EASC 101 Lecture Notes - Geothermal Gradient, Schist, Protolith
21 Nov 2012
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Document Summary
One rock into another (pressure, temp +composition) - no/very little melting involved. Parent rock (or protolith) the following are process metamorphic this occurs at surface and at depth igneous sedimentary metamorphic. Fluids -> volatiles (c02), enhances migration of ions (helps with recrystalization) Pore spaces of sedimentary rocks fracture in igneous rocks. Crystallization, recrystallization & chemical reactions are slow (millions of years) Two sources of heat: igneous intrusion, increase temperature with depth -> geothermal gradient (20-60 degrees celsius/km, 30-450 degrees celsius at 15km) Pressure increase with burial depth confining pressure applied equally in all directions (uniform pressure) differential stress -> when unequal in different directions. Texture: size, shape, and arrangement of grains with rock. Foliation: any planar arrangement of mineral/grains of structural features within rock. Subduction zone metamorphism-> dragging down (describes environment at depth) Burial metamorphism can occur in two ways: contact or subduction zone metamorphism.
