Authors / CoAuthors
Williams, N.C.
Abstract
Physical property measurements provide a critical link between geological observations and geophysical measurements and modelling. To enhance the reliability of gravity and magnetic modelling in the Yilgarn Craton's Agnew-Wiluna greenstone belt, mass and magnetic properties were analysed on 157 new rock samples and combined with an existing corporate database of field measurements. The new samples include sulphide ore, serpentinised and olivine-bearing ultramafic host rocks, granitoid, and felsic and mafic volcanic and volcaniclastic country rock. Synthesis of the data provides a useful resource for future geophysical modelling in the region. Several rock types in the region have sufficiently distinct physical properties that a discriminant diagram is proposed to facilitate a basic classification of rock types based on physical properties. However the accumulation of emplacement, metamorphic, hydrothermal and structural processes has complicated the physical properties of the rocks by imposing duplicate and sometimes opposing physical property trends. The data confirms that massive sulphide and ultramafic rocks have the most distinctive mass and magnetic properties but with variability imposed by their complex history. Sulphide content imposes the strongest control on densities, but can only be identified when comprising > 10 vol. % of the rock. The pyrrhotite-rich Ni-sulphide assemblages generally have similar magnetic properties to the host ultramafic rocks, but can have much lower susceptibilities where the thermal history of the rocks has favoured development of hexagonal pyrrhotite over monoclinic pyrrhotite. In ultramafic rocks that contain < 10 vol. % sulphides, density and susceptibility are primarily controlled by serpentinisation, with olivine breaking down to serpentine and magnetite in the presence of water.
Product Type
nonGeographicDataset
eCat Id
68821
Contact for the resource
Custodian
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Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
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- External PublicationScientific Journal Paper
- ( Theme )
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- palaeomagnetism
- ( Theme )
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- alteration
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- AU-WA
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
Publication Date
2009-01-01T00:00:00
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unknown
Topic Category
geoscientificInformation
Series Information
56
Lineage
Unknown
Parent Information
Extents
[-28.0, -27.0, 120.0, 121.5]
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Spatial Resolution
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