Two-pronged kill mechanism at the end-Triassic mass extinction

Abstract

High-resolution biomarker and compound-specific isotope distributions, coupled with the degradation of calcareous fossil remnants reveal that intensive euxinia and decalcification (acidification) driven by Central Atlantic Magmatic Province (CAMP) activity formed a two pronged kill mechanism at the end-Triassic mass extinction. In a newly proposed extinction interval for the basal Blue Lias Formation (Bristol Channel Basin, UK), biomarker distributions reveal an episode of persistent photic zone euxinia (PZE) that extended further upwards into the surface waters. In the same interval shelly taxa almost completely disappear. Beginning in the basal paper shales of the Blue Lias Formation, a Lilliput assemblage consisting of only rare calcitic oysters (Liostrea) and ghost fossils of decalcified aragonitic bivalves are preserved. The stressors of PZE and decalcification parsimoniously explain the extinction event and inform possible combined causes of other biotic crises linked to emplacements of large igneous
provinces, notably the end-Permian mass extinction where PZE occurred on a broad and perhaps global scale.

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