论文部分内容阅读
首次测定扬子板块西缘古老的结晶基底岩石沙坝麻粒岩Sm Nd矿物等时线年龄为 114 0± 110Ma ,代表中元古代末期麻粒岩相变质作用时代。Rb -Sr矿物等时线年龄为 2 18± 11Ma ,可能为晚古生代至早中生代基性岩浆侵入的热扰动改造年龄。其亏损地幔模式年龄TDM 为115 8Ma ,表明沙坝麻粒岩的原岩在成岩之后不久即经受麻粒岩相变质作用。根据上述年龄以及紫苏辉石中Nd同位素封闭温度和40 Ar/ 3 9Ar年龄等资料的计算表明 ,以沙坝麻粒岩为代表的下地壳岩石抬升运动速率是缓慢的
For the first time, the Sm Nd mineralogy of the ancient crystalline basement rock in the western margin of the Yangtze plate was determined to be 114 0 ± 110 Ma, representing the age of the Mesoproterozoic granulite facies metamorphism. The isochron age of Rb-Sr mineral is 2 18 ± 11Ma, which may be the age of thermal perturbation transformation from Late Paleozoic to Early Mesozoic basic magmatic intrusion. The depleted mantle model age TDM is 115 8Ma, indicating that the protolith of the Shaba granulite underwent granulite facies metamorphism shortly after diagenesis. Based on these ages and the calculations of Nd isotope closure temperature and age of 40 Ar / 3 9Ar in periclase, it shows that the rate of uplift movement of the lower crust, represented by the Shaba granulite, is slow