GLY 101 1st Edition Lecture 10Outline of Current Lecture I. What is MetamorphismII. What Drives MetamorphismIII. Metamorphic TexturesA. foliated texturesIV.Common metamorphic rockCurrent LectureI. What is metamorphism- metamorphism is the transformation of one rock into another rock type.- parent rock- the rock from which a metamorphic rock was formed-metamorphism is the process that leads to changes in the mineralogy,texture, and chemical composition of the parent rock.- the mineralogy of a rock can change when it is subjected to new conditions such as change in temperature or pressure.- the texture of a rock can also be altered - how much the parent rock changes during metamorphism is metamorphic grade- low grade and high grade-metamorphism can also make it difficult to identify the parent rock if temperature and pressures were extreme,- in high grade metamorphism, bedding planes, fossils, and vesicles that may exist in the parent rock are obliterated.- during metamorphism the rock remains essentially solidThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.II. What Drives Metamorphism- heat, pressure, directional stress, and chemically active fluids are agents of metamorphism- heat is the most important factor- heat provides the energy needed for chemical reactions that result inrecrystallization- recrystallization is the formation of new mineral grains that tend to be larger than the original grains.-the 2 primary sources of heat1. increasing temperature that occurs deeper in earth’s interior2. heat being released to the surrounding rocks as magma cools- buried rocks are subjected to confining pressureIII. Metamorphic Textures- texture describes the size, shape, and arrangement of the mineral grains within a rock.- foliation refers to any planar arrangement of mineral grains or crystals within a rock.- examples of foliation : the parallel alignment of platy minerals, or compositional banding in which the separation of dark and light minerals generates a layered appearance.A. Foliated textures- the type of foliation exists depending upon the grade of metamorphism and mineralogy of the parent rock- rocks that split into thin slaps exhibit rock cleavage.- the excellent property that rock cleavage exhibit is called slaty cleavage.- rocks that have a separated or banded appearance called gneissic texture or gneissic banding.- metamorphic rocks that do not exhibit foliated textures are nonaffiliated- metamorphic rocks may also contain some unusually large grains, porphyroblastsIV. Common Metamorphic Rocks-types of foliated rocks1. slate2. phyllite3.schist4.gneiss- non foliated