Volcanoes - 1 Fig. 6.1 Fig. 6.1 1. Magma, which originates...

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Unformatted text preview: 1 Fig. 6.1 Fig. 6.1 1. Magma, which originates in the partially melted asthenosphere 2. rises through the lithosphere to form a magma chamber. 1. Magma, which originates in the partially melted asthenosphere Fig. 6.1 3. Lavas erupt from the magma chamber through central and side vents 2. rises through the lithosphere to form a magma chamber. 1. Magma, which originates in the partially melted asthenosphere Fig. 6.1 4. accumulating on the surface to form a volcano. 3. Lavas erupt from the magma chamber through central and side vents 2. rises through the lithosphere to form a magma chamber 1. Magma, which originates in the partially melted asthenosphere Fig. 6.1 2 Types of Lavas Types of Lavas Basaltic Basaltic lavas : low-viscosity mafic lavas, typically erupted at 1000 o to 1200 o C; cool to form basalt. Rhyolitic Rhyolitic lavas : high-viscosity felsic lavas, typically erupted at 800 o to 1200 o C; cool to form rhyolite. Andesitic Andesitic lavas : intermediate in composition and viscosity between mafic and felsic magmas; cool to form andesite. Types of Basalts Types of Basalts Flood Basalts Flood Basalts : thick, widespread accumulations of basalt, typically fed by fissures Pahoehoe Pahoehoe : a very low viscosity basaltic lava characterized by a ropy texture Aa Aa : a relatively low viscosity basaltic lava characterized by a jagged, blocky texture Pillow Basalts Pillow Basalts : a basaltic lava extruded beneath the water, characterized by glassy pillows filled with crystalline basalt Fig. 6.2 Flood Basalts of the Columbia Plateau Flood Basalts of the Columbia Plateau Fig. 6.2 Fig. 6.3Fig....
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This note was uploaded on 11/20/2010 for the course LIR 30 taught by Professor Thornley,k during the Spring '08 term at Santa Rosa.

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Volcanoes - 1 Fig. 6.1 Fig. 6.1 1. Magma, which originates...

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