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Lihir Alkalic Epithermal Gold Deposit, Papua New Guinea

Cooke, DR ORCID: 0000-0003-3096-5658, Sykora, S, Lawlis, EEC ORCID: 0000-0002-6355-0654, Blackwell, JL, Ageneau, M, Jansen, NH, Harris, AC and Selley, D 2020 , 'Lihir Alkalic Epithermal Gold Deposit, Papua New Guinea', in RH Sillitoe and RJ Goldfarb and F Robert and SF Simmons (eds.), Society of Economic Geologists Special Publication Number 23: Geology of the World’s Major Gold Deposits and Provinces , Society of Economic Geologists, Inc, United States, pp. 579-597.

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Abstract

The Lihir gold deposit, Papua New Guinea, is the world’s largest alkalic low-sulfidation epithermal gold deposit in terms of contained gold (50 Moz). The deposit formed over the past million years and records a progression from porphyry- to epithermal-style hydrothermal activity. The early porphyry stage was characterized by biotite- anhydrite-pyrite ± K-feldspar ± magnetite alteration and weak gold ± copper mineralization and produced abundant anhydrite ± carbonate veins and anhydrite ± biotite-cemented breccias. These features collectively characterize the deep-seated anhydrite zone at Lihir. Several hundred thousand years ago, one or more catastrophic mass-wasting events unroofed the porphyry system after porphyry-stage hydrothermal activity ceased. Mass wasting may have been facilitated in part by dissolution of porphyry-stage anhydrite veins. Epithermal mineralization occurred after sector collapse, resulting in phreatic and hydraulic brecciation and veining, widespread adularia-pyrite ± carbonate alteration, and formation of mineralized zones at Lienetz, Minifie, Kapit, Kapit NE, Coastal, and Borefields. A NE- to ENE-striking fault array localized several of these orebodies. The pyrite-rich veins and pyrite-cemented breccias that formed during epithermal-stage hydrothermal activity define the sulfide zone at Lihir. This zone mostly contains refractory gold in pyrite, with minor free gold and precious metal tellurides hosted in late-stage quartz veins. A period of diatreme volcanism disrupted the Luise amphitheater during the latter stages of epithermal mineralization. The diatreme breccia complex truncated several of the epithermal ore zones and was crosscut locally by late-stage epithermal veins. Recent geothermal activity produced a steam-heated clay alteration blanket that has overprinted the refractory sulfide-rich epithermal assemblage near the present-day land surface. Gold was remobilized downward from the steam-heated zone into the sulfide zone during argillic and advanced argillic alteration, producing thin gold-rich rims around pyrite grains. This process produced a high-grade tabular enrichment zone immediately beneath the base of the clay blanket.

Item Type: Book Section
Authors/Creators:Cooke, DR and Sykora, S and Lawlis, EEC and Blackwell, JL and Ageneau, M and Jansen, NH and Harris, AC and Selley, D
Keywords: Lihir, alkalic, epithermal, gold, Papua New Guinea, exploration, Lienetz, Minifie, Kapit
Publisher: Society of Economic Geologists, Inc
DOI / ID Number: 10.5382/SP.23.28
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Copyright 2020 Society of Economic Geologists, Inc.

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