Chlorine isotope homogeneity of the mantle, crust and carbonaceous chondrites
journal contributionposted on 2023-05-16, 21:35 authored by Sharp, ZD, Barnes, JD, Brearley, AJ, Chaussidon, M, Fischer, TP, Vadim KamenetskyVadim Kamenetsky
Chlorine in the Earth is highly depleted relative to carbonaceous chondrites and solar abundances. Knowledge of the Cl concentrations and distribution on Earth is essential for understanding the origin of these depletions. Large differences in the stable chlorine isotope ratios of meteoritic, mantle and crustal materials have been used as evidence for distinct reservoirs in the solar nebula and to calculate the relative proportions of Cl in the mantle and crust. Here we report that large isotopic differences do not exist, and that carbonaceous chondrites, mantle and crust all have the same 37Cl/35Cl ratios. We have further analysed crustal sediments from the early Archaean era to the Recent epoch and find no systematic isotopic variations with age, demonstrating that the mantle and crust have always had the same Î´37Cl value. The similarity of mantle, crust and carbonaceous chondrites establishes that there were no nebular reservoirs with distinct isotopic compositions, no isotopic fractionation during differentiation of the Earth and no late (post-core formation) Cl-bearing volatile additions to the crustal veneer with a unique isotopic composition. Â©2007 Nature Publishing Group.
Department/SchoolSchool of Natural Sciences
PublisherNature Publishing Group
Place of publicationUK