In the upper parts of the Earth’s lithosphere, where the rocks are relatively cool, most of the deformation takes place by fracturing, giving rise to joints, faults and thrusts. Because the temperatures are relatively low, this deformation may not be accompanied by metamorphic reactions, involving the breakdown of one mineral species and the appearance of new mineral species. Mechanical processes are dominant. However, within and close to fractures, mechanical processes frequently operate on the grain-size scale, producing very extensive modifications of rock fabrics. There may be some metamorphic reactions, but the mechanical processes are the dominant ones.
KeywordsShear Zone Regional Metamorphism Calcite Crystal Arabian Plate Calcite Vein
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