Paleoproterozoic hydration of gabbronorite from the Mesoarchean Lechana layered complex, eastern Botswana

Rajesh, H.M.; Safonov, O.G.; Mfa, D.T.; Belyanin, G.A.

Авторы: Rajesh H.M., Safonov O.G., Mfa D.T., Belyanin G.A.
Журнал: Journal of African Earth Sciences
Том: 199
Год издания: 2023
Издательство: Pergamon Press Ltd.
Местоположение издательства: United Kingdom
Первая страница: 104849
Последняя страница: 104849
DOI: 10.1016/j.jafrearsci.2023.104849
Аннотация: Amphibole in mafic rocks of Archean layered complexes could be magmatic, metamorphic or metasomatic inorigin. In this study, we use a combined field, petrography, mineral chemistry, phase equilibria modeling and40Ar/39Ar geochronology approach to characterize amphibole in gabbronorites from the Mesoarchean Lechanalayered complex in eastern Botswana. To get a better understanding of the overprint events, the characteristics ofamphibole in the spatially associated amphibolite are also included. The gabbronorite preserves magmaticcumulate texture, with brownish amphibole replacing pyroxene as widespread thin (up to 80 μm) rims. Incomparison, the greenish amphibole in amphibolite form part of granoblastic polygonal texture. Amphibolitepreserve evidence for anatectic and metasomatic overprints, while the gabbronorite only exhibit effects of thelater. Phase equilibria modeling provide P-T conditions and H2O content for the amphibole formation in thegabbronorite. The 40Ar/39Ar geochronology gave an age of 2037 ± 27 Ma for this process. We relate the Paleoproterozoichydration to form amphibole in gabbronorite to the residual aqueous fluids expelled during crystallizationof an anatectic melt in the spatially associated amphibolite. The results highlight an example of theformation of amphibole in Archean layered mafic rocks via a post-magmatic hydration event.
Добавил в систему: Сафонов Олег Геннадьевич

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Paleoproterozoic hydration of gabbronorite from the Mesoarchean Lechana layered complex, eastern Botswanaстатья

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