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Lithofacies associations and evolution of the volcanic host succession to the Minifie ore zone: Ladolam gold deposit, Lihir Island, Papua New Guinea

Citation

Blackwell, JL and Cooke, DR and McPhie, J and Simpson, KA, Lithofacies associations and evolution of the volcanic host succession to the Minifie ore zone: Ladolam gold deposit, Lihir Island, Papua New Guinea, Economic Geology, 109, (4) pp. 1137-1160. ISSN 0361-0128 (2014) [Refereed Article]

Copyright Statement

Copyright 2014 Society of Economic Geologists, Inc.

DOI: doi:10.2113/econgeo.109.4.1137

Abstract

The 46-million-ounce Ladolam gold deposit, the largest alkalic epithermal gold deposit in the world in terms of contained gold, is composed of four ore zones: Minifie, Lienetz, Kapit, and Coastal. This detailed lithofacies study of the Minifie ore zone recognized three evolutionary stages: (1) volcanosedimentary strata (part of an alkalic composite volcanic island), (2) a porphyry-style breccia dike, and (3) epithermal-style breccias. The Plio-Pleistocene volcanosedimentary stratigraphy reflects the transition from subaerial deposition of pyroclastic surge deposits close to vent to a subaqueous, quiet depositional environment into which a cryptodome was emplaced. The stratigraphy is predominantly composed of polymictic, matrix-supported breccia and sandstone interbedded with lavas and shallow intrusions. The Minifie strata have a shallow southward dip as a result of Quaternary uplift. Overprinting the volcanosedimentary stratigraphy are three hydrothermally cemented breccia facies—one deposited in the porphyry environment and two deposited in the epithermal environment.

Porphyry-style alteration assemblages and a 3- to 5-m-wide biotite-K-feldspar-calcite-anhydrite–cemented breccia dike are focused around the central "Minifie shear" fault. The porphyry alteration assemblages are overprinted by shallow-level and deeper-level epithermal-style features. The deeper-level (below the present mining surface; >140 m below sea level) epithermal vein stockwork is composed of quartz-calcite-adularia-anhydrite–cemented breccias and shallowly northward to near-horizontal dipping veins that have gold grades of 1 to >60 g/t Au. Shallow-level epithermal facies (adularia-quartz-pyrite–cemented breccias, veins, and associated alteration) host the bulk mineable gold ore, and typically yield >4 g/t Au over 12-m blast hole samples.

Item Details

Item Type:Refereed Article
Keywords:hydrothermal, breccia epithermal, Lihir
Research Division:Earth Sciences
Research Group:Geology
Research Field:Volcanology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Blackwell, JL (Ms Jacqueline Blackwell)
Author:Cooke, DR (Professor David Cooke)
Author:McPhie, J (Professor Jocelyn McPhie)
Author:Simpson, KA (Dr Kirstie Simpson)
ID Code:98244
Year Published:2014
Funding Support:Australian Research Council (CE0561595)
Web of Science® Times Cited:4
Deposited By:Earth Sciences
Deposited On:2015-02-06
Last Modified:2017-11-02
Downloads:0

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