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geo notes exam 1 notes notes notes - Chapter 11:Igneous...

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Chapter 11:Igneous Rocks, Intrusive Activity and the Origin of Igneous Rocks Chapter 11:Igneous Rocks, Intrusive Activity and the Origin of Igneous Rocks Intrusive Rocks Intrusive Rocks 0. The major difference between extrusive and intrusive igneous rocks is where they solidify- on the Earth’s surface or within it. 1. Intrusive rocks appear to have crystallized from magma emplaced in surrounding rock. 2. Intrusive rocks are usually coarse grained because they form under the Earth's surface and take a long time to cool . 3. Bodies of intrusive rocks are exposed to us only after erosion and, usually uplift. Country Rock Country Rock 0. The country rock is an accepted term for any older rock into which an igneous body is intruded. 1. The country rock adjacent to intrusive rock is seen to have been baked or metamorphosed along the contact with the intrusive rock. 2. This has been caused by the transfer of heat from the igneous rock to the country rock. Intrusive vs Extrusive Igneous Rocks Intrusive vs Extrusive Igneous Rocks 0. Intrusive rocks are the builders of the continental crust and mountain belts. 1. Extrusive rocks are the volcanics that created the oceanic crust . 2. Granite (intrusive) is the igneous rock most common on the continents, basalt (extrusive) is most common on the ocean floor, and andesite (extrusive, usually on or near continental margins) is the building material of young volcanic mountain ranges. 0. A coarse grained texture is the most significant difference between plutonic (intrusive) rocks and extrusive rocks which are likely to be fine-grained . Ultramafic Rock Ultramafic Rock 0. Ultramafic rock is composed entirely or almost entirely of ferromagnesian minerals. 1. No feldspars or quartz are present. Most have less than 45% silica. 2. Since they are all formed in the mantle rather than on the surface, Ultramafic rocks do not have a fine- grained (extrusive) counterpart. Bowen’s Differentiation Bowen’s Differentiation 0. Only three major families of magma exist (mafic, intermediate and felsic), but there are literally hundreds of different kinds of igneous rocks . 1. Norman L. Bowen found a way for both felsic and mafic rocks to form from a single basaltic (mafic) parent magma, this explained the vast array of igneous rocks. 2. His experiments involved differentiation a process by which different ingredients separate from an originally homogenous mixture. An example is the separation of whole milk into cream and skim milk. Chapter 12:Weathering and Soils
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This note was uploaded on 03/01/2011 for the course GEO 303 taught by Professor Leon during the Fall '08 term at University of Texas at Austin.

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geo notes exam 1 notes notes notes - Chapter 11:Igneous...

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