THERMAL STABILITIES OF PARAMAGNETIC DEFECT AND IMPURITY CENTERS IN QUARTZ - BASIS FOR ESR DATING OF THERMAL HISTORY

Thermal stabilities of E', Al, and Ti centers in quartz from the Mannari granite were investigated by electron spin resonance (ESR) with isothermal and isochronal annealing experiments. Second order decay kinetics best explain the results. The closure temperatures at which the ESR clocks start were estimated to be 91-degrees-C, 78-degrees-C, and 31-degrees-C for E', Al, and Ti centers, respectively, with a cooling rate of about 10-degrees-C/Ma. Closure temperatures were also estimated for rocks around an intrusive dike. The thermal history of a quartz bearing rock can be investigated using ESR ages for different centers.