成果归属作者：

柯珊

成果归属机构：

地球科学与资源学院

作者：

Teng, Fang-Zhen ; Li, Wang-Ye ; Ke, Shan ; Marty, Bernard ; Dauphas, Nicolas ; Huang, Shichun ; Wu, Fu-Yuan ; Pourmand, Ali

单位：

Univ Arkansas, Isotope Lab, Dept Geosci, Fayetteville, AR 72701 USA;Univ Arkansas, Arkansas Ctr Space & Planetary Sci, Fayetteville, AR 72701 USA;Univ Sci & Technol China, CAS Key Lab Crust Mantle Mat & Environm, Sch Earth & Space Sci, Hefei 230026, Peoples R China;China Univ Geosci, State Key Lab Geol Proc & Mineral Resources, Sch Earth Sci & Mineral Resources, Beijing 100083, Peoples R China;CNRS, Ctr Rech Petrog & Geochim, F-54501 Vandoeuvre Les Nancy, France;Univ Chicago, Origins Lab, Dept Geophys Sci, Chicago, IL 60637 USA;Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA;Harvard Univ, Dept Earth & Planetary Sci, Cambridge, MA 02138 USA;Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China;Univ Miami, Dept Marine Geol & Geophys, Miami, FL 33149 USA

摘要：

To constrain further the Mg isotopic composition of the Earth and chondrites, and investigate the behavior of Mg isotopes during planetary formation and magmatic processes, we report high-precision (+/-0.06 parts per thousand on delta(25)Mg and +/-0.07 parts per thousand on delta(26)Mg, 2SD) analyses of Mg isotopes for (1) 47 mid-ocean ridge basalts covering global major ridge segments and spanning a broad range in latitudes, geochemical and radiogenic isotopic compositions; (2) 63 ocean island basalts from Hawaii (Kilauea, Koolau and Loihi) and French Polynesia (Society Island and Cook-Austral chain); (3) 29 peridotite xenoliths from Australia, China, France, Tanzania and USA; and (4) 38 carbonaceous, ordinary and enstatite chondrites including 9 chondrite groups (CI, CM, CO, CV, L, LL, H, EH and EL). Oceanic basalts and peridotite xenoliths have similar Mg isotopic compositions, with average values of delta(25)Mg = -0.13 +/- 0.05 (2SD) and delta(26)mg = -0.26 +/- 0.07 (2SD) for global oceanic basalts (n = 110) and delta(25)Mg = 0.13 +/- 0.03 (2SD) and delta(26)Mg = -0.25 +/- 0.04 (2SD) for global peridotite xenoliths (n = 29). The identical Mg isotopic compositions in oceanic basalts and peridotites suggest that equilibrium Mg isotope fractionation during partial melting of peridotite mantle and magmatic differentiation of basaltic magma is negligible. Thirty-eight chondrites have indistinguishable Mg isotopic compositions, with delta(25)Mg = 0.15 +/- 0.04 (2SD) and delta(26)Mg = 0.28 +/- 0.06 (2SD). The constancy of Mg isotopic compositions in all major types of chondrites suggest that primary and secondary processes that affected the chemical and oxygen isotopic compositions of chondrites did not significantly fractionate Mg isotopes. Collectively, the Mg isotopic composition of the Earth's mantle, based on oceanic basalts and peridotites, is estimated to be 0.13 +/- 0.04 for delta(25)Mg and 0.25 +/- 0.07 for delta(26)Mg (2SD, n = 139). The Mg isotopic composition of the Earth, as represented by the mantle, is similar to chondrites. The chondritic composition of the Earth implies that Mg isotopes were well mixed during accretion of the inner solar system. (C) 2010 Elsevier Ltd. All rights reserved'.

基金：

NSF [EAR-0838227, EAR0820807]; Arkansas Space Grant [SW19002]; NASA [NNX09AG59G]; Packard fellowship

语种：

英文

DOI：

10.1016/j.gca.2010.04.019

来源：

GEOCHIMICA ET COSMOCHIMICA ACTA,2010(14):4150-4166.

出版日期：

2010-07-15

提交日期：

2017-12-14

引用参考：

Teng, Fang-Zhen; Li, Wang-Ye; Ke, Shan; Marty, Bernard; Dauphas, Nicolas; Huang, Shichun; Wu, Fu-Yuan; Pourmand, Ali. Magnesium isotopic composition of the Earth and chondrites[J]. GEOCHIMICA ET COSMOCHIMICA ACTA,2010(14):4150-4166.