<p>The end-Triassic mass extinction has long been linked to the emplacement of the Central Atlantic Magmatic Province (CAMP). However, the environmental perturbations, ecological shifts, and climatic instabilities that triggered the extinction event, particularly in the eastern Tethys, remain poorly understood. In this study, organic geochemical data and biomarker evidence of methanogenic archaea, along with morphological evidence of methane release from the Suobucha Formation in the Wenquan section of the Qiangtang Basin, are provided. Paleontological observations indicate the extinction of four endemic brachiopod species, attributed to the end-Triassic extinction event. Geochemical proxies, such as the pristane to phytane ratio and redox-sensitive elements, such as Mo, Ni, and Cr, suggest that the depositional environment of Suobucha Formation became increasingly anoxic at Triassic-Jurassic boundary (TJB). These findings align with similar widespread anoxic to euxinic conditions observed in the western Tethys and Panthalassa, linked to the intense volcanism of the CAMP. Increased iron (Fe) content in putative fossil archaea suggests that the archaea may have participated in a denitrification process and a reduction of Fe(III) during the end-Triassic. This indicates that methane release by methanogenic archaea, occurring under low sulfate concentrations, contributed to a global increase in benthic methane flux. Aerobic oxidation of methane possibly exacerbated oxygen depletion, which further intensified bottom-water hypoxia, and methane released to the atmosphere contributes to the Late Triassic greenhouse. These results suggest that the methane release played a crucial role in driving environmental instabilities and ocean anoxia leading up to a big influence on the end-Triassic extinction event. </p>