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Assessing copper fertility of intrusive rocks using field portable X-Ray fluorescence (pXRF) data

Citation

Ahmed, A and Crawford, A and Leslie, C and Phillips, J and Wells, T and Garay, A and Hood, SB and Cooke, DR, Assessing copper fertility of intrusive rocks using field portable X-Ray fluorescence (pXRF) data, Geochemistry: Exploration, Environment, Analysis, 20, (2020) pp. 81-97. ISSN 1467-7873 (2019) [Refereed Article]


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Copyright Statement

Copyright © 2019 The Author(s). Published by The Geological Society of London for GSL and AAG. All rights reserved.

DOI: doi:10.1144/geochem2018-077

Abstract

Based on a global compilation of whole-rock geochemical data, Sr/Y and Sr/MnO are identified as effective discriminators between ore-forming and unprospective intrusions in the porphyry Cu setting. Intrusive rocks are classified into three fertility groups – prospective, unprospective and mixed-signal – designed to assist explorers as a discrimination tool, narrowing the exploration search space in porphyry Cu districts.

Portable X-ray fluorescence (pXRF) data of Sr, Y and MnO were collected on pulp powders and rock slabs from six porphyry Cu (±Mo ± Au) districts. Pre- and post-mineralization intrusions from porphyry Cu districts have lower Sr/Y and Sr/MnO values than syn-mineralization intrusions from the same districts, although absolute values are variable between districts.

pXRF data were compared to conventional whole-rock data to determine if pXRF data were appropriate substitutes for conventional whole-rock methods of evaluating the ore-forming potential of intrusive rocks. pXRF data collected on pulp material were found to be more accurate (within 16% of conventional methods) and more precise (<5% relative standard deviation (RSD)) than those collected on intact rock slabs (within 37% of conventional methods and <24% RSD). These differences are attributed to the grain size and mineral homogeneity of samples. Despite the low precision of pXRF analyses on individual rock slabs (mean RSD of 24% Sr/Y and 32% Sr/MnO), the mean values for each sample plot in the expected fertility field on the Sr/Y and Sr/MnO diagram. Our results demonstrate that in situ pXRF data collection provides an effective discriminator of Cu fertility, and represents a powerful field exploration tool.

Item Details

Item Type:Refereed Article
Keywords:porphyry, fertility, whole rock geochemistry, pXRF, copper, gold
Research Division:Earth Sciences
Research Group:Geochemistry
Research Field:Exploration geochemistry
Objective Division:Mineral Resources (Excl. Energy Resources)
Objective Group:Mineral exploration
Objective Field:Copper ore exploration
UTAS Author:Ahmed, A (Ms Ayesha Ahmed)
UTAS Author:Crawford, A (Professor Anthony Crawford)
UTAS Author:Leslie, C (Mr Christopher Leslie)
UTAS Author:Phillips, J (Mr Joshua Phillips)
UTAS Author:Wells, T (Mr Tristan Wells)
UTAS Author:Garay, A (Mr Merril Garay Maurerira)
UTAS Author:Hood, SB (Mr Shawn Hood)
UTAS Author:Cooke, DR (Professor David Cooke)
ID Code:150744
Year Published:2019
Web of Science® Times Cited:7
Deposited By:School of Natural Sciences
Deposited On:2022-06-27
Last Modified:2022-07-08
Downloads:7 View Download Statistics

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