Palaeomagnetic results from Mounts Gambier and Schank, South Australia

Barbetti, Mike; Sheard, M.J.

doi:10.1080/00167618108729177

Cited by 16 publications

(8 citation statements)

References 16 publications

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“…Gambier basaltic eruptives showed that the entire sequence (comprising two main eruption periods) had been erupted over a short time interval because the PSV measurements at the start and end of activity were identical (Barbetti and Sheard, 1981). At the same time, the palaeomagnetic directions differed from those obtained from nearby Mt Schank meaning that the two volcanoes had not erupted contemporaneously, being at least three centuries apart (although it has not yet been determined which erupted first) (Sheard, 1990(Sheard, , 1995Robertson et al, 1996).…”

Section: Magnetostratigraphymentioning

confidence: 99%

Tephrochronology and its application: A review

Lowe

2011

Quaternary Geochronology

651

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: Magnetostratigraphymentioning

confidence: 99%

Tephrochronology and its application: A review

Lowe

2011

Quaternary Geochronology

651

535

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“…The youngest of the volcanoes in this province comprise two isolated basaltic eruption centres at Mounts Gambier and Schank. These near-contemporaneous centres are ∼10 km apart and are between ∼5500 and 4300 y old (Barbetti & Sheard, 1981;Smith & Prescott, 1987;Robertson et al, 1996;Gouramanis et al, 2010;Murray-Wallace, 2011). Soils formed from the basaltic scoria (cinders), lapilli, and ash spread ∼10-12 km from each source were studied at ten sites: six near Mount Gambier, three near Mount Schank, and one at an intermediate site (Lowe & Palmer, 2005;Takesako et al, 2010).…”

Section: F O R M At I O Nmentioning

confidence: 99%

Unique but diverse: some observations on the formation, structure and morphology of halloysite

et al. 2016

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New insights from the recent literature are summarised and new data presented concerning the formation, structure and morphology of halloysite. Halloysite formation by weathering always requires the presence of water. Where substantial drying occurs, kaolinite is formed instead. Halloysite formation is favoured by a low pH. The octahedral sheet is positively charged at pH < ~8, whereas the tetrahedral sheet is negatively charged at pH > ~2. The opposing sheet charge would facilitate interlayer uptake of H 2 O molecules.When halloysite intercalates certain polar organic molecules, additional (hkl) reflections appear in the X-ray diffractogram, suggesting layer re-arrangement which, however, is dissimilar to that in kaolinite. Associated oxides and oxyhydroxides of Fe and Mn may limit the growth of halloysite particles as does incorporation of Fe into the structure. Particles of different shape and iron content may occur within a given sample of halloysite.

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“…Aboriginal middens have been discovered buried under volcanic ash, the charcoal enabling age estimates of the eruptions that are described in some of the Dreamtime stories. The youngest eruptions in Western Victoria and southeast South Australia are dated at between 1000 and 5000 years ago (Barbetti and Sheard, 1981).…”

Section: Introductionmentioning

confidence: 99%

Australia: historical earthquake studies

McCue¹

2009

Annals of Geophysics

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Historical studies of earthquakes in Australia using information dating back to 1788 have been comprehensive, if not exhaustive. Newspapers have been the main source of historical earthquake studies. A brief review is given here with an introduction to the pre-European aboriginal dreamtime information. Some of the anecdotal information of the last two centuries has been compiled as isoseismal maps. Relationships between isoseismal radii and magnitude have been established using post-instrumental data allowing magnitudes to be assigned to the pre-instrumental data, which can then be incorporated into the national earthquake database. The studies have contributed to hazard analyses for the building codes and stimulated research into microzonation and paleo-seismology.

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Palaeomagnetic results from Mounts Gambier and Schank, South Australia

Cited by 16 publications

References 16 publications

Tephrochronology and its application: A review

Tephrochronology and its application: A review

Unique but diverse: some observations on the formation, structure and morphology of halloysite

Australia: historical earthquake studies

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