--> Abstract: Middle Devonian Submarine Fans in the Eastern Sierra Nevada, California, by C. H. Stevens, T. Pelley, and D. C. Greene; #90958 (1995).

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Abstract: Middle Devonian Submarine Fans in the Eastern Sierra Nevada, California

Calvin H. Stevens, Tina Pelley, David C. Greene

Calcareous sandstones composed of continentally-derived quartz sand interfinger with deep-water, hemipelagic, dark-colored shale and chert in the Mount Morrison, Deadman Pass, Gull Lake, Northern Ritter Range, and Log Cabin Mine pendants in the eastern Sierra Nevada. Stratigraphic and paleontologic studies indicate that these sandstones, which are Middle and Late Devonian in age, probably represent different parts of two superimposed submarine fans. At McGee Mountain, two thick sequences of conglomerate composed of boulders of chert and limestone with a calcareous quartz sandstone matrix are present. These beds mark the position of the major fan channels.

At Tinemaha Reservoir, in the western Inyo Mountains east of the Sierra Nevada, a conglomerate lithologically and temporally identical to those at McGee Mountain is interpreted to be part of the lower channel, offset dextrally by about 65 km. Elsewhere in the Inyo Mountains, submarine channels, that were cut into Early Devonian to early Middle Devonian slope rocks immediately prior to the main development of the submarine fan system in the Sierra Nevada, have been identified. These channels, up to at least 85 m deep, eventually were filled with Late Devonian radiolarian chert. During the Middle Devonian, these slope channels probably acted as conduits for the transport of sand from the shallow shelf in the eastern Inyo Mountains, where shallow-water quartzose sands are present, throug the main channel to the submarine fans in the Sierra Nevada.

Very similar sandstones of about the same age as those described here occur in the Antler allochthon in the Miller Mountain area of western Nevada and in the El Paso Mountains and Knob Valley in southern California. These rocks also may be parts of the same fans that have been offset on major dextral and sinistral faults, respectively.

AAPG Search and Discovery Article #90958©1995 AAPG Pacific Section Meeting, San Francisco, California