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A SIMS U-Pb (zircon) and Re-Os (molybdenite) isotope study of the early Paleozoic Macquarie Arc, southeastern Australia: Implications for the tectono-magmatic evolution of the paleo-Pacific Gondwana margin

Blevin, Philip; Kemp, A. I. S.; Norman, Marc; EIMF

Description

New SIMS U-Pb (zircon) data for intrusive rocks of the Macquarie Arc and adjacent granitic batholiths of the Lachlan Orogen (southeastern Australia) provide insight into the magmatic and tectonic evolution of the paleo-Pacific Gondwana margin in the early Paleozoic. These data are augmented by Re-Os dates on molybdenite from four CuAu mineralised porphyry systems to place minimum age constraints on igneous crystallization. The simplicity of the zircon age distributions, and absence of older...[Show more]

dc.contributor.authorBlevin, Philip
dc.contributor.authorKemp, A. I. S.
dc.contributor.authorNorman, Marc
dc.contributor.authorEIMF
dc.date.accessioned2020-09-07T01:30:53Z
dc.identifier.issn1342-937X
dc.identifier.urihttp://hdl.handle.net/1885/209343
dc.description.abstractNew SIMS U-Pb (zircon) data for intrusive rocks of the Macquarie Arc and adjacent granitic batholiths of the Lachlan Orogen (southeastern Australia) provide insight into the magmatic and tectonic evolution of the paleo-Pacific Gondwana margin in the early Paleozoic. These data are augmented by Re-Os dates on molybdenite from four CuAu mineralised porphyry systems to place minimum age constraints on igneous crystallization. The simplicity of the zircon age distributions, and absence of older inheritance, stands in contrast to previous geochronological studies. The earliest magmatism within the Macquarie Arc is registered by a ca. 503 Ma gabbro from the Monza igneous complex, whereas a monzodiorite from the same drillhole records the youngest (ca. 432 Ma). Igneous activity in the Macquarie Arc thus overlapped deformation and magmatism in the craton-proximal Delamerian Orogen to the west, and the emplacement of the Lachlan granitic batholiths at 435-430 Ma; the thermal pulse associated with the latter may have triggered the formation of richly mineralised Silurian porphyries in the Macquarie Arc. The juvenile Hf isotope signature of the Monza Gabbro, together with the lack of zircon inheritance and the radiogenic Hf-Nd isotope systematics of Ordovician Macquarie Arc rocks, is consistent with early development of the arc, or a precursor magmatic belt, in an oceanic setting remote from continental influences, and with the arc being built on primitive Cambrian mafic crust. Outboard arc magmatism in the Cambrian may have initiated in response to convergent Delamerian orogenesis adjacent the Gondwana margin. Overlapping radiogenic isotope-time trends are consistent with the evolution of the Macquarie Arc and the Gondwana continental margin being linked from the Cambrian to the Silurian. These data provide further evidence for the growth of continental crust along the southeastern Australian segment of this margin being related to the dynamics of an extensional accretionary orogenic system.
dc.format.mimetypeapplication/pdf
dc.language.isoen_AU
dc.publisherElsevier
dc.rightsCrown Copyright © 2020 Published by Elsevier B.V. on behalf of International Association for Gondwana Research
dc.sourceGondwana Research
dc.source.urihttps://dx.doi.org/10.1016/j.gr.2019.12.015
dc.titleA SIMS U-Pb (zircon) and Re-Os (molybdenite) isotope study of the early Paleozoic Macquarie Arc, southeastern Australia: Implications for the tectono-magmatic evolution of the paleo-Pacific Gondwana margin
dc.typeJournal article
local.description.notesImported from ARIES
local.identifier.citationvolume82
dc.date.issued2020
local.identifier.absfor040303 - Geochronology
local.identifier.absfor040313 - Tectonics
local.identifier.ariespublicationu6269649xPUB437
local.type.statusPublished Version
local.contributor.affiliationBlevin, Philip, Geological Survey of New South Wales
local.contributor.affiliationKemp, A I S, The University of Western Australia
local.contributor.affiliationNorman, Marc, College of Science, ANU
local.contributor.affiliationEIMF, E, University of Edinburgh
local.description.embargo2037-12-31
local.bibliographicCitation.startpage73
local.bibliographicCitation.lastpage96
local.identifier.absseo970104 - Expanding Knowledge in the Earth Sciences
dc.date.updated2020-05-17T08:23:42Z
local.identifier.scopusID2-s2.0-85078976716
CollectionsANU Research Publications

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