Rapid pyrolysis of paleo-oil pools recorded by fluid inclusions in an Ediacaran carbonate reservoir, southern China: Implications for the end-Guadalupian mass extinction

Abstract Thermogenic greenhouse gas emission associated with large igneous province emplacement has previously been hypothesized as a possible contributor to global warming that triggered mass extinctions in Earth's history, yet this issue remains inadequately understood due to a lack of robust evidence. We present a well-preserved mineralogical, fluid inclusion, and geochemical record indicating a rapid pyrolysis of vast paleo-oil pools in an Ediacaran carbonate reservoir in the central Sichuan Basin (southern China) relating to the eruption of the Emeishan large igneous province that potentially contributed to the end-Guadalupian extinction (ca. 259 Ma). We conclude that the pyrolysis of the paleo-oil pools occurred at ca. 258.4 ± 7.3 Ma associated with the emplacement of the Emeishan large igneous province, causing a rapid increase of temperature and pressure with an estimated transient reservoir pressure of nearly twice that of the lithostatic pressure. A subsequent drop in the formation pressure occurred as the temperature continued to rise, indicating that massive over-pressured methane in the reservoir had been rapidly emitted into the atmosphere along faults or magmatic pipes, ultimately contributing to the end-Guadalupian extinction. Our study highlights the significance of massive emission of thermogenic methane related to large igneous provinces for climate change, carbon cycling, and biological evolution in Earth's history.