中文摘要：

用标明日期方法的激光 40Ar/39Ar，我们从 Jiuquan 得到了 lawsonite blueschist 和绿帘石 blueschist 的变形年龄，北 Qilian 山， NW 中国。从 lawsonite blueschist glaucophane 标明日期的高质量的激光 40Ar/39Ar 给 413 的 isochron 年龄

英文摘要：

Using laser ^40Ar/^39Ar dating method, we have gotten the metamorphic ages of lawsonite blueschist and epidote blueschist from Jiuquan, northern Qilian Mountain, NW China. The high quality laser ^40Ar/^39Ar dating of glaucophane from lawsonite blueschist gives an isochron age of 413±5 Ma. The isochron age obtained from phengite in epidote blueschist is 415±7 Ma. These data, combining with peak metamorphic P-T conditions and regional geological setting, allow us to infer that the lower limit of the ages of the prograde subduction metamorphism from lawsonite blueschist facies to epidote blueschist facies occurred at ca. 413-415 Ma, which also suggests that the formation of lawsonite blueschist in the northern Qilian Mountain maybe resulted from the corner flow in the cold subduction zone. This study shows that the final closing time of the northern Qilian remnant oceanic basin is about 413-4 15 Ma, which also represents the convergent age between the North China Craton and the Qaidam block.