DIVERSITY AND ECOLOGY OF FORAMINIFERA FROM THE GABBS FORMATION (NORIAN–RHAETIAN, NEVADA, USA)

The Norian and Rhaetian stages of the Late Triassic experienced substantial environmental upheavals, biotic turnover, and mass extinction. Microfossils such as foraminifera are widely used in paleontology as geochemical proxies and for paleoenvironmental reconstruction. However, no systematic surveys of foraminiferan diversity or paleoecology has been performed on key Late Triassic sections in the Gabbs Formation, a GSSP ancillary section for the Triassic–Jurassic boundary and the end-Triassic mass extinction. Foraminifera were liberated from the carbonate matrix with buffered acetic acid, and were observed in petrographic thin section. Four benthic foraminiferan taxa were observed, including both epifaunal and infaunal taxa, and all were silicified. Identified genera include: Cornuspira, Frondicularia, cf. Lenticulina, and Marginulina. All four genera have been previously reported from the Norian–Rhaetian, but only Marginulina is known from Panthalassa - the other taxa are primarily from Tethys or Southern Hemisphere (Australia and New Zealand). This is the first systematic examination of foraminifera from the Late Triassic Gabbs Formation, and expands the known geographic ranges of the reported foraminiferan genera.