气候变化领域集成服务门户(CCPortal): A Mg Isotopic Perspective on the Mobility of Magnesium During Serpentinization and Carbonation of the Oman Ophiolite

CCPortal

DOI	10.1029/2020JB020237
	A Mg Isotopic Perspective on the Mobility of Magnesium During Serpentinization and Carbonation of the Oman Ophiolite
	de Obeso J.C.; Santiago Ramos D.P.; Higgins J.A.; Kelemen P.B.
发表日期	2021
ISSN	21699313
卷号	126 期号:2
英文摘要	Alteration of mantle peridotite in the Samail ophiolite forms secondary minerals, mainly serpentine and Mg-rich carbonates. Magnesium accounts for ∼25 – 30% of peridotite mass and its mobility can be used to trace this alteration. We report the first set of Mg isotope measurements from peridotites and their alteration products in Oman. Partially serpentinized peridotites have Mg isotope ratios that are indistinguishable from estimates for the average mantle and bulk silicate earth (δ26Mg = −0.25 ± 0.04‰). However, more extensively altered peridotite samples show large shifts in Mg isotopic composition. The range of δ26Mg values for our suite of alteration products from the mantle section is ∼4.5‰ (from −3.39‰ to 1.19‰), or >60% of the total range of terrestrial variability in δ26Mg values. Serpentine veins are typically enriched in 26Mg (max δ26Mg value = 0.96‰) whereas Mg-carbonate veins are associated with low 26Mg/24Mg ratios (magnesite δ26Mg = −3.3‰, dolomite δ26Mg = −1.91‰). Our preferred explanation for the range in δ26Mg values involves coprecipitation of serpentine and carbonates at water-to-rock ratios >103. The coincidence of alteration products characterized by δ26Mg values that are both lower and higher than bulk silicate Earth and the finite 14C ages of the carbonates suggest that both serpentinization and carbonation are ongoing in Oman. Rates of calcite precipitation in travertines inferred from Δ26Mgcal-fl suggest that travertine formation in Oman sequesters a total of 106–107 kg CO2/yr, consistent with previous estimates. © 2020. American Geophysical Union. All Rights Reserved.
英文关键词	carbonation; Mg isotopes; Oman; ophiolite; peridotite; serpentinization
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/187334
作者单位	Lamont Doherty Earth Observatory, Columbia University, Palisades, NY, United States; Now at Department of Geoscience, University of Calgary, Calgary, AB, Canada; Department of Geosciences, Princeton University, Princeton, NJ, United States; Now at Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, United States; Department of Earth and Environmental Sciences, Columbia University, Palisades, NY, United States
推荐引用方式 GB/T 7714	de Obeso J.C.,Santiago Ramos D.P.,Higgins J.A.,et al. A Mg Isotopic Perspective on the Mobility of Magnesium During Serpentinization and Carbonation of the Oman Ophiolite[J],2021,126(2).
APA	de Obeso J.C.,Santiago Ramos D.P.,Higgins J.A.,&Kelemen P.B..(2021).A Mg Isotopic Perspective on the Mobility of Magnesium During Serpentinization and Carbonation of the Oman Ophiolite.Journal of Geophysical Research: Solid Earth,126(2).
MLA	de Obeso J.C.,et al."A Mg Isotopic Perspective on the Mobility of Magnesium During Serpentinization and Carbonation of the Oman Ophiolite".Journal of Geophysical Research: Solid Earth 126.2(2021).