Hafnium Isotopic Composition of the Bushveld Complex Requires Mantle Melt–Upper Crust Mixing: New Evidence from Zirconology of Mafic, Felsic and Metasedimentary Rocks

Abstract

The origin of magmas that formed the Bushveld Complex remains highly debated in spite of many decades of intense research. Previous geochemical-petrological studies have shown a strong mantle derivation resulting ultimately in highly economic ore bodies of platinum group elements and chromium. However, geochemistry also points to the contribution of a significant crustal component which may have been derived singly or in combination from a number of different sources. These include subcontinental lithospheric mantle which was enriched prior to Bushveld magma formation, possibly by subduction, assimilation of lower and upper crust during magma ascent, and contamination during magma chamber accretion within sedimentary rocks of the enclosing Transvaal Supergroup. In this study, the contributions of these various reservoirs will be evaluated by employing Hf isotopic data of © The Author(s) 2020. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: [email protected] D ow naded rom http/academ ic.p.com /petrology/advance-articoi/10.1093/petrology/egaa004/5736141 by gest on 27 Feruary 2020