EARLY EOCENE HYPERTHERMALS IN THE SOUTHEASTERN TETHYS: INSIGHT FROM TRACE ELEMENT GEOCHEMISTRY AND STABLE CARBON AND NITROGEN ISOTOPES

Five rapid global warming events, also known as Early Eocene hyperthermals, occurred between 56 and 53 million years ago (Ma), and are considered as ancient analogues for future climate change. These hyperthermal events are well studied in many deep-sea sites and shallow marine sites in the western Tethys, but the shallow eastern Tethys region remains enigmatic. Here, we report new geochemical data from the Paleogene Qumiba section of the Tingri region in the southern Tibetan Plateau, China. The site was located south of the Yarlung Tsangpo suture in southern Tibet, and represents the youngest marine strata in the eastern Tethys Ocean. In the early Paleogene, southern Tibet was located in the Tethyan Himalaya of the northern Greater Indian continental margin. The studied Qumiba section consists of the Enba Formation characterized by silty marl, marl and lithic sandstone and the Zhaguo Formation dominated by mudstone and a few thin layers of lithic sandstone. Nannofossil assemblages suggest the closure time for the eastern Tethys Ocean is 54.17 to 53.7 Ma. A total of 66 samples were analyzed for major, trace and rare Earth element (REE) to understand the interplay between the initial stage of the India-Asia collision and the early Eocene hyperthermal events. Additionally, stable carbon and nitrogen isotopic data of marine organic matter were collected to study the perturbations of carbon and nitrogen cycle in the shallow southeastern Tethys, a task that has never been done before in this understudied region.