Late Pennsylvanian and Early Permian Sedimentation in Northeast Nevada

Abstract

The Upper Pennsylvanian and Lower Permian sequence in northeast Nevada is more than 6,000 ft (1,828 m) thick. Facies recognized and linked to depositional environments are (1) fusulinid biomicrite, (2) dasyclad algae--mollusk biomicrite, (3) brachiopod-bryozoan biomicrite, (4) ooid sparite, (5) crinoid-foraminifer biosparite, (6) biolithite, (7) dolomite, (8) conglomerate, (9) bimodal sand, and (10) very fine sand. Carbonate facies were deposited in shallow, warm-water, generally low-energy environments. Shallow depth and long distances from open-marine water resulted in restricted water circulation, which influenced the distribution of facies. Underlying structural control also affected the type and distribution of facies. A Late Pennsylvanian--Wolfcampian episode of upl ft north of an east-west line through the Jasper Tunnel area is indicated by variations in sediment type and thinning of the sequence. This uplift may indicate rejuvenation along the Cortez-Uinta axis, which is an older linear positive element that extends from eastern Utah to central Nevada. A second structural feature that exercised control over sedimentation was a positive element forming a platform near the White Pine-Elko County border. The resulting stratigraphic sequence is thinner over this feature than in surrounding areas and is typified by sediments deposited under very shallow-marine to subaerial conditions.