oa Insights to the Compound Specific Sulfur Isotope Distribution During the Cretaceous-Paleogene Boundary in the Southern Tethys Upwelling Belt

The Golan ecosystem (southern Tethys) exhibited rapid recovery (<11 kyr) and high productivity following the K-Pg mass extinction, despite persistent anoxia, euxinia, and water column stratification, as indicated by biomarker proxies. The sulfur cycle in the Golan might affect the strong resilience following the mass extinction, as the Golan ecosystem was already adaptive to strong anoxic conditions. Under such conditions, sulfurization of organic molecules preserves sedimentary organic matter during early diagenesis. The sulfurization products, i.e. organosulfur compounds (OSCs), often retain structural similarities to their biological precursors and, together with their d34S values, serve as additional molecular proxies for paleo-environmental conditions. To the best of our knowledge, sulfur isotopes research related to the K-PgB is limited and there is no study to date that has recorded how organic sulfur, and their isotopes responded to the K-Pg mass extinction. Our results reveal various groups of OSCs, including mid-chain i-C20Ts, BTs, DBTs, n-alkylthiolanes, and polycyclic terpenoid sulfides, with most OSCs exhibiting no significant isotopic variation across the K-PgB, although internal d³4S variations reach up to 12‰. Interestingly, polycyclic terpenoid sulfide being an early diagenetic product, exhibit a distinct isotopic response towards the K-PgB and may represent a sensitive proxy for such paleoenvironmental events.