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的生产比被认为反映了由于经向翻转环流向南大洋的平流输出。与显著的冷暖事件相关的231Pa230th移位次数支持MOC变化可能引发气候变化的结论。然而，冰川大西洋231Pa230th的边界清理的影响是一个很大的讨论问题。该项目的目标是更好地了解全新世231Pa230th和冰川沉积物的行为，无论是在开阔的大洋还是在东大西洋的上升区。量化可能的边界清除效应的能力将大大提高我们对作为MOC强度替代指标的沉积231Pa230Th记录的理解和解释。为了达到这一目标，对纳米比亚沿海的两个高生产率岩心和西非一个近海的231Pa230度沉积剖面与北大西洋、西大西洋和南大西洋的沉积剖面进行了比较。来自非洲边缘的高生产率沉积岩心的231Pa230Th首次被AMS和ICPMS以足够的精度测量。分析的重点是最近30年的KYR。所选沉积物岩心的高累积速率允许非常好的时间分辨率。因此，有可能研究231Pa230th沉积对几个短期气候事件(如海因里希事件)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).