The Mesozoic maximum of 87Sr/86Sr ratio: a critical turning point after the end-Permian mass extinction

• Tao Xie ^[1] ; Qiyue Zhang ^[1] ; Shixue Hu ^[1] ; Changyong Zhou ^[1] ; Jinyuan Huang ^[1] ; Wen Wen ^[1]
  1. [1] Chengdu Center of China Geological Survey
• Localización: Carbonates and Evaporites, ISSN 0891-2556, Vol. 34, Nº. 3, 2019, págs. 1021-1029
• Idioma: inglés
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• Resumen

  • The secular change in 87Sr/86Sr ratio of the Mesozoic recorded the highest value above 0.7083 in Early–Middle Triassic boundary, i.e., the Triassic maximum, suggesting that a major reform in oceanography occurred after the end-Permian mass extinction. We have detected correlative highest 87Sr/86Sr value from the Triassic carbonate, including our data. The stratigraphic horizon of the maximum was constrained to the Olenekian–Anisian boundary (OAB) (247.2 Ma), by conodont. As the oceanic data represent the global average, the present study confirmed the chemostratigraphical utility of the “Triassic maximum” of 87Sr/86Sr ratio in global correlation. After the sharp rise throughout Early Triassic since the end-Permian mass extinction, a remarkable turnover of seawater-87Sr/86Sr values appeared in the OAB. A major global change likely appeared in the OAB to change the Sr-isotope balance in seawater from a continental flux-dominated to a mantle flux-dominated regime. The sharp turning point in 87Sr/86Sr values likely has recorded the timing of the biological influence on the environment.