Biogeochemical evidence for environmental changes from the Uppermost Permian to the Lower Triassic

Abstract

The mass extinction at the end of Permian was the severest crisis in the Earth’s history. Oceanic euxinia and acidification as well as global warming all have been hypothesized as causes for the mass extinction. However, oceanic euxinia occurred much earlier than the mass extinction, and oceanic acidification and global warming postdated. Accordingly, the cause for the end-Permian mass extinction is not fully understood. Organic geochemical studies have been the most extensively performed for the mass extinction event, and revealed important findings such as soil erosion, photic zone euxinia, and proliferation of cyanobacteria for the event. Recovery from the mass extinction was much delayed and took place in the Middle Triassic, after 5 million years from the mass extinction. Subsequently, the Early Triassic period is the transition interval from the mass extinction to the recovery. The environments in the Early Triassic were rather instable, and another mass extinctions and recoveries repeatedly occurred. Organic geochemical studies have suggested photic zone euxinia, stressful environments, and an occurrence of a previously undiscovered type of microbialite during the Early Triassic. In the present paper, I introduce the evidences of environmental and biotic changes through the end-Permian mass extinction to the Early Triassic.