New Zealand Journal of Geology and Geophysics abstracts
Quaternary faulting in the offshore Flaxbourne and Wairarapa Basins, southern
Cook Strait, New Zealand
PHILIP M. BARNES
National Institute of Water and Atmospheric Research
P.O. Box 14901, Kilbirnie
Wellington, New Zealand
email: p.barnes@niwa.cri.nz
JEAN-CHRISTOPHE AUDRU
UMR Géosciences Azur
Université de Nice - Sophia Antipolis
06560 Valbonne, France
Present address: Bureau de Recherches Géologiques et Minieres, BP6009,
45060 Orleans, France.
Abstract Marine seismic reflection profiles,
bathymetric data, and seabed samples reveal the stratigraphy and Quaternary
structure of the southern Wairarapa and Flaxbourne Basins in southeastern Cook
Strait and eastern Marlborough. These SW-NE-trending basins began forming
before the late Miocene (>10 Ma), but their development has been mainly
during and since that time and continues today within the Pacific-Australia
plate boundary zone. Recently active structures deforming and bounding the
basins are recognised by growth strata and deformation of Quaternary sediments.
Observed structural geometries reflect Pliocene-Recent changes in the
kinematics of faulting in central New Zealand. The 12-22 km wide southern
Wairarapa Basin contains up to c. 2.9 km of strata and is deforming between
offshore segments of the dextral strike-slip Wairarapa Fault and associated
Wharekauhau Thrust on the western margin, and offshore extensions of the
Aorangi Mountains range-front reverse faults on the eastern margin. To the
southwest, in the eastern Marlborough Fault System, the 15-20 km wide, 80 km
long Flaxbourne Basin contains >4.5 km of strata and is deforming by
strike-slip and oblique-slip faults including offshore sections of the Hope and
Kekerengu Faults. A new set of strike-slip faults, probably younger than 1 Ma,
strike parallel (c. 080 +/- 10¡) to the current Pacific-Australian plate
motion vector and obliquely to inherited structural trends. Three of these
faults are possibly separating the Flaxbourne and Wairarapa Basins in central,
southern Cook Strait. Curved traces of the Needles and Wairarapa Faults on the
western margins of the basins are aligned, and may cut across disrupted Miocene
structures to link part of the eastern Marlborough Fault System with the North
Island Dextral Fault Belt.
Keywords Cook Strait; Marlborough; Wairarapa; plate boundary;
tectonic; faulting; structure; Quaternary; seismic reflection; bathymetry;
stratigraphy; sedimentary basins
New Zealand Journal of Geology & Geophysics, 1999, Vol. 42:
349-367
0028-8306/99/4203-0349 $7.00/0 (c) The Royal Society of New Zealand
1999
PDF file of entire paper: medium quality (6678K); (scanned from paper original: notes about this process)
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