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Complex Petrogenesis of Porphyry-Related Magmas in the Cowal District, Australia: Insights from LA ICP-MS Zircon Imaging

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posted on 2023-05-22, 19:52 authored by Leslie, C, Sebastien MeffreSebastien Meffre, David CookeDavid Cooke, Thompson, J, Howard, N, Barker, A

Zircon-based laser ablation inductively coupled plasma-mass spectrometry (LA ICP-MS) trace element imaging and spot analysis methods are used to investigate the petrogenesis of porphyry Cu-related magmas in the Cowal district, Australia. These data discriminate premineralization magmas from synmineralization fertile magmas and provide insights into a complex petrogenesis that culminated in low-temperature, hydrous, and oxidized magma compositions.

The intragrain trace element distribution in zircons from synmineralization intrusions spatially correlates with abrupt changes in zircon textures demarked by dissolution surfaces. Mapping of key fractionation, temperature, hygrometer, and oxybarometer indices (e.g., Th/U, Gd/Yb, (Ce/Nd)/Yb, and Eu/Eu*) show in some cases that multiple crystal-fractionation events, including the cofractionation of titanite, apatite, and hornblende, are recorded in single zircon grains spatially separated by dissolution surfaces. These resorbed boundaries are interpreted to record periods of discrete magma recharge events that affected the temperature and trace element budget of the magma. In many cases, the highest relative magmatic water content and highest oxidation signature are concentrated near the crystal rims, which suggests magmatic fertility increased late during the evolution of these magmas - evidently triggered as a result of magma recharge. An evolution to cooler, hydrous, oxidized conditions with transient periods of magma recharge and higher temperature conditions are considered prerequisites for fertile magma petrogenesis in the Cowal district. The relationship between zircon complexity and fertility should be a useful tool for zircon-based fertility studies informed by cathodoluminescence imagery.


Australian Research Council

Alkane Exploration NL

AngloGold Ashanti Australia Limited

CMOC Mining Services Pty Ltd T/A Northparkes Mines

Department of Economic Development, Jobs, Transport and Resources

Department of State Growth (Tas)

Emmerson Resources Limited

Evolution Mining

Geological Survey of New South Wales - Department of Industry

Geoscience Australia

Heron Resources Limited

New South Resources Limited

Rio Tinto Limited

Sandfire Resoures NL


Publication title

Society of Economic Geologists Special Publication 24, Tectonomagmatic Influences on Metallogeny and Hydrothermal Ore Deposits


A, Sholeh and R, Wang






School of Natural Sciences


Society of Economic Geologists, Inc

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Rights statement

Copyright 2021 Society of Economic Geologists, Inc. This paper is published under the terms of the CC-BY-NC license.

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  • Open

Socio-economic Objectives

Copper ore exploration; Precious (noble) metal ore exploration

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