Deepwater evolution in the inner Labrador Sea over the last 30 ka BP (DEEPTELLs)

过去 30 ka BP 内拉布拉多海的深水演化 (DEEPTELLs)

• 批准号: 326649832
• 负责人: Dr. Janne Repschläger
• 金额: --
• 依托单位: Leibniz-Labor für Altersbestimmung und Isotopenforschung
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/326649832?language=en
• 关键词: Deepwater; evolution; inner; Labrador; Sea

The formation of Labrador Sea Water (LSW) through deepwater convection in the Labrador Sea is supposed to stabilize the modern ocean circulation since about 7 ka BP. Despite its importance in the modern ocean circulation, it is suggested that deepwater formation in the Labrador Sea is a unique feature in the Holocene and did not occur during the last Glacial period. Instead, low glacial delta13C signatures reconstructed from benthic foraminifera in sediment cores off Cape Hatteras in the outflow pathway of deepwater from the Labrador Sea are interpreted as southern sourced deepwater that reached up to high northern latitudes. This simplified concept is recently questioned, as changes in the end member composition of the glacial deepwater originating from the North Atlantic region and even deepwater formation in the Labrador Sea need to be considered. Previous studies from the Labrador Sea are based on sedimentological and surface water reconstruction, thus little is known about the glacial and deglacial deepwater composition and -structure in the Labrador Sea. In the proposed study we aim to reconstruct the water mass structure and composition in the Labrador Sea during the last Glacial and the Deglaciation in order to test whether LSW formation was active during the last Glacial and which importance it had for the glacial state of the Atlantic Overturning Circulation (AMOC). The reconstructions will be conducted on four sediment cores taken in the Inner Labrador Sea at water depth between 1200 and 3300 m, covering the different deepwater masses that are filling the Labrador Sea. To identify potential end member composition changes, delta13C and delta18O analyses on benthic foraminifera and Mg/Ca temperature reconstruction from benthic foraminifera and ostracods will be used. The results of the study can help to gain a better understanding of the importance of the Labrador Sea for the Glacial and Deglacial global AMOC changes and for more stable AMOC modes. This will be also pivotal to assess the importance of the Labrador Sea under anthropogenic forced climate warming and should help to further test and improve climate models used to predict future climate change.

拉布拉多海深水对流形成的拉布拉多海水（LSW）稳定了约7ka BP以来的现代海洋环流。尽管拉布拉多海深水地层在现代海洋环流中具有重要意义，但它在全新世是一个独特的特征，而不是在末次冰期发生的。相反，在来自拉布拉多海深水流出通道的Hatteras角沉积物岩心中，从底栖有孔虫中重建的低冰川三角洲13c特征被解释为南部深水，达到北纬高纬度。这种简化的概念最近受到了质疑，因为需要考虑来自北大西洋地区甚至拉布拉多海深水地层的冰川深水端段组成的变化。以往对拉布拉多海的研究主要基于沉积学和地表水重建，对拉布拉多海的冰川和去冰川深水组成和结构了解甚少。本研究旨在重建末次冰期和消冰期拉布拉多海的水团结构和组成，以检验末次冰期LSW的形成是否活跃，以及它对大西洋翻转环流（AMOC）的冰川状态的重要性。重建将对四个沉积物岩心进行，这些岩心取自拉布拉多内海，水深在1200至3300米之间，覆盖了填充拉布拉多海的不同深水块体。利用底栖有孔虫的delta13C和delta18O分析以及底栖有孔虫和介形虫的Mg/Ca温度重建来确定潜在的端元组成变化。研究结果有助于更好地认识拉布拉多海对冰川和去冰期全球AMOC变化的重要性，以及对更稳定的AMOC模式的重要性。这对于评估拉布拉多海在人为气候变暖下的重要性也至关重要，并有助于进一步测试和改进用于预测未来气候变化的气候模型。