The geology of the Permian Carbon Ridge Formation, east-central Nevada

Abstract

Wolfcampian carbonate sediments of the Carbon Ridge Formation, near Eureka, Nevada, and unnamed Wolfcampian to late Leonardian carbonate and clastic sediments in the northern Diamond Range were studied. Numerous species of fusulinids of the genera Triticites, Schwagerina, Paraschwagerina, Pseudo schwagerina, Boultonia, and Parafusulina provided stratigraphic control. The lateral and vertical extent of the Carbon Ridge Formation have been revised. Wolfcampian sediments of the Carbon Ridge Formation consist of silty lime mudstones, siltstones, fossiliferous wackestones, and bio- clastic packstones. Deposition of marine sediments on a carbonate ramp of normal marine salinity, generally below wave base, is indicated. To the south, marine deposition was overwhelmed by terrigenous elastics of the Garden Valley Formation during early Leonardian time. In the northern Diamond Range a shoaling upward cycle of carbonate deposition continued into middle Leonardian time. By late Leonardian time carbonate deposition was overwhelmed by sandstones and conglomerates of the Garden Valley Formation.