Boundary scavenging at the East Atlantic margin does not negate use of up>231 up>Pa/up>230 up>Th to trace Atlantic overturning
- 作者：Jö ; rg Lippold
- 关键词：231Pa/230Th ; AMOC ; boundary scavenging ; North Atlantic Deep Water ; LGM ; African margin
- 刊名：Earth and Planetary Science Letters
- 出版年：2012
- 期刊代码：18_0012821x
- 类别：ph
- 出版时间：1 June, 2012
- 卷：333-334
- 期：Complete
- 页码：317-331
- 文件大小：867 K
摘要
The up>231 up>Pa/up>230 up>Th method is a promising tool to reconstruct Ocean circulation over the past Glacial-Interglacial cycle. However, marine particle flux may constrain the applicability of this ratio as a direct quantitative proxy for the strength of Atlantic Meridional Overturning Circulation (AMOC) by influencing the fractionation between the in situ produced up>231 up>Pa and up>230 up>Th in ocean water. Here we present up>231 up>Pa/up>230 up>Th down-core profiles from high particle flux areas off Namibia and Senegal covering the past 鈭?5 ka. The up>231 up>Pa/up>230 up>Th profiles at these sites show very different responses to temporal variations of particle fluxes and to changes in water masses. Our results show that sedimentary up>231 up>Pa/up>230 up>Th in the Eastern Atlantic margin is linked to particle flux, but controlled primarily by the mode of the AMOC. Our data suggest that during the past 鈭?0 ka the high productivity Eastern margin was not capable of importing and storing significant amounts of up>231 up>Pa from the open Ocean. Consequently, the applicability of the up>231 up>Pa/up>230 up>Th proxy to reconstruct past ocean circulation is not hampered by this potentially additional up>231 up>Pa sink.