A late Early Pleistocene tephrochronological and pollen record from Auckland, New Zealand

Abstract

A late Early Pleistocene pollen record was obtained from a coastal site in Auckland, New Zealand. A combination of isothermal plateau fission track ages on interbedded tephras, palaeomagnetism, palynostratigraphy and orbital tuning to the marine oxygen isotope record of Ocean Drilling Program Site 677 constrained the age of the topmost 28 m of sediments to c. 1.4–1.0 Ma (Marine Isotope Stages (MIS) 45–28). For this interval a diverse pollen record consisting of mostly extant pollen types shows multiple compositional shifts from a Nothofagus-dominated to conifer-dominated regional vegetation. These shifts are broadly correlated to changes in the marine oxygen isotope record. The inferred climate was moist, temperate, stable, and cooler than at present, but never as cool as the last glacial maximum. A permanent increase in Nothofagus forest in the region after MIS 35 seems to be related to a long-term palaeoclimatic shift that probably included greater temperature extremes between warm and cool stages and decreases in humidity and increased seasonality during cool stages. Although the Patiki pollen record predates the mid-Pleistocene revolution by c. 100 ka, the nature of climate change itself was already in transition, and becoming more similar to the climate regime experienced in northern New Zealand in the Late Pleistocene.

Persistence of New Zealand Quaternary beetles

“…Seeds of Pittosporum eugenioides, a forest margin and riparian species found in lowland and montane locations, were also recovered. At the time of deposition of the Waiuku Tephra (about 1 Ma), the pollen record indicates that tall trees dominated in Agathis/podocarp forest, but Nothofagus was also present (Byrami et al 2005). Our fossil beetle data are consistent with the pollen record.…”

“…3. The sites are stratigraphically well described (Alloway et al 2004;Byrami et al 2005) and are correlated with three volcanic events dated about 0.53 Ma, 1 Ma and 1.3 Ma. They are interpreted as palaeo-forest and wetland environments buried by up to 1.4 m of volcanic deposits (Alloway et al 2004).…”

“…During the last glaciation, Nothofagus (southern beech) dominated while podocarps were reduced in abundance and some areas were grassland (Sandiford et al 2003). Early and Mid-Pleistocene pollen data for the region also show a record of Nothofagus-dominated forests during glacials and podocarps dominating forests during interglacials (Byrami et al 2005). …”

Vegetation and climate of Auckland, New Zealand, since ca. 32 000 cal. yr ago: support for an extended LGM

“…This situation contrasts strongly with records from sites south of Auckland, where, apart from at sheltered coastal localities (Lees et al, 1998), near-complete forest cover during warm (interglacial) stages was reduced to grassland or shrubland with at most patchy forest during cold (glacial) stages (McGlone, 1988;Newnham et al, 1989Newnham et al, , 1999b. Previous pollen records from Auckland imply a Quaternary history intermediate between the patterns recorded to the north and to the south Byrami et al, 2005). Thus the modern biogeographic boundary straddled by Auckland also marks an important distinction between regions with contrasting histories.…”

Stratigraphy, age and correlation of middle Pleistocene silicic tephras in the Auckland region, New Zealand: A prolific distal record of Taupo Volcanic Zone volcanism

“…(9) The PDC and transitional deposits of Waiuku tephra in southern and central parts of the Manukau lowlands overlie a prominent carbonaceous paleosol. Assuming that present ecological affinities are essentially similar, the pollen evidence (Sandiford 2001;Byrami et al in press) collectively indicates a cooler than present climate, but certainly not a glacial maximum. The (Briggs et al 1993;Shane 1993), and AT-311 from ODP core 1124 (see Table 1).…”