Variability of the Mediterranean Outflow on glacial-interglacial and millennial time scales

地中海流出水(MOW)通过对大西洋中深层盐度收支的贡献，对北大西洋地区晚更新世的古海洋学和气候演变产生了重大影响。由于直布罗陀海峡的基岩深度较浅(286米)，海平面的变化强烈地影响了海平面的变化，但地中海和热带大西洋环流的水文变化也对海平面的变化产生了很大影响。在这项研究中，我们建议通过放射性成因的Nd2+和Pb2+同位素分析，详细地重建MoW与其他北大西洋东部水团的流动路径、流动强度和过去的混合，这有可能以前所未有的细节和精度揭示MoW的演化。我们将从散装沉积物的自生锰铁涂层中提取底层水体中溶解的放射性同位素特征。粘土组分的同位素组成将对水团过去的流动路径提供独立的约束。这项研究将对葡萄牙边缘、加迪斯湾和西地中海阿尔博兰海的一套测年准确的半深海沉积物岩芯进行研究，这将使东大西洋的海洋表层沉积物动力学恢复到大约30ka。最近的许多证据表明，在上一次重大气候转变(终止1)期间，海洋湿润天气对海洋变化起着关键作用，这就是为什么将特别重视这段时间内海洋湿润天气变化的高分辨率记录。

Mediterranean Outflow Water (MOW) has exerted significant influence on the Late Pleistocene paleoceanography and climate evolution in the North Atlantic region through its contribution to the mid-depth Atlantic salinity budget. The MOW has been strongly influenced by changes in sea level due to the shallow (286 m) sill depth of the Strait of Gibraltar but also by changes in the hydrology of the Mediterranean Sea and the tropical Atlantic gyre. In this study we propose to reconstruct in detail the flow path, flow strength and past mixing of MOW with other eastern North Atlantic water masses through radiogenic isotope analyses of neodymium (Nd) and lead (Pb), which have the potential to unravel the evolution of MOW at unprecedented detail and precision. We will extract the dissolved radiogenic isotope signatures of bottom waters from authigenic ferromanganese coatings of bulk sediments. The isotope composition of the clay fraction will provide independent constraints on the past flow paths of the water masses. The study will be carried out on a suite of well-dated cores of hemipelagic sediments from the Portuguese margin, the Gulf of Cadiz, and from the Alboran Sea in the Western Mediterranean, which will allow the reconstruction of MOW dynamics in the eastern Atlantic Ocean back to approximately 30 ka. A lot of recent evidence points to a critical role of MOW for oceanographic changes during the last major climatic transition (Termination 1), which is why particular emphasis will be on a high resolution record of MOW variability during this period of time.