metamorphism and end of sed rocks with notes

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Metamorphism and Metamorphic Rocks Correctly place the following statements in the Venn Diagram Igneous Rocks Occurs at divergent boundaries Occurs at convergent boundaries Forms as a result of melting (magma) Temperature is an agent Pressure is an agent Generates foliated rocks Forms as a result of being near an intrusion of magma Found in mountain belts May have been originally been a metamorphic rock 10 Form at temperatures above 200 oC 11 May underlie several adjacent states al hic on orp gi Re etam M cks ro Daily Question Contact Metamorphic Rocks Definitions Metamorphism – mineralogical, chemical, and physical changes that occur in solid rocks Occurs at depths greater than that of lithification (Diagenesis) Solid state recrystallization – changes that occur without the rock melting (rocks that melt are igneous) Factors influencing Metamorphism • • • • Temperature Pressure Fluid Time Agents of Metamorphism Factors influencing Metamorphism Temperature • below about 150oC, most minerals are stable (little or no metamorphism) • above 150oC, reaction rate increases as temperature increases, new minerals begin to form • above 600oC, some minerals begin to melt (transition to igneous rocks) • Temperature a function of depth within the Earth and the presence of a magma Factors influencing Metamorphism Pressure • as pressure increases, pore spaces reduced and density increases, pore fluids are expelled • Minerals recrystallize and begin to realign Differential stress • pressure is greater in one direction than in another Temperature, Pressure and Rock Type Factors influencing Metamorphism Pore fluids (water and carbon dioxide) • as pressure increases, pore fluids are expelled • Pore fluids increase the rate of metamorphic reactions by: • storing ions involved in reactions • moving ions from one place to another Chemical Fluids from Magmas • Carry ions from the melt • Fluids increase the temperature in the rock Low Grade Metamorphism Example: Slate • Rocks become more dense and compact • forms at low temperature and pressure • microscopic crystals • dull luster • clay and mica minerals • foliated Low Grade - Slate Metamorphic Grade Intermediate Grade Metamorphism Example: Phyllite • • • • • intermediate temperature and pressure small crystals shiny luster mostly mica minerals foliated Intermediate Grade – Phyllite Metamorphic Grade High Grade Metamorphism Example: Schist • • • • high temperature and pressure large crystals mica-rich foliated High Grade - Schist Metamorphic Grade High Grade Metamorphism Example: Gneiss • • • • high temperature and pressure large crystals mica-poor foliated High Grade - Gneiss Rock Cycle Regional Revisited Slate Phyllite Schist, Gneiss Magma Metamorphic Facies Different minerals form at different temperatures and pressures Group of stable minerals define a facies [...]... Contact Metamorphism Types of Metamorphism Regional metamorphism • Large scale – large volume of rock is affected • Associated with convergent plate margins and mountain building • Folding and faulting increase thickness of the crust • Occurs over a range of temperatures and pressures • Fluids are also present • Low grade to high grade metamorphism • Will have zones of contact metamorphism Regional Metamorphism. ..Veins Solutions are deposited in fractures and joints Factors influencing Metamorphism Time • solid state recrystallization is a slow process • in general, size of minerals increases with time Types of Metamorphism 1 Burial Metamorphism 2 Contact Metamorphism 3 Regional Metamorphism Metamorphism & Plate Tectonics Types of Metamorphism Burial Metamorphism • most common type, occurs where crust... temperature and pressure (low grade metamorphism) Maximum stress vertical, foliation parallel to ground surface Types of Metamorphism Contact metamorphism • Occurs in rocks around a magma body • High temperature (heat from magma) “bakes” the rock around the magma creating an alternation • High temperature & fluid primary agents, little to no pressure (occurs at shallow depths in the crust) Contact Metamorphism. .. Regional Metamorphism Metamorphic Grade Low Grade Metamorphism Example: Slate • Rocks become more dense and compact • forms at low temperature and pressure • microscopic crystals • dull luster • clay and mica minerals • foliated Low Grade - Slate Metamorphic Grade Intermediate Grade Metamorphism Example: Phyllite • • • • • intermediate temperature and pressure small crystals shiny luster mostly mica... shiny luster mostly mica minerals foliated Intermediate Grade – Phyllite Metamorphic Grade High Grade Metamorphism Example: Schist • • • • high temperature and pressure large crystals mica-rich foliated High Grade - Schist Metamorphic Grade High Grade Metamorphism Example: Gneiss • • • • high temperature and pressure large crystals mica-poor foliated High Grade - Gneiss Rock Cycle Regional Revisited Slate
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