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Linking gold mineralization to regional-scale drivers of mineral systems using in situ U-Pb geochronology and pyrite LA-ICP-MS element mapping

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Fielding, IOH, Johnson, SP, Meffre, S ORCID: 0000-0003-2741-6076, Zi, J, Sheppard, S, Large, RR and Rasmussen, B 2019 , 'Linking gold mineralization to regional-scale drivers of mineral systems using in situ U-Pb geochronology and pyrite LA-ICP-MS element mapping' , Geoscience Frontiers, vol. 10, no. 1 , pp. 89-105 , doi: 10.1016/j.gsf.2018.06.005.

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Abstract

Proterozoic orogens commonly host a range of hydrothermal ores that form in diverse tectonic settings atdifferent times. However, the link between mineralization and the regional-scale tectonothermal evolutionof orogens is usually not well understood, especially in areas subject to multiple hydrothermal events.Regional-scale drivers for mineral systems vary between the different classes of hydrothermal ore, but allinvolve an energy source and a fluid pathway to focus mineralizing fluids into the upper crust. The MountOlympus gold deposit in the Proterozoic Capricorn Orogen of Western Australia, was regarded as anorogenic gold deposit that formed at ca. 1738 Ma during the assembly of Proterozoic Australia. However,the trace element chemistry of the pyrite crystals closely resembles those of the Carlin deposits of Nevada,with rims that display solid solution gold accompanied by elevated As, Cu, Sb, Hg, and Tl, surroundinggold-poor cores. New SHRIMP U-Pb dating of xenotime intergrown with auriferous pyrite and ore-stagealteration minerals provided a weighted mean 207Pb*/206Pb* date of 1769 +/- 5 Ma, interpreted as the age ofgold mineralization. This was followed by two discrete episodes of hydrothermal alteration at 1727 +/-7Maand 1673 +/- 8 Ma. The three ages are linked to multiple reactivation of the crustal-scale Nanjilgardy Faultduring repeated episodes of intracratonic reworking. The regional-scale drivers for Carlin-like goldmineralization at Mount Olympus are related to a change in tectonic regime during the final stages of theintracratonic 1820-1770 Ma Capricorn Orogeny. Our results suggest that substantial sized Carlin-like golddeposits can form in an intracratonic setting during regional-scale crustal reworking.

Item Type: Article
Authors/Creators:Fielding, IOH and Johnson, SP and Meffre, S and Zi, J and Sheppard, S and Large, RR and Rasmussen, B
Keywords: Western Australia, geochronology, xenotime, SHRIMP, LA-ICP-MS, gold mineralization, Capricorn orogen
Journal or Publication Title: Geoscience Frontiers
Publisher: Zhongguo Dizhi Daxue, China University of Geosciences
ISSN: 1674-9871
DOI / ID Number: 10.1016/j.gsf.2018.06.005
Copyright Information:

Copyright 2018 China University of Geosciences (Beijing) and Peking University. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) https://creativecommons.org/licenses/by-nc-nd/4.0/

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