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Vikraman Selvaraja

PhD student
Centre for Exploration Targeting (CET)

Contact details

Address
Robert Street Building, Rm 207
Centre for Exploration Targeting (CET)
The University of Western Australia (M006)
35 Stirling Highway
CRAWLEY WA 6009
Australia

Email
20660415@student.uwa.edu.au

Thesis
Mineralisation in the Capricorn Orogen: Where, When and How

Summary
The Capricorn Orogen is a highly prospective but underexplored region of Western Australia. Poor outcrop has prevented previous exploration efforts. However, new geophysical and geochemical tools are now available to assist in exploration in this terrain. As part of the UNCOVER initiative, an integrated geophysical and geochemical dataset is being developed to add to the explorers toolbox in the region and to assist the understanding of crustal evolution in the orogen. My project focuses on the mineralisation in the orogen and its relationship to the evolution of the orogeny in a spatial and temporal sense.

In most mineralised systems, sulfides play a fundamental role in trasporting and concentrating a wide range of metals. Minerals such as pyrite (FeS2), chalcopyrite (CuFeS2), galena (PbS) are common in both hydrothermal and magmatic ore systems. However, it is generally difficult to determine origin and timing of sulfides in ore systems. Most sulfur isotope studies in ore systems are focussed on 34S (which is not as insightful as it can be easily reset and modified).
This study will utilise multiple S isotopes (34S , 33S and 36S) to accurately fingerprint sulfur source and map fluid pathways in magmatic and hydrothermal ore systems. I am also attempting to utilise the trace element (Se, Te, Co, Ni, As, Sb, Au, Ag) compositions of pyrite which can also be used to correlate sources and sinks of ore forming fluids (Large, 2009). A multiple sulfur isotopic map of the orogen is the final goal: a layer of key information to superimpose and integrate with other datasets.

Another focus of my project is dating the formation of ore deposits in the Proterozoic, which is a notoriously difficult exercise. However, some tools are available, allowing us to directly date the formation of sulfides in mineralised systems. This will help us place mineralisation in space and time, integrating this information with other isotopic system work (Lu-Hf-O in zircons), to create 4D “time-slices” of the orogen. The Re-Os radiometric dating system is a robust dating mechanism which has been utilised in a variety of environments and on rocks of varying ages. This part of the project will involve close collaboration with GSWA and Curtin University.
Spatial distribution of isotopes will be mapped out and integrated with the current geophysical datasets that are being produced through the SIEF projects and pre-existing isotopic datasets and products of that type will be available for mining and exploration companies to use for exploration in the region.

Why my research is important
1)    Opens up a new region of WA to exploration and mining activity, boosting the WA economy and job creation along with creating stable new supplies of critical industrial inputs.
2)    Proof of concept in terms of integrating multiple isotopic and chronological datasets to understand mineral systems in a large, multi-stage orogen.
3)    Understanding the crustal architecture and structure of the Capricorn Orogen, a key building block in the story of the formation of the West Australian craton.