EPSC 201 Lecture Notes - Lecture 27: Feldspar, Pyroxene, Mudstone
20 Jul 2016
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Document Summary
O heat o pressure o differential stress (push, pull or shear) o bathing in hydrothermal fluids: heat o metamorphism occurs between 250c and 850c and the depth to this temperature varies with tectonic setting. o sources of heat: the geothermal gradient, magmatic intrusions, and tectonic compression. o heat causes the atoms to vibrate faster, stretching and bending chemical bonds. Mineral grains grow larger at the expense of smaller ones until they interlock: pressure o under the effect of pressure, mineral grains will deform depending on how fast and how the pressure is applied o as pressure increases, the space between mineral grains is eliminated as grains are pressed together. Such transformations involve phase changes and/or neocrystallization: pressure and temperature o when pressure and temperature increase, the original mineral assemblage in a rock becomes unstable, and a new assemblage forms out of minerals that are stable, differential stress o shear.
