青藏高原西部的抬升速率:叶城-狮泉河花岗岩^(40)Ar-^(39)Ar年龄的地质解释

The Uplifting Rates for the Western Qinghai Xizang Plateau: Interpretation of 40 Ar 39 Ar Dating Data for the Granites in the Area from Yecheng to Shiquanhe

通过对叶城－狮泉河剖面花岗岩中黑云母４０Ａｒ－３９Ａｒ法年龄研究，获得西昆仑北岩带库地岩体海拔高度２９５０ｍ和２８５０ｍ黑云母的封闭年龄分别为３９６．９Ｍａ和３８８．９Ｍａ，西昆仑南岩带塔西土路克、三十里营房和奇台大坂岩体黑云母的封闭年龄为１９５．８～１８３．９Ｍａ，班公湖－喀喇昆仑北岩带日土岩体黑云母封闭年龄为８０．３～７９．６Ｍａ，其时代分别为加里东期、印支期和燕山晚期。年龄结果表明，同一岩体海拔高的黑云母封闭年龄大于海拔低的黑云母封闭年龄，根据海拔高程差和坪年龄差计算出岩体的抬升速率，表明青藏高原西部从加里东期到燕山晚期，隆起速度有增大的趋势，而且具脉动性。

The closing ages of biotite samples collected from different altitudes in the five granite belts in the western Qinghai Xizang plateau were determined by the 40 Ar 39 Ar stepped heating technique. The results indicate that the age of higher altitude biotite is older than that of lower one for the same granite bodies, which suggests that the biotite at shallow block was formed earlier than that at depths. According to the ratio of the altitude discrepancies to the age discrepancies (△ h /△ t ), the uplifting rates of the granite bodies were calculated and the results indicated the ever faster plateau uplift from the Caledonian to the Yanshan period.