GLY 101 11th Edition Lecture 11Outline of Last Lecture I. Metamorphic rocks and the metamorphic texturesOutline of Current Lecture II.Metamorphic EnvironmentA. Contact MetamorphismB. Hydrothermal MetamorphismC. Burial MetamorphismD. Regional Metamorphism III. Metamorphic Facies IV. Metamorphic ZonesCurrent LectureII. Metamorphic Environments- chemical reactions and physical reorganization of mineral crystals that we call metamorphism can be triggered by diverse geologic situations- convergent and divergent plate boundaries are both sites of metamorphism- altered rocks occur in a zone called a metamorphic aureole- large molten bodies cool to form batholiths and produce aureoles that extend outward, these large aureoles often consist of distinct zones of metamorphismA. Contact Metamorphism-contact metamorphism or thermal metamorphism occurs in earth’s upper crust when rocks surrounding a molten igneous body are baked.-occurs when heat is the dominant variableThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.B. Hydrothermal Metamorphism- when hot iron rich water circulates through pore spaces or fractures in rock, a chemical alteration called hydrothermal metamorphism.- hydrothermal metamorphism occurs in limited areas-water is the agent of heat transfer-hot water dissolves a variety of ions and may cause metamorphic reactions - produces economically important deposits of metal oreC. Burial Metamorphism-burial metamorphism tends to occur where massive amounts of sedimentary or volcanic material accumulate in a subsiding basin.-under confining pressure and elevated temperatures cause metamorphic reactionsD. Regional Metamorphism- regional metamorphism is a common widespread type of metamorphism typically associated with mountain building where large segments of earth’s crust are folded.-regional metamorphism produces some of the most common metamorphic rocks- the thickening of the crust that occurs during mounting building results in buoyant lifting-buoyant lifting is when deformed rocks are elevated high above sea level-fault is a loosely coherent rock that is made of broken and crushed rock fragments.III. Metamorphic Facies-Common metamorphic facies: hornfels, zeolite, greenschist, amphibolite, granulite, blueschist, and eclogite-the facies get their name based off of the minerals that define them-the name of each metamorphic facies refers to a metamorphic rock derived from a basaltic parent-Pentti Eskola focused his work on the metamorphism of basalts, his terminology remains the same- the names of Eskola’s facies are labels for particular combinations oftemperatures and pressures. IV. Metamorphic Zones-rocks change due to metamorphism- the amount of change increases as the rocks are exposed to higher temperatures and pressures- grain size increases with higher levels of metamorphism-example: under higher temperatures and pressures shale may turn into slate, then phyllite, to schist, and to gneiss- certain mineral act as indicators of the temperature/pressure that the metamorphic rock experienced-example: chlorite is a mineral associated with low grade metamorphism, sillimanite is a sign of high metamorphic grade, garnet and staurolite are index minerals for intermediate metamorphic grades- at high temperatures the minerals with the lowest melting points canturn to