The age and petrology of the Chimbadzi Hill Intrusion, NW Zimbabwe: first evidence for early Paleoproterozoic magmatism in Zimbabwe

Manyeruke, T. D., Blenkinsop, Thomas G. ORCID: https://orcid.org/0000-0001-9684-0749, Buchholz, P., Love, D., Oberthur, T., Vetter, U. K. and Davis, D. W. 2004. The age and petrology of the Chimbadzi Hill Intrusion, NW Zimbabwe: first evidence for early Paleoproterozoic magmatism in Zimbabwe. Journal of African Earth Sciences 40 (5) , pp. 281-292.

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Abstract

The mafic-ultramafic Chimbadzi Hill intrusion in the NW of the Zimbabwe craton is a dyke with inward-dipping margins comprising magnetite peridotite, troctolite and magnetite melatroctolite. The magnetite peridotite is composed of about equal amounts of V- and Ti-bearing magnetite and olivine (∼Fo60). The troctolite is composed of about 50% olivine (∼Fo50-54), 40% plagioclase (An53-58), 7% clinopyroxene and minor apatite and magnetite with ilmenite lamellae. Geochemical trends suggest that the Chimbadzi Hill Intrusion formed by fractional crystallisation from a single initial magma. However, the more primitive magnetite peridotite overlies the more evolved troctolite in the intrusion. This ‘apparent’ inverted stratigraphy may be due to emptying of a fractionated magma chamber from the top, or to floor subsidence during intrusion. U–Pb dating on baddeleyite reveals that the age of the Chimbadzi Hill Intrusion is 2262 ± 2 Ma. This age does not correspond to any known tectono-thermal event in the Zimbabwe Craton or adjacent metamorphic belts. It is ∼300 Ma younger than the late Archean Great Dyke, and ∼230 Ma older than other Paleoproterozoic events in and around the craton. Therefore, it may represent a so far undocumented very early Proterozoic igneous event in the Zimbabwe Craton. The intrusion represents a vanadium resource for Zimbabwe, with titanium potentially being mined as by-product.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Earth and Environmental Sciences
Subjects:	Q Science > QE Geology
Uncontrolled Keywords:	Fractional crystallisation; Intrusion; Magnetite peridotite; Troctolite Paleoproterozoic; Mafic-ultramafic complex; Cumulate
Publisher:	Elsevier
ISSN:	1464-343X
Last Modified:	24 Oct 2022 12:07
URI:	https://orca.cardiff.ac.uk/id/eprint/50610

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