Holocene marine terraces at Aramoana and Pourerere, eastern North Island, New Zealand

Abstract

Abstract Holocene coastal plains preserved at Aramoana and Pourerere, eastern North Island, are subdivided into three levels (T1, T2, and T3) at Aramoana and two levels (TH and TL) at Pourerere. Infilled valley features, presence of estuarine silt, and radiocarbon age of shells in estuarine deposits (7530 ± 100 yr B.P. at Aramoana and 7330 ± 70 yr B.P. at Pourerere) indicate that T1 and TH were formed in association with postglacial sea-level rise. A radiocarbon age of 5850 ± 80 yr B.P. from deposits on T1 suggests that its emergence was at about 6000 yr B.P. Shells from T2 are dated at 5400 ± 90 yr B.P. and shells from T3 are dated at 3200 ± 35 yr B.P. It is likely that T3 is correlated to TL. The formation of the sequence of marine terraces is considered to be the result of episodic uplift due to large earthquakes. Aramoana and Pourerere coastal plains must lie on a separate structural block from Waimarama to the north, because there are no Holocene marine terraces with a common date of uplift.