Geochemical evidence for increased sediment supply from the Deccan basalts during the Late Holocene aridity

IF 1.9 3区 地球科学 Q3 GEOGRAPHY, PHYSICAL
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Abstract

The drainage basins of Peninsular India are characterized by silicate-dominated lithologies, and influenced by Indian Summer Monsoon (ISM) precipitation. The Godavari River Basin (GRB), the largest river basin in Peninsular India situated within the ISM region, represents an ideal case for assessing weathering and climate interaction at different timescales. In this contribution, major and trace elemental geochemistry of a radiocarbon-dated sediment core (CY; 54.2 m long) from the Godavari delta region was investigated to reconstruct erosional changes in the Godavari basin in response to ISM variations during the Late Holocene. Comparison of geochemical data for the CY sediments and their possible sources confirm dominant sediment supply from the Deccan basalts and Archean Gneisses to the site. A distinct increase in Ti/Al, Ca/Al, and Cr/Al, along with a decrease in CIA* and LREE/HREE at 3.2 ka BP, point to relative increase in sediment supply from the Deccan Traps. Inverse model calculations of Al-normalized ratios of selected elements (Ti, Fe, V, Cr, Cu, Co) estimate that the core site on average receives ∼41 % sediments from the Deccan regions, which increased by ∼20% since last 3.2 ka BP. This accelerated erosion is attributed to the coupled effect of aridity-induced Deccan upland erosion with a relative decrease from the Archean rock source. This period of accelerated erosion coincides with the abandonment of Chalcolithic settlements.

全新世晚期干旱时期德干玄武岩沉积物供应增加的地球化学证据
印度半岛的流域以硅酸盐岩为主,并受到印度夏季季风(ISM)降水的影响。戈达瓦里河流域(GRB)是印度半岛最大的河流流域,位于印度夏季季风区域内,是评估不同时间尺度下风化与气候相互作用的理想案例。本文研究了戈达瓦里三角洲地区放射性碳年代沉积物岩芯(CY;54.2 米长)的主要和痕量元素地球化学,以重建戈达瓦里流域在全新世晚期随 ISM 变化而发生的侵蚀变化。对 CY 沉积物及其可能来源的地球化学数据进行比较后证实,该地点的沉积物主要来自德干玄武岩和阿尔川片麻岩。在 3.2 ka BP 时,Ti/Al、Ca/Al 和 Cr/Al 明显增加,CIA* 和 LREE/HREE 下降,表明来自德干陷阱的沉积物相对增加。通过对选定元素(Ti、Fe、V、Cr、Cu、Co)的Al归一化比率进行反演模型计算,估计岩芯区平均有41%的沉积物来自德干地区,比前3.2 ka BP增加了20%。这种加速侵蚀是由于干旱引起的德干高原侵蚀与来自阿契安岩源的相对减少的耦合效应造成的。这一时期的加速侵蚀恰好发生在旧石器时代居住区被遗弃的时期。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Quaternary International
Quaternary International 地学-地球科学综合
CiteScore
5.60
自引率
4.50%
发文量
336
审稿时长
3 months
期刊介绍: Quaternary International is the official journal of the International Union for Quaternary Research. The objectives are to publish a high quality scientific journal under the auspices of the premier Quaternary association that reflects the interdisciplinary nature of INQUA and records recent advances in Quaternary science that appeal to a wide audience. This series will encompass all the full spectrum of the physical and natural sciences that are commonly employed in solving Quaternary problems. The policy is to publish peer refereed collected research papers from symposia, workshops and meetings sponsored by INQUA. In addition, other organizations may request publication of their collected works pertaining to the Quaternary.
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