Late quaternary coseismic uplift history of Huon Peninsula, Papua New Guinea

Abstract

Repeated episodic uplift at Huon Peninsula is represented by regressive terraces cut into raised late Quaternary reef tracts. Up to six regressive terraces occur on the Holocene reef tract and up to 15 occur on reef tracts II and III, which span the interval from 33 ka to 52 ka. The uplift events are believed to be coseismic. The uplift behaviour along 40 km of coast is now defined by surveys and radiocarbon dates from 15 new Holocene sites that add to previous results from 13 other sites (Ota et al., 1993), plus detailed surveys of three late Pleistocene sequences. The mean recurrence interval of uplift events was 1000 to 1300 years in both the Holocene and late Pleistocene. The amplitude of uplift events averages about 3 m and generally increases from northwest to southeast in keeping with the regional late Quaternary trend, but for some events the uplift is approximately horizontal over 20 km or so. Two tectonic subregions are recognised, which were uplifted together by some Holocene events but not by others. There is no surface trace of Holocene faulting between the subregions and a buried fault probably separates them.