Silurian Reef Complex and Associated Facies, Central Nevada

Abstract

The Silurian System of the Great Basin comprises at least three major facies: (1) a dolomite fades, developed in Utah and in eastern and central Nevada (Laketown dolomite and Lone Mountain dolomite), (2) a limestone facies, locally dolomitized, exposed in central Nevada (Roberts Mountains formation), and (3) a chert-shale facies, probably deposited originally in central and western Nevada, but since carried eastward into central Nevada by large-scale thrust faulting. Mapping in the Roberts Mountains region in central Nevada shows that the Lone Mountain dolomite and the Roberts Mountains formation are largely, and perhaps wholly, lateral equivalents. Evidence from textures, structures, and fossils indicates that the Lone Mountain dolomite represents a reef complex, most of whose original features are obliterated by dolomitization, and that the Roberts Mountains formation comprises deeper-water reef-flank, off-reef, and basin deposits. A regional isopach map shows a generally north-trending band through the...