Chapter 28: Lihir Alkalic Epithermal Gold Deposit, Papua New Guinea

Cooke, David R.; Sykora, S; Lawlis, Erin; Blackwell, Jacqueline L.; Ageneau, M; Jansen, Nicholas H.; Harris, Anthony C.; Selley, D

doi:10.5382/sp.23.28

Cited by 4 publications

(1 citation statement)

References 37 publications

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“…The Luise amphitheatre is 4 × 3.5 km wide, and elongated and breached to the northeast. The pre-mining depth of the amphitheatre floor was 80 m relative to sea level (RSL), and the height of the walls was 640 m RSL (Blackwell 2010;Cooke & Sykora 2020). The original volcanic cone height is estimated to have been 1,100 m RSL (Wallace et al 1983;Tregoning 2002;Blackwell 2010).…”

Section: Island and Deposit Geologymentioning

confidence: 99%

Development of a fully constrained structural model in a volcano caldera and its influence on open pit slope design

Stoch,

Darakjian,

Zorzi

et al. 2023

SSIM 2023: Third International Slope Stability in Mining Conference

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The Ladolam gold deposit, is located on Lihir Island, part of the Tabar-Lihir-Tanga-Feni island chain, New Ireland Province, Papua New Guinea. The Luise volcano hosts the deposit, presenting a 4 × 3.5 km-wide amphitheatre, elongated and breached to the northeast. A detailed structural model of the site is required in order to incorporate the influence of structure on slope stability for pit design and optimisation. Complex tectonic evolution, late diatreme intrusion, significant metasomatic overprint, ongoing hydrothermal activity and weathering of the country rock present challenges to developing a comprehensive, fully constrained structural model across the deposit. Given this geological complexity, structural model development and structural characterisation has utilised an evidence-based approach, with inputs from numerous disparate datasets ranging from high-resolution photogrammetry to field mapping data, core logs and downhole photographs. Photogrammetry data proved highly effective in delineating deposit scale structural trends, particularly in areas that are no longer accessible or that have historically been omitted from study. Geological structures and geotechnical variations have implications for slope design and operational risk management. Strain shadows of major north-south trending structures present zones of rheological weakness and preferential fluid ingress at Lihir, further highlighting the potential influence of geological structure on slope stability. Ongoing structural characterisation has important safety and economic benefits. As the structural model is further developed, it supports the identification of potentially higher-risk areas in current slope design. This, in turn, justifies more detailed analysis or monitoring controls to ensure safe and efficient mining and/or mine design adjustments to mitigate hazards. The following work is presented in this paper: 1) the methodology used to identify and delineate key structures, 2) characterisation methodologies employed, and 3) how identification and characterisation of structural systems have successfully informed decision-making at Lihir gold mine.

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Section: Island and Deposit Geologymentioning

confidence: 99%

Development of a fully constrained structural model in a volcano caldera and its influence on open pit slope design

Stoch,

Darakjian,

Zorzi

et al. 2023

SSIM 2023: Third International Slope Stability in Mining Conference

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Epithermal Ag–Au mineralization at Galim-Legalgorou, Cameroon Volcanic Line: insights from alteration mineralogy and mineral chemistry of electrum and sphalerite

Ngang,

Suh,

Wagner

et al. 2024

Int J Earth Sci (Geol Rundsch)

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The Galim-Legalgorou area, located along the north-western branch of the Cameroon Volcanic Line (CVL), is known for artisanal gold mining and primary gold exploration, but the style and origin of the mineralization has not been fully described in the scientific literature. The close spatial association of the mineralization with Tertiary volcanic rocks raises the question of whether or not this is an epithermal system in a region where all previously studied gold occurrences have been classified as orogenic. In this contribution, we use ore mineral and alteration assemblage and mineral microchemistry to constrain the origin and evolution of the mineralization. Gold is alloyed mainly with Ag (max. 53.1 wt%) and show fineness values that vary 379 and 721 with an average of 455. A cumulative percentile plot of Ag concentrations in the cores of all electrum particles, and the observed step-change from Au-rich cores to more Ag-rich mantles in zoned electrum particles, suggest that the mineralization was deposited by two distinct hydrothermal fluid influxes. The observed ore mineral association-electrum, Se/Tl-acanthite, pyrite, Fe-rich sphalerite, ± galena; the measured FeS contents of sphalerite (average 23.1 mol%), and the presence of colloform banded chalcedony and hydrothermal breccia are all consistent with features of low sulfidation epithermal deposits. This study, therefore, demonstrates for the first time, the presence of significant low sulfidation epithermal Ag–Au mineralization on the CVL, an intracontinental rift region only previously known for orogenic gold mineralization. Graphical Abstract

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Metallogenic models as the key to successful exploration — a review and trends

Pohl

2022

Miner Econ

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Metallogeny is the science of ore and mineral deposit formation in geological space and time. Metallogeny is interdisciplinary by nature, comprising elements of natural science disciplines such as planetology to solid state physics and chemistry, and volcanology. It is the experimental forefront of research and bold thinking, based on an ever-growing foundation of solid knowledge. Therefore, metallogeny is not a closed system of knowledge but a fast-growing assemblage of structured and unstructured information in perpetual flux. This paper intends to review its current state and trends. The latter may introduce speculation and fuzziness. Metallogeny has existed for over 100 years as a branch of Earth Science. From the discovery of plate tectonics (ca. 1950) to the end of the last century, metallogeny passed through a worldwide phase of formally published ‘metallogenetic’ maps. In the last decades, a rapidly growing number of scientists, digitization and splendid new tools fundamentally boosted research. More innovations may be expected by the growing use of an evolving systematic ‘Geodata Science’ for metallogenic research by an increasingly global human talent pool. Future requirements for metallic and mineral raw materials, especially the critical natural elements and compounds that are needed for the nascent carbon-free economy, already drive activities on stock markets and in the resource industry. State geological surveys, academia and private companies embrace the challenges. The new age requires intensified metallogenic backing. In this paper, principles of metallogeny are recalled concerning concepts and terms. A metallogenic classification of ore and mineral deposits is proposed, and the intimate relations of metallogenesis with geodynamics are sketched (ancient lid tectonics and modern plate tectonics). Metallogenic models assemble a great diversity of data that allow an ever better understanding of ore formation, foremost by illuminating the geological source-to-trap migration of ore metals, the petrogenetic and geodynamic–tectonic setting, the spatial architecture of ore deposits and the nature and precise timing of involved processes. Applied metallogeny allows companies to choose strategy and tactics for exploration investment and for planning the work. Based on comprehensive metallogenic knowledge, mineral system analysis (MSA) selects those elements of complex metallogenic models, which are detectable and can guide exploration in order to support applications such as mineral prospectivity mapping, mineral potential evaluation and targeting of detailed investigations. MSA founded on metallogenic models can be applied across whole continents, or at the scale of regional greenfield search, or in brownfields at district to camp scale. By delivering the fundamental keys for MSA, supported by unceasing innovative research, the stream of new metallogenic insights is essential for improving endowment estimates and for successful exploration.

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Chapter 28: Lihir Alkalic Epithermal Gold Deposit, Papua New Guinea

Cited by 4 publications

References 37 publications

Development of a fully constrained structural model in a volcano caldera and its influence on open pit slope design

Development of a fully constrained structural model in a volcano caldera and its influence on open pit slope design

Epithermal Ag–Au mineralization at Galim-Legalgorou, Cameroon Volcanic Line: insights from alteration mineralogy and mineral chemistry of electrum and sphalerite

Metallogenic models as the key to successful exploration — a review and trends

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