Offshore Sedimentary Basins at the Southern End of the Alpine Fault, New Zealand

  1. Peter F. Ballance and
  2. Harold G. Reading
  1. R. J. Norris and
  2. R. M. Carter

Published Online: 20 APR 2009

DOI: 10.1002/9781444303735.ch14

Sedimentation in Oblique-Slip Mobile Zones

Sedimentation in Oblique-Slip Mobile Zones

How to Cite

Norris, R. J. and Carter, R. M. (1980) Offshore Sedimentary Basins at the Southern End of the Alpine Fault, New Zealand, in Sedimentation in Oblique-Slip Mobile Zones (eds P. F. Ballance and H. G. Reading), Blackwell Publishing Ltd., Oxford, UK. doi: 10.1002/9781444303735.ch14

Author Information

  1. University of Otago, Dunedin, New Zealand

Publication History

  1. Published Online: 20 APR 2009
  2. Published Print: 11 SEP 1980

ISBN Information

Print ISBN: 9780632006076

Online ISBN: 9781444303735

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Keywords:

  • Offshore sedimentary basins at New Zealand;
  • concurrent tectonic activity from the late Eocene, influencing Cainozoic sedimentation in southwest New Zealand;
  • seismic profiles of the offshore region, showing presence of two major basins;
  • Moonlight Fault System, joining Fiordland Boundary Fault System;
  • youngest formations of Blackmount column - late Middle Miocene age;
  • Hump Ridge-Midbay High - complexly faulted basement high;
  • Fiordland Boundary Fault, forming part of Moonlight Fault System

Summary

Cainozoic sedimentation in southwest New Zealand was strongly influenced by concurrent tectonic activity from the late Eocene onwards. Fault-bounded flysch basins were filled with thick wedges of Oligo-Miocene redeposited and associated deep marine sediments. Changes in tectonic regime at about 10 m.y. BP (late mid-Miocene) led to folding and uplift of the sediments. Due to this mid-Miocene and later tectonism it is difficult to reconstruct the original size, shape or disposition of the onland Oligo-Miocene basins. Seismic profiles of the offshore region, in the head of the Solander Trough, show the presence of two major basins, the Balleny and Solander Basins, of similar size and style to the onshore basins, and separated from each other across the offshore extension of the Moonlight fault system. Four seismic units are recognized in each basin, with stratigraphic control provided by HIPCO's 3628 m deep PARARA-1 exploration well. Regional time-isopach maps for the lower seismic units (Eocene to early Miocene) show both basins were filled largely from their western margins; since no source regions exist to the west of either basin today, it is inferred that they have been shifted northeast by lateral movement on the Alpine and Moonlight fault systems. Time-isopach maps for the upper seismic units (late Miocene to Recent) show the Balleny Basin to have received a thin, mainly pelagic drape, whereas the Solander Basin has been filled by a thick shelf sequence, prograding from off the southern end of the New Zealand landmass.

The development of the basins of southwest New Zealand is related to the behaviour of the Fiordland microplate, a rigid block of continental crust located between the Moonlight and Alpine fault systems. During the Eo-Oligocene, extensional oblique-slip (transtension) on these fault systems led to the subsidence and final submergence of Fiordland. Compressive oblique-slip (transpression) since the middle Miocene has caused a northwards movement of the microplate, with associated deformation and uplift reaching a maximum in the north and decreasing in intensity southwards. The main modern drainage systems have thereby developed from north to south, more or less along the line of the Moonlight tectonic zone.