Uranium-Lead, Metamorphic Rocks
Definition: The word metamorphism derives from the Greek word “metamorphosis,” meaning change of form. Metamorphism is the process by which the mineralogy of rocks is changed as the result of pressure and temperature according to their composition and with the aid of fluid and deformation. Metamorphism is mainly concerned with the changes that take place when rocks are in the solid state, even though melt can be one of the phases present.
Dating of metamorphism in general aims to determining the absolute age of stages or phases of metamorphism. It requires dating of a mineral or mineral growth zone that reacted or formed during metamorphism. The age is determined by measuring the U–Th–Pb isotopic composition in the mineral (see Uranium-Lead Dating). The crucial step in dating metamorphism is to relate an absolute date to a metamorphic stage or reaction, ideally identified by specific pressure and temperature values. This step is particularly challenging for U–Pb dating as...
KeywordsInductively Couple Plasma Mass Spectrometry Metamorphic Rock Growth Zone Trace Element Composition Metamorphic Stage
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