Development and dismemberment of a Middle Devonian continental-margin submarine fan system in east-central California

摘要

A submarine fan system of Middle Devonian age, developed along the middle Paleozoic continental margin in east-central California, apparently is unique for a Paleozoic fan in the exposure of all elements of the system. The fan itself, the main distributary channel, and the lower interchannel slope are represented in pendants (or sedimentary rock septa) in the eastern Sierra Nevada. To the east, in the Inyo Mountains, a middle slope channel, lower and middle to upper interchannel slopes, two upper slope channels, and the shelf are exposed. The quartz sand and lime mud composing the fan were derived from the east or southeast and transported across the shelf during a lowstand of sea level preceding the great Taghanic overlap. This sediment was then swept into the heads of submarine channels in the western Inyo Mountains prior to being transformed episodically into sediment gravity flows that constructed the fan at the base of the slope. Similar successions of Middle Devonian calcareous sandstone and sandy limestone in extreme west-central Nevada and southeastern California, possibly dispersed parts of the Mount Morrison fan, can be utilized to estimate displacements on several major strike-slip faults in this region characterized by long-term tectonic activity.