New Zealand Journal of Geology and Geophysics abstracts

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Tilting of active folds and faults in the Manawatu region, New Zealand: evidence from surface drainage patterns

JAMES JACKSON

Bullard Laboratories
Madingley Road
Cambridge CB3 OEZ, United Kingdom

RUSS VAN DISSEN
KELVIN BERRYMAN

Institute of Geological & Nuclear Sciences
P.O. Box 30 368
Lower Hutt, New Zealand

Abstract  We examine the drainage system on four anticlinal ridges in Manawatu that affect a mid-Quaternary (c. 300 000 yr old) marine horizon. The folds are all located above buried, west-dipping, reverse faults in the basement that are c. 15-20 km long and capable of generating earthquakes of c. MW 6.5-7.0. The drainage systems allow us to distinguish a regional tectonic tilt from the normal plunge of an anticline axis towards its end. We estimate tilt rates of around 4 <-> 10^-8 rad/yr towards the south averaged over the last c. 300 000 yr. The regional tilting is related to the development and southward migration of the Pliocene-Pleistocene depocentre in the offshore South Wanganui Basin.

Keywords  geomorphology; drainage; faulting; active tectonics

New Zealand Journal of Geology & Geophysics, 1998, Vol. 41: 377-385

0028-8306/98/4104-0377 $7.00/0 (c) The Royal Society of New Zealand 1998

PDF file of entire paper: medium quality (2794K); (scanned from paper original: notes about this process)

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