Major hydrological shifts in the Black Sea “Lake” in response to ice sheet collapses during MIS 6 (130–184 ka BP)
Major hydrological shifts in the Black Sea “Lake” in response to ice sheet collapses during MIS 6 (130–184 ka BP)
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DOI：
10.1016/j.quascirev.2019.07.008
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发表时间：
2019-09
影响因子：
4
通讯作者：
A. Wegwerth;O. Dellwig;S. Wulf;B. Plessen;I. Kleinhanns;N. Nowaczyk;Liu Jiabo;H. Arz
中科院分区：
文献类型：
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作者：
A. Wegwerth;O. Dellwig;S. Wulf;B. Plessen;I. Kleinhanns;N. Nowaczyk;Liu Jiabo;H. Arz
萨利安冰川是第四纪最大的冰川之一，其冰盖延伸到欧亚大陆的范围比其他冰川时期要大得多。轨道变化导致冰盖在扩大和缩小之间切换。冰盖的部分消退和融化水的排放导致全球海平面上升和内陆海湖面上升，对环境产生了更广泛的影响。在海洋同位素第六阶段(MIS6)期间，融水进入以前封闭的黑海，至少是安纳托利亚洞穴δ18O记录中记录的两倍。本文介绍了黑海MIS6湖的沉积记录，并提供了三个熔水期的证据(BSWP-6-1：180-167ka BP，BSWP-6-2：160-145ka BP，BSWP-II：133-130ka BP)。当δ180ostracods和sr/Caostracodpoint显示明显的融水供应和盐度下降时，87sr/86srostracods揭示了融水的来源和途径。在这三个时期，融水很可能通过第聂伯河和伏尔加河流入黑海和里海，并将这两个盆地连接起来。在最古老的融水期，相对较低的87Sr/86Srostracod值表明，只有欧亚冰盖东部在融化。相比之下，在较年轻的融水期，异常高的87Sr/86Srostracods值指向来自欧亚冰盖西部的额外融水。田山和帕米尔山脉冰川融化的盈余最终通过阿姆河和斯里达里亚河进入里海，可能放大了高放射性成因锶同位素水的输入。我们还表明，较高的温度和生产力表明，在MIS6的前半部分，丹斯加德-奥施格式的气候变率。
The Saalian was one of the largest glaciations during the Quaternary with an ice sheet extending considerably wider into the Eurasian continent than during other glacials. Orbital variations caused the ice sheet to switch between growing and shrinking. The partial retreat of the ice sheet and meltwater discharge resulted in global sea-level rise and increased lake levels of inland seas with broader environmental implications. During Marine Isotope Stage 6 (MIS 6), meltwater entered the formerly enclosed Black Sea at least twice as documented in a δ18O record from Anatolian speleothems. Here we present a sedimentary record from the Black Sea “Lake” covering MIS 6 and provide evidence for three meltwater periods coinciding with insolation maxima (BSWP-6-1: 180-167 ka BP, BSWP-6-2: 160-145 ka BP, BSWP-II: 133-130 ka BP). While δ18Oostracodsand Sr/Caostracodspoint to pronounced meltwater supply and decreasing salinity,87Sr/86Srostracodsshed light on meltwater sources and pathways. During all three periods, meltwater drained most likely via the Dnieper and Volga into the Black and Caspian Seas and connected both basins. Relatively low87Sr/86Srostracodsvalues during the oldest meltwater period suggest melting solely of the eastern Eurasian Ice Sheet. In contrast, during the younger meltwater periods, exceptional high87Sr/86Srostracodsvalues point towards additional meltwater from the western Eurasian Ice Sheet. A surplus from melting glaciers in the Tian Shan and Pamir Mountains that finally entered the Caspian Sea via the Amu Darya and Sry Darya probably amplified the input of high radiogenic Sr-isotope water. We also show that higher temperatures and productivity suggest Dansgaard-Oeschger-like climate variability during the first half of MIS 6.