TETHYAN OCEANIC CURRENTS AND CLIMATE GRADIENTS 300 M.Y. AGO

Abstract

We reconstruct the oceanic circulation pattern of the Tethys Ocean 300 m.y. ago by placing Late Carboniferous-Early Permian climate-sensitive biotic associations from Gondwana and Laurasia on a Pangea paleogeography constrained by selected paleomagnetic data. Warm-climate fossils and facies from Iran, located at that time along the Gondwanan margin of Arabia, are compatible with the existence in the Tethys Ocean of a warm subtropical surface current gyre, whereas cold surface currents swept the glaciated Gondwanan margin at higher southern latitudes, redistributing cold biota toward the tropics. This Tethyan surface current system and the associated narrow zonal barrier show similarities to recent glacial climate patterns. When placed on a large-scale paleogeographic reconstruction of Pangea of the B type, it neatly explains the otherwise problematic observation that the Carboniferous-Permian biota of Iran and northern Arabia is dominated by warm Euramerican and/or Russian taxa that are strikingly different from typical cold Gondwanan associations.