Titanium isotope constraints on the mafic sources and geodynamic origins of Archean crust
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Titanium isotope constraints on the mafic sources and geodynamic origins of Archean crust. / Hoare, L.; Rzehak, L. J. A.; Kommescher, S.; Jansen, M.; Rosing, M. T.; Nagel, T.; Millet, M.-A.; Hoffmann, J. E.; Fonseca, R. O. C.
In: Geochemical Perspectives Letters, Vol. 28, 2023, p. 37-42.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Titanium isotope constraints on the mafic sources and geodynamic origins of Archean crust
AU - Hoare, L.
AU - Rzehak, L. J. A.
AU - Kommescher, S.
AU - Jansen, M.
AU - Rosing, M. T.
AU - Nagel, T.
AU - Millet, M.-A.
AU - Hoffmann, J. E.
AU - Fonseca, R. O. C.
N1 - Publisher Copyright: © 2023 The Authors Published by the European Association of Geochemistry.
PY - 2023
Y1 - 2023
N2 - The timing and formation of Earth’s first continents during the Archean are subjects of significant debate. By examining titanium isotope variations in Archean Tonalite-Trondhjemite-Granodiorite (TTG) rocks and using advanced thermodynamic modelling, we can narrow down the processes involved and emphasise the role of mafic precursor compositions. In our study of Eoarchean Isua metabasalts and Itsaq tonalites in southern West Greenland, we observed a pattern of increasing Ti isotope enrichment with higher SiO2 content, resembling the compositions found in modern subduction zone rocks. Our modelling suggests that the Ti isotope variations in TTGs can be best explained by a combination of partial melting of low TiO2 metabasalts and subsequent crystallisation of tonalitic magmas, resulting in heavier Ti isotopes. This means that Ti isotopes help us distinguish the contributions of various mafic sources and fractional crystallisation during TTG formation. In the case of Itsaq tonalites and many other Eoarchean TTGs, low TiO2 tholeiitic metabasalts with arc-like characteristics likely represent the mafic source rocks, suggesting the formation of some of Earth’s earliest continental crust within a proto-subduction zone setting.
AB - The timing and formation of Earth’s first continents during the Archean are subjects of significant debate. By examining titanium isotope variations in Archean Tonalite-Trondhjemite-Granodiorite (TTG) rocks and using advanced thermodynamic modelling, we can narrow down the processes involved and emphasise the role of mafic precursor compositions. In our study of Eoarchean Isua metabasalts and Itsaq tonalites in southern West Greenland, we observed a pattern of increasing Ti isotope enrichment with higher SiO2 content, resembling the compositions found in modern subduction zone rocks. Our modelling suggests that the Ti isotope variations in TTGs can be best explained by a combination of partial melting of low TiO2 metabasalts and subsequent crystallisation of tonalitic magmas, resulting in heavier Ti isotopes. This means that Ti isotopes help us distinguish the contributions of various mafic sources and fractional crystallisation during TTG formation. In the case of Itsaq tonalites and many other Eoarchean TTGs, low TiO2 tholeiitic metabasalts with arc-like characteristics likely represent the mafic source rocks, suggesting the formation of some of Earth’s earliest continental crust within a proto-subduction zone setting.
U2 - 10.7185/geochemlet.2342
DO - 10.7185/geochemlet.2342
M3 - Journal article
AN - SCOPUS:85182382610
VL - 28
SP - 37
EP - 42
JO - Geochemical Perspectives Letters
JF - Geochemical Perspectives Letters
SN - 2410-3403
ER -
ID: 380288986