The composition and structure of the deep crust of the Capricorn Orogen

Understanding how the Australian continent came together requires an understanding of structure in all levels of the lithosphere. Deep seismic reflection profiles across several Proterozoic orogens have revealed entirely buried tectonic elements, termed seismic provinces. Although undoubtedly import...

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Bibliographic Details
Published in:Australian journal of earth sciences 2018-01, Vol.65 (1), p.9-24
Main Authors: Alghamdi, A. H., Aitken, A. R. A., Dentith, M. C.
Format: Article
Language:English
Subjects:
Accretion
Basins
Capricorn Orogen
Composition
Cratons
Crustal structure
Density
Deposition
Depth profiling
Geophysical data
Geophysical studies
Geophysics
Gravitation
Gravity
Gravity data
Lithosphere
Magma
Orogeny
Precambrian
Profiles
Reflection
seismic
Seismic activity
Seismic data
Seismic reflection profiles
Seismic surveys
Seismic velocities
Seismological data
Talga Fault
Velocity
West Australian Craton
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Summary:Understanding how the Australian continent came together requires an understanding of structure in all levels of the lithosphere. Deep seismic reflection profiles across several Proterozoic orogens have revealed entirely buried tectonic elements, termed seismic provinces. Although undoubtedly important, the nature of these seismic provinces is typically not well characterised. The Capricorn Orogen is one such region, where the upper crust is relatively well known from geological and geophysical studies, but much of the deep crust is buried beneath Proterozoic basins. Here we combine geophysical datasets, including active and passive source seismic data and gravity data, to image the density, seismic velocity and compositional structure of the deep crust of the Capricorn Orogen. Crustal structure interpreted from deep seismic reflection studies is re-scaled using velocity information from receiver function studies. This modified geometry is used to construct a density model that satisfies Bouguer gravity data. Finally, after correcting for temperature and pressure dependencies, the velocity and density information is used to generate a compositional model of the orogen. This model indicates a varied structure with at least four distinct blocks between the Yilgarn and Pilbara cratons, bounded by major shear zones. We suggest that this variation is linked to multiple accretion events during the amalgamation of the West Australian Craton.
ISSN:0812-0099
1440-0952
DOI:10.1080/08120099.2018.1389769