This project reflects the assembly of a remarkable brain trust and marks a unique convergence of advances in analytical capability, intense industry interest and concomitant levels of funding. The project will also be the first to examine lithospheric architecture, its control on upper-crustal geology (stratigraphy, structure, mineral systems) through time by integrating structural, geophysical, geochemical and isotopic studies from the sub-grain scale to the scale of entire cratons.The study will focus on the time slice across the Neoarchean to Paleoproterozoic time periods between 2.7-1.7 billion years ago (Ga). This critical time period in Earth history is not only well endowed with mineral resources, but also reflects a fundamental transition in the geodynamic evolution of our planet, which profoundly and irreversibly impacted on the nature of the Earth’s biosphere-hydrosphere-atmosphere.
Recent work in the Yilgarn Craton of Western Australia (Champion and Cassidy, 2007; Mole et al., 2010; ARC LP0776780) has applied multi-isotopic analyses of zircons and whole-rock intrusive and volcanic rocks to reveal how the lithosphere has evolved through time (Figure 2). This lithospheric architecture is seen to control variations observed in mafic-ultramafic stratigraphy, as well as the distribution of komatiite-hosted nickel mineral systems through time (Mole et al., 2010; Begg et al. Econ. Geol., in press). Furthermore, work by McCuaig et al. (in press) has shown how this architecture correlates with other stratigraphic and metamorphic variations and the distribution of other mineral systems such as iron and gold.
The new study build on these recent research outcomes in the Yilgarn Craton and will produce similar multi-isotopic data sets over Paleoproterozoic terranes, in order to test (1) if the deep lithospheric architecture can be effectively mapped by isotopic proxy and (2) if the interpreted deep architecture exerts similar controls on observed variations in the upper crust, particularly on the spatial and temporal distribution of mineral systems. Specifically, the multi-modular study will address the Birimian Terranes of West Africa (2.2-2.0 Ma), building upon and integrating the AMIRA P934a WAXI-2 initiative, and the Tanami Inlier (1.9-1.7 Ma), building upon preliminary work completed as part of MERIWA M389 (Joly et al., 2010). The study takes advantages of the latest advances in technology, employing novel approaches to imaging the lithospheric architecture through the isotopic characterisation of igneous (volcanic and intrusive rocks) and sedimentary rocks. This integrated approach has never before been undertaken at the scale of this project.
The maps of fundamental lithospheric architecture through time produced during this study will fundamentally impact on exploration strategies (through the correlation with mineral deposit genesis and location), and on the hypotheses for Earth’s evolution over this unique and critical period of its history. It is anticipated that this study will be a benchmark for crustal evolution and mineralisation studies in Precambrian terranes.
The study firmly establishes CET as a leader in this area of research and in West African geology. Furthermore, the project is a clear demonstration of how CET is effectively leveraging maximum scientific and industry-relevant outcomes for its industry partners.