ERS120H5 Lecture Notes - Lecture 13: Metamorphic Rock, Metamorphism, Mafic
Document Summary
Temperature ( around 250 to 850 degrees celsius) Recrystallization (same composition, same minerals: same composition, same mineral (but different size or shape, solid state = no melting. Phase change (same composition, new minerals: same composition, new mineral atoms arranged differently, solid state = no melting. Neocrystallization (new composition, new minerals: same composition, new mineral, solid state = no melting. Alignment of tabular or elongate minerals (changes fabric of rock) Elongated and tabular will align a certain way when pressure (or stresses) is applied. Growth of porphyroblasts (changes fabric of rock) Composition: aluminous (rich in al, quartzo-feldspathic (rich in quartz and feldspar, calcareous (rich in calcite, mafic (rich in mafic minerals) Causes of metamorphism: mountain belt, contact, subduction zone, dynamic. Mountain belt (regional) metamorphism increasing temperature and pressure from edges to center. Produces a rock called hornfels which varies widely depending on the protolith composition.
