Late Ordovician environmental changes in Carnic Alps and central Nevada : a comparative study

Abstract

Abstract Correlation of the late Ordovician stratigraphic and faunal successions in the Carnic Alps, which lay in a mid-latitude site at the time, with those in Nevada, which was in the tropics at the time, reveal certain similarities. During much of the late Ordovician glacial interval, deep shelves in both areas were sites of carbonate debris flow accumulations. The debris was derived from inner or shallow shelf environments. Karst topographies developed in inner or shallow shelves in both areas during the later phase of glaciation and sea level drawdown. A quartz sand spread widely at the end of the glacial interval on deep shelf-slope environments in both areas. Perhaps coincidently, shelves in both areas were uplifted and exposed by tectonism after the late Ordovician glacial episode.