Using constrained gravity inversions to indentify high-heat producing granites buried beneath thick sedimentary cover in the Cooper Basin region of central Australia  

Authors / CoAuthors

Meixner, A.J. | Kirkby, A.L. | Horsepool, N.

Abstract

3D constrained gravity inversions have been applied to gravity data in the Cooper Basin region of South Australia to delineate low density regions within the basement, beneath thick sequences of sedimentary cover. The low density regions, which are interpreted as granite bodies, may act as heat sources beneath thermally insulating sediments, thereby enhancing geothermal prospectivity. The Cooper Basin is the site of Australia's first geothermal project , where elevated crustal temperatures result from high-heat producing granites of the Big Lake Suite beneath the basin sediments. A 3D map of sediment stratigraphy was populated with densities and used to constrain the contribution of low density cover sediments to the observed gravity field. The resulting constrained density inversion model produced low density regions in the basement that coincide with local gravity lows. Further gravity inversions were generated and combined with gravity worm data to constrain the lateral and vertical extent of these discrete low density regions which we interpret as granite bodies. These Interpreted Granite Bodies (IGBs) coincide with granites intersected in wells. Analyses of a regional thermal model generated for a previous study, indicate that extra heat-production is required in the regions of the model that coincide with a number of the IGBs. Further thermal modelling was undertaken to determine the heat production differential between these high-heat producing IGBs and the surrounding basement. Two regions were identified where the high-heat producing IGBs are located beneath thick sequences of thermally insulating sediments. These regions, located to the east of the Big Lake Suite granodiorite and in the centre of the study area coinciding with the Barrolka gravity low, are considered to have high geothermal prospectivity.

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nonGeographicDataset

eCat Id

75266

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Keywords

• External PublicationScientific Journal Paper

( Theme )

• 3D model

( Theme )

• density

( Theme )

• geothermal

( Theme )

• geophysics

• AU-QLDAU-NSWAU-SA

Australian and New Zealand Standard Research Classification (ANZSRC)

• Geothermics and Radiometrics

• Published_Internal

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2013-01-01T00:00:00

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Australian Government Security ClassificationSystem    

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Creative Commons Attribution 4.0 International Licence    

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geoscientificInformation

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Journal paper based on gravity inversion modelling and thermal modelling of the Cooper Basin region for the Geothermal Section.

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[-30.0, -24.0, 139.5, 144.0]

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