New Zealand Journal of Geology and Geophysics abstracts
Paleo-equilibrium line altitude estimates from late Quaternary glacial features
in the Inland Kaikoura Range, South Island, New Zealand
S. N. BACON
Department of Geology
Humboldt State University
Arcata, California 95521-8299, USA
T. J. CHINN
Alpine & Polar Processes Consultancy
National Institute of Water & Atmospheric Research
P.O. Box 6414
Dunedin, New Zealand
R. J. VAN DISSEN
Institute of Geological & Nuclear Sciences
P.O. Box 30 368
Lower Hutt, New Zealand
S. F. TILLINGHAST
Department of Geology
Northern Arizona University
Box 4099
Flagstaff, Arizona 86011, USA
H. L. GOLDSTEIN
Department of Earth & Environmental Science
New Mexico Tech
801 Leroy Place, MSEC #208
Socorro, New Mexico 87801, USA
R. M. BURKE
Department of Geology
Humboldt State University
Arcata, California 95521-8299, USA
Abstract A reconnaissance investigation of glacial features
in the Inland Kaikoura Range (IKR), South Island, New Zealand, confirms that
over 30 km of the length of the range, with a maximum elevation of 2885 m, has
been extensively glaciated in the past, in contrast to previous reports.
Identified glacial features include cirques, lateral moraines, moraine
fragments and associated features, and rock glaciers. Up to five glacial
advances have been identified in any one catchment in the range, with the most
complete sequence found in Branch Stream, which drains the steep southeastern
flank of the highest portion of the range. The lateral moraines of Branch
Stream are impressive; they range in elevation from c. 1700 to 1200 m, and,
because of their large size and relatively good state of preservation, they are
interpreted to be of late Otiran age. Glacial features that are less well
preserved and more fragmentary are found at lower elevations in other
catchments (e.g., Dart, Muzzle, and Bluff Streams), and are here inferred to be
of early-mid Otiran age. The lack of preservation of older glacial landforms is
attributed to the steep, unstable terrain of the IKR generated by the
relatively high uplift rate (c. 5 mm/yr), and consequent high erosion rate in
the range, which is located in the hanging wall of the active Clarence Fault. A
sequence of paleo-equilibrium line altitudes (paleo-ELAs) for the past glaciers
in the IKR have been derived using cirque floor elevations, accumulation-area
ratios (AARs) and interpolated estimates, and give snowline depressions below
the present (2530 m) of 830 m for the early-mid Otiran, 740 m for late Otiran,
575 m for final Otiran, 450 m for Late Glacial, 270 m for Neoglacial, and 150 m
for the Little Ice Age. Because glacial features in the IKR have yet to be
directly dated, these age estimates should be regarded as interpretive in
nature and are based solely on relative size, elevation, sequence position, and
degree of preservation. The paleo-ELAs have been normalised to a southerly
aspect using a correction established in the northern Southern Alps that has
yet to be tested in the IKR. Correcting for accrued uplift over the past c.
18 000 yr conceivably provides an additional c. 90 m of depression,
suggesting a total ELA depression of as much as c. 830 m during the late Otiran
compared to modern climate. The paleo-ELA depression estimates for the IKR
appear to be similar to estimates calculated in other areas in the South and
North Islands. Evidence of glacial features in the IKR, and the apparent
similarity of ELA depressions in the range with that elsewhere in New Zealand,
suggests that past climate fluctuations in the IKR have been, to at least some
degree, "in harmony" with those throughout the remainder of the country.
Keywords glacial geology; paleo-equilibrium line altitude
(paleo-ELA); paleoclimate; Otiran glaciation; Clarence Fault; Inland Kaikoura
Range
New Zealand Journal of Geology & Geophysics, 2001, Vol. 44: 55-67
0028-8306/01/4401-0055 $7.00/0 (c) The Royal Society of New Zealand
2001
PDF file of entire paper: medium quality (7027K); (scanned from paper original: notes about this process)
This year's abstracts |
Journal home page |
All abstracts |
Publishing home page
