Stratigraphy, age and correlation of middle Pleistocene silicic tephras in the Auckland region, New Zealand: A prolific distal record of Taupo Volcanic Zone volcanism

Alloway, Brent V.; Westgate, John A.; Pillans, Brad; Pearce, Nick; Newnham, Rewi M.; Byrami, Mairie; Aarburg, Susanne

doi:10.1080/00288306.2004.9515070

Cited by 59 publications

(44 citation statements)

References 43 publications

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“…A potential difficulty arises where the number or sequence of tephras erupted from a volcano is not known fully (as noted previously in Section 2.2), and thus distal units may not be correlatable (e.g., Alloway et al, 2004a;Kuehn and Negrini, 2010), or may be miscorrelated. In defining and naming new tephras, or re-defining them, the usual rules of stratigraphic nomenclature apply but the need for care is emphasised and specialist guidance should be sought to avoid compounding any previous correlation errors or misnomers (Lowe, 1986a;Wilson, 1993;Shane et al, 2003a;Davies et al, 2004a;Westgate et al, 2008).…”

Section: Defining and Using Type And Auxiliary Reference Locationsmentioning

confidence: 99%

Tephrochronology and its application: A review

Lowe

2011

Quaternary Geochronology

649

535

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Tephrochronology (from tephra, Gk "ashes") is a unique stratigraphic method for linking, dating, and synchronizing geological, palaeoenvironmental, or archaeological sequences or events. As well as utilizing the Law of Superposition, tephrochronology in practise requires tephra deposits to be characterized (or "fingerprinted") using physical properties evident in the field together with those obtained from laboratory analyses. Such analyses include mineralogical examination (petrography) or geochemical analysis of glass shards or crystals using an electron microprobe or other analytical tools including laser-ablation-based mass spectrometry or the ion microprobe. The palaeoenvironmental or archaeological context in which a tephra occurs may also be useful for correlational purposes. Tephrochronology provides greatest utility when a numerical age obtained for a tephra or cryptotephra is transferrable from one site to another using stratigraphy and by comparing and matching inherent compositional features of the deposits with a high degree of likelihood. Used this way, tephrochronology is an age-equivalent dating method that provides an exceptionally precise volcanic-event stratigraphy. Such age transfers are valid because the primary tephra deposits from an eruption essentially have the same short-lived age everywhere they occur, forming isochrons very soon after the eruption (normally within a year).As well as providing isochrons for palaeoenvironmental and archaeological reconstructions, tephras through their geochemical analysis allow insight into volcanic and magmatic processes, and provide a comprehensive record of explosive volcanism and recurrence rates in the Quaternary (or earlier) that can be used to establish time-space relationships of relevance to volcanic hazard analysis.The basis and application of tephrochronology as a central stratigraphic and geochronological tool for Quaternary studies are presented and discussed in this review. Topics covered include principles of tephrochronology, defining isochrons, tephra nomenclature, mapping and correlating tephras from proximal to distal locations at metre-through to sub-3 millimetre-scale, cryptotephras, mineralogical and geochemical fingerprinting methods, numerical and statistical correlation techniques, and developments and applications in dating including the use of flexible depositional age-modelling techniques based on Bayesian statistics.Along with reference to wide-ranging examples and the identification of important recent advances in tephrochronology, such as the development of new geoanalytical approaches that enable individual small glass shards to be analysed near-routinely for major, trace, and rare-earth elements, potential problems such as miscorrelation, erroneous-age transfer, and tephra reworking and taphonomy (especially relating to cryptotephras) are also examined. Some of the challenges for future tephrochronological studies include refining geochemical analytical methods further, improving understanding of cryptotephra dis...

