¹Merislava Anguelova,²Nicolas Vilela,³Sebastian Kommescher,^2,4Nicolas D. Greber,¹Manuela A. Fehr,¹Maria Schönbächler
Geochimica et Cosmochimica Acta (in Press) Open Access Link to Article [https://doi.org/10.1016/j.gca.2024.01.026]
¹Institute of Geochemistry and Petrology, ETH Zurich, 8092 Zurich, Switzerland
²Institute of Geological Sciences, University of Bern, 3012 Bern, Switzerland
³Institut für Geologie, Mineralogie und Geophysik, Ruhr-Universität Bochum, 44801 Bochum, Germany
⁴Muséum d’histoire naturelle de Genève, 1208 Genève, Switzerland
Copyright Elsevier

Titanium isotopes are a promising tracer for planetary differentiation processes. The application of this tracer is, however, currently hampered by the lack of a robust estimate for the chondritic reservoir. Here, we conducted an inter-comparison Ti isotope study of three laboratories with the aim of providing an accurate and precise estimate for the chondritic reservoir. While previous estimates may suffer from heterogeneities on the sampling scale, we chose ordinary chondrites to minimise uncertainties associated with the necessary corrections for nucleosynthetic isotope variations in chondrites, and to allow the analysis of sufficiently large sample sizes representative for bulk meteorites. Titanium isotope data reported by the different laboratories are in good agreement with each other. Ordinary chondrites of different subgroups (H, L, LL) and petrologic types (3–6) display identical Ti isotope compositions within uncertainties (average δ49Ti = +0.023 ± 0.009 ‰, 2SE, n = 20; permille deviation of 49Ti/47Ti from the OL-Ti standard). The average Ti isotope composition of ordinary chondrites is within 2SE identical to that of OIBs (+0.029 ± 0.005 ‰, 2SE, n = 52) and all pre 2.7 Ga mafic and komatiitic rocks (+0.019 ± 0.006 ‰, 2SE, n = 58), indicating that the δ49Ti values of the bulk silicate Earth and ordinary chondrites are indistinguishable. Furthermore, our average Ti isotope composition of ordinary chondrites overlaps with those of the Moon, Mars and Vesta, suggesting a homogeneous inner Solar System in terms of mass-dependent Ti isotopes.