Igneous Structures and Field Relations-CH4

Spatters may build cinder cones top clumps of molten

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Unformatted text preview: ild cinder cones Top: Clumps of molten lava (spatter) hurled above rim of spatter cone . Width of the image is about 3 m. Bottom: Close view of cooled, solidified spatter fragments hurled from active littoral cone on south shoreline of Kilauea Volcano. Impact of the molten spatter hitting ground flattened fragments into roughly circular disks. image source: http://volcanoes.usgs.gov/Products/Pglossary/spatter.html 6 2 8/27/2012 Properties of Magmas and Styles of Eruption iii. Evidence for volatiles in magmas d) Vesiculated porphyritic basalt with phenocrysts of olivine, pyroxene, and plagioclase e) Pumice - light-colored, highly-vesiculated glass image source: Hamblin and Christiansen (2001) Dacitic pumice fragments erupted by Mount Pinatubo, Philippines, during eruption on 15 June 1991. 7 image source: http://volcanoes.usgs.gov/Products/Pglossary/pumice.html Properties of Magmas and Styles of Eruption iii. Evidence for volatiles in magmas f) Violent eruption of volatile-rich high viscosity magma Explosive eruption from on Mount Spurr (left), Alaska, sent an eruption column to a height of about 18 km above sea level, and Mt. Cleveland (above) image source: 8 http://volcanoes.usgs.gov/Products/Pglossary/PlinianEruption.html Landforms - central vent eruptions Distinctive landforms The most general groupings of landforms are: a) shield volcano - flat b) composite volcano - steeper c) pyroclastic cone d) additional forms associated with craters Volcanic landforms associated with a central vent (all at same scale). image source: Winter (2010) 9 3 8/27/2012 Landforms - central vent eruptions a) Shield Volcano Rising gradually to >4 km above sea level, Mauna Loa is largest volcano on our planet. Its submarine flanks descend to sea floor an additional 5 km, and the sea floor in turn is depressed by Mauna Loa's g reat mass another 8 km. This makes the volcano's summit about 17 km (56,000 ft) above Image source: J.D. Griggs, January 10, 1985 its base! image source: Hamblin and Christia...
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This document was uploaded on 07/18/2013.

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