The Muddy Creek Formation: Depositional environment, provenance, and tectonic significance in the western Lake Mead area, Nevada and Arizona
In the River Mountains, the Muddy Creek Formation is informally divided into four members; the River Mountain conglomerate, the Boulder Basin conglomerate, the lakeshore member, and The Cliffs member; Clasts in the Muddy Creek Formation are composed of andesite, dacite, basalt, rhyolite, quartz monzonite, and granite. Paleocurrent data for the basal River Mountain conglomerate suggest that the transport direction was to the southeast, parallel to the regional strike of high-angle normal faults. The River Mountain conglomerate may have been transported along the axes of basins that were controlled by these faults; The River Mountain conglomerate was probably deposited during a period of active extensional faulting. Block rotation during faulting resulted in the formation of half-graben basins with coarse-grained sediments of the River Mountain conglomerate forming alluvial fans that were constrained to the basin margins. When extension subsided, coarse-grained material prograded into the basin, forming the Boulder Basin conglomerate. (Abstract shortened with permission of author.).
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