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首页> 外文期刊>Paleoceanography >Nutrients as the dominant control on the spread of anoxia and euxinia across the Cenomanian-Turonian oceanic anoxic event (OAE2): Model-data comparison
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Nutrients as the dominant control on the spread of anoxia and euxinia across the Cenomanian-Turonian oceanic anoxic event (OAE2): Model-data comparison

机译：营养物质是控制整个Cenomanian-Turonian海洋缺氧事件（OAE2）缺氧和游刃有余的主要控制因素：模型数据比较

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The Cenomanian-Turonian oceanic anoxic event (OAE2) is characterized by large perturbations in the oxygen and sulfur cycles of the ocean, potentially resulting from changes in oxygen supply (via oxygen solubility and ocean circulation) and in marine productivity. We assess the relative impact of these mechanisms, comparing model experiments with a new compilation of observations for seafloor dysoxia/anoxia and photic zone euxinia. The model employed is an intermediate-complexity Earth system model which accounts for the main ocean dynamics and biogeochemistry of the Cretaceous climate. The impact of higher temperature and marine productivity is evaluated in the model as a result of higher atmospheric carbon dioxide and oceanic nutrient concentrations. The model shows that temperature is not alone able to reproduce the observed patterns of oceanic redox changes associated with OAE2. Observations are reproduced in the model mainly via enhanced marine productivity due to higher nutrient content (responsible for 85% of the change). Higher phosphate content could have been sustained by increased chemical weathering and phosphorus regeneration from anoxic sediments, which in turn induced an enhanced nitrogen nutrient content of the ocean via nitrogen fixation. The model also shows that the presence of seafloor anoxia, as suggested by black-shale deposition in the proto-North Atlantic Ocean before the event, might be the result of the silled shape and lack of deep-water formation of this basin at the Late Cretaceous. Overall our model-data comparison shows that OAE2 anoxia was quasi-global spreading from 5% of the ocean volume before the event to at least 50% during OAE2.
机译：Cenomanian-Turonian海洋缺氧事件（OAE2）的特征是海洋中氧气和硫循环的扰动很大，可能是由于氧气供应（通过氧气溶解度和海洋环流）和海洋生产力的变化造成的。我们评估了这些机制的相对影响，将模型实验与新的海底dysoxia /缺氧/缺氧症和光化区游丝虫病观察结果进行了比较。使用的模型是中等复杂性地球系统模型，该模型解释了白垩纪气候的主要海洋动力学和生物地球化学。由于较高的大气二氧化碳和海洋营养物浓度，在模型中评估了较高温度和海洋生产力的影响。该模型显示，温度并非唯一能够重现观察到的与OAE2相关的海洋氧化还原变化的模式。由于较高的养分含量（负责变化的85％），主要通过提高海洋生产力来在模型中复制观测值。较高的磷酸盐含量可以通过增加化学风化和缺氧沉积物中的磷再生来维持，这反过来又通过固氮作用导致了海洋中氮素含量的增加。该模型还显示，事件发生前北大西洋原始黑泥页岩的沉积表明存在海底缺氧，这可能是该盆地晚些时候该盆地呈泥状和缺乏深水形成的结果。白垩纪。总体而言，我们的模型数据比较表明，OAE2缺氧是准全球性的，从事件发生前的海洋体积的5％到OAE2发生期间的至少50％。

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