Zinc isotope evidence for carbonate alteration of oceanic crustal protoliths of cratonic eclogites

نویسندگان

چکیده

Zinc isotopic compositions (?66ZnJMC-Lyon) of low-MgO (<13 wt.%) and high-MgO (>16 eclogites from the Koidu kimberlite complex, Sierra Leone, West African Craton, help constrain origins cratonic eclogites. The ?66Zn range MORB-like to significantly higher values (0.21‰ 0.75‰), correlate inversely with Zn concentrations. Since marine carbonates are characterized by lower concentration than basaltic rocks, suggested originate altered oceanic crustal protoliths that underwent exchange within crust during subduction. Compared eclogites, all but one also have high (0.35‰ 0.95‰), they concentrations Zn/Fe ratios, both which negatively correlated MgO contents. These features point formation via metasomatic overprinting through addition secondary clinopyroxenes crystallized infiltrating ultramafic melts. Thus, bear imprint subducted carbonate-bearing crust. Our study shows distinctively high-?66Zn signatures can be retained in deeply may contribute mantle sources intraplate alkali basalts elevated Zn/Fe. Therefore, isotopes provide a viable means trace carbonate recycling mantle.

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ژورنال

عنوان ژورنال: Earth and Planetary Science Letters

سال: 2022

ISSN: ['1385-013X', '0012-821X']

DOI: https://doi.org/10.1016/j.epsl.2022.117394