Results 241 to 250 of about 25,642 (273)
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1981
Tephra studies would benefit greatly from the development of simple, inexpensive, approximate-dating methods that would allow us to estimate the age of a tephra sample in the field office. Colleagues outside the discipline, whose main interest in tephra layers lie in the dates they represent, would benefit also.
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Tephra studies would benefit greatly from the development of simple, inexpensive, approximate-dating methods that would allow us to estimate the age of a tephra sample in the field office. Colleagues outside the discipline, whose main interest in tephra layers lie in the dates they represent, would benefit also.
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Correlation Techniques in Tephra Studies [PDF]
, 1981 Distinctive tephra layers constitute important time-parallel markers, which if widespread, offer the potential for reliable correlation over long distances. Confident correlations require a multiple criterion approach to tephra characterisation and equivalence of samples should only be considered firmly established if their stratigraphic ...
Michael P. Gorton, John A. Westgate
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Quaternary Science Reviews, 2019
Abstract Emerging lake sediment records are rapidly improving Iceland‘s Holocene tephra stratigraphy and chronology. Here, we expand upon these recent developments with a securely-dated tephrochronological record from the lake Haukadalsvatn in West Iceland.
David J. Harning +6 more
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Abstract Emerging lake sediment records are rapidly improving Iceland‘s Holocene tephra stratigraphy and chronology. Here, we expand upon these recent developments with a securely-dated tephrochronological record from the lake Haukadalsvatn in West Iceland.
David J. Harning +6 more
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Journal of Quaternary Science, 2019
ABSTRACTGlass composition‐based correlations of volcanic ash (tephra) traditionally rely on extensive manual plotting. Many previous statistical methods for testing correlations are limited by using geochemical means, masking diagnostic variability. We suggest that machine learning classifiers can expedite correlation, quickly narrowing the list of ...
Matthew S. M. Bolton +6 more
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ABSTRACTGlass composition‐based correlations of volcanic ash (tephra) traditionally rely on extensive manual plotting. Many previous statistical methods for testing correlations are limited by using geochemical means, masking diagnostic variability. We suggest that machine learning classifiers can expedite correlation, quickly narrowing the list of ...
Matthew S. M. Bolton +6 more
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Geochronology of Quaternary Tephra Deposits
1981Three radiometric methods have been used to date Quaternary tephra: fission-track (F-T), K-Ar, and radiocarbon (C-14). The fission-track and K~Ar methods provide direct ages for the tephra because they date phenocrysts from the source magma that were deposited by the eruption cloud. Radiocarbon dating provides only indirect ages because the carbon used
Glen A. Izett +3 more
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Hydration of abyssal tephra glasses
Journal of Non-Crystalline Solids, 1984Abstract Explosive volcanic eruptions frequently transport large amounts of silica-rich tephra glass to the deep sea. Some studies of the geochemistry of distal volcanoes are based on the assumption that no chemical exchange has taken place between the glass and adjacent pore water.
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TEPHRAS, chronologie, archéologie
2001En 1998, à Brives-Charensac (Haute-Loire), une réunion internationale sous le patronage de la Commission on Tephrochronology de l'INQUA (E. JUVIGNE, Vice-Président) et de la Commission 31 de l'UISPP Hommes et volcans actifs durant la Préhistoire et la Protohistoire (J.P.
Juvigné, Etienne, Raynal, Jean-Paul
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