CORRIGENDA: In the version of the record originally published, incorrect values for Hfi were repo... more CORRIGENDA: In the version of the record originally published, incorrect values for Hfi were reported in Tables A18 and A21. These errors have been corrected in the PDF version of the record and in the accompanying Excel Workbook NTGSRec2012-007_Appx (November 2016).
Economic geology and the bulletin of the Society of Economic Geologists, 2018
The Wafi-Golpu district of Papua New Guinea contains contrasting high- and intermediate-sulfidati... more The Wafi-Golpu district of Papua New Guinea contains contrasting high- and intermediate-sulfidation styles of epithermal veins and alteration that have overprinted and partially obscured the giant, high-grade Golpu porphyry Cu-Au deposit. The initial stages of magmatic-hydrothermal activity produced high-grade porphyrystyle assemblages that are zoned about the Golpu diorite intrusions, with most mineralization formed between 8.76 ± 0.02 and 8.73 ± 0.01 Ma. Porphyry mineralization was followed by the eruption of the Wafi diatreme, after which upward-widening zones of epithermal alteration and mineralization have overprinted both the mineralized Golpu diorites and the Wafi diatreme. Above the top of the Golpu porphyry, vein and alteration assemblages include quartz (locally vuggy), alunite, pyrophyllite, kaolinite, dickite, and diaspore, with high-sulfidation mineralization consisting of pyrite-covellite-chalcocite-tennantite ± enargite ± bornite that transitions outward to a distal assemblage of disseminated pyrite-sphalerite ± tennantite. A zone of intermediate-sulfidation epithermal carbonate-sulfide ± quartz ± adularia veins and montmorillonite-chlorite ± muscovite ± illite alteration occurs along the margins of the high-sulfidation domain. Most of the epithermal Au occurs near the transition from the high- to intermediate-sulfidation domains. New geochronological results indicate that the main stage of Golpu porphyry mineralization to the last stage of Wafi epithermal veins lasted between 120 and 220 k.y.
Hafnium (Hf) isotope composition of zircon has been integrated with U-Pb age to form a long-term ... more Hafnium (Hf) isotope composition of zircon has been integrated with U-Pb age to form a long-term (>4 b.y.) record of the evolution of the crust. In contrast, trace element compositions of zircon are most commonly utilized in local- or regional-scale petrological studies, and the most noteworthy applications of trace element studies of detrital zircon have been in “fingerprinting” potential source lithologies. The extent to which zircon trace element compositions varied globally over geological time scales (as, for example, zircon U-Pb age abundance, O isotope composition, and Hf isotope composition seem to have varied) has been little explored, and it is a topic that is well suited to the large data sets produced by detrital zircon studies. In this study we present new detrital zircon U-Pb ages and trace element compositions from a continent-scale basin system in Australia (the Centralian Superbasin) that bear directly on the Proterozoic history of Australia and which may be appl...
The generation of continental crust, its bulk composition and temporal evolution provide importan... more The generation of continental crust, its bulk composition and temporal evolution provide important records of plate tectonics and associated magma-generating processes. However, the long-term integrated effects of repeated magmatic events on crustal growth, composition and differentiation and, therefore, on crustal evolution are rarely considered. Here, we examine long-term (∼350 Myr) temporal compositional trends of granitic magmatism within a limited (∼200 km × 100 km) area in the Northern New England Orogen of Queensland, Australia to avoid lateral crustal variations in order to understand how temporal–compositional variations of silicic igneous rocks record crustal evolution. Long-term temporal compositional variations are tracked using whole-rock chemistry, zircon chronochemistry and zircon Hf isotopic compositions. We particularly focus on whole-rock U, Th and K abundances and calculated heat-production values as proxies for crustal evolution, and tracking crustal sources invo...
CORRIGENDA: In the version of the record originally published, incorrect values for Hfi were repo... more CORRIGENDA: In the version of the record originally published, incorrect values for Hfi were reported in Tables A18 and A21. These errors have been corrected in the PDF version of the record and in the accompanying Excel Workbook NTGSRec2012-007_Appx (November 2016).
Economic geology and the bulletin of the Society of Economic Geologists, 2018
The Wafi-Golpu district of Papua New Guinea contains contrasting high- and intermediate-sulfidati... more The Wafi-Golpu district of Papua New Guinea contains contrasting high- and intermediate-sulfidation styles of epithermal veins and alteration that have overprinted and partially obscured the giant, high-grade Golpu porphyry Cu-Au deposit. The initial stages of magmatic-hydrothermal activity produced high-grade porphyrystyle assemblages that are zoned about the Golpu diorite intrusions, with most mineralization formed between 8.76 ± 0.02 and 8.73 ± 0.01 Ma. Porphyry mineralization was followed by the eruption of the Wafi diatreme, after which upward-widening zones of epithermal alteration and mineralization have overprinted both the mineralized Golpu diorites and the Wafi diatreme. Above the top of the Golpu porphyry, vein and alteration assemblages include quartz (locally vuggy), alunite, pyrophyllite, kaolinite, dickite, and diaspore, with high-sulfidation mineralization consisting of pyrite-covellite-chalcocite-tennantite ± enargite ± bornite that transitions outward to a distal assemblage of disseminated pyrite-sphalerite ± tennantite. A zone of intermediate-sulfidation epithermal carbonate-sulfide ± quartz ± adularia veins and montmorillonite-chlorite ± muscovite ± illite alteration occurs along the margins of the high-sulfidation domain. Most of the epithermal Au occurs near the transition from the high- to intermediate-sulfidation domains. New geochronological results indicate that the main stage of Golpu porphyry mineralization to the last stage of Wafi epithermal veins lasted between 120 and 220 k.y.
Hafnium (Hf) isotope composition of zircon has been integrated with U-Pb age to form a long-term ... more Hafnium (Hf) isotope composition of zircon has been integrated with U-Pb age to form a long-term (>4 b.y.) record of the evolution of the crust. In contrast, trace element compositions of zircon are most commonly utilized in local- or regional-scale petrological studies, and the most noteworthy applications of trace element studies of detrital zircon have been in “fingerprinting” potential source lithologies. The extent to which zircon trace element compositions varied globally over geological time scales (as, for example, zircon U-Pb age abundance, O isotope composition, and Hf isotope composition seem to have varied) has been little explored, and it is a topic that is well suited to the large data sets produced by detrital zircon studies. In this study we present new detrital zircon U-Pb ages and trace element compositions from a continent-scale basin system in Australia (the Centralian Superbasin) that bear directly on the Proterozoic history of Australia and which may be appl...
The generation of continental crust, its bulk composition and temporal evolution provide importan... more The generation of continental crust, its bulk composition and temporal evolution provide important records of plate tectonics and associated magma-generating processes. However, the long-term integrated effects of repeated magmatic events on crustal growth, composition and differentiation and, therefore, on crustal evolution are rarely considered. Here, we examine long-term (∼350 Myr) temporal compositional trends of granitic magmatism within a limited (∼200 km × 100 km) area in the Northern New England Orogen of Queensland, Australia to avoid lateral crustal variations in order to understand how temporal–compositional variations of silicic igneous rocks record crustal evolution. Long-term temporal compositional variations are tracked using whole-rock chemistry, zircon chronochemistry and zircon Hf isotopic compositions. We particularly focus on whole-rock U, Th and K abundances and calculated heat-production values as proxies for crustal evolution, and tracking crustal sources invo...
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Papers by Charlotte M Allen