²³¹Pa/²³⁰Th: A proxy for upwelling off the coast of West Africa

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• 作者：Marcus Christl ; Jö ; rg Lippold ; Alex ; er Hofmann ; Lukas Wacker ; Yann Lahaye ; Hans-Arno Synal
• 关键词：Protactinium-231 ; Paleoceanography ; AMS ; Ocean circulation ; Upwelling
• 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 出版年：2010
• 出版时间：April 2010
• 年：2010
• 卷：268
• 期：7-8
• 页码：1159-1162
• 全文大小：681 K

文摘

²³¹Pa has widespread applications in the earth sciences including uranium series disequilibrium dating of carbonates and the reconstruction of ocean circulation or bio-productivity on glacial/interglacial timescales. Here we present the first ²³¹Pa profile from a marine sediment core (GeoB3722) located in the large upwelling area off West Africa (Northern Cape Basin) measured with Accelerator Mass Spectrometry (AMS). Together with the Th and U-data (obtained with ICP-MS) ²³¹Pa/²³⁰Th ratios were calculated covering the past 30,000 yr. Our results indicate that site GeoB3722 was located in the wind driven upwelling area during glacial times while it abruptly turned into an open ocean area at about 14,000 yr BP. A spatial shift of the large wind driven upwelling area off West Africa is consistent with the idea that atmospheric circulation patterns as well as ocean circulation dramatically changed at the last glacial interglacial transition.