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Old Crow tephra: a new Late Pleistocene stratigraphic marker across north-central Alaska and western Yukon Territory
  • Old Crow tephra: a new Late Pleistocene stratigraphic marker across north-central Alaska and western Yukon Territory
  • Alaska ; Amérique du Nord ; Arctique ; Canada ; Etats-Unis ; Géographie des régions polaires ; Old Crow tephra ; Pléistocène supérieur ; Quaternaire zones froides ; Stratigraphie ; Téphrochronologie ; Volcanisme ; Yukon Territory
  • Old Crow tephra is the first extensive Pleistocene tephra unit to be documented in the northwestern part of North America. It has an age between the limits of 60,000 and 12,000 yr, set by C and fission-track measurements, respectively. Old Crow
  • tephra has been recognized in the Koyukuk Basin and Fairbanks region of Alaska, and in the Old Crow Lowlands of the northern Yukon Territory, some 600 km to the east-northeast. The source vent is unknown, but these occurrences, considered in relation
  • to the distant locations of potential Quaternary volcanic sources, demonstrate the widespread distribution of this tephra and underscore its importance as a regional stratigraphic marker.
Mineralogy and phase chemistry of Mount St. Helens tephra sets W and Y as keys to their identification
  • Mineralogy and phase chemistry of Mount St. Helens tephra sets W and Y as keys to their identification
  • Voluminous and widespread tephras were produced frequently during the last 36,000 yr of volcanic activity at Mount St. Helens. Numerous tephra sets have been defined by D. R. Mullineaux, J. H. Hyde, and M. Rubin (1975, U. S. Geological Survey
  • petrographic and electron microprobe techniques) for numerous samples of individual layers within tephra sets W and Y to evaluate the degree of compositional variability within and between tephra layers and criteria by which to distinguish among Mount St
  • . Helens and other Pacific Northwest tephras.
Level of Lake Lahontan during deposition of the Trego Hot Springs tephra about 23,400 years ago
  • Level of Lake Lahontan during deposition of the Trego Hot Springs tephra about 23,400 years ago
  • ; Quaternaire zone chaude ; Trego Hot Spring tephra ; Téphrochronologie ; Téphrostratigraphie ; Zone subtropicale
  • The Trego Hot Springs tephra bed is a silicic tephra about 23,400 yr old, found at several localities in pluvial lake sediments in northern Nevada, southern Oregon, and northeastern California. It has been characterized petrographically
  • , by the major and minor element chemistry of its glass, and by its stratigraphic position with respect to other tephra layers. When the tephra fell, pluvial Lake Lahontan stood between 1256 and 1260 m, and that immediately thereafter the lake rose to at least
La Téphra de Bag : une retombée volcanique à large dispersion dans le loess pléistocène d'Europe centrale
  • La Téphra de Bag : une retombée volcanique à large dispersion dans le loess pléistocène d'Europe centrale
  • Plusieurs aspects d'une couche de téphra présente dans sept coupes de loess de Hongrie et de Tchécoslovaquie ont été étudiés : la granulométrie, l'association de minéraux mafiques et la composition chimique d'échantillons globaux ainsi que de
  • chinopyroxènes. La téphra a été reconnue identique dans tous les gîtes étudiés, et le nom de Téphra de Bag lui a été donné. Cette téphra permet de proposer une corrélation nouvelle entre les coupes de loess concernées. - (L'A.).
Dawson tephra : a prominent stratigraphic marker of Late Wisconsin age in west-central Yukon, Canada
  • Dawson tephra : a prominent stratigraphic marker of Late Wisconsin age in west-central Yukon, Canada
  • Le tephra de Dawson est le tephra le plus important des dépôts quaternaires des régions du Klondike et de Sixtymile au Yukon. Sa composition est très proche de celle du tephra bien connu de Old Crow et, comme ce dernier, indique une source de la
  • tephra au-dessus de l'Alaska et du Yukon.
Correlation of a tephra layer in Western Greece with a Late Pleistocene eruption in the Campanian Province of Italy
  • Correlation of a tephra layer in Western Greece with a Late Pleistocene eruption in the Campanian Province of Italy
  • The Kalodiki fen is a 2-km2 mire in a small basin within a tectonic depression in Epirus, western Greece. The basin has accumulated as much as 9 m of peat and a tephra layer appears in cores at depths ranging from 2.9 to 5.7 m. The likely age
  • of the tephra, its index of refraction, and its mineralogical and chemical characteristics display strong similarities to tephra from the Campanian province of Italy. Mineralogically similar tephra layers have also been reported from a peat deposit at Philippi
Arcal distribution, redeposition and mixing of tephra within deep-sea sediments of the eastern Mediterranean sea in Tephra studies.
  • Arcal distribution, redeposition and mixing of tephra within deep-sea sediments of the eastern Mediterranean sea in Tephra studies.
