Towards a climate event stratigraphy for New Zealand over the past 30 000 years (NZ‐INTIMATE project) |
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| Authors: | Brent V Alloway David J Lowe David J A Barrell Rewi M Newnham Peter C Almond Paul C Augustinus Nancy A N Bertler Lionel Carter Nicola J Litchfield Matt S McGlone Jamie Shulmeister Marcus J Vandergoes Paul W Williams NZ‐INTIMATE members |
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| Institution: | 1. GNS Science, Lower Hutt, New Zealand;2. Department of Earth and Ocean Sciences, University of Waikato, Hamilton, New Zealand;3. GNS Science, Dunedin Research Centre, Dunedin, New Zealand;4. School of Geography, University of Plymouth, Plymouth, UK;5. Soil and Physical Sciences Group, Division of Agriculture and Life Sciences, Lincoln University, Lincoln, Canterbury, New Zealand;6. Department of Geology and School of Geography and Environmental Science, University of Auckland, Auckland, New Zealand;7. Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand;8. National Institute of Water and Atmosphere (NIWA), Kilbirnie, Wellington, New Zealand;9. Landcare Research, Lincoln, Canterbury, New Zealand;10. Department of Geological Sciences, University of Canterbury, Christchurch, New Zealand;11. School of Geography and Environmental Science, University of Auckland, Auckland, New Zealand;12. New Zealand‐INTIMATE members (in alphabetical order) are: Brent Alloway, Peter Almond, Brian Anderson, Paul Augustinus, David Barrell, Nancy Bertler, Hannah Brackley, Phil Burge, John Carter, Lionel Carter, Ursula Cochran, Penny Cooke, James Crampton, Erica Crouch, Martin Crundwell, Yanbin Deng, Frank Drost, Ian Graham, Margaret Harper, Bruce Hayward, Chris Hendy, Chris Hollis, Matthew Hughes, David Kennedy, Liz Kennedy, Darren King, David J. Lowe, Nicola Litchfield, Andrew Mackintosh, Barbara Manighetti, Maureen Marra, Matt McGlone, Dallas Mildenhall, Uwe Morgenstern, Tim Naish, Helen Neil, David Nobes, Mike Page, Alan Palmer, Chris Prior, Uwe Rieser, Henrik Rother, Phil Shane, Jamie Shulmeister, Percy Strong, Pat Suggate, Julian Thomson, Phil Tonkin, Noel Trustrum, Russ Van Dissen, Marcus Vandergoes, Colin Vucetich, Paul Williams, Janet Wilmshurst, Craig Woodward and Albert Zondervan. For further information about NZ‐INTIMATE see www.paleoclimate.org.nz. |
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| Abstract: | It is widely recognised that the acquisition of high‐resolution palaeoclimate records from southern mid‐latitude sites is essential for establishing a coherent picture of inter‐hemispheric climate change and for better understanding of the role of Antarctic climate dynamics in the global climate system. New Zealand is considered to be a sensitive monitor of climate change because it is one of a few sizeable landmasses in the Southern Hemisphere westerly circulation zone, a critical transition zone between subtropical and Antarctic influences. New Zealand has mountainous axial ranges that amplify the climate signals and, consequently, the environmental gradients are highly sensitive to subtle changes in atmospheric and oceanic conditions. Since 1995, INTIMATE has, through a series of international workshops, sought ways to improve procedures for establishing the precise ages of climate events, and to correlate them with high precision, for the last 30 000 calendar years. The NZ‐INTIMATE project commenced in late 2003, and has involved virtually the entire New Zealand palaeoclimate community. Its aim is to develop an event stratigraphy for the New Zealand region over the past 30 000 years, and to reconcile these events against the established climatostratigraphy of the last glacial cycle which has largely been developed from Northern Hemisphere records (e.g. Last Glacial Maximum (LGM), Termination I, Younger Dryas). An initial outcome of NZ‐INTIMATE has been the identification of a series of well‐dated, high‐resolution onshore and offshore proxy records from a variety of latitudes and elevations on a common calendar timescale from 30 000 cal. yr BP to the present day. High‐resolution records for the last glacial coldest period (LGCP) (including the LGM sensu stricto) and last glacial–interglacial transition (LGIT) from Auckland maars, Kaipo and Otamangakau wetlands on eastern and central North Island, marine core MD97‐2121 east of southern North Island, speleothems on northwest South Island, Okarito wetland on southwestern South Island, are presented. Discontinuous (fragmentary) records comprising compilations of glacial sequences, fluvial sequences, loess accumulation, and aeolian quartz accumulation in an andesitic terrain are described. Comparisons with ice‐core records from Antarctica (EPICA Dome C) and Greenland (GISP2) are discussed. A major advantage immediately evident from these records apart from the speleothem record, is that they are linked precisely by one or more tephra layers. Based on these New Zealand terrestrial and marine records, a reasonably coherent, regionally applicable, sequence of climatically linked stratigraphic events over the past 30 000 cal. yr is emerging. Three major climate events are recognised: (1) LGCP beginning at ca. 28 000 cal. yr BP, ending at Termination I, ca. 18 000 cal. yr BP, and including a warmer and more variable phase between ca. 27 000 and 21 000 cal. yr BP, (2) LGIT between ca. 18 000 and 11 600 cal. yr BP, including a Lateglacial warm period from ca. 14 800 to 13 500 cal. yr BP and a Lateglacial climate reversal between ca. 13 500 and 11 600 cal. yr BP, and (3) Holocene interglacial conditions, with two phases of greatest warmth between ca. 11 600 and 10 800 cal. yr BP and from ca. 6 800 to 6 500 cal. yr BP. Some key boundaries coincide with volcanic tephras. Copyright © 2007 John Wiley & Sons, Ltd. |
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| Keywords: | Last glacial coldest period Last Glacial Maximum Antarctic Cold Reversal Termination I palaeoclimate vegetation dating tephra tephrochronology marine core foraminifera pollen speleothems glacial sequences river terraces loess aeolian quartz New Zealand |
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