Meltwater events and the Mediterranean reconnection at the Saalian-Eemian transition in the Black Sea
Meltwater events and the Mediterranean reconnection at the Saalian-Eemian transition in the Black Sea
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DOI：
10.1016/j.epsl.2014.07.030
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发表时间：
2014-10
影响因子：
5.3
通讯作者：
A. Wegwerth;O. Dellwig;J. Kaiser;G. Ménot;E. Bard;L. Shumilovskikh;B. Schnetger;I. Kleinhanns;M. Wille;H. Arz
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文献类型：
--
作者：
A. Wegwerth;O. Dellwig;J. Kaiser;G. Ménot;E. Bard;L. Shumilovskikh;B. Schnetger;I. Kleinhanns;M. Wille;H. Arz
最后一次冰期-间冰期过渡或终止I(TI)在黑海得到了很好的记录，而倒数第二次终止(T II)期间的气候和环境动态知之甚少。在这里，我们提出了一项基于黑海东南部沉积岩芯的多代理研究，覆盖了倒数第二次冰期和几乎整个伊米亚间冰期((133.5±0.70)-(122.5±1.7ka BP))。代用指标包括冰排碎屑(IRD)、氧和锶同位素以及底栖介形类的锶/钙、镁/钙和铀/钙比值、有机和无机沉积物地球化学，以及TeX 86和U K‘37水温。末次倒数第二次冰期(MIS6,133.5至129.9±0.7ka BP)的特征是由Tex86古温度计估计的湖面年平均温度约为9℃。这一时期受到两个黑海熔融水脉冲(BSWP-II-1和BSWP-II-2)的影响，这表明介形虫的锶/钙比值很低，但沉积的K/Al值很高。异常高的放射性成因87锶/86锶介形石值(最大0.70945)在BSWP-II-2期间，建议通过里海传递一个潜在的喜马拉雅来源。第二次升温开始于129.9±0.7ka BP，IRD突然消失，δ18 O介形虫数值增加，第一次Tex86派生的温升约2.5C。第二次突然增温步骤为约15.5ka BP，作为伊米亚暖期的前奏，记录于128.3 ka BP。地中海-黑海重新连接最有可能发生在128.1±0.7ka BP，表现为介形虫的锶/钙比值和U/钙比值的增加。介形类和总有机碳含量的消失标志着127.6 ka BP伊米亚腐泥岩形成的开始。在腐桨形成期间，Tex 86温度下降并稳定在9℃左右，而U K‘37温度保持在平均17℃左右。这种差异可能是由于Thaumarocota群落从表层向营养丰富的更深更冷的水域的栖息地转移所致，这些水域位于逐渐建立的晕层和氧化还原跃层之上。
The last glacial–interglacial transition or Termination I (TI) is well documented in the Black Sea, whereas little is known about climate and environmental dynamics during the penultimate Termination (T II). Here we present a multi-proxy study based on a sediment core from the SE Black Sea covering the penultimate glacial and almost the entire Eemian interglacial ((133.5±0.7)–(122.5±1.7) ka BP). Proxies comprise ice-rafted debris (IRD), O and Sr isotopes as well as Sr/Ca, Mg/Ca, and U/Ca ratios of benthic ostracods, organic and inorganic sediment geochemistry, as well as TEX 86 and U K′ 37 derived water temperatures. The ending penultimate glacial (MIS 6, 133.5 to 129.9±0.7 ka BP) is characterised by mean annual lake surface temperatures of about 9° C as estimated from the TEX 86 palaeothermometer. This period is impacted by two Black Sea melt water pulses (BSWP-II-1 and 2) as indicated by very low Sr/Ca ostracods but high sedimentary K/Al values. Anomalously high radiogenic 87 Sr/86 Sr ostracod values (max. 0.70945) during BSWP-II-2 suggest a potential Himalayan source communicated via the Caspian Sea. The T II warming started at 129.9±0.7 ka BP, witnessed by abrupt disappearance of IRD, increasing δ 18 O ostracod values, and a first TEX 86 derived temperature rise of about 2.5° C. A second, abrupt warming step to ca. 15.5° C as the prelude of the Eemian warm period is documented at 128.3 ka BP. The Mediterranean–Black Sea reconnection most likely occurred at 128.1±0.7 ka BP as demonstrated by increasing Sr/Ca ostracods and U/Ca ostracods values. The disappearance of ostracods and TOC contents> 2% document the onset of Eemian sapropel formation at 127.6 ka BP. During sapropel formation, TEX 86 temperatures dropped and stabilised at around 9° C, while U K′ 37 temperatures remain on average 17° C. This difference is possibly caused by a habitat shift of Thaumarchaeota communities from surface towards nutrient-rich deeper and colder waters located above the gradually establishing halo-and redoxcline.