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Magnesium and zinc isotopic evidence for the involvement of recycled carbonates in the petrogenesis of Gaussberg lamproites, Antarctica
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SYSNO ASEP 0561358 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Magnesium and zinc isotopic evidence for the involvement of recycled carbonates in the petrogenesis of Gaussberg lamproites, Antarctica Tvůrce(i) Liu, J.-Q. (CN)
Chen, J.H. (CN)
Wang, X.-J. (CN)
Zhang, X.Y. (CN)
Zeng, G. (CN)
Erdmann, S. (FR)
Murphy, D.T. (AU)
Collerson, K.D. (AU)
Komiya, T. (JP)
Krmíček, Lukáš (GLU-S) RID, ORCID, SAIČíslo článku 121067 Zdroj.dok. Chemical Geology. - : Elsevier - ISSN 0009-2541
Roč. 609, October (2022)Poč.str. 12 s. Forma vydání Tištěná - P Jazyk dok. eng - angličtina Země vyd. NL - Nizozemsko Klíč. slova Lamproites ; Recycled carbonates ; Mantle transition zone ; Magnesium isotopes ; Zinc isotopes Obor OECD Volcanology Způsob publikování Omezený přístup Institucionální podpora GLU-S - RVO:67985831 UT WOS 000851373400004 EID SCOPUS 85136454362 DOI 10.1016/j.chemgeo.2022.121067 Anotace Lamproites are rare mantle-derived peralkaline ultrapotassic rocks, and they are commonly geographically associated with the ultramafic lamprophyres and kimberlites. Their unique geochemistry and mineralogy make determining their mantle source and origin important because of the significance for inferring specific geodynamic processes. In this study, we further examine lamproite petrogenesis using new Mg and Zn isotopic data for the typical Gaussberg lamproites, Antarctica, the source of which were thought to be contributed by recycled crustal materials. Results show that these lamproites have lower δ26Mg (−0.44‰ to −0.39‰) and higher δ66Zn (0.36‰ to 0.39‰) values than terrestrial mantle (δ26Mg = −0.25 ± 0.04‰, δ66Zn = 0.18 ± 0.05‰). The post-magmatic alteration and crustal contamination as well as fractional crystallization and partial melting cannot account for these anomalous Mg and Zn isotopic values. By contrast, the involvement of sedimentary carbonates which are characterized by light δ26Mg (average approximately −2.0‰) and heavy δ66Zn (average ~ +0.91‰) values in their mantle source can explain these Mg and Zn isotopic anomalies. Quantitative modelling suggests that addition of 10–15% subducted dolomite into the source of Gaussberg lamproites can well reproduce their Mg and Zn isotopic values. The source component with light Mg and heavy Zn isotopic compositions can either be sub-continental lithospheric mantle metasomatized by carbonate melts or residue of subducted carbonate-bearing sediments after deep melting in the mantle transition zone. A lithospheric mantle contribution is indeed required to explain their strongly enriched radiogenic isotopic compositions. However, in terms of carbonate component, their positive Zrsingle bondHf anomalies (Hf/Hf* = 1.28–2.19), and extremely high K/U (~40, 000) and Ba/Th (~400) ratios lead us to favor the latter deep recycling model in which the recycled carbonate-bearing sediments subducted as K-hollandite and majorite underwent partial melting within the mantle transition zone. Pracoviště Geologický ústav Kontakt Jana Popelková, popelkova@gli.cas.cz, Sabina Janíčková, Tel.: 233 087 272 Rok sběru 2023 Elektronická adresa https://www.sciencedirect.com/science/article/pii/S0009254122003618?via%3Dihub
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