The Toarcian extinction event, also called the Pliensbachian-Toarcian extinction event,[1][2] the Early Toarcian mass extinction,[3] the Early Toarcian palaeoenvironmental crisis,[4] or the Jenkyns Event,[5][6][7] was an extinction event that occurred during the early part of the Toarcian age, approximately 183 million years ago, during the Early Jurassic. The extinction event had two main pulses,[4] the first being the Pliensbachian-Toarcian boundary event (PTo-E).[8] The second, larger pulse, the Toarcian Oceanic Anoxic Event (TOAE), was a global oceanic anoxic event,[9] representing possibly the most extreme case of widespread ocean deoxygenation in the entire Phanerozoic eon.[10] In addition to the PTo-E and TOAE, there were multiple other, smaller extinction pulses within this span of time.[8]
Occurring during the supergreenhouse climate of the Early Toarcian Thermal Maximum (ETTM),[11] the Early Toarcian extinction was associated with large igneous province volcanism,[12] which elevated global temperatures,[11] acidified the oceans,[13] and prompted the development of anoxia,[14] leading to severe biodiversity loss.[15] The biogeochemical crisis is documented by a high amplitude negative carbon isotope excursions,[16][17] as well as black shale deposition.[18]
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