Advancing Tools and Techniques for the Exploration of Undercover Ore Deposits: A Collection of Mineralogical, Geochemical, and Isotopic Studies to Increase the Detection of Element Migration from Ore Systems
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Authors
Pilsworth, Collette
Date
Type
thesis
Language
eng
Keyword
LA-ICP-MS , Gold , Uranium , Exploration Geochemistry , Fracture Coatings
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Abstract
This thesis presents three studies that focus on advancing new geochemical exploration tools and techniques to detect the geochemical expression of ore systems. The first study compares mechanical fragmentation and electrodynamic pulse disaggregation sample preparation methods for weak acid leach (2% HNO3) – a proven and effective exploration tool for unconformity-hosted uranium deposits. This study highlights how sample preparation methods result in variable mixes of the original minerals, affecting the element concentrations and Pb isotope ratios extracted by weak acid leach. Clay extracted by electrodynamic pulse disaggregation is the optimal exploration method for unconformity-hosted uranium deposits, producing higher pathfinder element contents and radiogenic Pb values (i.e., 207Pb/206Pb<0.70). The second study highlights a novel laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) technique for measuring elemental content and 207Pb/206Pb on rough fracture coatings to aid exploration programs. Fractures aid element dispersion at depth by providing permeable pathways through which syn- and post-mineralizing fluids can move from mineralization into the surrounding rocks and overburden. If these fluids are associated with ore deposit formation or have encountered a nearby ore deposit, they can leave behind a distinct mineralogical and geochemical signature on the fracture surface as a coating, which could provide evidence of proximity to mineralization. Furthermore, we show that the Pb isotopic signature of buried mineralization is recorded on the fracture surfaces. The third study applies the second study’s LA-ICP-MS technique to measure elements in fractures overlying the Oberon gold deposit, North Territory, Australia. This is the first study looking at fracture coatings as a tool for mineral exploration within a regolith environment. Purple, black, and brown fracture types show the greatest potential as a vector for mineral exploration with fracture coatings associated with botryoidal goethite, high Fe values (up to 549,387 μg/g), and high pathfinder element values (up to 5535 μg/g Σ of Ni, Cu, Zn, Se, Mo, Ag, Sb, Te, W, Bi, and Pb). All studies presented show real potential to add value to future drilling exploration programs if implemented within the industry especially in areas where ore deposits reside at depth and undercover.
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ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.