The Windimurra Igneous Complex: an Archean Bushveld?
Timothy J. Ivanic, Oliver Nebel, John Brett, Ruth E. Murdie, 2018. "The Windimurra Igneous Complex: an Archean Bushveld?", Characterization of Ore-Forming Systems from Geological, Geochemical and Geophysical Studies, K. Gessner, T.G. Blenkinsop, P. Sorjonen-Ward
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The Archean Windimurra Igneous Complex consists of distinct components, including a thick layered series, with a cumulate mineral stratigraphy similar to the zones identified in the well-studied Bushveld Complex, South Africa. The complex is part of the plume-related and laterally extensive 2.81 Ga Meeline Suite, the intrusive component of a large igneous province. It is an anhydrous tholeiitic suite consisting of five layered mafic–ultramafic intrusions 25–85 km in the long dimension. These intrusions host significant V–Ti mineralization in their fractionated, Fe-rich upper zones. Recent mapping, combined with aeromagnetic, gravity and seismic surveys, has provided unparalleled three-dimensional constraints on the largest of these intrusions. The results of three-dimensional modelling show that it is thicker than previously recognized. At c. 11 km, it is the thickest layered mafic–ultramafic intrusion identified globally and one of the largest such intrusions volumetrically. The mineral zone stratigraphy and many other features associated with this complex share similarities with the c. 800 myr younger Bushveld Complex. On a large scale, three discordant units are delineated geometrically, providing fundamental constraints on a multi-stage genetic model for magma emplacement. The indication of a thick, subsurface Ultramafic Zone provides a potential target for Ni–Cr–platinum group element mineralization.
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Economically viable concentrations of mineral resources are uncommon in Earth’s crust. Most ore deposits that were mined in the past or are currently being extracted were found at or near Earth’s surface, often serendipitously. To meet the future demand for mineral resources, exploration success hinges on identifying targets at depth. Achieving this requires accurate and informed models of the Earth’s crust that are consistent with all available geological, geochemical and geophysical information, paired with an understanding of how ore-forming systems relate to Earth’s evolving structure. Contributions to this volume address the future resources challenge by (i) applying advanced microscale geochemical detection and characterization methods, (ii) introducing more rigorous 3D Earth models, (iii) exploring critical behaviour and coupled processes, (iv) evaluating the role of geodynamic and tectonic setting and (v) applying 3D structural models to characterize specific ore-forming systems.