Stratigraphy, optical dating chronology (IRSL) and depositional model of pre-LGM glacial deposits in the Hope Valley, New Zealand

Rother, Henrik, Shulmeister, James and Rieser, Uwe (2010) Stratigraphy, optical dating chronology (IRSL) and depositional model of pre-LGM glacial deposits in the Hope Valley, New Zealand. Quaternary Science Reviews, 29 3-4: 576-592. doi:10.1016/j.quascirev.2009.11.001

Author Rother, Henrik
Shulmeister, James
Rieser, Uwe
Title Stratigraphy, optical dating chronology (IRSL) and depositional model of pre-LGM glacial deposits in the Hope Valley, New Zealand
Journal name Quaternary Science Reviews   Check publisher's open access policy
ISSN 0277-3791
Publication date 2010-02-01
Year available 2010
Sub-type Article (original research)
DOI 10.1016/j.quascirev.2009.11.001
Open Access Status DOI
Volume 29
Issue 3-4
Start page 576
End page 592
Total pages 17
Place of publication Oxford, United Kingdom
Publisher Pergamon
Language eng
Subject 1907 Geology
2306 Global and Planetary Change
1105 Ecology, Evolution, Behavior and Systematics
Abstract A 110 m thick succession of glacial valley fill is described from Poplars Gully, central South Island, New Zealand. The section consists of eight lithofacies assemblages that represent different stages of ice occupation in the valley. Basal sediments record an ice retreat phase followed by a glacial re-advance which deposited mass flow diamictons and till. A subsequent ice retreat from the site is indicated by the stratigraphic transition from till to thick glacio-fluvial gravels. This is followed by a probably short-lived glacier re-advance that caused folding and thrusting of proglacial sediments. Final glacial retreat from the valley led to the formation of a large proglacial lake. In total, Poplars Gully holds evidence for two major ice advances, separated by a glacial retreat that resulted in complete ice evacuation from the lower Hope Valley. Infrared stimulated luminescence (IRSL) dating on ice-proximal sediments from Poplars Gully yielded six ages between 181 and 115 ka BP. Our stratigraphic logging and dating results show that the fill sequence was not, as previously thought, deposited in association with ice advances during the Last Glacial Maximum (LGM) nor indeed during the last glacial cycle. LGM glaciers later overran the fill but we find that the older glacial sequences are considerably more voluminous than those deposited during the last glacial cycle. We also show that the mid-Pleistocene glaciers carved a much deeper valley trough than did glaciers during the LGM. Taken together these features are likely to reflect a significant difference in the magnitude of successive Pleistocene glaciations in the valley, with the mid-Pleistocene ice advances having been considerably larger than those of the last glacial cycle. The recognition of the in-situ survival of extensive pre-MIS 5 (Marine Isotope Stage) deposits in valley troughs that were later occupied by LGM glaciers represents a new feature in the Quaternary stratigraphy of the Southern Alps. The results demonstrate that New Zealand's commonly very large soft-sedimentary valley fills provide a valuable, yet largely unexploited, terrestrial sedimentary archive of successive glaciations in the region. © 2009 Elsevier Ltd. All rights reserved.
Keyword Cosmogenic nuclide chronology
Last deglaciation
North Canterbury
Southern Alps
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID UoC 301
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Geography, Planning and Environmental Management Publications
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Created: Sun, 14 Mar 2010, 10:00:34 EST