Detailed surface exposure age chronology for last glacial sequences in the Rangitata and Waimakariri Valleys, South Island, New Zealand

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dc.contributor.authorRother, Hen_AU
dc.contributor.authorFink, Den_AU
dc.contributor.authorSchulmeister, Jen_AU
dc.contributor.authorEvans, Men_AU
dc.date.accessioned2020-10-26T00:00:27Zen_AU
dc.date.available2020-10-26T00:00:27Zen_AU
dc.date.issued2009-05-15en_AU
dc.date.statistics2020-10-26en_AU
dc.description.abstractThe response of mid-latitude Southern Hemisphere glaciers to Quaternary climate forcing has become a prime research focus in the debate on the dynamics of global climate teleconnections. Of key importance in this research is the investigation of the timings of late Quaternary mountain glacier fluctuations in New Zealand relating both to last glacial ice maxima and ice decay signals. To address these questions we collected 62 rock samples from glacial moraine sequences in two major valley systems of the central Southern Alps for surface exposure dating (SED). Here we present geomagnetically corrected ages derived from cosmogenic 10Be isotope concentrations that provide absolute age control for glacial events in these valleys from 23.0 ka to 13.7 ka. Results show that recession from extended LGM positions commenced close to 22 ka followed by a slow ice retreat and ice margin stabilization at 19-18 ka. This sequence is similar to other New Zealand sites but commences several ka earlier than in the Northern Hemisphere. Our data also show that the largest of the LGM advances in the Waimakariri Valley extended much further than previously recognized and overran the so-called Avoca surface (previously OIS 8). Further slow ice retreat re-commenced at around 16.5 ka resulting in multiple closely spaced retreat positions over a ~10 km distance in both valleys that date to 14.5 - 16.0 ka (Blackwater III in Waimakariri; Spider Lake / Lake Emma in Rangitata). The youngest late glacial moraines date to 14.0 ka (Poulter, Waimakiriri) and 13.7 ka (Lake Clearwater, Rangitata). In summary our findings document that: (1) the period 23.0 – 13.7 ka is characterized by a slow and gradual ice retreat interrupted by stabilization phases but no major ice re-advances (2) very extensive valley glaciers of 30 – 50 km length survived in New Zealand until at least 14 ka (3) as a consequence of (2), either an accelerated retreat rate or a short-lived ice collapse would necessarily have occurred after 13.7 ka in order to restrict ice limits to upper valley positions prior to the onset of the Holocene.en_AU
dc.identifier.citationRother, H., Fink, D., Schulmeister, J., Evans, M. (2009). Detailed surface exposure age chronology for last glacial sequences in the Rangitata and Waimakariri Valleys, South Island, New Zealand. Paper presented at the Past Climates meeting, Wellington New Zealand, May 15-17, 2009.en_AU
dc.identifier.conferenceenddate17 May 2009en_AU
dc.identifier.conferencenamePast Climates meetingen_AU
dc.identifier.conferenceplaceWellington, New Zealanden_AU
dc.identifier.conferencestartdate15 May 2009en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/9940en_AU
dc.language.isoenen_AU
dc.publisherGNS Scienceen_AU
dc.subjectGlaciersen_AU
dc.subjectNew Zealanden_AU
dc.subjectSouthern Hemisphereen_AU
dc.subjectQuaternary perioden_AU
dc.subjectIceen_AU
dc.subjectAlpsen_AU
dc.subjectValleysen_AU
dc.subjectIsotopesen_AU
dc.subjectBeryllium 10en_AU
dc.titleDetailed surface exposure age chronology for last glacial sequences in the Rangitata and Waimakariri Valleys, South Island, New Zealanden_AU
dc.typeConference Presentationen_AU
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