<p>Marine carbon-sulfur cycles experienced long-term frequent perturbations through the Latest Permian to Early Triassic. However, relationships between carbon and sulfur isotopes are still unclear. Here, we report δ<sup>13</sup>C<sub>carb</sub> and δ<sup>34</sup>S<sub>CAS</sub>, and elemental proxies (U<sub>EF</sub>, Mo<sub>EF</sub>, Mn/Th, Cd/Mo and Co × Mn) from the Wuchiapingian to Spathian successions (Zuodeng Section) in the southern Nanpanjiang Basin, South China. Sudden decreases in both U<sub>EF</sub> and Mo<sub>EF</sub> values (from ∼150 to &lt; 10, and ∼60 to &lt; 10, respectively) and a gentle increase in Mn/Th ratios (&lt; 200 to ∼1 000) indicate a locally anoxic seawater condition during the Late Permian and an oxic condition during the Early Triassic. Variations of Cd/Mo, Co × Mn and TOC suggest that the Late Permian anoxic condition was related to locally intensive oceanic circulation (e.g., upwelling) and higher marine productivity, which was probably controlled by a relatively cool climate regime, whereas the Early Triassic climate warming may have resulted in intensive oceanic stratification, suppressed marine productivity, and thus narrowed the spatial distribution of the oxygen minimum zone, leaving the study site apart from anoxic water mass in that time. Both δ<sup>13</sup>C<sub>carb</sub> and δ<sup>34</sup>S<sub>CAS</sub> excursions were coupled during the Griesbachian and Dienerian substages probably due to elevated or suppressed marine productivity and co-burial of organic matter and pyrite driven by climatic variations. Decoupled δ<sup>13</sup>C<sub>carb</sub>-δ<sup>34</sup>S<sub>CAS</sub> excursions occurred during the Late Permian and the Smithian global warming, respectively probably because of elevated bacterial sulfate reduction and pyrite burial rate induced by serious global-oceanic anoxia. This study deciphers that dynamic variations of marine carbon-sulfur cycles may have been controlled by extremely environmental changes through the Late Permian to Early Triassic.</p>

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Dynamic Variations of Carbon-Sulfur Cycles through the Late Permian to Early Triassic

  • Biao Ma,
  • Laishi Zhao,
  • Lei Zhang,
  • Zihu Zhang,
  • Shunling Wu,
  • Zhengyi Lyu,
  • Xiangdong Wang,
  • Chao Li

摘要

Marine carbon-sulfur cycles experienced long-term frequent perturbations through the Latest Permian to Early Triassic. However, relationships between carbon and sulfur isotopes are still unclear. Here, we report δ13Ccarb and δ34SCAS, and elemental proxies (UEF, MoEF, Mn/Th, Cd/Mo and Co × Mn) from the Wuchiapingian to Spathian successions (Zuodeng Section) in the southern Nanpanjiang Basin, South China. Sudden decreases in both UEF and MoEF values (from ∼150 to < 10, and ∼60 to < 10, respectively) and a gentle increase in Mn/Th ratios (< 200 to ∼1 000) indicate a locally anoxic seawater condition during the Late Permian and an oxic condition during the Early Triassic. Variations of Cd/Mo, Co × Mn and TOC suggest that the Late Permian anoxic condition was related to locally intensive oceanic circulation (e.g., upwelling) and higher marine productivity, which was probably controlled by a relatively cool climate regime, whereas the Early Triassic climate warming may have resulted in intensive oceanic stratification, suppressed marine productivity, and thus narrowed the spatial distribution of the oxygen minimum zone, leaving the study site apart from anoxic water mass in that time. Both δ13Ccarb and δ34SCAS excursions were coupled during the Griesbachian and Dienerian substages probably due to elevated or suppressed marine productivity and co-burial of organic matter and pyrite driven by climatic variations. Decoupled δ13Ccarb34SCAS excursions occurred during the Late Permian and the Smithian global warming, respectively probably because of elevated bacterial sulfate reduction and pyrite burial rate induced by serious global-oceanic anoxia. This study deciphers that dynamic variations of marine carbon-sulfur cycles may have been controlled by extremely environmental changes through the Late Permian to Early Triassic.