The Pershing olistostrome: Evidence for the Triassic shelf-basin transition in the western Great Basin
Frederick R. Heck, 2000. "The Pershing olistostrome: Evidence for the Triassic shelf-basin transition in the western Great Basin", Great Basin and Sierra Nevada, David R. Lageson, Stephen G. Peters, Mary M. Lahren
Download citation file:
The Pershing district of the southern Humboldt Range, northwestern Nevada, contains a large, Upper Triassic submarine olistostrome containing carbonate clasts from pebble size to 700 m in length that are supported mostly my lime-mud matrix. The olistostrome comprises debris flows separated by intervals of hemipelagic sedimentation, turbidity flows, and density modified grain flows. The olistostrome body is triangular-prism shaped with a flat top and keel-like base. It lies in a thick sequence of fine-grained siliciclastic rocks. The lower submarine gravity flows were deposited in a preexisting trough at a lower slope or base-of-slope position. The highest gravity flow filled the trough and spilled over its sides. The source of the olistostrome clasts and matrix was a carbonate platform (Dun Glen Formation) to the northeast that formed on the surface of a preexisting shallow-marine delta. The olistostrome and older shelf-basin transitional rocks of the Humboldt Range indicate the existence of a Middle and Upper Triassic shelf-basin transition with an arcuate trace that is convex to the southwest at the southern Humboldt Range.