TY - JOUR

T1 - Lithium isotope composition of ordinary and carbonaceous chondrites, and differentiated planetary bodies

T2 - Bulk solar system and solar reservoirs

AU - Seitz, Hans Michael

AU - Brey, Gerhard P.

AU - Zipfel, Jutta

AU - Ott, Ulrich

AU - Weyer, Stefan

AU - Durali, Soodabeh

AU - Weinbruch, Stephan

N1 - Funding information: This study was financially supported by the Deutsche Forschungsgemeinschaft (Grant No. BR 1012/24-1). We profited much from discussions with Yann Lahaye, Dmitri Ionov, Frank Brenker and Andrei Girnis. For technical assistance we thank Anna Karina Neumann, Thomas Kautz, and Franz Kneissl. Rick Carlson (editorial handling), Roberta Rudnick and Rachel James are thanked for their constructive reviews.

PY - 2007/8/30

Y1 - 2007/8/30

N2 - In order to better constrain the Li isotope composition of the bulk solar system and Li isotope fractionation during accretion and parent body processes, Li isotope compositions and concentrations were determined on a number of meteorite falls and finds. This is the first comprehensive study that systematically investigates a representative set of samples from carbonaceous chondrites (CI, CM2, CO3, CV3, CK4 and one ungrouped member), enstatite chondrites (EH, EL), ordinary chondrites (H, L, LL), and achondrites (one eucrite, diogenites, one pallasite, and a silicate inclusion from a IAB iron). Carbonaceous chondrites have an average isotope composition of δ7Li = + 3.2‰ ± 1.9 (2σ) which agrees with the average composition of relatively pristine olivines (representative for the bulk composition) from the Earth primitive upper mantle (PUM). This is lighter than the average δ7Li of the basaltic differentiates of the Earth, Moon and Mars and the achondrites. It is an important observation, however, that the lighter end of the isotopic range of the differentiates always coincides with the averages of the mantle olivines and the carbonaceous chondrites. From this we conclude that the bulk of the inner solar system consists mostly of material from carbonaceous chondrites and that the variation seen in the differentiates is due to planetary body processes. Ordinary chondrites are significantly lighter than carbonaceous chondrites. No significant differences in δ7Li exist between enstatite chondrites (n = 3) and carbonaceous or ordinary chondrites. The difference between carbonaceous and ordinary chondrites and the variability within the chondrites could indicate the existence of distinct Li isotope reservoirs in the early solar nebula.

AB - In order to better constrain the Li isotope composition of the bulk solar system and Li isotope fractionation during accretion and parent body processes, Li isotope compositions and concentrations were determined on a number of meteorite falls and finds. This is the first comprehensive study that systematically investigates a representative set of samples from carbonaceous chondrites (CI, CM2, CO3, CV3, CK4 and one ungrouped member), enstatite chondrites (EH, EL), ordinary chondrites (H, L, LL), and achondrites (one eucrite, diogenites, one pallasite, and a silicate inclusion from a IAB iron). Carbonaceous chondrites have an average isotope composition of δ7Li = + 3.2‰ ± 1.9 (2σ) which agrees with the average composition of relatively pristine olivines (representative for the bulk composition) from the Earth primitive upper mantle (PUM). This is lighter than the average δ7Li of the basaltic differentiates of the Earth, Moon and Mars and the achondrites. It is an important observation, however, that the lighter end of the isotopic range of the differentiates always coincides with the averages of the mantle olivines and the carbonaceous chondrites. From this we conclude that the bulk of the inner solar system consists mostly of material from carbonaceous chondrites and that the variation seen in the differentiates is due to planetary body processes. Ordinary chondrites are significantly lighter than carbonaceous chondrites. No significant differences in δ7Li exist between enstatite chondrites (n = 3) and carbonaceous or ordinary chondrites. The difference between carbonaceous and ordinary chondrites and the variability within the chondrites could indicate the existence of distinct Li isotope reservoirs in the early solar nebula.

KW - bulk silicate Earth BSE

KW - carbonaceous and enstatite chondrites

KW - HEDs

KW - IAB silicate inclusions

KW - lithium isotopes

KW - ordinary

KW - pallasite

UR - http://www.scopus.com/inward/record.url?scp=34447499998&partnerID=8YFLogxK

U2 - 10.1016/j.epsl.2007.06.019

DO - 10.1016/j.epsl.2007.06.019

M3 - Article

AN - SCOPUS:34447499998

VL - 260

SP - 582

EP - 596

JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

SN - 0012-821X

IS - 3-4

ER -