Abstract: After sampling and ore-dressing of the NNE fracture zone in the Jinshanbang granitic batholith in Suzhou, as well as chemical etching and neutron radiation of its heavymineral——apatite, we observed and statistically analysed its spontaneous and inducedfission track by means of white mica external probe. Our conclusions are as following:1) the fission track dating of samples No. 1, 2, 3 and 4 are 1.724±0.077×10⁸ -2.12 ± 0.076× 10⁸ years and mostly 1.724 ± 0.077 × 10⁸-1.88 ± 0.038× 10⁸ years, showing that the granitic batholith intruded in Jurassic-Cretaceous period;2) the fission track year of sample No.5 is 0.1920± 0.013× 10⁸ years, indicating that the geological event of the fault-breaking trace was in Miocene. In combination with historical earthquake and other geological information, we suggest that the earth's crust in this area has been relatively active in recent period; and3) it looks promising to apply the fission track method to active fault dating.

Key words: Apatite, Fission track, Active fault

摘要： 本文通过对苏州金山浜花岗岩岩体中北北东向断裂带取样,选矿及对其重矿物——磷灰石分别进行化学蚀刻和热中子辐射,采用白云母外探测器法分别进行自发裂变径迹与诱发裂变径迹的观察、统计及裂变径迹年龄的计算。认为该岩体形成年代是侏罗-白垩纪,而断层破裂形迹的地质事件是晚第三纪中新世。说明运用裂变径迹的方法来研究活断层的测年工作是可取的。

关键词: 磷灰石, 裂变径迹, 活断层