Quaternary tephra marker beds and their potential for palaeoenvironmental reconstruction on Chatham Island, east of New Zealand, Southwest Pacific Ocean

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doi: 10.1002/jqs.1397
Author(s): Holt, Katherine A.; Wallace, R. Clel; Neall, Vincent E.; Kohn, Barry P.; Lowe, David J.
Author Affiliation(s): Primary:
Massey University, Institute of Natural Resources, Palmerston North, New Zealand
University of Melbourne, Australia
University of Waikato, New Zealand
Volume Title: JQS. Journal of Quaternary Science
Source: JQS. Journal of Quaternary Science, 25(7), p.1169-1178. Publisher: John Wiley and Sons for the Quaternary Research Association, Chichester, United Kingdom. ISSN: 0267-8179
Note: In English. 78 refs.; illus., incl. 2 tables, sketch map
Summary: Tephras provide one of the most reliable methods of time control and synchronisation within Quaternary sequences. We report on the identification of two widespread rhyolitic tephras - the Kawakawa and Rangitawa tephras - preserved in extensive peat deposits on Chatham Island ∼900 km east of New Zealand. The tephras, both products of supereruptions from the Taupo Volcanic Zone, occur as pale, fine-ash dominated layers typically 10-150 mm thick. Mineralogically they are dominated by rhyolitic glass, together with subordinate amounts of quartz, feldspar, hypersthene, hornblende, Fe-Ti oxides and zircon. Phlogopite/biotite was identified additionally in Rangitawa Tephra. Ages for each tephra were obtained via mineralogical and major element glass composition-based correlation with well-dated equivalent deposits on mainland New Zealand, and we also obtained a new zircon fission-track age for Rangitawa Tephra (350 ± 50 ka) on Chatham Island. Both tephras were erupted at critical times for palaeoenvironmental reconstructions in the New Zealand region: the Kawakawa at ca. 27 cal. ka, near the beginning of the 'extended' LGM early in marine isotope stage (MIS) 2; and the Rangitawa at ca. 350 ka near the end of MIS 10. The time constraints provided by the tephras demonstrate that Chatham Island peats contain long-distance pollen derived from mainland New Zealand, which provides a reliable proxy for identifying glacial-interglacial climate conditions, in this case during the MIS 11-10 and MIS 2-1 cycles. The two tephras thus provide important chronostratigraphic tie-points that facilitate correlation and synchronisation not only across the Quaternary deposits of the Chatham Islands group but also with climatically significant terrestrial and marine records in the wider New Zealand region. Abstract Copyright (2010), John Wiley & Sons, Ltd.
Year of Publication: 2010
Research Program: DSDP Deep Sea Drilling Project
IPOD International Phase of Ocean Drilling
Key Words: 03 Geochronology; 24 Surficial Geology, Quaternary Geology; Assemblages; Cenozoic; Chatham Islands; Chatham Rise; Chemical composition; DSDP Site 594; Deep Sea Drilling Project; Electron probe data; Fission-track dating; Geochronology; IPOD; Igneous rocks; Kawakawa Tephra; Leg 90; MIS 10; MIS 2; Microfossils; Miospores; Pacific Ocean; Palynomorphs; Pleistocene; Pollen; Pyroclastics; Quaternary; Rangitawa Tephra; South Pacific; Southwest Pacific; Tephrochronology; Tephrostratigraphy; Upper Pleistocene; Volcanic rocks; West Pacific; West Pacific Ocean Islands
Coordinates: S453129 S453128 E1745653 E1745652
S443000 S433000 W1760000 W1770000
Record ID: 2011034852
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom