Results 151 to 160 of about 9,073 (173)
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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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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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Seven tephra isochrones in Scotland
The Holocene, 1995This paper reports the presence and geochemical characteristics of seven separate tephras in Scotland that fell in AD 1510, and about 450 BP, 2100 BP, 3600 BP, 3830 BP, 5600 BP and around 6000 BP. The results come from 14 peat bogs spread throughout the Highlands and Islands where 26 tephra deposits have been characterized using over 400 grain ...
Andrew J. Dugmore +2 more
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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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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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Journal of Quaternary Science, 2018
Tephra from Icelandic volcanic eruptions is frequently dispersed to northern Europe, but so far tephra has not been detected in Finnish sedimentary records. We report the first finding of a cryptotephra layer in southern and central Finland.
M. Kalliokoski +2 more
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Tephra from Icelandic volcanic eruptions is frequently dispersed to northern Europe, but so far tephra has not been detected in Finnish sedimentary records. We report the first finding of a cryptotephra layer in southern and central Finland.
M. Kalliokoski +2 more
semanticscholar +1 more source
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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