Distribution, age, and uplift patterns of pleistocene marine terraces of the northern raukumara Peninsula, North Island, 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. © 2007 Taylor & Francis Group, LLC.