The Anatomy of an Alkalic Porphyry Cu-‐Au System: Geology and Alteration at Northparkes Mines, NSW, Australia
The Late Ordovician-Early Silurian (~455-435 Ma) Northparkes system is a group of silica-saturated, alkalic porphyry deposits and prospects which developed within the Macquarie Island Arc. The system is host to a spectacular and diverse range of rocks and alteration-mineralization textures that faci...
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Society of Economic Geologists
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Online Access: | http://hdl.handle.net/10141/622527 https://doi.org/10.5382/econgeo.4644 |
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ftnhmlondon:oai:nhm.openrepository.com:10141/622527 2023-07-30T04:04:48+02:00 The Anatomy of an Alkalic Porphyry Cu-‐Au System: Geology and Alteration at Northparkes Mines, NSW, Australia Pacey, A Wilkinson, JJ Owens, J Priest, D Cooke, DR Millar, IL 2019-06-03T13:25:23Z http://hdl.handle.net/10141/622527 https://doi.org/10.5382/econgeo.4644 unknown Society of Economic Geologists Adam Pacey, Jamie J. Wilkinson, Jeneta Owens, Darren Priest, David R. Cooke, Ian L. Millar; The Anatomy of an Alkalic Porphyry Cu-Au System: Geology and Alteration at Northparkes Mines, New South Wales, Australia. Economic Geology 114 (3): 441–472. doi: https://doi.org/10.5382/econgeo.4644 0361-0128 https://doi.org/10.5382/econgeo.4644 http://hdl.handle.net/10141/622527 Economic Geology 114 3 441 - 472 (31) closedAccess Northparkes Macquarie Arc porphyry deposit propylitic alteration hydrothermal copper gold alkalic Journal Article 2019 ftnhmlondon https://doi.org/10.5382/econgeo.4644 2023-07-11T05:39:06Z The Late Ordovician-Early Silurian (~455-435 Ma) Northparkes system is a group of silica-saturated, alkalic porphyry deposits and prospects which developed within the Macquarie Island Arc. The system is host to a spectacular and diverse range of rocks and alteration-mineralization textures that facilitate a detailed understanding of its evolution, in particular into the nature and controls of porphyry-related propylitic alteration. The first intrusive phase at Northparkes is a pre- to early-mineralization pluton that underlies all the deposits and varies in composition from a biotite quartz monzonite (BQM) to alkali feldspar granite (AFG). Prior to total crystallization, this pluton was intruded by a more primitive quartz monzonite (QMZ) that marks the onset of a fertile fractionation series. Towards its upper levels, the QMZ is porphyritic and locally rich in Cu sulfides. Subsequently, a complex series of syn-mineralization quartz monzonite porphyries (QMP) were emplaced. The QMP intrusions have a distinct pipe-like morphology and are ubiquitously K-feldspar altered with a crystal-crowded porphyritic texture. The textures of the QMPs and common occurrence of porphyry-cemented contact breccias indicate they were forcibly emplaced and of relatively low viscosity. The QMPs are therefore interpreted as crystal-bearing, silicate melt-aqueous fluid slurries that represent the conduits through which deep-seated magmatic-derived ore fluid was discharged into the shallow crust (1-2 km depth). Each deposit is centred on a multiphase cluster of QMP intrusions that drove discrete hydrothermal systems. Initial fluid evolution was similar in all the deposits, with three major alteration facies developed as largely concentric zones around the QMP complexes. The innermost zone is host to Cu sulfide ore and dominated by K-feldspar alteration. This transitions outwards through a shell of magnetite ± biotite alteration, with pyrite and minor chalcopyrite, to an outer halo of propylitic alteration. Generally, epidote, chlorite and ... Article in Journal/Newspaper Macquarie Island Natural History Museum Repository Economic Geology 114 3 441 472 |
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Natural History Museum Repository |
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ftnhmlondon |
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unknown |
topic |
Northparkes Macquarie Arc porphyry deposit propylitic alteration hydrothermal copper gold alkalic |
