Crustal architecture of the south-east Superior Craton and controls on mineral systems

Abstract

Crustal and lithospheric architecture provide a first-order control on Earth evolution, including mineral systems. The ability to understand the internal nature and margins of crustal and lithospheric blocks, in both space and time, is vital in order to use continent architecture as a predictive tool in mineral exploration. In this study, we use U-Pb-Hf-O-trace element (TE) geochemical data from zircon grains in felsic magmatic rocks to isotopically map the south-east Superior Craton, producing a time-constrained architecture of the Archean crust in this area. We then assess the localization of volcanogenic massive sulphide (VMS), komatiite-hosted Ni-Cu-PGE, and syn- to post-tectonic Au systems within that architecture, constraining the first-order crustal-scale controls on these mineral systems. In terms of zircon data, at ca. >2750–2695 Ma, the central and north-west Abitibi subprovince has more juvenile εHf, light to mantle-like δ18O, lower (Eu/Eu*)/Y*10000 (drier/shallower crust), reduced ΔFMQ, less continental initial-U (Ui)/Yb, and more mantle-like Ui/Nb, relative to surrounding crust. The syn-volcanic mineral systems are localised in this juvenile zone. At ca. 2704–2695 Ma, there is a marked transition in multiple datasets, including increases in δ18O, (Eu/Eu*)/Y*10000, ΔFMQ, Ui/Yb and Ui/Nb data, and a decrease in εHf. These data represent a more evolved continental signature and the transition to a relatively homogenous regional Hf-O-TE architecture. World-class orogenic gold mineralization occurring at ca. <2680 Ma is predominantly localized into the same region as the syn-volcanic deposits, demonstrating the profound role of early architecture on the localisation of later mineral systems. Show more