Authors / CoAuthors
Roy, I.G. | Qin, X. | Blewett, R.S. | Neumann, N.L.
Abstract
Crustal magnetism is caused by the magnetic properties commonly due to ferrimagnetic minerals, especially magnetite and/or titano-magnetite, distributed in rocks throughout the crust. One of the common visualisation tools of these properties is a total magnetic intensity (TMI) map or image, from which a number of tectonic and structural inferences regarding the cause of this distribution can be made. However, one often overlooked, and important attribute of magnetism, is the fact that magnetisation is strongly temperature dependent, and ferrimagnetic material lost its properties at the Curie temperature. Generally, temperature in the crust increases with depth. Therefore, with the known magnetic mineral assemblages of the crust and geothermal gradient it is theoretically possible to calculate the 'Curie depth', where the minerals with the ferrimagnetic property become paramagnetic. Alternatively, where the vertical distribution of magnetic minerals in the crust is homogeneous, the 'Curie depth' can be estimated from spectral analysis of magnetic data. It is the depth of bottom of the magnetic anomaly source that is inferred to be a proxy for the 'Curie depth'. We have generated a new 'Curie depth' map over the Olympic Dam supergiant iron-oxide-copper-gold-uranium mineral system in the Gawler Craton of South Australia. The area benefits from high quality airborne TMI data, as well as magnetotelluric and deep seismic reflection data, and numerous local heat-flow determinations.
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nonGeographicDataset
eCat Id
69978
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- External PublicationAbstract
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- TMI
- ( Theme )
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- geophysics
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- AU-SA
- Australian and New Zealand Standard Research Classification (ANZSRC)
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- Earth Sciences
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- Published_Internal
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2010-01-01T00:00:00
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geoscientificInformation
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Abstract version of conference paper recorded as Geocat 70800. Note minor change in title in the full paper version.
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