Geochemical evidence for intermediate water circulation in the westernmost Mediterranean over the last 20kyrBP and its impact on the Mediterranean Outflow
Geochemical evidence for intermediate water circulation in the westernmost Mediterranean over the last 20kyrBP and its impact on the Mediterranean Outflow
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过去 20kyrBP 地中海最西端中间水循环的地球化学证据及其对地中海流出的影响
DOI：
10.1016/j.gloplacha.2015.10.001
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发表时间：
2015
影响因子：
3.9
通讯作者：
Jiménez-Espejo F
中科院分区：
文献类型：
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作者：
Jiménez-Espejo F
地中海外流（MOW）是由地中海不同盆地的深层水和中层水产生的。尽管对地中海水体进行了大量研究，但对地中海最西端中间水域的来源和性质及其与 MOW 的联系却很少进行研究。在这里，我们检查了过去 20 公里的三个海洋沉积物记录，这些记录位于关键深度，以追踪阿尔博兰海沿岸的中间水域。我们使用氧化还原敏感元素的组合，可以作为代理来重建水柱氧合和有孔虫铁锰涂层的 Nd 同位素组成的变化，以重建东/西地中海水域的水团来源。根据测量，εNd<−9.2 和冰期期间的低 U/Th 比可归因于 研究地点存在西地中海深水（WMDW）。在冰消过程中，较高的 Nd 同位素组成和 U/Th 比表明改良黎凡特中层水 (LIW) 的贡献增强。我们的数据与其他 LIW 和 MOW 记录之间的比较表明，i）MOW 的下部分支与冰期期间的 WMDW 有关，ii）MOW 中部分支在冰消期期间遵循 LIW 活动，而 iii）上部分支在全新世晚期更加活跃，与腐泥沉积后 LIW 形成增加相一致。这种重建对于理解 MOW 的演化具有重要意义。
The Mediterranean Outflow (MOW) is generated by deep and intermediate waters from different basins in the Mediterranean Sea. Despite the number of studies on Mediterranean water masses, little work has been done on the source and properties of intermediate waters in the westernmost Mediterranean Sea and their links with MOW. Here we examine three marine sediment records spanning the last 20 kyr, located at key depths to trace intermediate waters along the Alboran Sea. We use a combination of redox-sensitive elements, which can serve as proxies to reconstruct variations in the water column oxygenation and the Nd isotopic composition of foraminiferal ferromanganese coatings, in order to reconstruct water mass provenance of Eastern/Western Mediterranean waters.As measured, εNd< − 9.2 and a low U/Th ratio during glacial periods can be attributed to the presence of Western Mediterranean Deep Water (WMDW) at the study sites. During deglaciation, higher Nd isotopic compositions and U/Th ratios point to an enhanced contribution of the modified Levantine Intermediate Water (LIW). The comparison between our data and other LIW and MOW records suggests that i) the lower branch of MOW is linked to WMDW during the glacial period, ii) the middle MOW branch follows LIW activity during deglaciation, while iii) the upper branch is more active during late Holocene, coinciding with LIW formation increase after sapropel deposits. This reconstruction has significant implications for an understanding of the MOW evolution.