Seawater oxygenation during the Paleocene-Eocene Thermal Maximum
Seawater oxygenation during the Paleocene-Eocene Thermal Maximum
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DOI：
10.1130/g32977.1
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发表时间：
2012-07-01
期刊：
影响因子：
5.8
通讯作者：
Coe, Angela L.
中科院分区：
文献类型：
--
作者：
Dickson, Alexander J.;Cohen, Anthony S.;Coe, Angela L.
鉴于全球突然变暖的地质事件往往伴随着海水含氧量的降低，对未来几十年海水氧化轨迹的不确定性尤其令人关切。在这里，我们从这些变暖事件之一--古新世-始新世最高温度(PETM，55.9英里)的间隔来评估全球海水的含氧量。)。我们的结果来自北冰洋综合海洋钻探计划探险302地点M0004，基于钼同位素测定和钼、Re和铀的丰度。这些数据表明，与今天相比，PETM间期上部的低氧海洋环境在全球范围内出现了小幅扩张。更广泛的海水脱氧作用可能已经发生了长达100 K.Y.年，与PETM开始时全球变暖和碳氧化的高速率有关。我们的数据还显示，北冰洋沉积物中的钼同位素组成超出了目前海洋环境中记录的范围。这些特殊的成分可能反映了热液输入或与硫化钼形态有关的平衡同位素分馏的影响。
Uncertainty over the trajectory of seawater oxygenation in the coming decades is of particular concern in the light of geological episodes of abrupt global warming that were frequently accompanied by lowered seawater oxygen concentrations. Here we present an assessment of global seawater oxygenation from an interval of one of these warming episodes, the Paleocene-Eocene Thermal Maximum (PETM, 55.9 m.y. ago). Our results, obtained from Integrated Ocean Drilling Program Expedition 302 Site M0004 in the Arctic Ocean, are based on molybdenum isotope determinations and molybdenum, rhenium, and uranium abundances. These data indicate a small global expansion of low-oxygen marine environments in the upper part of the PETM interval compared with the present day. More extensive seawater deoxygenation may have occurred for as long as similar to 100 k.y., associated with a high rate of global warming and carbon oxidation at the start of the PETM. Our data also reveal molybdenum isotope compositions in Arctic Ocean deposits that are outside the range currently documented in marine environments. These exceptional compositions could reflect either the influence of hydrothermal inputs or equilibrium isotope fractionations associated with molybdenum sulfide speciation.