Metamorphism - Metamorphism Changes in Rock Composition or...

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Unformatted text preview: Metamorphism Changes in Rock Composition or Texture Due to Heat, Pressure and Action of Fluids Take-Away Points 1. Rocks change due to heat, pressure, and fluids 2. Heat in the earth is original heat plus heat from radioactive decay 3. Pressure is simply from the weight of overlying rocks. Pressure = Depth 4. What happens during metamorphism 5. Different metamorphic conditions result in different rocks and minerals 6. Metamorphic rocks reveal temperature and pressure conditions in the earth. We Do Not Live at Normal Conditions By the standards of Earths interior, we live in a frozen vacuum Things that look abnormal to us are normal behavior for materials Solids can flow Solids can react chemically with each other A given material can have several different atomic structures Chemical Changes in Rocks Weathering At Surface Diagenesis Sedimentary Rocks Metamorphism Starts about 200 C Outside range of normal near- surface conditions 1. Rocks change due to heat, pressure, and fluids Where Does the Heat Come from? Some Heat is Probably Original Much heat is from Radioactive Decay Uranium and Thorium Other Elements + Lead + Radiation (about 90%) Potassium-40 Calcium-40 or Argon-40 + Radiation (about 10%) Typical temperature increase 25 C per kilometer near surface 1-2 C per kilometer in deep earth 2. Heat in the earth is original heat plus heat from radioactive decay Where Does the Pressure Come from? Air Pressure = 14 P.s.i. (1 Atmosphere or 1 Bar) Pressure Beneath 10 Meters (33 Ft.) Of Pressure Beneath 10 Meters (33 Ft....
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This note was uploaded on 12/08/2011 for the course GEO 121 taught by Professor Staff during the Fall '11 term at North South University.

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Metamorphism - Metamorphism Changes in Rock Composition or...

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