Palynological, tephra, and 14C records from southern Kaitoke, Great Barrier (Aotea) Island, New Zealand, since c. 30,000 cal. yr BP

Abstract

Here we present results of the last remaining three, unreported pollen and stratigraphic profiles from our previous investigations on Great Barrier Island from southern Kaitoke. The 14C and pollen data extend the island’s previous maximum pollen-vegetation date from c. 7000 cal. yr BP to close to the end of MIS 3 c. 30,000 cal. yr BP. The oldest 14C date (34,380-28,190 cal. yr BP) and the presence of secondary deposition fragments of Rotoehu Tephra in the basal brown sands and nearby dune deposits implies their formation between c. 30,000 and 45,000 yr BP. The basal sand deposits and palynology in Profile 1 indicate that the site was close to sea-level at the time. Subsequently, the sediments reflect the Last Glacial Coldest Period, characterised by increased Fuscospora pollen.

Following the relative stability of the mid-Holocene high sea-level stand, alternations between drier and wetter (freshwater) conditions, with depositional hiatuses, are congruent with evidence for erratic sea-level falls causing blockage of coastal drainage and rear-dune flooding since c. 2,700 cal. yr BP; layers of preserved wood and in-situ stumps overlying firmer palaeosols were followed by fresh-water peats at two of the sites reported here and other, previously reported sites. Polynesian settlement and forest clearance occurs around the time of the 1314 ± 12 AD Kaharoa Tephra, consistent with the project’s previous reports, and with the timing from elsewhere in New Zealand.

Keywords

Pleistocene, Last Glacial Maximum, sea level, Holocene, dune-impounded swamps, human impacts, pollen analysis.