地球地幔的氯同位素组成。

The chlorine isotope composition of Earth's mantle.

作者信息

Bonifacie M, Jendrzejewski N, Agrinier P, Humler E, Coleman M, Javoy M

机构信息

Equipe de Physico-Chimie des Fluides, Géologiques, Institut de Physique du Globe de Paris (IPGP) and Université Paris, Diderot (UPD), CNRS-INSU-Unité Mixte de Recherche (UMR) 7154, 75251 Paris Cedex 05, France.

出版信息

Science. 2008 Mar 14;319(5869):1518-20. doi: 10.1126/science.1150988.

DOI:10.1126/science.1150988

PMID:18339936

Abstract

Chlorine stable isotope compositions (delta37Cl) of 22 mid-ocean ridge basalts (MORBs) correlate with Cl content. The high-delta37Cl, Cl-rich basalts are highly contaminated by Cl-rich materials (seawater, brines, or altered rocks). The low-delta37Cl, Cl-poor basalts approach the composition of uncontaminated, mantle-derived magmas. Thus, most or all oceanic lavas are contaminated to some extent during their emplacement. MORB-source mantle has delta37Cl </= -1.6 per mil (per thousand), which is significantly lower than that of surface reservoirs (approximately 0 per thousand). This isotopic difference between the surface and deep Earth results from net Cl isotopic fractionation (associated with removal of Cl from the mantle and its return by subduction over Earth history) and/or the addition (to external reservoirs) of a late volatile supply that is 37Cl-enriched.

摘要

22个大洋中脊玄武岩（MORB）的氯稳定同位素组成（δ³⁷Cl）与氯含量相关。高δ³⁷Cl、富氯的玄武岩受到富氯物质（海水、卤水或蚀变岩石）的高度污染。低δ³⁷Cl、贫氯的玄武岩接近未受污染的地幔源岩浆的组成。因此，大多数或所有大洋熔岩在侵位过程中都受到了一定程度的污染。MORB源地幔的δ³⁷Cl≤-1.6‰（千分比），这明显低于地表储库的δ³⁷Cl（约为0‰）。地表与深部地球之间的这种同位素差异是由净氯同位素分馏（与地幔中氯的去除及其在地球历史上通过俯冲作用返回有关）和/或添加了富含³⁷Cl的晚期挥发性物质（进入外部储库）导致的。