Clay Li isotopes reveal contrasting responses of chemical weathering intensity to hydroclimate changes in South Asia

IF 3.6 2区地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS

Chemical Geology Pub Date : 2025-02-04 DOI:10.1016/j.chemgeo.2025.122652

Jingrui Li , Xuefa Shi , Shengfa Liu , Hui Zhang , Zhaowei Jing , Xiaoming Miao , Kaikai Wu , Rui Jiang , Somkiat Khokiattiwong , Narumol Kornkanitnan

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引用次数: 0

Abstract

Weathering processes in orogenic belts play a pivotal role in Earth's climate regulation. However, the link between silicate weathering and hydroclimatic fluctuations remains elusive. Here, we investigate the lithium‑neodymium isotopic compositions (δ⁷Li, εNd) and clay mineralogy of sediments in the northeastern Bay of Bengal to determine if the δ⁷Li can be used as a reliable tracer of the chemical weathering intensity and to assess how weathering responses to hydroclimate changes. δ⁷Li and εNd values range from −2.4 ‰ to 0.4 ‰ and − 12.5 to −8.9, respectively, with clay mineralogy dominated by illite (57 % on average). A decline in δ⁷Li since 13.5 ka, averaging −1.3 ‰, compared to −0.7 ‰ between 25 ka and 13.5 ka, indicates intensified weathering aligned with monsoon variations. Prominent millennial-scale δ⁷Li fluctuations (2.8 ‰ in maximum) during the last deglaciation, showing lower values during the cold events (Younger Drys and Heinrich stadial 1), imply a different mechanism of weathering response to hydroclimate changes. Shift of high mountain- versus floodplain-dominated weathering regimes and hydrology induced changes in water-rock interaction time or water residence time, are suggested to be responsible for δ⁷Li changes at glacial-interglacial scale and millennial scale, respectively. Our study provides key evidence for weathering response to short-term climate change, and highlights the carbon sink role of silicate weathering in floodplains at short-term scales and the potential of Li isotopes in reconstructing past hydroclimate changes.

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来源期刊

Chemical Geology 地学-地球化学与地球物理

CiteScore

7.20

自引率

10.30%

发文量

374

审稿时长

3.6 months

期刊介绍： Chemical Geology is an international journal that publishes original research papers on isotopic and elemental geochemistry, geochronology and cosmochemistry. The Journal focuses on chemical processes in igneous, metamorphic, and sedimentary petrology, low- and high-temperature aqueous solutions, biogeochemistry, the environment and cosmochemistry. Papers that are field, experimentally, or computationally based are appropriate if they are of broad international interest. The Journal generally does not publish papers that are primarily of regional or local interest, or which are primarily focused on remediation and applied geochemistry. The Journal also welcomes innovative papers dealing with significant analytical advances that are of wide interest in the community and extend significantly beyond the scope of what would be included in the methods section of a standard research paper.