Crustal imaging of a mobile belt using magnetotellurics: An example of the Fowler Domain in South Australia

Brief description

This record was harvested by RDA at 2024-02-14T09:51:54.897+11:00 from NCI's Data Catalogue where it was last modified at 2019-07-16 10:59:31.

Full description

A long-period magnetotelluric data set was obtained in 2005 along a two-dimensionalprofile across the western part of the late Archaean early Proterozoic Gawler Craton,South Australia. The study is aimed at delineating the electrical conductivity structure ofthe crust and upper mantle underneath an east-west trending profile extending fromthe Gawler Range Volcanics in the east, crossing the Nuyts Domain and the highly prospective Meso-Proterozoic Fowler Domain, and terminating in the Eucla Basin to thewest. The resistivity model shows a very electrically resistive crust and upper mantleunderneath the Nuyts and Fowler Domain, possibly representing the cratonic root of the Gawler Craton extending to depths of approx. 160 km. The resistive cratonic root is closer to the surface underneath the Fowler Domain compared to the Nuyts Domain which supportsfindings from outcrops of metasediments of higher metamorphic grade in the FowlerDomain. A subvertical conductor marks the western terminus of the Fowler Domain and isimaged to upper mantle depths. On the eastern side of the Fowler Domain, anothersubvertical conductor extends to similar depths. These features spatially coincide withthe Tallacootra and Coorabie shear zone at the surface, respectively, and their higherconductivity is likely due to a reduction in grain size of olivine associated with an increasein influence of grain boundary diffusion and thus enhanced conductivity. A comparisonof the results with other surveys across mobile belts worldwide shows a more resistiveresponse of the interpreted mobile belt of the Fowler Domain raising questions as tothe nature of the domain.

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