首页> 外文期刊>Proceedings of the Indian Academy of Sciences. Earth and Planetary Sciences >Biological productivity, terrigenous influence and noncrustal elements supply to the Central Indian Ocean Basin: Paleoceanography during the past ~1 Ma
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Biological productivity, terrigenous influence and noncrustal elements supply to the Central Indian Ocean Basin: Paleoceanography during the past ~1 Ma

机译:中部印度洋盆地的生物生产力,陆源影响和非地壳元素供应:过去〜1 Ma的古海洋学

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A 2 m-long sediment core from the siliceous ooze domain in the Central Indian Ocean Basin (CIOB; 13°03′S: 74°44′E; water depth 5099 m) is studied for calcium carbonate, total organic carbon, total nitrogen, biogenic opal, major and few trace elements (Al, Ti, Fe, K, Mg, Zr, Sc,V, Mn, Cu, Ni, Zn, Co, and Ba) to understand the productivity and intensity of terrigenous supply. The age model of the sediment core is based on U-Th dating, occurrence of Youngest Toba Tuff of ~74 ka and Australasian microtektites of ~770 ka. Low carbonate content (< 1%) of sediment core indicates deposition below the carbonate compensation depth. Organic carbon content is also very low, almost uniform (mean 0.2 wt%) and is of marine origin. This suggests a well-oxygenated bottom water environment during the past ~1100 ka. Our data suggest that during ~1100 ka and ~400 ka siliceous productivity was lower, complimented by higher supply of terrigenous material mostly derived from the metasedimen-tary rocks of High Himalayan crystalline. However, during the last ~400 ka, siliceous productivity increased with substantial reduction in the terrigenous sediment supply. The results suggest that intensity of Himalayan weathering, erosion associated with monsoons was comparatively higher prior to 400 ka. Manganese, Ba, Cu, Ni, Zn, and Co have around 90% of their supply from noncrustal (excess) source and their burial to seafloor remained unaffected throughout the past ~1100 ka.
机译:研究了中印度洋盆地硅质软泥域(CIOB; 13°03′S:74°44′E;水深5099 m)中一个长2 m的沉积岩心,以测定碳酸钙,总有机碳,总氮,生物蛋白石,主要和少量微量元素(Al,Ti,Fe,K,Mg,Zr,Sc,V,Mn,Cu,Ni,Zn,Co和Ba)以了解陆源供应的生产力和强度。沉积物芯的年龄模型基于U-Th测年,〜74 ka的最年轻多巴凝灰岩和〜770 ka的澳大利亚微晶石。沉积物岩心的碳酸盐含量低(<1%)表明沉积物低于碳酸盐补偿深度。有机碳含量也非常低,几乎是均匀的(平均0.2 wt%),是海洋来源的。这表明在过去〜1100 ka的时间里,底水环境充氧良好。我们的数据表明,在〜1100 ka和〜400 ka期间,硅质生产力较低,这主要是由喜马拉雅山高位准变质岩中衍生的陆源物质供应增加所致。然而,在最后一个〜400 ka期间,硅质生产力增加,而陆源性沉积物供应量却大大减少。结果表明,在400 ka之前,与季风有关的喜马拉雅风化侵蚀强度相对较高。锰,钡,铜,镍,锌和钴的约90%来自非结壳(过量)源,其埋葬到海底的行为在过去1100 ka内没有受到影响。

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