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Full-Text Articles in Physical Sciences and Mathematics
Volcanic Ash From The 1362 A.D. Oræfajokull Eruption (Iceland) In The Greenland Ice Sheet, J. M. Palais, K. Taylor, Paul Andrew Mayewski, P. Grootes
Volcanic Ash From The 1362 A.D. Oræfajokull Eruption (Iceland) In The Greenland Ice Sheet, J. M. Palais, K. Taylor, Paul Andrew Mayewski, P. Grootes
Earth Science Faculty Scholarship
A continuous record of electrical conductivity measurements (ECM) was made on site during the drilling of a 200 m ice core at Summit, Greenland and was used to identify horizons in the ice that might be linked to volcanic eruptions. In one detailed section that we studied a large peak in the number of particles, two orders of magnitude above the background, was measured. The particle peak was not associated with an ECM peak, however. The particles were identified as volcanic ash on the basis of both particle morphology and chemical composition. The ash composition suggests an explosive rhyolitic eruption …
Evidence For A Frozen Bed, Byrd Glacier, Antarctica, John P. Scofield, James L. Fastook, Terence J. Hughes
Evidence For A Frozen Bed, Byrd Glacier, Antarctica, John P. Scofield, James L. Fastook, Terence J. Hughes
Earth Science Faculty Scholarship
Ice thickness, computed within the fjord region of Byrd Glacier on the assumptions that Byrd Glacier is in mass-balance equilibrium and that ice velocity is entirely due to basal sliding, are on average 400 m less than measured ice thicknesses along a radio-echo profile. We consider four explanations for these differences: (1) active glacier ice is separated from a zone of stagnant ice near the base of the glacier by a shear zone at depth; (2) basal melting rates are some 8 m/yr; (3) internal shear occurs with no basal sliding in much of the region above the grounding zone; …
Tertiary Minette And Melanephelinite Dikes, Wasatch Plateau, Utah - Records Of Mantle Heterogeneities And Changing Tectonics, David G. Tingey, Erich H. Christiansen, Myron G. Best, Joaquin Ruiz, Daniel R. Lux
Tertiary Minette And Melanephelinite Dikes, Wasatch Plateau, Utah - Records Of Mantle Heterogeneities And Changing Tectonics, David G. Tingey, Erich H. Christiansen, Myron G. Best, Joaquin Ruiz, Daniel R. Lux
Earth Science Faculty Scholarship
A swarm of minette and melanephelinite dikes is exposed over 2500 km2 in and near the Wasatch Plateau, central Utah, along the western margin of the Colorado Plateaus in the transition zone with the Basin and Range province. To date, 110 vertical dikes in 25 dike sets have been recognized. Strikes shift from about N80-degrees-W for 24 Ma dikes, to about N60-degrees-W for 18 Ma, to due north for 8-7 m.y. These orientations are consistent with a shift from east-west Oligocene compression associated with subduction to east-west late Miocene crustal extension. Minettes are the most common rock type; mica-rich minette …