Causes of the marine productivity and oxygen changes associated with the Permian-Triassic boundary: A reevaluation with ocean general circulation models
Causes of the marine productivity and oxygen changes associated with the Permian-Triassic boundary: A reevaluation with ocean general circulation models
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DOI：
10.1016/j.margeo.2005.02.011
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发表时间：
2005-06
期刊：
影响因子：
2.9
通讯作者：
A. Winguth;E. Maier‐Reimer
中科院分区：
文献类型：
--
作者：
A. Winguth;E. Maier‐Reimer
海洋沉积物中广泛存在的缺氧和缺氧沉积与二叠纪-三叠纪（P-Tr）界线的停滞海洋有关。这一P-Tr边界也与古生代最大的物种大规模灭绝之一有关，标志着向中生代的过渡。在这里，我们回顾最近的三维数值模式研究，调查可能的流通模式在P-Tr边界。此外，我们进行了新的敏感性实验与耦合的海洋-大气模型的中等复杂性，包括海洋化学，研究深海氧气分布的变化与（1）水文循环的显着变化和（2）大量释放的甲烷气体水合物从海洋沉积物。沿南极泛大陆西海岸沿着的强淡水源对海表水体进行的再补给，在热带泛萨海洋东部的中间深度和海底产生了一个显著的局部最低氧气浓度。在大气CO2浓度为工业化前CO2水平18倍的情况下进行的甲烷释放实验模拟了海表温度的大幅上升（约4.5 °C）和强有力的深海环流。与以前的研究得出的结论相反，在P-Tr边界的海洋环流的重新分析有利于在深海的大部分地区的强通风。因此，可能需要海洋碳清单的重大变化和与更强的生物泵相关的海洋生产力的重组，以解释缺氧沉积矿床。
Widespread anoxic and dysoxic deposition in marine sediments has been associated with a stagnant ocean at the Permian–Triassic (P–Tr) boundary. This P–Tr boundary is also associated with one of the largest mass extinctions of species of the Paleozoic, marking the transition to the Mesozoic. Here we review recent three-dimensional numerical model studies that have investigated possible circulation patterns at the P–Tr boundary. In addition, we conduct new sensitivity experiments with a coupled ocean–atmosphere model of intermediate complexity, including marine chemistry, to study changes of the deep-sea oxygen distribution associated with (1) a significant change in the hydrological cycle and (2) a massive release of methane gas hydrates from marine sediments. Freshening of sea surface water masses by a strong freshwater source along the west coast of south polar Pangea produces a significant local minimum in oxygen in the eastern tropical Panthalassa ocean at intermediate depth and at the sea floor. The methane release experiment with an atmospheric CO2concentration of 18 times the preindustrial CO2level simulates a strong increase in sea surface temperature (about 4.5 °C) and a vigorous deep-sea circulation. In contrast to the conclusions drawn from previous studies, this reanalysis of the ocean circulation at the P–Tr boundary favors a strong ventilation in most parts of the deep-sea. Thus, a significant change in the oceanic carbon inventories and a reorganization of the marine productivity associated with a stronger biological pump may be required to explain the anoxic sedimentary deposits.