New Zealand Journal of Geology & Geophysics abstracts
Drainage reorientation in Marlborough Sounds, New Zealand, during
the Last Interglacial
Dave Craw
Geology Department
University of Otago
PO Box 56
Dunedin 9054, New Zealand
dave.craw@stonebow.otago.ac.nz
Leigh Anderson
Environmental Science Programme
University of Otago
PO Box 56
Dunedin 9054, New Zealand
Uwe Rieser
School of Earth Sciences
Victoria University of Wellington
PO Box 600
Wellington 6140, New Zealand
Jon Waters
Zoology Department
University of Otago
PO Box 56
Dunedin 9054, New Zealand
Abstract Regional drainage of the Marlborough
Sounds area, northern South Island, New Zealand, discharged water and
sediment towards the south until the Last Interglacial. Drainage
reversal occurred at that time, and discharge is now northwards.
Drainage reversal was facilitated by regional subsidence and tilting,
and build-up of a thick (c. 60 m) sedimentary pile in the former main
southward axial drainage channel comprising the Kaituna and Are Are
valleys (the Kaituna corridor), before the Last Interglacial. Minor
southward flow persisted in the Kaituna valley after the Last
Interglacial, but this involved locally derived sediments only. Dating
of these latter sediments by OSL techniques constrains the minimum age
of drainage reversal to be c. 70 ka. The maximum inferred age of
reversal (c. 130 ka) is based on regional correlation of glacial
outwash terraces. These age estimates are consistent with each other
and with geomorphological and stratigraphic observations within the
Kaituna corridor. The drainage reversal occurred when ponding of
sediment in the south allowed overtopping of a low drainage divide
farther north in what is now Pelorus Sound. Subsequent erosion through
this divide was probably facilitated by shoreline retreat and
associated downcutting during sea level high-stands of the Last
Interglacial.
Keywords river capture; geomorphology;
Quaternary; OSL dating; tectonics; sedimentation; Marlborough Sounds
G06020; Online publication date 1 March 2007; Received 3 July 2006;
accepted 22 December 2006
New Zealand Journal of Geology & Geophysics, 2007, Vol. 50:
13 - 20
0028 - 8306/07/5001 - 0013 © The Royal Society of New Zealand
2007
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