End-Permian marine ecosystem collapse was a direct consequence of deforestation: Evidence from the Kockatea Shale of the Perth Basin, Western Australia

Abstract

The end-Permian mass extinction event resulted in devastated continental biomes, desolated land, and toxic waters. Anoxia led to widespread extinctions in marine ecosystems, affecting most oceanic clades. In this paper, the palynofacies of the marine Kockatea Shale, Western Australia, was studied in drill cores Hovea-3 and Redback-2, with the aim of linking changes in the marine and continental realms across the Permian–Triassic boundary interval in Australia. We show that the post-extinction ‘Dead Zone’ of the Frazer Beach Member of the Sydney Basin, eastern Australia, whose base is dated to 252.10 ± 0.06 Ma, directly correlates to the lower part of the Kockatea Shale in the Perth Basin, the so-called Inertinitic Interval. We demonstrate that the extinction of Permian Glossopteris forests observed in the Perth Basin had an immediate impact on the marine faunas due to the massive buildup of organic matter, leading to euxinia in the photic zone and ultimately pushing the marine faunas to an ecological extinction. The last lingering occurrence of marine invertebrates of Permian aspect occur in layers that may tentatively mark the Permian–Triassic boundary, positioned just below the appearance of Triassic floras of the Kraeuselisporites saeptatus Zone (equivalent to the Lunatisporites pellucidus Zone). A striking feature at the base of the Early Triassic Sapropelic Interval of the Hovea Member is the sudden and synchronous appearances of anomalously abundant acritarchs and lycophyte spores, alongside the mass occurrence of the bivalve Claraia, allowing correlation with the rise of the eastern Australian post-extinction pioneer floras in the Early Triassic. This demonstrates a significant lag time between the recovery of the terrestrial versus the marine pioneer biota in high-latitude Gondwana, with a significant delay for the faunal recovery.