Concentrations of Ti, Fe, and Al and radiogenic isotope data for sediments of ODP Leg 177

Identifying terrigenous sources in deep-sea sediments may reveal temporal trends in paleocirculation and the relative role of eolian, upwelled, and hemipelagic Fe sources to surface waters. Bulk elemental and isotopic geochemistry of deep-sea sediments recovered during Ocean Drilling Program Leg 177 in the southeastern Atlantic sector of the Southern Ocean reveal several important aspects of paleocirculation and terrigenous provenance. The sites studied span 43°-53°S and represent different oceanographic settings relative to regional hydrography and sediment type. Bulk sediment geochemistry indicates that terrigenous provenance varied over the past 600 k.y. Site 1089, the northernmost site, exhibits clear glacial-interglacial variability in provenance, while provenance appears to vary regardless of climate state at the more southerly sites (Site 1093 and 1094). Nd and Sr isotopes and Sm/Nd ratios of the terrigenous fraction indicate that study sites have geochemically distinguishable provenance. Nd and Sr isotopes further suggest that Sites 1089 and 1094 both contain detrital components that originated in South America over the past 30 k.y.; however, Site 1089 is also influenced by southern African sources and the strength of the Agulhas Current. The e-Nd data support a more hemipelagic source for the terrigenous material rather than an eolian source based on comparisons with Antarctic ice core data and known sea-ice extent.

识别深海沉积物中的陆源物质来源，可揭示古环流的时间演化趋势，以及风成、上升流和半远洋铁质来源对表层水体的相对贡献。南大西洋东南海域大洋钻探计划（Ocean Drilling Program）第177航次所获取的深海沉积物的全岩元素与同位素地球化学特征，揭示了古环流与陆源物源的多项关键信息。本次研究的站位分布于南纬43°至53°之间，涵盖了区域水文条件与沉积物类型各异的多种海洋环境。全岩沉积物地球化学特征显示，过去60万年以来陆源物源发生了显著变化。最北侧的1089站位的物源表现出明显的冰期-间冰期旋回变化，而更南侧的1093、1094站位的物源变化则与气候状态无关。陆源组分的钕（Neodymium, Nd）、锶（Strontium, Sr）同位素以及钐/钕（Sm/Nd）比值特征表明，各研究站位的物源具有地球化学上的可区分性。钕与锶同位素特征进一步显示，在过去3万年以来，1089和1094站位均存在源自南美洲的碎屑组分；但1089站位同时还受到非洲南部物源以及厄加勒斯海流（Agulhas Current）强度的影响。结合南极冰芯数据与已知海冰范围的对比分析，ε钕（ε-Nd）数据表明，该研究中的陆源物质更倾向于半远洋来源而非风成来源。