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4D lithospheric evolution and controls on mineral systems in Western Superior

Superior Craton, Canada

The objective of the three-year project is to map the lithospheric architecture, determine the relationship between this architecture and the distribution of mineral deposits, and produce mappable exploration criteria for Archaean mineral systems.  

This project will investigate the U-Pb- Lu-Hf-O isotope characteristics of zircons from key units in the Wabigoon subprovince of the western Superior Province, in order to obtain a better understanding of the evolution, architecture and preservation of this complex 3.0-2.7 Ga Archaean terrane and the mineral deposits that formed within it.

The proposed project will utilise an extensive collection of igneous rock samples collected for geochronological studies by Greg Stott at the Ontario Geological Survey, which have already been characterised in terms of location and context, whole rock geochemistry, U-Pb geochronology and in many cases whole rock Sm-Nd, but only limited Lu-Hf and no O-isotope analyses. Additional selective sampling of critical units across interpreted terrane boundaries will be undertaken in order to ascertain the location of the these boundaries in a whole lithospheric context.

The resultant images of isotopic character of lithosphere will be correlated with observed variations in the stratigraphy, metamorphic grade, upper crustal structure and potential field and seismic datasets (all of which are high quality and readily available) to build a comprehensive understanding of the nature of the lithosphere through time and determine how deep lithospheric architecture is expressed in the Archaean upper crust.

This study will test whether the spatial distribution of large mineral systems (Fe, VMS, NiS, Au, PGE) is controlled by this architecture at the scale of entire terranes in the Western Superior (it has been argued this is the case in the Yilgarn). The enhanced understanding of the interplay between lithospheric architecture, composition and evolution has the potential to cause a paradigm shift in exploration strategy within the mineral industry, driving industry to obtain more high precision multi-isotopic datasets to aid area selection on the large scale.

Marco Fiorentini

Research Professor