Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

Geological Magazine

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by DODSON, M. H. Articles by KRAMERS, J. D. Search for Related Content GeoRef GeoRef Citation

The Mushandike granite: further evidence for 3.4 Ga magmatism in the Zimbabwe craton

M. H. DODSON^*,, I. S. WILLIAMS^* and J. D. KRAMERS^,

^* Research School of Earth Sciences, The Australian National University, Canberra ACT 0200, Australia
Department of Geology, University of Zimbabwe, P.O. Box M.P.167, Mount Pleasant, Harare, Zimbabwe

Author for correspondence: mdodson{at}chevin.u-net.com; present address: School of Earth Sciences, University of Leeds, Leeds LS2 9JT, UK.

The conflict between independently published ages for the Mushandike Granite, Zimbabwe (2.92 ± 0.17 Ga and 3.45 ± 0.13 Ga) has been resolved in favour of the older age by SHRIMP U–Pb analyses of zircon. Two samples yield indistinguishable estimates of 3374 ± 7 and 3368 ± 11 Ma for the crystallization age of the magma. Together with published data from elsewhere in southern Zimbabwe, the results imply a widespread magmatic event at about 3.35 Ga. A single zircon core giving 3.46 Ga, together with the granite’s previously measured Nd model age, suggests that the Mushandike magma could have incorporated remobilized basement similar to the c. 3.5 Ga Tokwe gneisses which crop out 30 km to the west. The published Rb–Sr and Pb–Pb datasets show evidence of late Archaean disturbance of Sr and Pb isotope systematics. In the absence of exposed contacts between the Mushandike granite and the neighbouring Mushandike stromatolitic limestone, the new U–Pb emplacement age suggests that the limestone is unconformable on the granite.