New Zealand Journal of Geology & Geophysics abstracts

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Distribution, age, and uplift patterns of Pleistocene marine terraces of the northern Raukumara Peninsula, North Island, New Zealand

Kate Wilson^1*

Nicola Litchfield²

Kelvin Berryman²

Tim Little¹

¹School of Earth Sciences
Victoria University of Wellington
PO Box 600
Wellington 6140, New Zealand

²GNS Science
PO Box 30368
Lower Hutt 5040, New Zealand

^*Present address: GNS Science, PO Box 30368, Lower Hutt 5040, New Zealand.

Abstract The distribution and age of Pleistocene marine terraces fringing the northern Raukumara Peninsula, North Island, New Zealand, is revised. Two terraces, the higher Otamaroa Terrace and the lower Te Papa Terrace, are present from the eastern Bay of Plenty to near East Cape. Six optically stimulated luminescence (OSL) ages obtained from the terrace deposits and coverbeds represent the first radiometric ages from these terraces. Loess from the Te Papa Terrace has an age of 62.6 ± 6 ka and the underlying sand has an age of 58.3 ± 4.1 ka. Four OSL ages obtained from sand resting on the bedrock strath of the higher Otamaroa Terrace range from 64.5 ± 4.7 to 79.2 ± 5.5 ka. These OSL ages suggest that the Te Papa Terrace was formed during early Oxygen Isotope Stage (OIS) 3 and the Otamaroa Terrace was formed during OIS 5a. However, global geomorphological and regional loess unit correlations would imply the extensive Otamaroa Terrace correlates with OIS 5e and the loess on the Te Papa Terrace correlates to the Porewan loess of OIS 4, indicating the Te Papa Terrace formed during OIS 5a or earlier. Regardless of terrace age, the morphology of the terraces shows the coastal uplift mechanism is not related to upper plate faults, but is probably driven by deep-seated subduction zone processes.

Keywords Raukumara Peninsula; Quaternary; marine terraces; tectonic uplift rates

G06027; Online publication date 17 July 2007; Received 22 August 2006; accepted 4 May 2007

New Zealand Journal of Geology & Geophysics, 2007, Vol. 50: 181–191
0028–8306/07/5003–0181  © The Royal Society of New Zealand 2007

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