PRECISE ~(40)Ar-~(39)Ar DATING OF THE SUZHOU COMPOSITE GRANITE
苏州复式花岗岩体的精确40Ar—39Ar定年

The Suzhou composite granite is composed of intrusions of three stages. Biotites from different rock units of the Suou body are dated by the ~(40)Ar-~(39)Ar technique. Because of a specially designed irradiation configuration the uncertainties in J value due to the effects of fluence gradient is canceled. Therefore, very small possible age difference between different rock units can be compared. The result indicates that the Suzhou composite intrusion was formed at about 123 Ma in a short time span perhaps less than 0.5Ma.