231Pa/230Th profiles from highly accumulating Atlantic sediment cores - a proxy for deep water circulation over the past 30,000 years

在大西洋沉积231Pa/230Th低于0.093的产生比被认为反映了经向翻转环流（MOC）导致231Pa向南大洋的平流输出。231Pa/230Th移位次数与显著的变冷和变暖事件相关，支持MOC变化可能引发气候变化的结论。然而，边界清除对冰川大西洋231Pa/230Th的影响是一个值得讨论的问题。该项目的目标是更好地了解231Pa/230Th在全新世和冰川沉积物中的行为，在开阔的海洋和东大西洋的上升流区。量化可能的边界清除效应的能力将大大提高我们对沉积231Pa/230 - th记录作为MOC强度的代表的理解和解释。为了实现这一目标，我们将纳米比亚海岸两个高产岩心和西非一个岩心的沉积231Pa/230Th剖面与北大西洋、西大西洋和南大西洋的剖面进行了比较。首次利用AMS和ICP-MS对非洲边缘高生产力沉积物岩心的231Pa/230Th进行了高精度测量。分析的重点是过去30年。所选沉积物岩心的高堆积速率使其具有很好的时间分辨率。因此，有可能研究沉积231Pa/230Th对几个短期气候事件（如Heinrich事件）的响应。

In the Atlantic Ocean sedimentary 231Pa/230Th below the production ratio of 0.093 are believed to mirror the advective export of 231Pa to the Southern Ocean due to the meridional overturning circulation (MOC). Times of shifted 231Pa/230Th related with prominent events of cooling and warming support the conclusion that variations in the MOC may incite climate changes. However, the impact of boundary scavenging on the 231Pa/230Th in the glacial Atlantic is a great matter of discussion.The goal of this project is to better understand the behaviour of 231Pa/230Th in Holocene and Glacial sediments both, in the open Ocean and in the upwelling areas in the East Atlantic. The ability to quantify possible boundary scavenging effects will substantially improve our understanding and the interpretation of sedimentary 231Pa/230Th-records as a proxy for the strength of MOC. To approach this goal sedimentary 231Pa/230Th profiles from two high-productivity cores off the coast of Namibia and one off West-Africa are compared with those from the North-, West-, and South- Atlantic Ocean. For the first time 231Pa/230Th from high productivity sediment cores from the African margin at adequate accuracy are being measured by AMS and ICP-MS. The analysis is focused on the last 30 kyr. The high accumulation rates of the selected sediment cores allow a very good time resolution. Therefore, it will be possible to examine the response of the sedimentary 231Pa/230Th to several short-term climate events (e.g. Heinrich Events).