Two distinct episodes of marine anoxia during the Permian-Triassic crisis evidenced by uranium isotopes in marine dolostones

Feifei Zhang, Shu‐zhong Shen, Ying Cui, Timothy M. Lenton, Tais W. Dahl, Hua Zhang, Quan-feng Zheng, Wenqian Wang, Karl Krainer, Ariel D. Anbar