Cooling and ice growth across the Eocene-Oligocene transition
Cooling and ice growth across the Eocene-Oligocene transition
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DOI：
10.1130/g24584a.1
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发表时间：
2008-03-01
期刊：
影响因子：
5.8
通讯作者：
Rosenthal, Yair
中科院分区：
文献类型：
--
作者：
Lear, Caroline H.;Bailey, Trevor R.;Rosenthal, Yair
始新世-渐新世（E-O）气候转变（约1000年）34 Ma）标志着南极冰增长的时期，也是从新生代早期温室条件向今天冰川气候状态迈出的重要一步。这种转变表现为深海底栖有孔虫氧同位素（δ O-18）值的增加，这反映了海水温度和δ O-18的两个主要步骤。现有的底栖镁/钙古温度记录没有显示整个过渡冷却，可能反映了在深水站点的底栖有孔虫镁/钙比的饱和状态的影响。在这里，我们提出的数据保存非常完好的有孔虫沉积远高于方解石补偿深度，提供了第一个代理证据，类似于2.5摄氏度的海洋冷却与冰的增长。这允许解释E-O三角洲O-18记录，而无需调用北方大陆尺度的冰。
The Eocene-Oligocene (E-O) climate transition (ca. 34 Ma) marks a period of Antarctic ice growth and a major step from early Cenozoic greenhouse conditions toward today's glaciated climate state. The transition is represented by an increase in deep-sea benthic foraminiferal oxygen isotope (delta O-18) values occurring in two main steps that reflect the temperature and delta O-18 of seawater. Existing benthic Mg/Ca paleotemperature records do not display a cooling across the transition, possibly reflecting a saturation state effect on benthic foraminiferal Mg/Ca ratios at deep-water sites. Here we present data from exceptionally well preserved foraminifera deposited well above the calcite compensation depth that provide the first proxy evidence for an similar to 2.5 degrees C ocean cooling associated with the ice growth. This permits interpretation of E-O delta O-18 records without invoking Northern Hemisphere continental-scale ice.