Testing the silica leakage hypothesis with sedimentary opal records from the eastern equatorial Pacific over the last 150 kyrs
Testing the silica leakage hypothesis with sedimentary opal records from the eastern equatorial Pacific over the last 150 kyrs
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DOI：
10.1029/2006gl026651
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发表时间：
2006-08
影响因子：
5.2
通讯作者：
S. Kienast;M. Kienast;S. Jaccard;S. Calvert;R. Francois
中科院分区：
文献类型：
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作者：
S. Kienast;M. Kienast;S. Jaccard;S. Calvert;R. Francois
我们测量了赤道东太平洋（EEP）几个岩心中230 Th归一化的蛋白石通量，以检验“二氧化硅泄漏”假说的有效性，该假说声称，在末次冰期期间，南大洋到低纬度的草酸的重新分布是大气二氧化碳（CO2）减少的重要原因。二氧化硅泄漏假说预测较高的蛋白石通量在EEP和较低的蛋白石通量在南大洋期间的低大气CO2。这些预测是不承担的沉积记录在冰川氧同位素阶段2（OIS 2，13-27 kyrs B. P.）。然而，我们发现一个突出的蛋白石通量最大值在EEP在中间的OIS 3（约。40-60 kyrs BP），与亚南极带几个岩心中的低蛋白石通量相一致。这一观察结果与OIS 3期间南大洋向赤道上涌区域的二氧化硅泄漏一致，当时低尘埃通量和扩展海冰可能有助于限制南大洋的硅藻生产力。由于这一事件与东方冰记录中的CO2明显最小值无关，因此它对大气CO2的影响似乎很小。
We have measured 230Th‐normalized opal fluxes in several cores from the eastern equatorial Pacific (EEP) to test the validity of the “silica leakage” hypothesis, which purports that redistribution of silicic acid from the Southern Ocean to the low latitudes was responsible for a significant portion of the reduction in atmospheric carbon dioxide (CO2) during the last glacial period. The silica leakage hypothesis predicts higher opal fluxes in the EEP and lower opal fluxes in the Southern Ocean during periods of low atmospheric CO2. These predictions are not borne by the sedimentary record during glacial oxygen isotope stage 2 (OIS 2, 13–27 kyrs B.P.). However, we find a prominent opal flux maximum in the EEP in the middle of OIS 3 (ca. 40–60 kyrs BP) coinciding with low opal fluxes in several cores from the subantarctic zone. This observation is consistent with silica leakage from the Southern Ocean to the equatorial upwelling region during OIS 3, when both low dust flux and extended sea ice could have contributed to limiting diatom productivity in the Southern Ocean. Since this event is not associated with a clear minimum in the Vostok ice record of CO2, its impact on atmospheric CO2 appears to be small.