Paleoclimate and Paleoecology of the Selandian-Thanetian Transition Event (Stte) in the Lower Wilcox, Texas Gulf Coast

Abstract

The Selandian-Thanetian Transition Event (STTE) marks a critical interval of global climate and carbon cycle instability during the Paleocene, preceding the more extreme Paleocene-Eocene Thermal Maximum (PETM). Despite increasing recognition of its significance, records of the STTE remain limited, particularly from marginal marine settings. This study presents the first high-resolution record of the STTE from the Texas Gulf Coast, derived from two shallow marine wells (Moczygemba VT #11 and Vogelsang Frieda #1). Using a multi-proxy approach integrating palynology, nannofossil biostratigraphy, organic carbon isotopes, and geochemical weathering indices, we reconstruct paleoenvironmental conditions across this interval. Negative carbon isotope excursions (CIEs) recorded in both cores indicate major carbon cycle perturbations, potentially linked to increased terrestrial organic matter input, methane release, and/or shifts in oceanic productivity. Elevated Chemical Index of Alteration (CIA) and Mean Annual Precipitation (MAP) estimates point to enhanced silicate weathering and hydrological cycling, consistent with transient warming. Palynological evidence reveals significant shifts in vegetation, suggesting ecosystem responses to climatic fluctuations. These findings confirm the STTE as a globally significant event, providing new insights into the mechanisms that preconditioned Earth’s climate system for later hyperthermal events and highlighting the importance of marginal marine records in reconstructing past climate dynamics.

Keywords: Selandian-Thanetian Transition Event (STTE), Paleocene, Paleoclimate, Carbon cycle, Lower Wilcox Group