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https://hdl.handle.net/2440/118370
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Type: | Journal article |
Title: | Defining IOCG signatures through compositional data analysis: a case study of lithogeochemical zoning from the Olympic Dam deposit, South Australia |
Author: | Dmitrijeva, M. Ehrig, K.J. Ciobanu, C.L. Cook, N.J. Verdugo-Ihl, M.R. Metcalfe, A.V. |
Citation: | Ore Geology Reviews, 2019; 105:86-101 |
Publisher: | Elsevier |
Issue Date: | 2019 |
ISSN: | 0169-1368 1872-7360 |
Statement of Responsibility: | Marija Dmitrijeva, Kathy J. Ehrig, Cristiana L. Ciobanu, Nigel J. Cook, Max R. Verdugo-Ihl, Andrew V. Metcalfe |
Abstract: | The Olympic Dam Cu-U-Au-Ag deposit is dominantly composed of mineralised hematite-breccias and occurs entirely within the Roxby Downs Granite. Multivariate statistical analysis of a large whole-rock, 15 m-interval geochemical dataset (10,565 samples) was undertaken to identify geochemical signatures characteristic of iron-oxide copper gold (IOCG)-style mineralization and constrain the conspicuous lithogeochemical zonation observed at Olympic Dam. Statistical analyses include principal component analysis on centred logratio (clr)-transformed data coupled with hierarchical clustering. Certain groups of elements that can be interpreted in terms of an evolving hydrothermal system relative to host lithologies are derived from data analysis: granitophile (U-W-Sn-Mo); siderophile (Ni-Co); chalcophile (Ag-Bi) and related elements (As-Sb and Au-Te). The distributions of elements within each group are investigated through three vertical cross-sections and are compared with known lithological and Cu-(Fe)-sulphide zonation. Throughout the Olympic Dam Breccia Complex, the IOCG signature is defined by multi-element combinations of the commodity metals Cu, U, Au, and Ag, coupled with a range of trace elements. Overall, the IOCG signature overlaps well with Fe-metasomatism despite mismatch which is likely due to discrete styles of mineralisation found only on the margins of the deposit and also to the presence of mineralised domains within Fe-poor zones. The IOCG signature is composed of two geochemical associations, which exhibit distinct spatial distributions. The first group, Cu-U3O8-Se-S, shows concentric zonation whereas the second group, Au-W-Mo-Sb-As, forms a vertical ∼1800 m deep corridor in the southeastern lobe of the deposit. The specific Au-W-Mo-As-Sb signature could potentially be generic within IOCG systems across the Olympic Cu-Au province and if so, would provide a proxy model for near-mine exploration. |
Keywords: | Principal component analysis; hierarchical clustering; whole-rock dataset; IOCG deposits; lithogeochemical zoning; Olympic Dam |
Rights: | © 2018 Elsevier B.V. All rights reserved. |
DOI: | 10.1016/j.oregeorev.2018.12.013 |
Grant ID: | http://purl.org/au-research/grants/arc/IH130200033 |
Published version: | http://dx.doi.org/10.1016/j.oregeorev.2018.12.013 |
Appears in Collections: | Aurora harvest 8 Geology & Geophysics publications |
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