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 © 2019 The Author(s). Published by The Geological Society of London for GSL and AAG. All rights reserved.
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 Type:||Refereed Article|
|Keywords:||porphyry, fertility, whole rock geochemistry, pXRF, copper, gold|
|Research Division:||Earth Sciences|
|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)|
|Web of Science® Times Cited:||7|
|Deposited By:||School of Natural Sciences|
|Downloads:||7 View Download Statistics|
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