New Zealand Journal of Geology and Geophysics abstracts
Change in direction of the Pelorus River, Marlborough, New Zealand:
evidence from composition of Quaternary gravels
NICK MORTIMER
Institute of Geological & Nuclear Sciences
Private Bag 1930
Dunedin, New Zealand
PAUL WOPEREIS
Consultant Geologist
P.O. Box 963
Nelson, New Zealand
Abstract Clasts in greenish subsurface gravels of presumed
Quaternary age in the Kaituna valley comprise mainly metamorphosed and variably
foliated volcanic litharenite of the Pelorus Group, but also contain some Dun
Mountain Ophiolite Belt lithologies. These clast compositions are inconsistent
with the gravel source being either the surrounding schist basement or the
nearby Wairau River, but instead strongly suggest a source in the Pelorus River
catchment. Thus, at some time in the Quaternary, the Pelorus River flowed south
into the Wairau River instead of east and north into Pelorus Sound as it does
now. The change in drainage direction since then was due either to non-tectonic
river capture and/or northward regional tilting.
Keywords Marlborough; gravels; river terraces; Quaternary;
Pelorus Group; tectonics
New Zealand Journal of Geology and Geophysics, 1997, Vol. 40: 307-313
0028-8306/97/4003-0307 $7.00/0 (c) The Royal Society of New Zealand
1997
PDF file of entire paper: medium quality (1593K); (scanned from paper original: notes about this process)
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