关键词: ⁴⁰Ar-³⁹Ar年龄谱, 全熔年龄, 不均匀Ar丢失, 断层活动

Abstract: Some problems emerging during analysis of basalt, diabase and clay minerals from fault gouge using ⁴⁰Ar-³⁹Ar method are discussed. Difference between ⁴⁰Ar-³⁹Ar total gas age and K-Ar age can be explained by inhomogeneous loss of Ar from different minerals during fast neutron irradiation. ⁴⁰Ar-³⁹Ar age spectra of three diabase samples from diabase viens indicate intrusive ages of the veins and show that despersion of K-Ar age values in the same area could be caused by effect of later geologic events. For clay mineral samples from fault gouge, ³⁹Ar recoil loss during fast neutron irradiation could increase ⁴⁰Ar-³⁹Ar total gas ages of <1μm grain-size fraction. Lower step ages at lower temperature in ⁴⁰Ar-³⁹Ar age spectra of <1μm and 2-10μm grain-size fractions may be a result of stronger late movement alone the fault.

Key words: ⁴⁰Ar-³⁹Ar age spectrum, Total gas age, Inhomogeneous Ar loss, Fault movement