GEOL 1001 : Test 2 Metamorphism
Document Summary
Transition of one rock into another by temperatures and/or pressures unlike those in which it formed. About metamorphism: change in heat, pressure, and the chemical environment of rocks can alter mineral compositions and crystalline textures, metamorphic changes occur in the solid state, so there is no melting. Two sources of heat: contact metamorphism heat from magma, an increase in temperature with depth geothermal gradient, pressure and differential stress. Confining pressure applies forces equally in all directions. Differential stress unequal in different directions: chemically active fluids. Sources of fluids: pore spaces of sedimentary rocks, fractures in igneous rocks, hydrated minerals such as clays and micas, the importance of parent rock. Most metamorphic rocks have the same overall chemical compostition as the original parent rock. Texture size, shape, and arrangement of mineral grains. Foliation any planar arrangement of mineral grains or structural features within a rock. Parallel alignment of platy and/or elongated minerals (micas) Closely spaced planar surfaces along which rocks split.
