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首页> 外文期刊>Palaeogeography, Palaeoclimatology, Palaeoecology: An International Journal for the Geo-Sciences >Geochemistry of buried river sediments from Ghaggar Plains, NW India: Multi-proxy records of variations in provenance, paleoclimate, and paleovegetation patterns in the Late Quaternary
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Geochemistry of buried river sediments from Ghaggar Plains, NW India: Multi-proxy records of variations in provenance, paleoclimate, and paleovegetation patterns in the Late Quaternary

机译：来自印度西北部加格加尔平原的地下河床沉积物的地球化学：第四纪晚期物源，古气候和古植被模式变化的多代理记录

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摘要

We report the first geochemical record in two drill-sediment cores from a buried channel in the Ghaggar Plains of NW India, which are used to infer variations in provenance, paleoclimate, and paleovegetation in the locality during the Late Quaternary. Aeolian sediments (similar to 150 ka) in both the cores are overlain by fluvial sediments (similar to 75 ka-recent). Major oxide compositions of the core sediments (n = 35) generally vary between that observed for the modern-day Ghaggar/Sutlej and Yamuna river sand. The isotopic composition (Sr-87/Sr-86: 0.7365 to 0.7783 and epsilon(Nd):-14.6 to -19.0) of core sediments (n = 18) suggest binary mixing of sediments from compositionally distinct Higher Himalaya (HH) and Lesser Himalaya (LH) endmembers in the catchment, and support involvement of a river system originating in the Himalayan hinterland. Distinctly higher Sr-87/Sr-86 and lower epsilon(Nd) in the core sediments during glacial periods can be explained by increasing sediment contribution from LH (high Sr-87/Sr-86 and low epsilon(Nd)) due to an increase in glacial cover over HH. Whereas relatively less glacial cover over HH during interglacial periods resulted in more erosion and sediment contribution from HH. The down-core Sr-Nd isotopic variability clearly reflects climate-controlled sediment erosion in the Himalayan catchment. Temporal variations in delta O-18 and delta C-13 of carbonate nodules (n = 27) are consistent with that reported from the Ganga interfluves. The delta C-13 variability (-4.1 parts per thousand to 1.2 parts per thousand.) in carbonates is mainly controlled by the extent of silicate (HH) versus carbonate (LH) source weathering due to significant climatic shifts. The delta C-13 of sediment organic matter -27.4%. to-232 parts per thousand, n = 24) suggests dominantly C-3 plants in the catchment during the last similar to 75 ka. More negative delta C-13 values in sediments during glacial periods relative to those during interglacial periods can be explained by increasing C-4 abundance during interglacial periods characterized with both higher summer rainfall and mean annual temperature. (C) 2016 Elsevier B.V. All rights reserved.
机译：我们报告了来自印度西北部加格平原的一个埋藏通道中的两个钻探沉积岩心的第一个地球化学记录，用于推断晚第四纪时该地区的物源，古气候和古植被的变化。两个岩心的风成沉积物（约150 ka）被河流沉积物覆盖（近75 ka）。核心沉积物的主要氧化物组成（n = 35）通常在现代Ghaggar / Sutlej和Yamuna河沙之间观察到。核心沉积物（n = 18）的同位素组成（Sr-87 / Sr-86：0.7365至0.7783和epsilon（Nd）：-14.6至-19.0）表明来自组成不同的喜马拉雅山（HH）和小河床的沉积物的二元混合喜马拉雅山（LH）的最终成员在该流域，并支持源自喜马拉雅腹地的河流系统的参与。在冰川期，核心沉积物中Sr-87 / Sr-86明显较高，而ε（Nd）较低，这可以解释为LH增加的沉积物贡献（高Sr-87 / Sr-86和低ε（Nd））由于与HH相比，冰川覆盖增加。在冰间期，HH的冰川覆盖相对较少，导致HH的侵蚀和沉积物贡献更大。下游Sr-Nd同位素变异性清楚地反映了喜马拉雅流域受气候控制的沉积物侵蚀。碳酸盐结节（n = 27）的δO-18和δC-13的时间变化与恒河插层的报道一致。碳酸盐中C-13的变化量（-4.1千分之至1.2千分之几）主要受硅酸盐（HH）与碳酸盐（LH）源风化的程度控制，这归因于明显的气候变化。沉积物有机质的δC-13为-27.4％。到每千分之232的数量，n = 24）表明在最后一个类似于75 ka的流域中主要是C-3植物。相对于间冰期，冰川期沉积物的δC-13负值可以更大，这可以通过以夏季降雨和平均年均气温较高为特征的冰期中C-4丰度的增加来解释。 （C）2016 Elsevier B.V.保留所有权利。

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