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Section: Defining and Using Type And Auxiliary Reference Locationsmentioning

confidence: 99%

Tephrochronology and its application: A review

Lowe

2011

Quaternary Geochronology

649

535

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“…This provided us with a simple framework for uplift reconstruction (Vella et al, 1988;Marden and Neall, 1990;Pillans, 1990;Newnham and Lowe, 1991;Pillans, 1994;Eden and Froggatt, 1996;Naish et al, 1996;Shane et al, 1996a;Lowe et al, 1999;Lowe et al, 2001;Sandiford et al, 2002;Shane and Hoverd, 2002;Alloway et al, 2004;Newnham et al, 2004;Litchfield, 2008;Marden et al, 2008). In New Zealand, the rhyolitic Taupo and Okataina caldera volcanoes, within the central Taupo Volcanic Zone, are the two most frequently active rhyolite centres and their tephra deposits have been extensively studied (Wilson,1993;Black et al,1996;Shane, 2000;Litchfield, 2008).…”

Section: Tephrochronologymentioning

confidence: 98%

“…Many coastal terrace sequences in New Zealand are covered by tephra layers, produced by numerous volcanic eruptions from the central North Island. In this context, fission track dating of volcanic glass has become a common technique for dating coastal terraces or marine strata in general (Milne, 1973;Chappell, 1975;Pillans, 1990;Shane et al, 1996a;Lowe et al, 2001;Alloway et al, 2004;Litchfield, 2008). Marine terraces in New Zealand have been studied mainly in locations with softer lithologies and moderate to high uplift rates, such as (1991) Numbers 1-9 refer to locations in Fig.…”

Section: Terrace Research In New Zealandmentioning

confidence: 98%

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A Quaternary uplift record for the Auckland region, North Island, New Zealand, based on marine and fluvial terraces

Claessens

Veldkamp

Broeke

et al. 2009

Global and Planetary Change

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“…The raw samples were largely selected from sources outside of the AVF, as many of those within the AVF have been weathered, contaminated by organic material and/or disturbed or removed by human activity (e.g. Alloway et al 2004;Cassidy and Locke 2004;Howe et al 2011;Adams 2013). Our samples were modified through pulverisation to achieve a range of particle diameter size distributions possible in Auckland and thus likely contain a higher than natural proportion of particles that are blocky in nature with a high degree of angularity due to the milling process (Broom 2010).…”

Section: Ash Typementioning

confidence: 99%

Visibility in airborne volcanic ash: considerations for surface transportation using a laboratory-based method

2018

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All modes of surface transportation can be disrupted by visibility degradation caused by airborne volcanic ash. Despite much qualitative evidence of low visibility on roads following historical eruptions worldwide, there have been few detailed studies that have attempted to quantify relationships between visibility conditions and observed impacts on network functionality and safety. In the absence of detailed field observations, such gaps in knowledge can be filled by developing empirical datasets through laboratory investigations. Here, we use historical eruption data to estimate a plausible range of ashsettling rates and ash particle characteristics for Auckland city, New Zealand. We propose and implement a new experimental set-up in controlled laboratory conditions, which incorporates a dual-pass transmissometer and solid aerosol generator, to reproduce these ash-settling rates and calculate visual ranges through the associated airborne volcanic ash. Our findings demonstrate that visibility is most impaired for high ash-settling rates (i.e. [ 500 g m -2 h -1 ) and particle size is deemed the most influential ash characteristic for visual range. For the samples tested (all \ 320 lm particle diameter), visibility was restricted to * 1-2 m when ash settling was replicated for very high rates (i.e. * 4000 g m -2 h -1 ) and was especially low when ash particles were fine-grained, more irregular in shape and lighter in colour. Finally, we consider potential implications for disruption to surface transportation in Auckland through comparisons with existing research which investigates the consequences of visual range reduction for other atmospheric hazards such as fog. This includes discussing how our approach might be utilised in emergency and transport management planning. Finally, we summarise strategies available -018-3205-3 for the mitigation of visibility degradation in environments contaminated with volcanic ash.

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Stratigraphy, age and correlation of middle Pleistocene silicic tephras in the Auckland region, New Zealand: A prolific distal record of Taupo Volcanic Zone volcanism

Abstract: Coastal sections in the Auckland region reveal highly carbonaceous and/or highly weathered claydominated cover-bed successions with numerous discrete distal volcanic ash (tephra) layers, fluvially reworked G03058;

Cited by 59 publications

References 43 publications

Tephrochronology and its application: A review

Tephrochronology and its application: A review

A Quaternary uplift record for the Auckland region, North Island, New Zealand, based on marine and fluvial terraces

Visibility in airborne volcanic ash: considerations for surface transportation using a laboratory-based method

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