HW3-igneousrocks - within 2-5 km depth from the surface In...

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Trupti Bulsara Homework#3 (10 points) – Igneous Rocks Due Date: 9/27/10 1. Construct a table of four different types of magma and their percentages of silica contents? TYPE OF MAGMA SILICA CONTENT Ultramafic < 45% Mafic 45% -52% Intermediate 53%-65% Felsic > 65% Four Types of Magma 2. Briefly (about 5 sentences) describe formation of Hawaiian volcanic islands? Magma is formed at the depth of 100-300 km beneath the surface. Magma can also be formed near the lower crust and upper mantle region. In the tectonic boundaries, magma is found relatively at the shallower depth. In the spreading center, magma is formed because of the low-pressure condition and is found
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Unformatted text preview: within 2-5 km depth from the surface. In the subduction zone, the magma forms at 20-30 km depth. Here melting is enhanced by the release of fluids from hydrated rocks of the oceanic crust. Magma also travels from very deep beneath the surface almost as deep as the Core Mantle Boundary. This magma traverses toward the surface as magma plume and forms volcanic islands. 3. List types of texture of igneous rocks and give an example of each? Porphyritic Glassy Vesicles Pyroclastic Basalt Gabbro Amphibole Obsidian-volcanic glass Pumice Tuff TYPE OF IGNEOUS ROCK EXAMPLE TYPES OF IGNEOUS ROCKS AND EXAMPLE Aphanitic Phaneritic...
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