Himalayan sedimentary pulses recorded by silicate detritus within a ferromanganese crust from the Central Indian Ocean
Himalayan sedimentary pulses recorded by silicate detritus within a ferromanganese crust from the Central Indian Ocean
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DOI：
10.1016/s0012-821x(02)01062-2
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发表时间：
2003-01
影响因子：
5.3
通讯作者：
V. Banakar;A. Galy;N. Sukumaran;G. Parthiban;A. Y. Volvaiker
中科院分区：
文献类型：
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作者：
V. Banakar;A. Galy;N. Sukumaran;G. Parthiban;A. Y. Volvaiker
中印度洋深水海山水成铁锰结壳（SS 663-Crust）含有数量不等（7-23%）的碎屑物质（硅酸盐碎屑）。考虑到自生组分的生长速率，计算了硅质碎屑的积累速率，结果表明，在过去25±2 Ma的生长历史中，硅质碎屑的积累速率总体上呈下降趋势。这些硅酸盐碎屑显示Nd（0）在−7.7和−12.7之间，87 Sr/86 Sr在0.7083和0.7215之间。Sr-Nd同位素组成记录了SS 663-地壳生长过程中两种碎屑端元混合物的变化。虽然一个端员显然是喜马拉雅派生的材料，其他组件是不太明确的，但可能与印尼弧后盆地的火山成分。我们已经解读了这两种成分在SS 663地壳的硅酸盐碎屑中的比例，以量化在过去的25 Ma中喜马拉雅来源的硅酸盐碎屑的积累速率的变化。结果表明，本区有3个高成藏速率期（现代、10 Ma前后和16 Ma以前）。这些沉积脉冲已经被识别和描述的浊积岩从远孟加拉扇，这是位于超过1000公里，从SS 663地壳位置，这表明这些沉积脉冲是区域意义，而不是本地的重要性。晚第三纪喜马拉雅源硅质碎屑含量升高的时间与主中央冲断带、主边界冲断带和主前缘冲断带的喜马拉雅隆升沿着。这进一步强调了构造控制的沉积物生产的侵蚀活动的造山带及其分布在一个广阔的地区。此外，SS 663-地壳中早中新世碎屑脉冲与河流Sr同位素正偏移的密切叠加表明，早中新世喜马拉雅山的物理和化学风化强烈耦合，而空间解耦似乎只发生在12-14 Ma左右。
A Central Indian Ocean deep-water seamount hydrogenous ferromanganese crust (SS663-Crust) contains variable (7–23%) amounts of detrital material (silicate-detritus). Taking into account the growth rate of the authigenic component, the accumulation rate of the silicate-detritus has been calculated, which shows an overall decrease during the past 25±2 Ma growth history of the specimen. This silicate-detritus displays ϵNd(0) between −7.7 and −12.7, and87Sr/86Sr between 0.7083 and 0.7215. The Sr–Nd isotopic compositions record the variation in the mixture of two detrital end-members throughout the growth history of the SS663-Crust. While one end-member clearly appears to be Himalayan-derived material, the other component is less well defined, but could be related to the volcanogenic component from the Indonesian back-arc basin. We have unscrambled the proportion of these two components in the silicate-detritus of the SS663-Crust to quantify the variation in the accumulation rate of the Himalayan-derived silicate-detritus during the last 25 Ma. The result shows three periods of high accumulation rates (modern, around 10 Ma and prior to 16 Ma). These sedimentary pulses have already been recognised and described in the turbidites from the distal Bengal Fan, which is located more than 1000 km away from the SS663-Crust location, suggesting that these sedimentary pulses are of regional significance rather than of local importance. The timings of elevated contents of the Himalayan-derived silicate-detritus in the specimen during the Neogene closely superimpose the periods of the Himalayan uplift along the Main Central Thrust, the Main Boundary Thrust, and the Main Frontal Thrust. This further emphasises the tectonic control of the sediment production by the erosion of an active orogenic range and its distribution over a vast area. Additionally, close superimposition of the Early Miocene detritus pulse in the SS663-Crust on the riverine Sr isotopic positive excursion suggests that the physical and chemical weathering of the Himalaya was strongly coupled during the Early Miocene, while the spatial decoupling appears to have taken place only around 12–14 Ma.