Abstract
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‰ on δ25Mg and ±0.07‰ on δ26Mg, 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 δ25Mg = -0.13 ± 0.05 (2SD) and δ26Mg = -0.26 ± 0.07 (2SD) for global oceanic basalts (n = 110) and δ25Mg = -0.13 ± 0.03 (2SD) and δ26Mg = -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 δ25Mg = -0.15 ± 0.04 (2SD) and δ26Mg = -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 δ25Mg and -0.25 ± 0.07 for δ26Mg (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.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 4150-4166 |
| Number of pages | 17 |
| Journal | Geochimica et Cosmochimica Acta |
| Volume | 74 |
| Issue number | 14 |
| DOIs | |
| State | Published - Jul 2010 |
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ASJC Scopus subject areas
- Geochemistry and Petrology
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Magnesium isotopic composition of the Earth and chondrites. / Teng, Fang Zhen; Li, Wang Ye; Ke, Shan; Marty, Bernard; Dauphas, Nicolas; Huang, Shichun; Wu, Fu Yuan; Pourmand, Ali.
In: Geochimica et Cosmochimica Acta, Vol. 74, No. 14, 07.2010, p. 4150-4166.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Magnesium isotopic composition of the Earth and chondrites
AU - Teng, Fang Zhen
AU - Li, Wang Ye
AU - Ke, Shan
AU - Marty, Bernard
AU - Dauphas, Nicolas
AU - Huang, Shichun
AU - Wu, Fu Yuan
AU - Pourmand, Ali
PY - 2010/7
Y1 - 2010/7
N2 - 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‰ on δ25Mg and ±0.07‰ on δ26Mg, 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 δ25Mg = -0.13 ± 0.05 (2SD) and δ26Mg = -0.26 ± 0.07 (2SD) for global oceanic basalts (n = 110) and δ25Mg = -0.13 ± 0.03 (2SD) and δ26Mg = -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 δ25Mg = -0.15 ± 0.04 (2SD) and δ26Mg = -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 δ25Mg and -0.25 ± 0.07 for δ26Mg (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.
AB - 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‰ on δ25Mg and ±0.07‰ on δ26Mg, 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 δ25Mg = -0.13 ± 0.05 (2SD) and δ26Mg = -0.26 ± 0.07 (2SD) for global oceanic basalts (n = 110) and δ25Mg = -0.13 ± 0.03 (2SD) and δ26Mg = -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 δ25Mg = -0.15 ± 0.04 (2SD) and δ26Mg = -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 δ25Mg and -0.25 ± 0.07 for δ26Mg (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.
UR - http://www.scopus.com/inward/record.url?scp=77953686917&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=77953686917&partnerID=8YFLogxK
U2 - 10.1016/j.gca.2010.04.019
DO - 10.1016/j.gca.2010.04.019
M3 - Article
AN - SCOPUS:77953686917
VL - 74
SP - 4150
EP - 4166
JO - Geochmica et Cosmochimica Acta
JF - Geochmica et Cosmochimica Acta
SN - 0016-7037
IS - 14
ER -