New Zealand Journal of Geology and Geophysics abstracts

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The structure and deformation of the Murchison Basin, South Island, New Zealand

JOANNE C. LIHOU

Department of Geology
Research School of Earth Sciences
Victoria University of Wellington
P.O. Box 600
Wellington, New Zealand*

*Present address: Department of Earth Sciences, University of Oxford, Oxford OX1 3PR, United Kingdom.

Abstract The Murchison Basin lies close to the Alpine Fault and has an evolution that is intimately related to the development of the New Zealand plate boundary during the Tertiary. Faults in the Murchison Basin follow a regional NNE structural grain which is inherited from Paleozoic sutures that were zones of weakness prior to the late Eocene inception of the basin. The Tainui Fault may be the southern extension of the Paleozoic Anatoki Thrust that was reactivated during late Cenozoic compression. The Matin and Maunga Faults, which mark the western margin to the basin and the junction with a structurally high Karamea Batholith, are late Eocene normal faults that have similarly been reactivated and overturned. The eastern boundary is formed by the Tutaki Fault, a southeast-dipping thrust fault which delineates the Rotoroa Complex basement block. Folds within the basin reach a depth of 8 km, whereas, on the basin margins, they have formed as gentle drape folds over a warped basement surface. The dominant structural control for the Murchison Basin is WNW-oriented compression and reactivation of basement block-faults, rather than dextral or sinistral transpression associated with Alpine Fault movement. This has resulted in the basin being the deepest and most intensely deformed of the West Coast region.

Keywords basin; structure; Paleozoic sutures; Anatoki Thrust; faults; Mount Murchison block; folds; compression

Received 13 May 1992; published 13 April 1993
New Zealand Journal of Geology & Geophysics, 1991, Vol. 36: 95—105
0028Ð8306/06/3601—0095 ©The Royal Society of New Zealand 1991

PDF file of entire paper: medium quality (3028K); (scanned from paper original: notes about this process). Digitisation of this article from the printed journal was kindly facilitated by the Geological Society of New Zealand

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