A 28000–7600 cal yr BP pollen record of vegetation and climate change from Pukaki Crater, northern New Zealand

摘要

A pollen record of vegetation and climate change representing the interval ca. 28000–7600 cal yr BP was obtained from a 52.5-m sediment core taken from a volcanic explosion crater at present sea level in Auckland, New Zealand (36°59'S). This provides one of the few continuous terrestrial records covering Marine Isotope Stage 2 and part of Stage 1 from the mid-latitudes of the Southern Hemisphere. Chronology of the record is underpinned by eight distal Taupo Volcanic Zone rhyolitic tephra of known age augmented by thirteen AMS radiocarbon dates. The Last Glacial Maximum cooling extended from at least c. 28000 cal yr BP to ca. 18000 cal yr BP when vegetation apparently consisted of patches of beech-dominated forest embedded within shrubland and grassland. Forest patches were probably larger or more widespread than those in central North Island to the south but less extensive than further to the north, in Northland. Climate warming commenced ca. 18000 cal yr BP, marked by the replacement of beech by conifers and angiosperms, and by the expansion of forest at the expense of shrubland and grassland. No clear Late Glacial climatic reversal is evident at this site. Early Holocene forest is characterised by the replacement of the dominant forest tree Prumnopitys taxifolia by Dacrydium cupressinum. Following breach of the crater rim ca. 7600 cal yr BP by rising sea level the maar was rapidly infilled with marine sediments over a period of ca. 1000 years.