  • Regional distributions of tephra deposits within Upper Quaternary pelagic sediments of the eastern Mediterranean and southern Aegean Seas have been determined from cores of deep-sea sediments. Slumping or other mass-wasting processes on the sea
  • -floor have significantly altered tephra distributions| local variability can be equally significant. Additional dispersal or mixing due to oceanic currents and biological activity have also been important physical processes in both pre-and post-burial
Correlation of Late Quaternary tephra Layers in a long pluvial sequence near Summer Lake, Oregon
  • Correlation of Late Quaternary tephra Layers in a long pluvial sequence near Summer Lake, Oregon
  • Near Summer Lake in southern Oregon, 54 tephra beds of late Quaternary age are exposed in pluvial lake sediments of lake Chewaucan. Seven of the tephra beds near the top can be correlated with tephra deposits younger than 117,000 yr at Mount St
  • . Helens, Washington, at Crater Lake, Oregon, and in northwestern Nevada in the deposits of pluvial Lake Lahontan. These seven tephra beds are from 6800 to about 90,000 yr old. Extrapolation of these ages through assumption of constant depositional rate
Traces of Laacher See tephra in cover-beds near Chagny, Bourgogne, France
  • Traces of Laacher See tephra in cover-beds near Chagny, Bourgogne, France
  • Etude de la fraction fine et des minéraux lourds des formations superficielles aux environs de Chagny. Comparaison avec les données du tephra du Laacher See (LST) et géochronologie.
Stratigraphic context of Old Crow tephra, Holitna lowland, interior southwest Alaska
  • Stratigraphic context of Old Crow tephra, Holitna lowland, interior southwest Alaska
  • The purpose of this paper is to document the stratigraphic and paleoenvironmental context of Old Crow tephra at the southwestern limit of its known distribution, thus contributing to interregional efforts to reconstruct Pleistocene paleoclimates
Thermoluminescence dating of the Pleistocene Old Crow tephra and adjacent loess, near Fairbanks, Alaska
  • Thermoluminescence dating of the Pleistocene Old Crow tephra and adjacent loess, near Fairbanks, Alaska
  • Utilisation de deux techniques différentes de thermoluminescence pour dater le tephra pléistocène Old Crow. Un dépôt a été daté directement à 110+- 16 ka pour ce tephra a été obtenu indirectement par l'analyse de grains du loess, immédiatement sus
Deux retombées volcaniques tardiglaciaires dans le Cézallier (Massif Central, France)
  • Cézallier ; France ; Géochimie ; Géographie de l'Europe ; Massif Central ; Paléo-environnement ; Quaternaire ; Stratigraphie ; Tardiglaciaire ; Tourbière ; Téphra ; Téphrochronologie ; Volcanisme
  • La découverte des téphra 4 et 5 de Godivelle Nord permet de distinguer 2 phases d'activité volcanique. La phase ancienne est attestée par les téphra 4 mugéaritiques et les téphra 5 hawaïtiques. Elle date d'environ 10 750 B.P. et sa durée est de 2
Characterization, identity, distribution, and source of late Cenozoic tephra beds in the Klondike district of the Yukon, Canada
  • Characterization, identity, distribution, and source of late Cenozoic tephra beds in the Klondike district of the Yukon, Canada
  • Dans cet article, les AA. donnent une description détaillée de 41 échantillons de tephra siliceux, préservés dans les dépôts cénozoïques tardifs de la région du Klondike, Territoire du Yukon. Discussion sur les origines et les âges de ces différents
  • lits de tephra.
Heterogeneity, correlatives, and proposed stratigraphic nomenclature of Hayes tephra set H, Alaska
  • Heterogeneity, correlatives, and proposed stratigraphic nomenclature of Hayes tephra set H, Alaska
  • Several Holocene tephra deposits of Hayes volcano constitute a marker horizon in southern and east-central Alaska. Their identification is aided by high amphibole/pyroxene ratio and biotite in trace amounts, unique among Holocene tephra deposits
Permafrost aggradation caused by tephra accumulation over snow-covered surfaces : examples from the Hekla-2000 eruption in Iceland
  • Permafrost aggradation caused by tephra accumulation over snow-covered surfaces : examples from the Hekla-2000 eruption in Iceland
  • The aim of this paper is an analysis of tephra accumulation on a pre-eruption winter snow cover and its influence on permafrost aggradation. Based on multi-annual field observations at the Hekla volcano, southern Iceland, a conceptual model
  • concerning the relationship between winter-fallen tephra and buried snow preservation is suggested. Furthermore, the relation of volcanic eruptions and potential preservation of buried snow in permafrost conditions on a global scale is discussed.
Correlation techniques in tephra studies in Tephra studies.
  • Correlation techniques in tephra studies in Tephra studies.
Quaternary tephrochronology in the Mediterranean region in Tephra studies.
  • Quaternary tephrochronology in the Mediterranean region in Tephra studies.
  • Quaternary volcanism in the Mediterranean region was highly explosive, especially in the Roman-Campanian province, the Aeolian Islands and the Hellenic island arc. Pantelleria and Etna were less explosive. Tephra layers originating from all
  • of these volcanoes have been encountered in Quaternary sediments. A summary of tephra layer occurrences in the Mediterranean Quaternary record is given in this paper. Correlation results and petrographic characterization techniques are described.
Quaternary tephra of northern Central America in Tephra studies.
  • Quaternary tephra of northern Central America in Tephra studies.
X-ray fluorescence analysis as a rapid method of identifying tephras discovered in archaeological sites in Tephra studies.
  • X-ray fluorescence analysis as a rapid method of identifying tephras discovered in archaeological sites in Tephra studies.
The Hayes tephra deposits, an upper Holocene marker horizon in south-central Alaska
  • The Hayes tephra deposits, an upper Holocene marker horizon in south-central Alaska