Geochemistry of core sediments along the Active Channel, northeastern Indian Ocean over the past 50,000 years: Sources and climatic implications
Geochemistry of core sediments along the Active Channel, northeastern Indian Ocean over the past 50,000 years: Sources and climatic implications
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过去 5 万年印度洋东北部活动水道沿线岩心沉积物的地球化学：来源和气候影响
DOI：
10.1016/j.palaeo.2019.02.021
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Shi Xuefa
中科院分区：
文献类型：
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作者：
Liu Jianguo;Zhu Zhu;Xiang Rong;Cao Li;He Wei;Liu Shengfa;Shi Xuefa
通过对印度洋东北部两个重力岩心（10 YDY 09和12 I 712）沉积物的常量和微量元素分析，探讨了沉积物的物源及其与50 ka以来气候变化的关系。分析了恒河-雅鲁藏布江（G-B）、戈达瓦里-克里希纳河（G-K）和马哈纳迪河（Mahanadi）等主要潜在源区的稀土元素（REE）组成，估算了沉积物的贡献。研究结果表明，研究区沉积物是上述三条河流排放的混合物。全新世期间，降雨量增加，G-K河流对沉积物的贡献显著增加，这可能是由于东印度沿岸流（EICC）的加强，G-K河流提供了大量沉积物。来自G-B河流的较高沉积物贡献证明了活动通道在将沉积物输送到孟加拉扇远端中的作用。末次盛冰期（LGM），特别是后期，印度夏季风减弱，而冬季风增强，导致印度洋东北部化学风化和元素富集减少。当降雨量较小时，由于风化时间较长，沉积物钾流失，化学风化作用增强，K2 O/TiO 2比值降低。然而，当海平面在全新世达到一定高度时，河流沉积物不容易通过海底通道进入深水环境，孟加拉扇非常发育。
Major and trace elements of sediments from two gravity cores (10YDY09 and 12I712) in the northeastern Indian Ocean have been analyzed for sediment provenance and the relationship of the sediments with climate change since 50 ka. The rare earth element (REE) compositions were analyzed, and the sediment contributions were estimated for the major potential sources, including the Ganges-Brahmaputra (G-B), Godavari-Krishna (G-K) and Mahanadi Rivers. Our results showed that the sediments in the study area were a mixture of sediments discharged from the above three rivers. The sediment contribution of the G-K Rivers increased notably during the Holocene when the rainfall increased, which may be caused by the strengthening of the East Indian Coastal Current (EICC) and the resulting large amounts of sediments supplied by the G-K Rivers. The higher sediment contribution from the G-B Rivers demonstrated the role of the Active Channel in transporting sediments to the distal Bengal Fan. During the last glacial maximum (LGM), especially in the late period, the Indian summer monsoon weakened, but the winter monsoon strengthened, resulting in a decrease in chemical weathering and elemental enrichment in the northeastern Indian Ocean. Conversely, when the rainfall was low, the chemical weathering strengthened and K2O/TiO2ratios were lowered due to the longer weathering time and resulting sediment potassium loss. However, when the sea level reached a certain height during the Holocene, the fluvial sediments could not easily enter deep-water environments through submarine channels, which were well developed in the Bengal Fan.