were deposited under fluctuating fluviatile and lacustrine conditions, but paludal conditions prevailed locally. Abrupt facies changes and numerous local unconformities indicate that deposition was not uniform within a given basin. The sedimentary rocks range in age from late Miocene to late Pliocene. The oldest reliably dated rocks in the Esmeralda Formation are 13.1 m.y. by K-Ar (Barstovian), and all sedimentary strata are younger than an ash-flow sheet dated at 21.5 m.y. by K-Ar. An air-fall tuff in the upper part of the section has a K-Ar age of 4.3 m.y. Rocks of the Silver Peak volcanic center, 4.8 to 6.1 m.y. by K-Ar, crop out principally in the central part of the Silver Peak Range. Along the margins of the range, they overlie and interfinger with the various sedimentary sequences. The volcanic rocks are mostly rhyolite and trachyandesite tuffs and flows with subordinate basalts and andesites. Basin and Range faulting began in late early to middle Miocene time and has continued intermittently to the present, but present topography was largely established by late Pliocene time.

California, Nevada↗
USGS1968

Summary of regional evidence for right-lateral displacement in the western Great Basin

Right-lateral displacement of 80 to 120 miles across the western Great Basin is indicated by the consistent disruption of sedimentary facies and thickness trends of formations ranging in age from late Precambrian to Mesozoic. Some of this displacement occurs as fault slip and some as a more pervasive large-scale drag (oroflexural bending).

California, Nevada↗
USGS1967

Belt of sigmoidal bending and right-lateral faulting in the western great basin

Betweeen the northwest-trending Sierra Nevada and the north-northeast-trending ranges that characterize most of the Great Basin section of the Basin and Range province is a belt of confused and divergent topographic forms, which is approximately 50 miles wide and 300 miles long. Along the eastern part of this belt is a topographically low lineament called the Walker Lane. A number of the ranges along the belt have an arcuate form which is controlled by the structure of rocks that are mainly of pre-Cretaceous age; locally, in the southern part of the belt, rocks as young as early Miocene show the arcuate form. The strike of tilted beds, fold axes, and in places elongate plutons, parallels the trend of the arcuate ranges, herein called “oroflexes”—defined as mountain ranges with arcuate trends that result from tectonic bending of the crust. The gross structural pattern of pre-middle Miocene rocks along the belt is a series of sigmoidal bends that suggest gigantic dextral drag. The sigmoidal bends define the oroflexes, facies boundaries, and structural trend lines. These features are cut in places by at least three, and probably five, major northwest-trending faults having right-lateral separations of many miles. Along the strike, the two largest faults seem to die out and the movement is believed to be taken up by bending. The indicated total horizontal displacement by bending and faulting along the belt is 80–120 miles, the Great Basin having moved southeastward relative to the Sierra Nevada. This movement is most likely restricted to the crust, which at some depth is thought to have moved freely over deeper material —either a deeper segment of the crust or the mantle. Available evidence permits the interpretation that the deformation began possibly as early as late Early Jurassic and that the same movement pattern has prevailed ever since. The bending and major strike-slip faulting must have been completed by early or middle Miocene time but much of it may have taken place as long ago as the Jurassic. More recent movements have been restricted to faulting.

California, Nevada↗