A late Early Pleistocene tephrochronological and pollen record from Auckland, New Zealand
Published:January 01, 2005
M. L. Byrami, R. M. Newnham, B. V. Alloway, B. Pillans, J. Ogden, J. Westgate, D. C. Mildenhall, 2005. "A late Early Pleistocene tephrochronological and pollen record from Auckland, New Zealand", Early–Middle Pleistocene Transitions: The Land–Ocean Evidence, M.J. Head, P.L. Gibbard
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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.
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Early–Middle Pleistocene Transitions: The Land–Ocean Evidence
The Early–Middle Pleistocene transition (around 1.2 to 0.5 Ma) marks a profound shift in Earth’s climate state. Low-amplitude 41 ka climate cycles, dominating the earlier part of the Pleistocene, gave way progressively to a 100 ka rhythm of increased amplitude that characterizes our present glacial—interglacial world. This volume assesses the biotic and physical response to this transition both on land and in the oceans: indeed it examines the very nature of Quaternary climate change. Milankovitch theory, palaeoceanography using isotopes and microfossils, marine organic geochemistry, tephrochronology, the record of loess and soil deposition, terrestrial vegetationa! change, and the migration and evolution of hominins as well as other large and small mammals, are all considered. These themes combine to explore the very origins of our present biota.