Chemostratigraphy Across the Triassic–Jurassic Boundary

Abstract

The Triassic‐Jurassic transition (~201.5 Ma) is marked by one of the largest mass extinctions in Earth’s history. This was accompanied by significant perturbations in ocean and atmosphere geochemistry, including the global carbon cycle, as expressed by major fluctuations in carbon isotope ratios. Central Atlantic Magmatic Province (CAMP) volcanism triggered environmental changes and played a key role in this biotic crisis. Biostratigraphic and chronostratigraphic studies link the end‐Triassic mass extinction with the early phases of CAMP volcanism, and notable mercury enrichments in geographically distributed marine and continental strata are shown to be coeval with the onset of the extrusive emplacement of CAMP. Sulfuric acid induced atmospheric aerosol clouds from subaerial CAMP volcanism can explain a brief, relatively cool seawater temperature pulse in the mid‐paleolatitude Pan‐European seaway across the T–J transition. The occurrence of CAMP‐induced carbon degassing may explain the overall long‐term shift toward much warmer conditions. The effect of CAMP volcanism on seawater 87Sr/86Sr values might have been indirect by driving enhanced continental weathering intensity. Changes in ocean‐atmosphere geochemistry and associated (causative) effects on paleoclimatic, paleoenvironmental, and paleoceanographic con­ditions on local, regional, and global scales are however not yet fully constrained.