A molybdenum isotope record of Eocene Thermal Maximum 2: Implications for global ocean redox during the early Eocene
A molybdenum isotope record of Eocene Thermal Maximum 2: Implications for global ocean redox during the early Eocene
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DOI：
10.1029/2012pa002346
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发表时间：
2012-09
期刊：
影响因子：
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通讯作者：
A. Dickson;A. Cohen
中科院分区：
文献类型：
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作者：
A. Dickson;A. Cohen
在始新世早期，一系列短期的全球变暖事件（“高温”）发生，以应对碳迅速释放到海洋和大气中。为了研究海洋氧化还原对全球变暖的响应，我们测定了北冰洋综合大洋钻探计划302考察站M0004 A中始新世热峰2期（ETM-2，54.1Ma）样品的钼同位素组成（δ 98/95 Mo）。在我们的样本组中，最高的δ 98/95 Mo（2.00±0.11‰）对应于ETM-2高峰期M0004 A站局部洋地黄的发展，我们认为这是当时全球海水δ 98/95 Mo的记录。ETM-2海水δ 98/95 Mo与最近估计的早期高温海水δ 98/95 Mo（古新世始新世热极大期（PETM，55.9Ma），δ 98/95 Mo = 2.08±0.11‰）没有区别。认为ETM-2和PETM期间海水δ 98/95 Mo的相似性是由于在每次超高温期间北冰洋中短暂的真石漆的发展导致该盆地中沉积物积累以捕获早始新世海水的长期δ 98/95 Mo。因此，我们的新数据对始新世早期高温期间短暂的全球海底脱氧的幅度提出了最低限度的限制。
During the early Eocene, a series of short-term global warming events (‘hyperthermals’) occurred in response to the rapid release of carbon into the oceans and atmosphere. In order to investigate the response of ocean redox to global warming, we have determined the molybdenum isotope compositions (δ 98/95 Mo) of samples spanning one such hyperthermal (Eocene Thermal Maximum 2 (ETM-2, 54.1Ma)), from Integrated Ocean Drilling Program Expedition 302 Site M0004A in the Arctic Ocean. The highest δ 98/95 Mo in our sample set (2.00±0.11‰) corresponds to the development of local euxinia at Site M0004A during the peak of ETM-2, which we interpret as recording the global seawater δ 98/95 Mo at that time. The ETM-2 seawater δ 98/95 Mo is indistinguishable from a recent estimate of seawater δ 98/95 Mo from an earlier hyperthermal (Paleocene Eocene Thermal Maximum (PETM, 55.9Ma), δ 98/95 Mo = 2.08±0.11‰). It is argued that the similarity in seawater δ 98/95 Mo during ETM-2 and the PETM was caused by the development of transient euxinia in the Arctic Ocean during each hyperthermal that allowed sediments accumulating in this basin to capture the long term δ 98/95 Mo of early Eocene seawater. Our new data therefore place a minimum constraint on the magnitude of transient global seafloor deoxygenation during early Eocene hyperthermals.