Geo 102 Lecture 13 Outline of Last Lecture I Geologic Time Outline of Current Lecture II Radio isotopes III How do we count Atoms IV What are we dating V The age of the Earth Current Lecture Radio isotopes There are many isotope systems Each has important differences Half life Mineral hosts Abundances Decay pathways Origins What do we date volcanic ash feldspar mica zircon carbon These 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 garnet some limestone coral Many others How do we count atoms Decay counting Mass spectrometry Particle accelerators Other Dating Techniques Dendrochronology Varve and layer counting Electron spin resonance Fission track Luminescence Logic Relative Dating So what are we actually dating The age a system becomes closed Crystallization of igneous rocks What about sedimentary rocks Minerals usually formed much earlier in an igneous or metamorphic rock Fossils can sometimes be directly dated Metamorphic Dates are reset with heat The Age of the Earth Oldest mineral yet dated is a bit younger than this Australian zircon The earth is about 4 55 4 6 Ga
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