RESP  > 地球快报-2018年第10期
DOI: 10.1016/j.gca.2017.09.046
篇名:
Mineralogy, early marine diagenesis, and the chemistry of shallow-water carbonate sediments
作者: Higgins, J. A.; Blattler, C. L.; Lundstrom, E. A.; Santiago-Ramos, D. P.; Akhtar, A. A.; Ahm, A-S. Cruger; Bialik, O.; Holmden, C.; Bradbury, H.; Murray, S. T.; Swart, P. K.
通讯作者: Higgins, JA (reprint author), Princeton Univ, Dept Geosci, Princeton, NJ 08544 USA.
发表期刊: GEOCHIMICA ET COSMOCHIMICA ACTA
ISSN: 0016-7037
EISSN: 1872-9533
出版年: 2018
卷: 220, 页码:512-534
发表日期: 2018
语种: 英语
领域: 地球科学 ; 资源环境 ; 气候变化
英文摘要: Shallow-water carbonate sediments constitute the bulk of sedimentary carbonates in the geologic record and are widely used archives of Earth's chemical and climatic history. One of the main limitations in interpreting the geochemistry of ancient carbonate sediments is the potential for post-depositional diagenetic alteration. In this study, we use paired measurements of calcium (Ca-44/Ca-40 or delta Ca-44) and magnesium (Mg-26/Mg-24 or delta Mg-26) isotope ratios in sedimentary carbonates and associated pore-fluids as a tool to understand the mineralogical and diagenetic history of Neogene shallow-water carbonate sediments from the Bahamas and southwest Australia. We find that the Ca and Mg isotopic composition of bulk carbonate sediments at these sites exhibits systematic stratigraphic variability that is related to both mineralogy and early marine diagenesis. The observed variability in bulk sediment Ca isotopes is best explained by changes in the extent and style of early marine diagenesis from one where the composition of the diagenetic carbonate mineral is determined by the chemistry of the fluid (fluid-buffered) to one where the composition of the diagenetic carbonate mineral is determined by the chemistry of the precursor sediment (sediment-buffered). Our results indicate that this process, together with variations in carbonate mineralogy (aragonite, calcite, and dolomite), plays a fundamental and underappreciated role in determining the regional and global stratigraphic expressions of geochemical tracers (delta C-13, delta O-18, major, minor, and trace elements) in shallow-water carbonate sediments in the geologic record. Our results also provide evidence that a large shallow-water carbonate sink that is enriched in Ca-44 can explain the mismatch between the delta Ca-44/40 value of rivers and deep-sea carbonate sediments and call into question the hypothesis that the delta Ca-44/40 value of seawater depends on the mineralogy of primary carbonate precipitations (e.g. 'aragonite seas' and 'calcite seas'). Finally, our results for sedimentary dolomites suggest that paired measurements of Ca and Mg isotopes may provide a unique geochemical fingerprint of mass transfer during dolomitization to better understand the paleo-environmental information preserved in these enigmatic but widespread carbonate minerals. (C) 2017 Elsevier Ltd. All rights reserved.
英文关键词: Carbonate geochemistry ; Isotopes ; Carbon ; Calcium ; Magnesium
收录类别: SCI-E
WOS记录号: WOS:000416502300030
WOS关键词: GREAT BAHAMA BANK ; MG ISOTOPE FRACTIONATION ; CALCIUM ISOTOPES ; EXPERIMENTAL CALIBRATION ; PHANEROZOIC SEAWATER ; PLATFORM CARBONATES ; CENOZOIC DOLOMITES ; INORGANIC CALCITE ; NUMERICAL-MODELS ; BRINE REFLUX
WOS学科: Geochemistry & Geophysics
WOS研究方向: Geochemistry & Geophysics
Citation statistics:
被引频次[WOS]:2   [查看WOS记录]     [查看WOS中相关记录]
资源类型: 期刊论文
条目标识符: http://119.78.100.173/handle/2MONF3CL/87301
Appears in Collections:地球快报-2018年第10期

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Recommended Citation:
Higgins, J. A.,Blattler, C. L.,Lundstrom, E. A.,et al. Mineralogy, early marine diagenesis, and the chemistry of shallow-water carbonate sediments[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2018,220:512-534.
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