Guex Jean, Pilet Sebastien, Müntener Othmar, Bartolini Annachiara, Spangenberg Jorge, Schoene Blair, Sell Bryan, Schaltegger Urs
Institute of Earth Sciences, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland.
Muséum National d'Histoire Naturelle, CNRS UMR 7207 Paleobiodiversité et Paléoenvironnements, CP38, 8 rue Buffon, F-75005 Paris, France.
Sci Rep. 2016 Mar 24;6:23168. doi: 10.1038/srep23168.
The temporal coincidence between large igneous provinces (LIPs) and mass extinctions has led many to pose a causal relationship between the two. However, there is still no consensus on a mechanistic model that explains how magmatism leads to the turnover of terrestrial and marine plants, invertebrates and vertebrates. Here we present a synthesis of ammonite biostratigraphy, isotopic data and high precision U-Pb zircon dates from the Triassic-Jurassic (T-J) and Pliensbachian-Toarcian (Pl-To) boundaries demonstrating that these biotic crises are both associated with rapid change from an initial cool period to greenhouse conditions. We explain these transitions as a result of changing gas species emitted during the progressive thermal erosion of cratonic lithosphere by plume activity or internal heating of the lithosphere. Our petrological model for LIP magmatism argues that initial gas emission was dominated by sulfur liberated from sulfide-bearing cratonic lithosphere before CO2 became the dominant gas. This model offers an explanation of why LIPs erupted through oceanic lithosphere are not associated with climatic and biotic crises comparable to LIPs emitted through cratonic lithosphere.
大火成岩省（LIPs）与大规模灭绝事件在时间上的巧合，使得许多人认为二者之间存在因果关系。然而，对于解释岩浆活动如何导致陆地和海洋植物、无脊椎动物及脊椎动物更替的机制模型，目前仍未达成共识。在此，我们综合了来自三叠纪-侏罗纪（T-J）和普连斯巴奇阶-托尔阶（Pl-To）边界的菊石化石生物地层学、同位素数据以及高精度U-Pb锆石年代，表明这些生物危机均与从初始冷期到温室条件的快速转变相关。我们将这些转变解释为地幔柱活动或岩石圈内部加热导致克拉通岩石圈渐进性热侵蚀过程中释放的气体种类变化的结果。我们关于LIP岩浆活动的岩石学模型认为，在二氧化碳成为主要气体之前，初始气体排放主要由含硫克拉通岩石圈释放的硫主导。该模型解释了为何通过大洋岩石圈喷发的LIPs与通过克拉通岩石圈喷发的LIPs所引发的气候和生物危机不同。
