New Zealand Journal of Geology and Geophysics abstracts
Optical luminescence dating of uplifted marine terraces along the
Akatore Fault near Dunedin, South Island, New Zealand
J. REES-JONES*
W. J. RINK
School of Geography and Geology
McMaster University
Hamilton, Ontario, Canada L8S4M1
R. J. NORRIS
N. J. LITCHFIELD
Geology Department
University of Otago
P.O. Box 56
Dunedin, New Zealand
*Present address: Department of Geography, Royal Holloway, University of
London, Egham, Surrey, United Kingdom TW20 0EX.
Abstract The south Otago coast is characterised by a flight
of marine terraces which have formed and been uplifted in Quaternary time.
Optical luminescence dating along the recently active Akatore Fault has
provided burial ages for beach sands resting upon a wave-cut platform in the
upthrown block that are equal to or younger than 71 +/- 14 ka, and a
burial age of c. 20 ka for the loess cap. The ages on beach sands
clearly indicate that motion on this fault has been relatively limited since
the last interglacial, while the loess date constrains the age of at least one
faulting event on the Akatore Fault at this locality, and two events on the
fault farther south, to be younger than 21 ka. The 6 m high (above
high sea level) sand units in the terrace shown here to date from the late part
of the last interglacial, suggest that sea levels at that time (oxygen isotope
substage 5a) may not have been as low as -18 m, but rather closer to
modern sea level. These applications of optical luminescence dating, using
green light and infrared stimulation of quartz luminescence, constitute a new
approach to studying tectonic rates on faults and paleo-sea levels.
Keywords optical luminescence dating; infrared stimulated
luminescence; geochronology; marine terraces; faulting; tectonic rates;
uplift
New Zealand Journal of Geology & Geophysics, 2000, Vol. 43:
419-424
0028-8306/00/4303-0419 $7.00/0 (c) The Royal Society of New Zealand
2000
PDF file of entire paper: medium quality (690K); (scanned from paper original: notes about this process)
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