New Zealand Journal of Geology and Geophysics abstracts

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Holocene history and a thermoluminescence based chronology of coastal dune ridges near Leithfield, North Canterbury, New Zealand

JAMES SHULMEISTER

Research School of Earth Sciences
Victoria University of Wellington
P.O. Box 600
Wellington, New Zealand

ROBERT M. KIRK

Department of Geography
University of Canterbury
Private Bag 4800
Christchurch, New Zealand

Abstract  Dunes of the Pegasus Bay progradation sequence, North Canterbury, New Zealand, have been assigned previously to three soil-based systems, with age estimates based on inferred rates of coastal progradation and soil development. The present study of the coastal reach between the Kowai and Ashley Rivers, Pegasus Bay, identifies five transverse dune systems. The dune ridge systems trend subparallel to the coast and each system relates to a specific, relict or active, sand and/or mixed sand and gravel beach. A morphogenetic classification based on the relationship of the dunes to the prior strandlines is proposed. This is supported by an absolute (coarse fraction thermoluminescence) chronology of the dune systems. Dune-forming events occurred at c. 6500, <6000, <2600, 1000, and 500 years ago.

The transverse dune ridges relate to onshore northeasterly winds. The effective inland penetration of these winds with respect to sand transport is limited to a few hundred metres. Transverse dunes inland of the modern coast are being slowly degraded by the development of low-amplitude parabolic dunes aligned with the northwest föhn wind. These winds are blowing sand back towards the beach.

Keywords  Canterbury; Pegasus Bay; dune ridges; Holocene; thermoluminescence dating; C-14 dating; föhn wind

New Zealand Journal of Geology and Geophysics, 1996, Vol. 39: 25-32

0028-8306/96/0025 $2.50/0 (c) The Royal Society of New Zealand 1996

PDF file of entire paper: medium quality (1511K); (scanned from paper original: notes about this process)

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