Program > By author > Nie Ying

The Early Aptian Oceanic Anoxic Event (OAE 1a, ~120 Ma) represents an episode of severe paleoenvironmental disturbance during the Cretaceous, marked with widespread deposition of organic-rich sediments. The OAE 1a has been extensively studied in the Pacific, Boreal and western and southern Tethyan regions. However, few investigations regarding the OAE 1a have been conducted in the eastern Tethys (especially in southern Tibet). Here, we present high-resolution geochemical and mineralogical data to reconstruct paleoenvironmental conditions of the OAE 1a in the Gucuo area of southern Tibet, eastern Tethys. Oxic-to-suboxic environments occurred prior to and at the base of OAE 1a. A redox shift from oxic to suboxic condition was recorded prior to OAE 1a, while the redox condition was changed from suboxic to oxic at the base of OAE 1a. A warm-humid climate prevailed prior to and at the base of OAE1a. This climate condition was a regional response to global warming during this interval. Freshwater-dominated salinity conditions prior to and at the base of OAE 1a suggested that massive freshwater was injected into the ocean due to a warm-humid climate occurred in this interval. High bioproductivity driven by global warming was responsible for organic matter accumulation in the Gucuo area prior to and at the onset of OAE1a. Massive freshwater injection and enhanced runoff under a warming climate promoted fluvial delivery of nutrients into the ocean, and thus flourished marine bioproductivity. A high surficial bioproductivity would generate massive organic matter, contributing to organic matter enrichment.