The cosmic molybdenum-ruthenium isotope correlation

被引:148
作者
Dauphas, N
Davis, AM
Marty, B
Reisberg, L
机构
[1] Univ Chicago, Dept Geophys Sci, Chicago, IL 60637 USA
[2] Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA
[3] Univ Chicago, Chicago Ctr Cosmochem, Chicago, IL 60637 USA
[4] CNRS, Ctr Rech Petrog & Geochim, UPR 2300, F-54501 Vandoeuvre Les Nancy, France
[5] Ecole Natl Super Geol, F-54501 Vandoeuvre Les Nancy, France
基金
美国国家航空航天局;
关键词
isotope anomalies; molybdenum; ruthenium; s-process; accretion;
D O I
10.1016/j.epsl.2004.07.026
中图分类号
P3 [地球物理学]; P59 [地球化学];
学科分类号
0708 ; 070902 ;
摘要
Dauphas et al. [Astrophys. J. 565 (2002) 640-644] reported molybdenum isotopic anomalies in differentiated and bulk primitive meteorites. It is shown here that these isotopic anomalies correlate with one another in exactly the way expected from nucleosynthesis theory if different regions of the nebula received different contributions of s-process matter synthesized in low-mass AGB stars. Furthermore, when bulk measurements are grouped by meteorite class, the molybdenum isotopic anomalies correlate with the ruthenium isotopic anomalies recently reported by Chen et al. [Lunar Planet. Sci. XXXIV (2003) #1789], again indicating a heterogeneous distribution of s-process matter. As molybdenum is only moderately siderophile, most of the molybdenum presently in the mantle was delivered before the completion of core formation. In contrast, because ruthenium is highly siderophile, nearly all of the mantle ruthenium was delivered by a late veneer, after the end of core formation. Thus, the fact the silicate Earth lies on the Mo-Ru cosmic correlation supports the idea that the Earth accreted homogeneously. Stated otherwise, the feeding zone of the Earth did not change drastically with time, as both the bulk of the Earth and the late veneer accreted from material from the same Mo-Ru isotopic reservoir. (C) 2004 Elsevier B.V. All rights reserved.
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页码:465 / 475
页数:11
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