Pliocene climate change of the Southwest Pacific and the impact of ocean gateways
Pliocene climate change of the Southwest Pacific and the impact of ocean gateways
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DOI：
10.1016/j.epsl.2010.10.028
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发表时间：
2011-01-03
影响因子：
5.3
通讯作者：
Garbe-Schoenberg, Dieter
中科院分区：
文献类型：
--
作者：
Karas, Cyrus;Nuernberg, Dirk;Garbe-Schoenberg, Dieter
从上新世早期的“温暖室”气候到目前的“冰室”气候的转变以及网关动力学的作用受到了激烈的争论。中美洲海道和印度尼西亚门户的收缩都影响了上新世的海洋环流和气候。在这里，我们使用来自地表和地下水平的浮游有孔虫（海洋原生动物）的 Delta O-18 和 Mg/Ca 比率组合来重建西南太平洋深海钻探项目 (DSDP) 站点 590B 从 6.5 Ma 到 2.5 Ma 的热结构和盐度变化。我们的数据表明，当中美洲海道关闭达到临界阈值时，西太平洋暖池和西南太平洋之间的经向温度梯度在大约 4.6-4 Ma 期间逐渐降温约 2 摄氏度，海面清新。大约3.5 Ma之后，受限制的印度尼西亚门户可能放大了东澳大利亚洋流，从而在全球气候逐渐变冷时增强了向西南太平洋的热量输送，同时减少了经向温度梯度。与此同时，我们的数据表明亚南极模式水（SAMW）的冷却和清新或/和 SAMW 向站点 590B 的北流增加，这可能是迈向当前南极锋面系统的第一步。 (C) 2010 Elsevier B.V. 保留所有权利。
The transition from the early Pliocene "Warmhouse" towards the present "Icehouse" climate and the role of Gateway dynamics are intensively debated. Both, the constrictions of the Central American Seaway and the Indonesian Gateway affected ocean circulation and climate during the Pliocene epoch. Here, we use combined delta O-18 and Mg/Ca ratios of planktonic foraminifera (marine protozoa) from surface and subsurface levels to reconstruct the thermal structure and changes in salinities from the Southwest Pacific Deep Sea Drilling Project (DSDP) Site 590B from 6.5 to 2.5 Ma. Our data suggest a gradual cooling of similar to 2 degrees C and freshening of the sea surface during similar to 4.6-4 Ma with an increased meridional temperature gradient between the West Pacific Warm Pool and the Southwest Pacific when the closing of the Central American Seaway reached a critical threshold. After similar to 3.5 Ma, the restricted Indonesian Gateway might have amplified the East Australian Current, allowing enhanced heat transport towards the Southwest Pacific with reduced meridional temperature gradients when the global climate gradually cooled. At the same time our data suggest a cooling and freshening of Subantarctic Mode Water (SAMW) or/and an increased northward flow of SAMW towards Site 590B, possibly a first step towards the present Antarctic Frontal System. (C) 2010 Elsevier B.V. All rights reserved.