Glacial induced closure of the Panamanian Gateway during Marine Isotope Stages (MIS) 95–100 (∼2.5 Ma)
Glacial induced closure of the Panamanian Gateway during Marine Isotope Stages (MIS) 95–100 (∼2.5 Ma)
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海洋同位素阶段 (MIS) 95–100 (~2.5 Ma) 期间冰川导致巴拿马门户关闭
DOI：
10.1016/j.epsl.2014.08.007
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发表时间：
2014
影响因子：
5.3
通讯作者：
R. Tiedemann
中科院分区：
文献类型：
--
作者：
J. Groeneveld;E. Hathorne;S. Steinke;H. Debey;A. Mackensen;R. Tiedemann
上新世晚期，巴拿马门关闭的最后阶段和北方半球冰川作用（NHG）的加强都发生在这一时期。因此，冰川-间冰期（G-IG）的海平面变化可能对东太平洋和加勒比海之间的剩余连接产生重大影响。在这里，我们展示了东太平洋大洋钻探计划（ODP）1241站点和加勒比海大洋钻探计划999站点的有孔虫Mg/Ca和δ 18 O综合测量值。所研究的时间段涵盖了NHG强化后的前三个主要的G-IG海洋同位素阶段（MIS 95-100，102.5Ma）。分析进行了浮游有孔虫Neogloboquadrina dutertrei和Globigerinoides sacculifer，分别代表在温跃层和混合层的水团性质。海水温度，相对盐度和水柱分层的变化强烈表明，巴拿马网关暂时关闭在冰川MIS 98和100，由于冰量的变化相当于海平面下降60-90米。由G. Sacculifer的研究表明，在1241号站点，冰川温度下降了2.5° C，但在999号站点，在冰川MIS 98和100期间，温度上升了3° C，这表明巴拿马门户在这些冰川时期关闭。N.杜特尔特雷在东太平洋保持相对稳定，但在这些冰期开始时，加勒比地区确实显示出3° C的变暖，这表明门户的关闭也改变了水柱分层。我们推断，冰川关闭的门户允许西大西洋暖池延伸到加勒比海南部，增加SST（G。sacculifer）和加深温跃层（N. Dutertrei）。此外，在MIS 100期间，冰量似乎已经变得足够大，足以在相对短暂的间冰期MIS 99中幸存下来，因此门户保持关闭。接近MIS 98结束时，在MIS 97和MIS 96期间，两侧的温度基本相似，表明水团再次交换。此外，加勒比海的SST和δ 18 O水的变化遵循岁差样的周期性，而不是东太平洋和许多其他热带地区的特征性的湿度控制的变化，这表明与信风和热带辐合带（ITCZ）有关的区域大气过程在加勒比海具有主导影响。
The final phase of the closure of the Panamanian Gateway and the intensification of Northern Hemisphere Glaciation (NHG) both occurred during the Late Pliocene. Glacial–interglacial (G–IG) variations in sea level might, therefore, have had a significant impact on the remaining connections between the East Pacific and the Caribbean. Here, we present combined foraminiferal Mg/Ca and δ 18 O measurements from Ocean Drilling Program (ODP) Site 1241 from the East Pacific and ODP Site 999 from the Caribbean. The studied time interval covers the first three major G–IG Marine Isotope Stages (MIS 95–100,∼ 2.5 Ma) after the intensification of NHG. Analyses were performed on the planktonic foraminifera Neogloboquadrina dutertrei and Globigerinoides sacculifer, representing water mass properties in the thermocline and the mixed-layer, respectively. Changes in sea water temperature, relative salinity, and water column stratification strongly suggest that the Panamanian Gateway temporarily closed during glacial MIS 98 and 100, as a result of changes in ice volume equivalent to a drop in sea level of 60–90 m. Reconstructed sea surface temperatures (SST) from G. sacculifer show a glacial decrease of 2.5° C at Site 1241, but increases of up to 3° C at Site 999 during glacial MIS 98 and 100 suggesting that the Panamanian Gateway closed during these glacial periods. The Mg/Ca-temperatures of N. dutertrei remain relatively stable in the East Pacific, but do show a 3° C warming in the Caribbean at the onset of these glacial periods suggesting that the closing of the gateway also changed the water column stratification. We infer that the glacial closure of the gateway allowed the Western Atlantic Warm Pool to extend into the southern Caribbean, increasing SST (G. sacculifer) and deepening the thermocline (N. dutertrei). Additionally, ice volume appears to have become large enough during MIS 100 to survive the relatively short lasting interglacial MIS 99 so that the gateway remained closed. Towards the end of MIS 98, during MIS 97 and into MIS 96 temperatures on both sides are mostly similar suggesting water masses exchanged again. Additionally, Caribbean variations in SST and δ 18 O water follow a precession-like cyclicity rather than the obliquity-controlled variations characteristic of the East Pacific and many other tropical areas, suggesting that regional atmospheric processes related to the trade winds and the InterTropical Convergence Zone (ITCZ) had a dominant impact in the Caribbean.
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影响因子：
3.5
作者：
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