The impact and implications of aragonite-to-calcite transformation on speleothem trace element composition

doi:10.1016/j.sedgeo.2021.106010

IEECAS OpenIR > 现代环境研究室

	The impact and implications of aragonite-to-calcite transformation on speleothem trace element composition
	He, Mei 1,3; Cai, Yanjun 1,2; Zhang, Haiwei 2; Xue, Gang 4; Cheng, Xing1,3 ; Lu, Yanbin 1; Wang, Guozhen 1,3; Qin, Xiuling 1; Ma, Le 1; Wei, Yingying 1,3; Huang, Shouyi 1,3; Chang, Hong1 ; Yan, Hong 1,2
通讯作者	Cai, Yanjun(yanjun_cai@xjtu.edu.cn)
	2021-11-01
发表期刊	SEDIMENTARY GEOLOGY
ISSN	0037-0738
卷号	425 页码:11
摘要	Trace elements in cave carbonates (both calcite and aragonite) have been considered major proxies in paleo-hydroclimatic research. However, their imprints in authigenic minerals might be altered by neomorphic processes (e.g., aragonite-to-calcite transformation). Therefore, it is crucial to understand the impacts of neomorphism on the trace element compositions of secondary calcite and understand the mechanisms of trace elements redistribution during neomorphic processes. In this study, two aragonite stalagmites (SN3 and SN15) from Shennong Cave, part of which were transformed into calcite, were further inspected and analyzed in terms of petrological observations, trace element geochemistry, and Mg compositional mapping. The results show that (1) the aragonite-to-calcite transformation in SN3 and SN15 occurs by a dissolution-precipitation mechanism and is influenced by several factors, including internal fluid compositions, microstructure (such as porosity and permeability) of the parent material, and crystal defects. (2) The primary aragonite is enriched in Sr but depleted in Mg compared with secondary calcite because of the crystallographic disparity. The non-equilibrium absorption of Mg and slow diffusive element transport may contribute to the extremely high Mg/Ca ratios in secondary calcite near the mineral phase boundary. Incorporation competition among trace elements also plays an important role in affecting the distribution of Sr and Mg in neomorphic calcite. Considering the previous study on the alteration of isotopes (delta O-18, delta C-13) associated with the aragonite-to-calcite transformation, we propose that intervening fluids play an important role in altering the secondary calcite oxygen isotopic composition and Mg/Ca ratio, while the composition of primary aragonite dictates the secondary calcite carbon isotopic composition and Sr/Ca ratio, provided that the transformation of aragonite to calcite caused by a dissolution-reprecipitation process occurring in trapped pore water. These results highlight the indispensability of petrographic analysis of speleothem specimens before using trace elements and isotopes for paleoclimate research. (C) 2021 Elsevier B.V. All rights reserved.
关键词	Speleothems Aragonite Calcite Transformation Trace element
DOI	10.1016/j.sedgeo.2021.106010
关键词[WOS]	SOUTHEASTERN CHINA ; CASTANAR CAVE ; DIAGENESIS ; REPLACEMENT ; GROWTH ; STALAGMITE ; MINERALOGY ; URANIUM ; MG2+ ; RECRYSTALLIZATION
收录类别	SCI ; SCI
语种	英语
资助项目	Strategic Priority Research program of Chinese Academyof Sciences[XDB 40010200] ; National Key Research and Development Program of China[2017YFA0603401]
WOS研究方向	Geology
项目资助者	Strategic Priority Research program of Chinese Academyof Sciences ; National Key Research and Development Program of China
WOS类目	Geology
WOS记录号	WOS:000711438400002
出版者	ELSEVIER
引用统计	被引频次：1[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.ieecas.cn/handle/361006/17140
专题	现代环境研究室
通讯作者	Cai, Yanjun
作者单位	1.Chinese Acad Sci, Inst Earth Environm, State Key Lab Loess & Quaternary Geol, Xian 710061, Peoples R China 2.Xi An Jiao Tong Univ, Inst Global Environm Change, Xian 710049, Peoples R China 3.Univ Chinese Acad Sci, Beijing 100049, Peoples R China 4.Northwest Univ, Dept Geol, State Key Lab Continental Dynam, Xian 710069, Peoples R China
推荐引用方式 GB/T 7714	He, Mei,Cai, Yanjun,Zhang, Haiwei,et al. The impact and implications of aragonite-to-calcite transformation on speleothem trace element composition[J]. SEDIMENTARY GEOLOGY,2021,425:11.
APA	He, Mei.,Cai, Yanjun.,Zhang, Haiwei.,Xue, Gang.,Cheng, Xing.,...&Yan, Hong.(2021).The impact and implications of aragonite-to-calcite transformation on speleothem trace element composition.SEDIMENTARY GEOLOGY,425,11.
MLA	He, Mei,et al."The impact and implications of aragonite-to-calcite transformation on speleothem trace element composition".SEDIMENTARY GEOLOGY 425(2021):11.