172 / 2025-04-13 19:23:59

Response of Shallow-Marine Biota in Southern Tibet to the End-Triassic Mass Extinction

Bivalve,end-Triassic mass extinction,paleoecology

Theme 3: Earth-Life Co-evolution Through Time > Session 3e: Mass extinctions and lesser calamities in the marine realm

The Late Triassic mass extinction event is widely considered to be closely associated with the formation of the Central Atlantic Magmatic Province (CAMP), which triggered a global marine biotic crisis. Previous studies have predominantly focused on the western margin of the Tethys Ocean. The southern Tibet region, situated along the southeastern margin of the Tethyan realm during this period, preserves continuous Triassic-Jurassic shallow marine deposits containing abundant fossils, including bivalves, cephalopods, gastropods, brachiopods, echinoderms, and ichnofossils. This study focuses on shallow marine fossils collected from the Middle-Upper Triassic Langnong, Tulong, and Nianduo sections, as well as the Upper Triassic/Lower Jurassic Germig section in southern Tibet, aiming to analyze the response patterns and extinction extent of shallow marine communities to the end-Triassic extinction. Through comprehensive studies of bivalves, ammonites, and palynomorphs, we have precisely delineated the Lower Jurassic strata in the Gemig-A section. Comparative analysis of ecological communities has revealed stratigraphic correlations among the Langnong, Tulong, and Nianduo sections, while documenting evolutionary succession patterns of dominant bivalve taxa. These findings were subsequently compared with Early Jurassic bivalve assemblages from the Gemig section. Comparative analysis reveals distinct ecological transition: Middle-Late Triassic bivalve communities were dominated by epifaunal, slow-moving suspension feeders, whereas Early Jurassic assemblages shifted to cementing filter-feeding taxa following a brief extinction interval. The fossil records of bivalves, ammonites and palynomorphs in southern Tibet confirm that the end-Triassic extinction exerted rapid and significant impacts on shallow marine ecosystems in the southeastern Tethys, with transient extinction pulses followed by rapid recovery and ecological restructuring.