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Unformatted text preview: on. Primarily zircon grains. for detrital mineral Thermochronology. geochronology. Detrital mineral Evolving rapidly geochronology (e.g., technique of the zircons, monazite, future to replace xenotime) SHRIMP. From Stern (1999) Wednesday, 15 August, 12 Diffusion and Closure Temperatures • Closure Temperature: temperature at which an element derived from radioactive decay cannot diffuse out of a crystal (also called a Blocking Temperature). • When you read about a U-Pb age (or any age for that matter) in the literature it reflects the age at which the rock cooled below the closure temperature for the mineral in question. • Example: Zircon has a closure T of ~900oC. Thus, if you have an age of 100 Ma this age reflects the age when the rock (and zircon) crystallized beneath 900oC. • Closure temperature is based on diffusion and different minerals have different closure temperatures, thus different minerals can give you the timing of different events. Wednesday, 15 August, 12 http://earth.leeds.ac.uk/dynamicearth/d...
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This document was uploaded on 03/06/2014 for the course ES 4502 at Memorial University.

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