Accumulation of structural radiation defects in quartz in cooling systems: basis for dating

Determination of the mineral age based on the creation of radiation structure defects depends on the thermal stability of these defects. Accumulation of radiation defects in solids in cooling systems taking into account their time dependent first-order as well as second-order annihilation is analyzed theoretically. Second-order kinetics in comparison with first-order leads to increased duration of a transitional period and to a lower accumulation rate. The contribution of the transitional period is determined by the cooling rate of the geological system and by the production rate of structure defects. Resulting formulas are applied for dating rock-forming quartz from the Eldzhurtinsky granite massif (Great Caucasus, Russia) with the help of electron paramagnetic resonance. It is shown that the EPR age calculated with the formulas derived in this study in comparison with the results of the conventional additive dose technique is closer to the results of 40Ar/39Ar dating. Due to annihilation of radiation defects even at low temperature the EPR dating method can be applied to a limited time range.