dc.contributor.author	Darragh, M.
dc.contributor.author	Cole, J.W.
dc.contributor.author	Nairn, I.A.
dc.contributor.author	Shane, P.
dc.date.accessioned	2008-06-24T21:55:57Z
dc.date.available	2008-06-24T21:55:57Z
dc.date.issued	2006	en
dc.description.abstract	The 21.9 ka Okareka and 17.6 ka Rerewhakaaitu rhyolite eruption episodes began the construction of Tarawera Volcano in the Okataina Volcanic Centre, Taupo Volcanic Zone. Examination of the proximal and medial stratigraphy of these moderate-size (c. 5 km3 magma) but poorly exposed pyroclastic deposits has increased understanding of their eruption and dispersal processes. The Okareka Tephra consists of at least nine units (A–I), with unit A basaltic scoria at the base, overlain by the rhyolitic units B–I. Unit C is the largest individual plinian fall deposit (c. 0.4 km3), dispersed from an eruption column that reached c. 19 km height in the presence of strong crosswinds. The other pyroclastic units record a variety of phreatomagmatic, sub-plinian, and small ignimbrite eruptions, which were followed by extrusion of voluminous lava flows. The Rerewhakaaitu Tephra consists of 15 rhyolitic fall units A–N. An initial short plinian phase dispersed lapilli-fall unit A, mostly to ENE, from columns c. 15 km in height. Units B–D have high ash contents, indicating phreatomagmatic eruptions with varying magma/water ratios, and were widely dispersed, with lobes to the northeast and southeast. Units E–J were deposited from 20–25 km high plinian eruption columns into strong crosswinds that dispersed tephra to the southeast. The E–J package contains the largest tephra volume of the episode (1.18 km3) and is thought to dominate the deposits widely dispersed in Pacific Ocean sediments to the east of New Zealand. Rerewhakaaitu pyroclastic deposits are interbedded with, and underlie, voluminous lavas.	en
dc.identifier.citation	Darragh, M., Cole, J.W., Nairn, I.A., Shane, P. (2006) Pyroclastic stratigraphy and eruption dynamics of the 21.9 ka Okareka and 17.6 ka Rerewhakaaitu episodes from Tarawera Volcano, Okataina Volcanic Centre, New Zealand. New Zealand Journal of Geology and Geophysics, 49(3), pp. 309-328.	en
dc.identifier.issn	0028-8036
dc.identifier.uri	http://hdl.handle.net/10092/715
dc.language.iso	en
dc.publisher	University of Canterbury. Geological Sciences.	en
dc.relation.uri	http://www.rsnz.org/publish/nzjgg/2006/027.php	en
dc.rights.uri	https://hdl.handle.net/10092/17651	en
dc.subject	eruption episode	en
dc.subject	Tarawera	en
dc.subject	rhyolite	en
dc.subject	tephra	en
dc.subject	stratigraphy	en
dc.subject	dispersal	en
dc.subject	grain sizes	en
dc.subject	components	en
dc.subject	column dynamics	en
dc.subject	duration	en
dc.subject.marsden	Fields of Research::260000 Earth Sciences::260100 Geology::260103 Vulcanology	en
dc.title	Pyroclastic stratigraphy and eruption dynamics of the 21.9 ka Okareka and 17.6 ka Rerewhakaaitu episodes from Tarawera Volcano, Okataina Volcanic Centre, New Zealand	en
dc.type	Journal Article

Pyroclastic stratigraphy and eruption dynamics of the 21.9 ka Okareka and 17.6 ka Rerewhakaaitu episodes from Tarawera Volcano, Okataina Volcanic Centre, New Zealand

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