Shifts in magnetic mineral assemblages support ocean deoxygenation before the end-Permian mass extinction

Shifts in magnetic mineral assemblages support ocean deoxygenation before the end-Permian mass extinction

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Abstract Expansion of oceanic anoxia is a prevailing hypothesis for driving the marine end-Permian mass extinction and is mainly based on isotopic geochemical proxies.However, long-term oceanic redox Jackets/Outerwear conditions before the end-Permian mass extinction remain unresolved.Here we report a secular redox trend based on rock magnetic experiments and cerium anomalies through the Changhsingian and across the Permian-Triassic boundary at the Meishan section, China.Magnetic mineral assemblages changed dramatically at ca.252.

8 million years age (Ma), which indicates that oceanic deoxygenation Quickstrikes started about 0.9 million years earlier than the end-Permian mass extinction.The magnetite-dominant post end-Permian mass extinction interval suggests a ferruginous dysoxic conditions with enhanced weathering in the earliest Triassic.Also, a gradual magnetite abundance decrease to pre-extinction levels is observed at ca.251.

5 Ma, coinciding temporally with the waning of Siberian Trap and arc volcanism.All of these observations demonstrate that environmental deterioration began much earlier than the end-Permian mass extinction and finally collapsed in the end-Permian.