Trace Elements and Sulfur Isotope Variations in Endowed and Non-Endowed Porphyry Systems of the Dawson Range Mineral Belt, Yukon Territory
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Authors
Akinleye, Funmilade Tobi
Date
2024-10-04
Type
thesis
Language
eng
Keyword
Yukon Territory , Trace elements , Sulfur Isotopes , Porphyry systems , Dawson Range Mineral Belt , Exploration Geochemistry , Geochemistry , Geology , Ore deposit modeling , Cordilleran orogeny , Hydothermal alteration , δ³⁴S variations , Endowed deposits vs. non-endowed occurrences , Exploration modeling , Petrography , Northern Canadian Cordillera , Dawson Range , Yukon-Tanana Terrane , Stikinia Terrane , Casino deposit , Kerr occurrence , Cash deposit , Minto deposit , Cyprus occurrence , Revenue deposit , Cockfield occurrence , Carmacks deposit
Alternative Title
Abstract
The Dawson Range Mineral Belt (DRMB) in the Yukon Territory is a geologically complex region with significant potential for critical mineral exploration. This study addresses the challenges of exploring this area, focusing on select trace elements and sulfur isotope analyses to distinguish between endowed deposits and non-endowed occurrences. The remote location, poor access, and extensive glacial deposits complicate exploration efforts. The study analyzed fifty-six samples from eight porphyry systems, classifying them into endowed deposits (Casino, Cash, Revenue, Carmacks, and Minto) and non-endowed occurrences (Kerr, Cyprus, and Cockfield).
Trace element analysis shows that endowed zones have higher concentrations of Cu, Mo, Au, Se and Re. Additionally, endowed samples had Cu concentrations ≥ 400 ppm, and non-endowed samples had Cu concentrations < 400 ppm.
Sulfur isotope analysis of fifty-two sulfides from different mineral deposit/occurrence and host setting showed that the general δ³⁴S value in the region range from -6.6 to +5.8‰, with endowed deposits having a narrower range (-3.9 to +3.4‰) compared to non-endowed occurrences (-6.6 to +5.8‰). The alteration zones and weathering profiles of the samples were assessed, providing insights into genetic relationships of both sample groups. A sequence observed in the classified subgroups revealed δ³⁴S values in the order of ‘Argillic ≤ SCC (sericite-clay-chlorite) ≤ Potassic ≤ Phyllic ≤ Propylitic ≤ Argillic’ for alteration zones, and ‘Hypogene ≤ Supergene sulfide ≤ Supergene oxide’ for weathering profiles. Notably, the argillic alteration exhibited the widest δ³⁴S range, reflective of complex sulfur sources and processes. The δ34S values provide valuable insights into the provenance, geological and fluid evolution, as well as potential alteration and weathering zones within porphyry systems. They are, however, insufficient to definitively confirm the endowment criteria of mineral deposits, as fractionation factors are subject to changing conditions throughout the ore system's geological history. Understanding the regional zonation of δ34S can be a useful complementary tool in refining exploration findings, particularly when combined with other geological and geochemical data. This study emphasizes how integrating geochemical and isotopic data can refine exploration strategies, lower costs, and potentially identify new economically significant deposits, enhancing the global supply of critical minerals.