Grade distribution of the giant Ok Tedi Cu-Au deposit, Papau New Guinea

Van Dongen, Michiel, Weinberg, Roberto F. and Tomkins, Andrew G. (2013) Grade distribution of the giant Ok Tedi Cu-Au deposit, Papau New Guinea. Economic Geology, 108 7: 1773-1781. doi:10.2113/econgeo.108.7.1773

Author Van Dongen, Michiel
Weinberg, Roberto F.
Tomkins, Andrew G.
Title Grade distribution of the giant Ok Tedi Cu-Au deposit, Papau New Guinea
Journal name Economic Geology   Check publisher's open access policy
ISSN 0361-0128
Publication date 2013-11
Year available 2013
Sub-type Article (original research)
DOI 10.2113/econgeo.108.7.1773
Open Access Status
Volume 108
Issue 7
Start page 1773
End page 1781
Total pages 9
Place of publication Littleton, CO, United States
Publisher Society of Economic Geologists
Collection year 2014
Language eng
Abstract The Ok Tedi porphyry Cu-Au deposit in Papua New Guinea is a world-class mineral deposit. In its pre-mining stage, it contained 5.5 Mt Cu and 18.1 Moz Au; skarn accounts for ~80% of the current 1.9 Mt Cu and 7.7 Moz Au in total resources. Two composite felsic stocks intruded a tectonostratigraphic sequence of clastic and carbonate rocks at ~1.16 ± 0.10 Ma, in a postcollisional tectonic setting. Ensuing magmatic-hydrothermal mineralization occurred within a geologically short time span of ~200 k.y. On the mine scale, heterogeneous metal grades (0–2.5% Cu) reflect contrasting styles of mineralization, conforming to classic skarn- and porphyry-type mineralization. A three-dimensional geologic model, alteration distribution, mineralization styles, and grade distribution indicate that fluids, exsolved from a deeper magma chamber, used shallow stocks as their preferred permeable pathway upward. Where limestone was present at depth, high-grade skarn formed, with the permeable stock having very low (<0.1% Cu) grade. In contrast, where the intrusions were encapsulated solely by impermeable silicified siltstone, economic grade (avg 0.6% Cu) developed within the intrusion, showing concentric patterns interpreted to represent individual magmatic pulses within the stock. The rare opportunity to visualize this in three dimensions and interact with the model is provided in the interactive electronic supplementary material.
Keyword Porphyry copper deposits
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
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