Mid-Pliocene climate change amplified by a switch in Indonesian subsurface throughflow
Mid-Pliocene climate change amplified by a switch in Indonesian subsurface throughflow
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DOI：
10.1038/ngeo520
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发表时间：
2009-06-01
影响因子：
18.3
通讯作者：
Bickert, Torsten
中科院分区：
文献类型：
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作者：
Karas, Cyrus;Nuernberg, Dirk;Bickert, Torsten
在上新世时期（类似于500万至200万年前），构造驱动的热带航道关闭改变了海洋环流，影响了气候的演变。板块构造重建表明，主要重组的一个这样的海道，印度尼西亚门户，发生在400万和300万年前。模型模拟表明，这将触发将印度尼西亚贯穿流注入印度洋的沃茨的来源发生转变，从南太平洋温暖的咸水沃茨转变为北太平洋凉爽和相对新鲜的沃茨。在这里，我们使用成对测量的三角洲O-18和Mg/Ca比的南极有孔虫重建热带印度洋东部的热结构，从5.5到200万年前。我们发现，海面条件保持相对稳定的整个间隔，而地下沃茨清新和冷却约4摄氏度之间的3.5和2.95万年前。我们认为，印度尼西亚门户的限制导致了热带印度洋温跃层的冷却和变浅。我们的结论是，这种构造重组的全球变浅的温跃层记录在上新世，可能有助于赤道东太平洋冷舌的发展。
The tectonically driven closure of tropical seaways during the Pliocene epoch (similar to 5-2 million years (Myr) ago) altered ocean circulation and affected the evolution of climate. Plate tectonic reconstructions show that the main reorganization of one such seaway, the Indonesian Gateway, occurred between 4 and 3 Myr ago. Model simulations have suggested that this would have triggered a switch in the source of waters feeding the Indonesian throughflow into the Indian Ocean, from the warm salty waters of the South Pacific Ocean to the cool and relatively fresh waters of the North Pacific Ocean. Here we use paired measurements of the delta O-18 and Mg/Ca ratios of planktonic foraminifera to reconstruct the thermal structure of the eastern tropical Indian Ocean from 5.5 to 2 Myr ago. We find that sea surface conditions remained relatively stable throughout the interval, whereas subsurface waters freshened and cooled by about 4 degrees C between 3.5 and 2.95 Myr ago. We suggest that the restriction of the Indonesian Gateway led to the cooling and shoaling of the thermocline in the tropical Indian Ocean. We conclude that this tectonic reorganization contributed to the global shoaling of the thermocline recorded during the Pliocene epoch, possibly contributing to the development of the equatorial eastern Pacific cold tongue.