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Northparkes Macquarie Arc porphyry deposit propylitic alteration hydrothermal copper gold alkalic Pacey, A Wilkinson, JJ Owens, J Priest, D Cooke, DR Millar, IL The Anatomy of an Alkalic Porphyry Cu-‐Au System: Geology and Alteration at Northparkes Mines, NSW, Australia |
topic_facet |
Northparkes Macquarie Arc porphyry deposit propylitic alteration hydrothermal copper gold alkalic |
description |
The Late Ordovician-Early Silurian (~455-435 Ma) Northparkes system is a group of silica-saturated, alkalic porphyry deposits and prospects which developed within the Macquarie Island Arc. The system is host to a spectacular and diverse range of rocks and alteration-mineralization textures that facilitate a detailed understanding of its evolution, in particular into the nature and controls of porphyry-related propylitic alteration. The first intrusive phase at Northparkes is a pre- to early-mineralization pluton that underlies all the deposits and varies in composition from a biotite quartz monzonite (BQM) to alkali feldspar granite (AFG). Prior to total crystallization, this pluton was intruded by a more primitive quartz monzonite (QMZ) that marks the onset of a fertile fractionation series. Towards its upper levels, the QMZ is porphyritic and locally rich in Cu sulfides. Subsequently, a complex series of syn-mineralization quartz monzonite porphyries (QMP) were emplaced. The QMP intrusions have a distinct pipe-like morphology and are ubiquitously K-feldspar altered with a crystal-crowded porphyritic texture. The textures of the QMPs and common occurrence of porphyry-cemented contact breccias indicate they were forcibly emplaced and of relatively low viscosity. The QMPs are therefore interpreted as crystal-bearing, silicate melt-aqueous fluid slurries that represent the conduits through which deep-seated magmatic-derived ore fluid was discharged into the shallow crust (1-2 km depth). Each deposit is centred on a multiphase cluster of QMP intrusions that drove discrete hydrothermal systems. Initial fluid evolution was similar in all the deposits, with three major alteration facies developed as largely concentric zones around the QMP complexes. The innermost zone is host to Cu sulfide ore and dominated by K-feldspar alteration. This transitions outwards through a shell of magnetite ± biotite alteration, with pyrite and minor chalcopyrite, to an outer halo of propylitic alteration. Generally, epidote, chlorite and ... |
format |
Article in Journal/Newspaper |
author |
Pacey, A Wilkinson, JJ Owens, J Priest, D Cooke, DR Millar, IL |
author_facet |
Pacey, A Wilkinson, JJ Owens, J Priest, D Cooke, DR Millar, IL |
author_sort |
Pacey, A |
title |
The Anatomy of an Alkalic Porphyry Cu-‐Au System: Geology and Alteration at Northparkes Mines, NSW, Australia |
title_short |
The Anatomy of an Alkalic Porphyry Cu-‐Au System: Geology and Alteration at Northparkes Mines, NSW, Australia |
title_full |
The Anatomy of an Alkalic Porphyry Cu-‐Au System: Geology and Alteration at Northparkes Mines, NSW, Australia |
title_fullStr |
The Anatomy of an Alkalic Porphyry Cu-‐Au System: Geology and Alteration at Northparkes Mines, NSW, Australia |
title_full_unstemmed |
The Anatomy of an Alkalic Porphyry Cu-‐Au System: Geology and Alteration at Northparkes Mines, NSW, Australia |
title_sort |
anatomy of an alkalic porphyry cu-‐au system: geology and alteration at northparkes mines, nsw, australia |
publisher |
Society of Economic Geologists |
publishDate |
2019 |
url |
http://hdl.handle.net/10141/622527 https://doi.org/10.5382/econgeo.4644 |
genre |
Macquarie Island |
genre_facet |
Macquarie Island |
op_relation |
Adam Pacey, Jamie J. Wilkinson, Jeneta Owens, Darren Priest, David R. Cooke, Ian L. Millar; The Anatomy of an Alkalic Porphyry Cu-Au System: Geology and Alteration at Northparkes Mines, New South Wales, Australia. Economic Geology 114 (3): 441–472. doi: https://doi.org/10.5382/econgeo.4644 0361-0128 https://doi.org/10.5382/econgeo.4644 http://hdl.handle.net/10141/622527 Economic Geology 114 3 441 - 472 (31) |
op_rights |
closedAccess |
op_doi |
https://doi.org/10.5382/econgeo.4644 |
container_title |
Economic Geology |
container_volume |
114 |
container_issue |
3 |
container_start_page |
441 |
op_container_end_page |
472 |
_version_ |
1772816404078133248 |