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dc.contributor.authorCunningham, Michael J.en_NZ
dc.contributor.authorLowe, David J.en_NZ
dc.contributor.authorWyatt, Justin Burnsen_NZ
dc.contributor.authorMoon, Vicki G.en_NZ
dc.contributor.authorChurchman, G. Jocken_NZ
dc.date.accessioned2016-10-17T21:03:27Z
dc.date.available2016-10-11en_NZ
dc.date.available2016-10-17T21:03:27Z
dc.date.issued2016-10-11en_NZ
dc.identifier.citationCunningham, M. J., Lowe, D. J., Wyatt, J. B., Moon, V. G., & Churchman, G. J. (2016). Discovery of halloysite books in altered silicic Quaternary tephras, northern New Zealand. Clay Minerals, 51(3), 351–372. http://doi.org/10.1180/claymin.2016.051.3.16en
dc.identifier.issn0009-8558en_NZ
dc.identifier.urihttps://hdl.handle.net/10289/10691
dc.description.abstractHydrated halloysite was discovered in books, a morphology previously associated exclusively with kaolinite. From ~1.5 μm to ~1500 μm in length, the books showed significantly greater mean Fe contents (Fe2O3 = 5.2 wt%) than tubes (Fe2O3 = 3.2 wt%), and expanded rapidly with formamide. They occurred, along with halloysite tubes, spheroids, and plates, in highly porous yet poorly-permeable, silt-dominated, Si-rich, pumiceous rhyolitic tephra deposits aged ~0.93 Ma (Te Puna tephra) and ~0.27 Ma (Te Ranga tephra) at three sites ~10-20 m stratigraphically below the modern land-surface in the Tauranga area, eastern North Island, New Zealand. The book-bearing tephras were at or near saturation, but have experienced intermittent partial drying, favouring the proposed changes: solubilized volcanic glass + plagioclase -> halloysite spheroids -> halloysite tubes -> halloysite plates -> halloysite books. Unlike parallel studies elsewhere involving both halloysite and kaolinite, kaolinite has not formed in Tauranga presumably because the low permeability ensures the sites largely remain locally wet so that the halloysite books are metastable. An implication of the discovery is that some halloysite books in similar settings may have been misidentified previously as kaolinite.en_NZ
dc.format.mimetypeapplication/pdf
dc.language.isoen
dc.publisherMineralogical Society of Great Britain and Irelanden_NZ
dc.rightsThis is an author’s accepted version of an article published in the journal: Clay Minerals. © 2016 Clay Minerals.
dc.subjectHalloysiteen_NZ
dc.subjectclay morphologyen_NZ
dc.subjectFe contenten_NZ
dc.subjectpyroclasticen_NZ
dc.subjecttephrochronologyen_NZ
dc.subjectTe Ranga tephraen_NZ
dc.subjectTe Puna tephraen_NZ
dc.subjectQuaternaryen_NZ
dc.titleDiscovery of halloysite books in altered silicic Quaternary tephras, northern New Zealanden_NZ
dc.typeJournal Article
dc.identifier.doi10.1180/claymin.2016.051.3.16en_NZ
dc.relation.isPartOfClay Mineralsen_NZ
pubs.begin-page351
pubs.elements-id142744
pubs.end-page372
pubs.issue3
pubs.volume51


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