Climatic changes recorded during the Jenkyns Event (Early Jurassic) in the lacustrine sediments of the Sichuan Basin (China)

The Toarcian lacustrine deposits of the Sichuan Basin (China) are represented mainly by silty marlstones and bivalve-rich limestones disposed in decametric-scale thickening upwards sequences. Dense accumulations of bivalve shells are related to episodes of mass mortality under oxygen depleted conditions in the bottom waters. The geochemical detrital proxies indicate a climatic turnover during the Toarcian. The lower part of the Toarcian succession is characterized by high values of Zr/Rb and Sr/Cu that point to warm and arid conditions, whereas the upper part is characterized by low values of Zr/Rb and Sr/Cu and enhanced C-value related to relatively more humid conditions.