New Zealand Journal of Geology and Geophysics abstracts

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The role of faulting in rock uplift in the Southern Alps, New Zealand

J. MARK TIPPETT
PETER J.J.KAMP

Geochronology Research Unit
Department of Earth Sciences
University of Waikato
Private Bag 3105
Hamilton 2001, New Zealand

Abstract Fission track data for a suite of basement rock samples from the Southern Alps is used to assess the role of faulting in the late Cenozoic rock uplift of the Pacific plate. The amount of rock uplift derived from sites on both sides of the Moonlight, Ostler, Harper, Torlesse, Porters Pass, and Hope Faults shows that for all faults the vertical offset lies within the uncertainty of the data, typically ±2 km, and is <30% of the surrounding uplift. Major faults are conspicuously absent in the zone of greatest uplift. Over a scale of kilometres, the pattern of rock uplift across the Southern Alps is continuous and regular. The amount of rock uplift increases nearly exponentially with increasing proximity to the Alpine Fault, and the pattern is maintained with little variation over the central 350 km long segment of the Southern Alps. This pattern is primarily the result of southeastward tilting of the middle and upper crust of the Pacific plate, which has ramped up the Alpine Fault in response to oblique convergence and crustal shortening. The geometry of the rock uplift implies that at least part of the Alpine Fault has a listric profile at depth.

Keywords Southern Alps; Alpine Fault; rock uplift; fission track analysis; deformation; faulting

Received 18 June 1992; published 3 December 1993
New Zealand Journal of Geology & Geophysics, 1991, Vol. 36: 497—504
0028Ð8306/06/3604—0497 ©The Royal Society of New Zealand 1991

PDF file of entire paper: medium quality (599K); (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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