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Provenance of terrigenous sediments in the central Bay of Bengal and its relationship to climate changes since 25 ka
Progress in Earth and Planetary Science ( IF 3.9 ) Pub Date : 2020-05-13 , DOI: 10.1186/s40645-020-00328-0
Jingrui Li , Shengfa Liu , Xuefa Shi , Min-Te Chen , Hui Zhang , Aimei Zhu , Jingjing Cui , Somkiat Khokiattiwong , Narumol Kornkanitnan

Lithogenic grain-size, geochemical elements of core sediments from the central Bay of Bengal (BoB) were analyzed to identify sediment provenance and explore the regional “source-sink” processes since 25 ka. Based on the geochemical compositions of core BoB-88, relative contributions of three end-member sources (Himalayan, Myanmar, Indian Peninsula) were calculated and support the general understanding that Himalayan sources were dominant since the last glacial period, which could reach 70% on average in our study. However, sediments from the Indian Peninsula and Myanmar also contributed nonnegligible materials to the central BoB since 25 ka, especially the former shows an obvious increase since 7.5 ka, which was neglected in the previous studies. To trace the sedimentary processes of different provenance terrigenous materials and reveal their response to climate changes, four typical stages with obvious provenance percent variation, including the Last Glacial Maximum period (LGM), Heinrich 1 (H1), Early Holocene Climate Optimum (EHCO), and mid-late Holocene period, were highlighted and discussed. Sea-level change played a dominant role in the glacial-interglacial scale by controlling the transition of deposition center between the shelf/subaquatic delta and the Bengal Fan, especially for sediment from the Himalayan source, exerting influence on contributions from different provenance end-members between the Holocene and the last glacial period. The opposite directions of the southwest and northeast monsoon current in the BoB have a significant influence on the transfer of the Indian Peninsula and Myanmar materials to the studied core, which led to an increase of up to 11% than the average of the Indian Peninsula and a decrease of up to 9% than the average of the Myanmar source during the Holocene. The balance between sea level (limited transport to the deep sea) and ISM (improved erosion production and output to the BoB) during the mid-late Holocene period maintained the stability of Himalayan source percent. Due to the control of the ISM variations, the Himalayan source showed a decrease of up to 20% and 21% than average during the LGM and H1 period, respectively, and an increase of up to 14% than average during the EHCO. The Myanmar source exhibited fluctuations around the average value during the LGM period, but an obvious increase of up to 21% during the H1 period and a decrease up to 8% during the EHCO, while the Indian Peninsula source percent showed little variations during the LGM and H1, but a decrease of up to 6% during the EHCO. Obvious 1/4 processional and millennial periodic changes (5.0 kyr and 1.1 kyr) of contribution proportions from three end-members provide additional evidences for the climate control on the regional source-sink processes and proved the controlled mechanisms of the orbital parameters and possible influence from the solar activity on millennial scales.


中文翻译:

自25 ka以来孟加拉中部海湾陆源性沉积物的来源及其与气候变化的关系

分析了孟加拉中部湾(BoB)的核心沉积物的成岩粒度,地球化学元素,以识别沉积物来源并探索自25 ka以来的区域“源-汇”过程。根据BoB-88核心的地球化学组成,计算了三个终端成员源(喜马拉雅山,缅甸,印度半岛)的相对贡献,并支持人们普遍认为,自上一个冰川期以来,喜马拉雅源一直占主导地位,这一比例可能达到70%平均而言,在我们的研究中。然而,自25 ka以来,印度半岛和缅甸的沉积物也对BoB的中部贡献了不可忽略的物质,尤其是前者自7.5 ka起就显示出明显的增加,这在先前的研究中被忽略。为了追踪不同物源陆源物质的沉积过程并揭示其对气候变化的响应,四个典型阶段具有明显的物源百分比变化,包括最后冰期最大时期(LGM),海因里希一世(H1),全新世早期气候最佳(EHCO) ,以及中新世晚期。海平面变化通过控制陆架/七水三角洲和孟加拉扇之间的沉积中心的转变,在冰川-间冰期范围内发挥了主导作用,尤其是对于喜马拉雅来源的沉积物,对不同出处的最终成员的贡献产生了影响在全新世和上一个冰川期之间。在BoB中,西南季风和东北季风的相反方向对印度半岛和缅甸物质向被研究岩心的转移有重大影响,导致印度半岛和缅甸物质的平均增加幅度高达11%。比全新世期间缅甸来源的平均水平下降多达9%。全新世中期后期,海平面(向深海的有限运输)与ISM(侵蚀的产量和向BoB的产出提高)之间的平衡保持了喜马拉雅源百分比的稳定性。由于对ISM变异的控制,喜马拉雅源在LGM和H1期间分别比平均降低多达20%和21%,在EHCO期间比平均升高多达14%。缅甸来源在LGM期间表现出围绕平均值的波动,但在H1期间明显增加高达21%,在EHCO期间减少高达8%,而印度半岛来源百分比在LGM期间几乎没有变化和H1,但在EHCO期间最多下降6%。来自三个末端成员的明显的1/4进程和千年周期周期性变化(5.0 kyr和1.1 kyr)为区域源汇过程的气候控制提供了额外的证据,并证明了轨道参数的受控机制和可能的影响来自太阳活动的千年尺度。而印度半岛的源百分比在LGM和H1期间几乎没有变化,但在EHCO期间下降了6%。来自三个终端成员的贡献比例的明显的1/4进程和千年周期变化(5.0 kyr和1.1 kyr)为区域源汇过程的气候控制提供了额外的证据,并证明了轨道参数的受控机制和可能的影响来自千年尺度的太阳活动。而印度半岛的源百分比在LGM和H1期间几乎没有变化,但在EHCO期间下降了6%。来自三个末端成员的明显的1/4进程和千年周期周期性变化(5.0 kyr和1.1 kyr)为区域源汇过程的气候控制提供了额外的证据,并证明了轨道参数的受控机制和可能的影响来自太阳活动的千年尺度。
更新日期:2020-05-13
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