Using speleothem 87Sr/86Sr variations tracking the controls on trace element (Sr-Mg) compositions

IF 4 1区地球科学 Q1 GEOGRAPHY, PHYSICAL

Global and Planetary Change Pub Date : 2025-05-09 DOI:10.1016/j.gloplacha.2025.104872

Rishui Chen , Shuyu Xue , Hongbin Zhang , Michael Griffiths , Yi Zhou , Xing Liu , Zhenli Zhu , Lin Chen , Wei Guo , Shitou Wu , Hai Cheng , Junhua Huang , Zongmin Zhu , Shucheng Xie

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引用次数: 0

Abstract

Speleothem Sr/Ca and Mg/Ca ratios have emerged as important hydroclimate proxies due to their geochemical responses under uniform hydrological conditions. However, inconsistent Sr/Ca-Mg/Ca patterns in individual or coeval speleothems within cave systems complicate hydroclimate reconstructions, highlighting the complexities in the controls of Sr-Mg compositions. Recent advances in cave monitoring and multiproxy studies demonstrated the potential of ⁸⁷Sr/⁸⁶Sr in discriminating the sources and hydrological processes of Mg and Sr variations. Nevertheless, systematic applications of ⁸⁷Sr/⁸⁶Sr in both modern process studies and paleoclimate reconstructions are lacking.

In this study, we presented two speleothems (HZZ41B-1 and HZZ11) with similar growing intervals and divergent Sr/Ca and Mg/Ca variations from Haozhu cave in central China. In order to decipher the underlying controls on trace element (Sr-Mg) compositions, we conducted a detailed investigation of ⁸⁷Sr/⁸⁶Sr and trace elements composition of the overlying soil, bedrock, cave sediment, drip water, and the two speleothems. The ⁸⁷Sr/⁸⁶Sr compositions in speleothems are closer to the bedrock end-member, suggesting a dominant bedrock contribution to speleothem Sr compositions. The ⁸⁷Sr/⁸⁶Sr values in speleothem HZZ41B-1 exhibit significant variations and positive correlation with Mg/Ca, which might be caused by the inconsistent dissolution of limestone and dolomite modulated by the varied water-rock interaction (WRI) time in the karst layer. In contrast, ⁸⁷Sr/⁸⁶Sr values in HZZ11 exhibit minimal variability, further supporting the prior calcite precipitation (PCP) control on the Sr-Mg compositions. In short summary, this study offers an approach to understanding the inconsistent variations in speleothem Sr/Ca and Mg/Ca by extra investigation of ⁸⁷Sr/⁸⁶Sr, further conducive to the recognition of the proper proxy for local hydroclimate.

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利用87Sr/86Sr变化的岩石层，追踪微量元素（Sr-Mg）组成的控制

岩石层Sr/Ca和Mg/Ca在均匀水文条件下的地球化学响应已成为重要的水文气候指标。然而，洞穴系统中单个或同时期洞穴主题中不一致的Sr/Ca- mg /Ca模式使水文气候重建复杂化，突出了Sr- mg成分控制的复杂性。近年来洞穴监测和多代理研究的进展表明，87Sr/86Sr在判别Mg和Sr变化的来源和水文过程方面具有潜力。然而，87Sr/86Sr在现代过程研究和古气候重建中的系统应用尚缺乏。本研究在华中好竹洞中发现了生长间隔相似、Sr/Ca和Mg/Ca变化差异较大的2个洞穴主题（HZZ41B-1和HZZ11）。为了揭示其对微量元素（Sr-Mg）组成的潜在控制因素，我们对上覆土壤、基岩、洞穴沉积物、滴水和两个洞穴的87Sr/86Sr和微量元素组成进行了详细的调查。岩浆岩的87Sr/86Sr组成更接近基岩端元，表明基岩对岩浆岩Sr组成的贡献占主导地位。HZZ41B-1岩洞中87Sr/86Sr值与Mg/Ca呈显著正相关，这可能是由于岩溶层中不同水岩相互作用（WRI）时间调节了灰岩和白云岩溶蚀不一致所致。相比之下，HZZ11的87Sr/86Sr值表现出最小的变化，进一步支持了方解石沉淀（PCP）对Sr-Mg组成的控制。综上所述，本研究通过对87Sr/86Sr的额外研究，为理解岩石层Sr/Ca和Mg/Ca的不一致变化提供了一条途径，有助于进一步识别当地水文气候的合适代用物。

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

Global and Planetary Change 地学天文-地球科学综合

CiteScore

7.40

自引率

10.30%

发文量

226

审稿时长

63 days

期刊介绍： The objective of the journal Global and Planetary Change is to provide a multi-disciplinary overview of the processes taking place in the Earth System and involved in planetary change over time. The journal focuses on records of the past and current state of the earth system, and future scenarios , and their link to global environmental change. Regional or process-oriented studies are welcome if they discuss global implications. Topics include, but are not limited to, changes in the dynamics and composition of the atmosphere, oceans and cryosphere, as well as climate change, sea level variation, observations/modelling of Earth processes from deep to (near-)surface and their coupling, global ecology, biogeography and the resilience/thresholds in ecosystems. Key criteria for the consideration of manuscripts are (a) the relevance for the global scientific community and/or (b) the wider implications for global scale problems, preferably combined with (c) having a significance beyond a single discipline. A clear focus on key processes associated with planetary scale change is strongly encouraged. Manuscripts can be submitted as either research contributions or as a review article. Every effort should be made towards the presentation of research outcomes in an understandable way for a broad readership.