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Chapter 8: Metamorphism and Metamorphic Rocks:New Rocks from Old
What is Metamorphism? 1) Metamorphism is the change in form that happens in earth's crustal rocks in response to changes in temperature and pressure
What is Metamorphism? (1) ◼ Metamorphism is the change in form that happens in Earth’s crustal rocks in response to changes in temperature and pressure
What is Metamorphism?(2) There are six major factors in metamorphism: a Chemical composition The change in temperature The change in pressure The presence or absence of fluids How long a rock is subjected to high pressure or high temperature a whether the rock is simply compressed or is twisted and broken during metamorphism
What is Metamorphism? (2) ◼ There are six major factors in metamorphism: ◼ Chemical composition. ◼ The change in temperature. ◼ The change in pressure. ◼ The presence or absence of fluids. ◼ How long a rock is subjected to high pressure or high temperature. ◼ Whether the rock is simply compressed or is twisted and broken during metamorphism
Chemical composition of Original rock a The greatest factor in determining the mineral assemblage of a metamorphic roc k a The chemical composition of the original rock controls the mineralogy of the metamorphosed rock
Chemical Composition of Original Rock ◼ The greatest factor in determining the mineral assemblage of a metamorphic rock. ◼ The chemical composition of the original rock controls the mineralogy of the metamorphosed rock
Temperature And Pressure (1) a The heat source is earths internal heat Rock can be heated by burial or by nearby igneous intrusion Burial is inevitably accompanied by an increase in pressure due to the weight of the overlying rocks。 An intrusion may be shallow, resulting in low pressure, or deep, resulting in high pressure
Temperature And Pressure (1) ◼ The heat source is Earth’s internal heat. ◼ Rock can be heated by burial or by nearby igneous intrusion. ◼ Burial is inevitably accompanied by an increase in pressure due to the weight of the overlying rocks. ◼ An intrusion may be shallow, resulting in low pressure, or deep, resulting in high pressure