Rb–Sr Geochronology (Igneous Rocks)
Application of the radioactive decay of 87Rb to 87Sr to determining the age of crystallization of igneous rocks.
Introduction and Background
Both rubidium (Rb) and strontium (Sr) are large ion lithophile elements and over the course of Earth history have become relatively concentrated in crustal lithologies, e.g., gneisses and granites, and sediments derived from these. Because of this, application of the Rb–Sr decay scheme was one of the first radiometric dating systems used to determine the age of rocks and remains a widely used system for dating geological units formed at relatively high temperatures, in particular volcanic, plutonic, and metamorphic rocks formed in the crust. Relatively low closure temperatures for commonly used minerals and susceptibility for disturbance of Rb and Sr complicate the use of the system as a geochronometer, and application of methods such as U–Pb in zircon is...
KeywordsFractional Crystallization Thermal Ionization Mass Spectrometry Closure Temperature Mineral Isochron Isochron Diagram
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