Disentangling inputs of aeolian dust, ice-rafted debris (IRD), and eroded continental detritus delivered by ocean currents to marine sediments provide important insights into Earth System processes and climate. This study uses Sr-Nd-Pb isotope ratios of the continent-derived (lithogenic) fraction in deep-sea core TN057-6 from the subantarctic Southern Ocean southwest of Africa over the past 150,000 y to identify source regions and quantify their relative contributions and fluxes utilizing a mixing model set in a Bayesian framework. The data are compared with proxies from parallel core Ocean Drilling Program Site 1090 and newly presented data from potential South America aeolian dust source areas (PSAs), allowing for an integrated investigation into atmospheric, oceanic, and cryospheric dynamics. PSA inputs varied on glacial/interglacial timescales, with southern South American sources dominating up to 88% of the lithogenic fraction (mainly Patagonia, which provided up to 68%) during cold periods, while southern African sources were more important during interglacials. During the warmer Marine Isotope Stage (MIS) 3 of the last glacial period, lithogenic fluxes were twice that of colder MIS2 and MIS4 at times, and showed unique isotope ratios best explained by Antarctic-derived IRD, likely from the Weddell Sea. The IRD intrusions contributed up to 41% at times and followed Antarctic millennial warming events that raised temperatures, causing instability of icesheet margins. High IRD was synchronous with increased bioavailable iron, nutrient utilization, high biological productivity, and decreased atmospheric CO 2 . Overall, TN057-6 sediments record systematic Southern Hemisphere climate shifts and cryospheric changes that impacted biogeochemical cycling on both glacial/interglacial and subglacial timescales.

中文翻译：

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巴塔哥尼亚尘埃、厄加勒斯洋流和南极冰筏碎片在过去 15 万年对南大西洋的贡献


解开洋流向海洋沉积物输送的风尘、冰筏碎片 (IRD) 和侵蚀的大陆碎屑的输入，为了解地球系统过程和气候提供了重要的见解。本研究利用过去 15 万年非洲西南部亚南极南大洋深海核心 TN057-6 中大陆衍生（成岩）部分的 Sr-Nd-Pb 同位素比来识别源区并量化其相对贡献和利用贝叶斯框架中设置的混合模型来生成通量。这些数据与来自并行核心海洋钻探计划站点 1090 的代理数据以及来自南美洲潜在风尘源区 (PSA) 的新近提供的数据进行了比较，从而可以对大气、海洋和冰冻圈动力学进行综合调查。 PSA 输入在冰期/间冰期时间尺度上有所不同，南美南部来源在寒冷时期占主导地位的成岩部分高达 88%（主要是巴塔哥尼亚，占 68%），而南部非洲来源在间冰期期间更为重要。在末次冰河期较温暖的海洋同位素阶段 (MIS) 3 期间，成岩通量有时是较冷的 MIS2 和 MIS4 的两倍，并且表现出独特的同位素比率，最好用源自南极的 IRD（可能来自威德尔海）来解释。 IRD 入侵的贡献有时高达 41%，并且是在南极千禧年变暖事件之后导致温度升高，导致冰盖边缘不稳定。高 IRD 与生物可利用铁、养分利用率、高生物生产力和大气 CO 2 减少同步增加。 总体而言，TN057-6 沉积物记录了系统性的南半球气候变化和冰冻圈变化，这些变化影响了冰川/间冰期和冰下时间尺度的生物地球化学循环。