New Zealand Journal of Geology and Geophysics abstracts

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Electrical structure along a transect of the central South Island, New Zealand

M. R. INGHAM

Institute of Geophysics
Victoria University of Wellington
P.O. Box 600
Wellington, New Zealand

Abstract  Regional magnetotelluric responses from a transect across the central South Island, New Zealand, have been inverted to produce a smooth two-dimensional model of electrical resistivity structure associated with the Southern Alps orogen. The resulting structure is consistent with proposed models for the orogen and shows a zone of enhanced conductivity at a depth of only 10 km beneath the Southern Alps. This can be interpreted as being caused by the presence of "wet" greenschist facies rocks upthrust from lower crustal depth. There is some indication of reduced resistivity at 25 km depth beneath the Canterbury Plains, which may be associated with the existence of a lower crustal detachment surface. A large resistivity contrast occurs near the Alpine Fault, and this may be an indication of a lack of lateral fluid movement across the fault zone.

Keywords  magnetotelluric; Southern Alps; electrical conductivity

New Zealand Journal of Geology and Geophysics, 1995, Vol. 38: 559-563

0028-8306/95/3804-0559 $2.50/0 (c) The Royal Society of New Zealand 1995

PDF file of entire paper: medium quality (929K); (scanned from paper original: notes about this process)

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