A REEF MOUND STRUCTURE FROM THE MIDDLE MEMBER OF THE AUGUSTA MOUNTAIN FORMATION -UPPER TRIASSIC (UPPER CARNIAN), NEW PASS RANGE, CENTRAL NEVADA

Results from a stratigraphic study of the carbonate section within South Canyon, New Pass Range, Nevada reveal a laterally restricted reef structure approximately 10-15 meters in thickness and approximately 40 meters in width. Stratigraphically, this reef structure is within the Middle Member of the Augusta Mountain Formation, approximately 45 meters below the Upper and Middle Member contact. Petrographic analysis using Dunham (1962) and Embry and Klovan (1971) for classification provided the basis for interpretations of depositional environment and biological development of the buildup. The structure is predominantly composed of rudstone indicating an overall shallow marine depositional environment. Calcified sponges, brachiopods, pectinid bivalves, gastropods, foraminifera and algal components comprise this structure. To date, no corals have been found. Based on the presence of rich bioclastic material within a mud matrix and the absence of in-situ frame-builders, we identify this structure as a reef mound