Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

Titanium stable isotope investigation of magmatic processes on the Earth and Moon

Millet, Marc-Alban, Dauphas, Nicolas, Greber, Nicolas D., Burton, Kevin W., Dale, Chris W., Debret, Baptiste, Macpherson, Colin G., Nowell, Geoffrey M. and Williams, Helen M. 2016. Titanium stable isotope investigation of magmatic processes on the Earth and Moon. Earth and Planetary Science Letters 449 , pp. 197-205. 10.1016/j.epsl.2016.05.039

[img]
Preview
PDF - Accepted Post-Print Version
Download (774kB) | Preview

Abstract

We present titanium stable isotope measurements of terrestrial magmatic samples and lunar mare basalts with the aims of constraining the composition of the lunar and terrestrial mantles and evaluating the potential of Ti stable isotopes for understanding magmatic processes. Relative to the OL–Ti isotope standard, the δ49Ti values of terrestrial samples vary from −0.05 to +0.55‰, whereas those of lunar mare basalts vary from −0.01 to +0.03‰ (the precisions of the double spike Ti isotope measurements are ca. ±0.02‰ at 95% confidence). The Ti stable isotope compositions of differentiated terrestrial magmas define a well-defined positive correlation with SiO2 content, which appears to result from the fractional crystallisation of Ti-bearing oxides with an inferred isotope fractionation factor of View the MathML source. Primitive terrestrial basalts show no resolvable Ti isotope variations and display similar values to mantle-derived samples (peridotite and serpentinites), indicating that partial melting does not fractionate Ti stable isotopes and that the Earth's mantle has a homogeneous δ49Ti composition of +0.005 ± 0.005 (95% c.i., n=29). Eclogites also display similar Ti stable isotope compositions, suggesting that Ti is immobile during dehydration of subducted oceanic lithosphere. Lunar basalts have variable δ49Ti values; low-Ti mare basalts have δ49Ti values similar to that of the bulk silicate Earth (BSE) while high-Ti lunar basalts display small enrichment in the heavy Ti isotopes. This is best interpreted in terms of source heterogeneity resulting from Ti stable isotope fractionation associated with ilmenite–melt equilibrium during the generation of the mantle source of high-Ti lunar mare basalts. The similarity in δ49Ti between terrestrial samples and low-Ti lunar basalts provides strong evidence that the Earth and Moon have identical stable Ti isotope compositions.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Earth and Ocean Sciences
Subjects: Q Science > QE Geology
Uncontrolled Keywords: stable isotopes; magma differentiation; bulk silicate Earth; lunar basalts
Publisher: Elsevier
ISSN: 0012-821X
Date of First Compliant Deposit: 18 August 2016
Date of Acceptance: 24 May 2016
Last Modified: 12 Jul 2017 13:42
URI: http://orca.cf.ac.uk/id/eprint/93319

Citation Data

Cited 1 time in Google Scholar. View in Google Scholar

Cited 31 times in Scopus. View in Scopus. Powered By Scopus® Data

Actions (repository staff only)

Edit Item Edit Item

Downloads

Downloads per month over past year

View more statistics