Authors / CoAuthors
Kirkby, A.L. | Musgrave, R. | Czarnota, K. | Doublier, M.P. | Duan, J. | Cayley, R.A. | Kyi, D.
Abstract
We present a resistivity model of the southern Tasmanides of southeastern Australia using Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP) data. Modelled lower crustal conductivity anomalies resemble concentric geometries revealed in the upper crust by potential field and passive seismic data. These geometries are a key part of the crustal architecture predicted by the Lachlan Orocline model for the evolution of the southern Tasmanides, in which the Proterozoic Selwyn Block drives oroclinal rotation against the eastern Gondwana margin during the Silurian period. For the first time, we image these structures in three dimensions (3D) and show they persist below the Moho. These include a lower crustal conductor largely following the northern Selwyn Block margin. Spatial association between lower crustal conductors and both Paleozoic to Cenozoic mafic to intermediate alkaline volcanism and gold deposits suggests a genetic association i.e. fluid flow into the lower crust resulting in the deposition of conductive phases such as hydrogen, iron, sulphides and/or graphite. The 3D model resolves a different pattern of conductors in the lithospheric mantle, including northeast trending anomalies in the northern part of the model. Three of these conductors correspond to Cenozoic leucitite volcanoes along the Cosgrove mantle hotspot track which likely map the metasomatised mantle source region of these volcanoes. The northeasterly alignment of the conductors correlates with variations in the lithosphere-asthenosphere boundary (LAB) and the direction of Australian plate movement, and may be related to movement of an irregular LAB topography over the asthenosphere. By revealing the tectonic architecture of a Phanerozoic orogen and the overprint of more recent tectono-magmatic events, our resistivity model enhances our understanding of the lithospheric architecture and geodynamic processes in southeast Australia, demonstrating the ability of magnetotelluric data to image geological processes over time.
Product Type
document
eCat Id
131637
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
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Keywords
- theme.ANZRC Fields of Research.rdf
-
- GEOPHYSICSGeodynamicsEARTH SCIENCESElectrical and Electromagnetic Methods in Geophysics
-
- AusLAMP
-
- magnetotellurics
-
- Published_External
Publication Date
2020-10-01T23:37:48
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Status
final
Purpose
Publication in Tectonophysics
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asNeeded
Topic Category
geoscientificInformation
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Not supplied.
Parent Information
Extents
[-39.00, -29.00, 140.00, 153.00]
Reference System
Spatial Resolution
Service Information
Associations
Association Type - crossReference
Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP): New South Wales: data release (Phase one)
eCat Identifier - 132148,
UUID - 27d4c7ea-a4ac-4fdc-8ff0-2c141c11854c
Association Type - crossReference
Australian Lithospheric Architecture Magnetotelluric Project (AusLAMP): Victoria: Data Release Report
eCat Identifier - 120864,
UUID - 322dab38-bace-4c32-ae5f-612c01d4a2ef
Association Type - crossReference
Resistivity model of the southeast Australian mainland from AusLAMP magnetotelluric data
eCat Identifier - 131889,
UUID - 222353d1-a4e0-46fd-a926-b553c2fc6e61
Source Information