中国阿尔泰造山带变质作用PTSt演化和热-构造-片麻岩穹窿形成机制

THE PRESSURE-TEMPERATURE-SPACE-TIMECPTSt EVOLUTION OF METAMORPHISM AND DEVELOPMENT MECHANISM OF THE THERMAL-STRUCTURAL-GNEISS DOMES IN THE CHINESE ALT AIDES

中国阿尔泰造山带中发育了一系列热-构造-片麻岩穹窿(简称 TSG穹窿)。由低级变质区向TSG穹窿中心,发育了绢云母-绿泥 石带、黑云母带、石榴石带、十字石带、蓝晶石(红柱石)带、夕线石- 堇青石(夕线石-石榴石)带、混合岩带、混合花岗片麻岩岩田。递增 变质带、混合岩带、混合花岗片麻岩的形成演化顺序与其由外部向 TSG穹窿中心在空间上的排布序列一致。由黑云母带至混合花岗片 麻岩,变质作用及花岗岩化作用的高峰温度由400℃递增至800℃, 而压力由1.05GPa递减至0.10GPa。造山带变质作用过程可以 用压力-温度-空间-时间模式(PTSt)描述。TSG穹窿是主期造山幕中,沿造山带中一系列区域热动力异常中心,深部热流、构造流上涌,发生递增变质作用、花岗岩化作用以及差异性隆起的过程中形成的。

During the main episode of the Chinese Altaides (Early Carboniferous), progressive metamorphic zones, migmatite zones and migmatitic granitic gneiss fileds developed around and in the regional thermodynamic anomalies in the orogenic belt and constitute a series of thermal domes and gneiss domes. Simultaneously five progressive deformation successions and five relevant deformation zones developed in turn from the outer part to the center of the regional thermodynamic anomalies; they constitute progressive deformation structural domes. The respective progressive metamorphic thermal dome, progressive deformation structural dome and migmatitic granitic dome display consistent and coordinative evolution in space and time and have close genetic relationship and constitute a thermal-structural-gneiss (TSG) trinity dome.The time of the peak of metamorphism of granitization for the progressive me-tamorphic zones, migmatite zones and migmatitic granitic gneiss field are dischron-ous and the succession correspounds to the spatial sequence of metamorphic zones, migmatite zones and migmatitic granitic gneiss fields from the outer part to the center of the regional thermodynamic anomalies.From the outer biotite zone to the migmatitic granitic gneiss field in the center the temperature of the peak of metamorphism and granitization increases successively from 440CCCCCCCCC to 800CCCCCCCCCCCcc, but the pressure decreases from 1.05Gpa to 0.10Gpa.In the main episode of the Chinese Altaides the deep heat flow and structural flow upwelled along the center of the regional thermodynamic anomalies, giving rise to progressive metamorphism, granitization, progressive deformation and the effect of differential uplift and forming TSG domes in the orogenic belt.Orogenic metamorphism is manifested by not only temporal evolution (England and Thompson, 1984) but also tridimensional spatial variation, and both constitute an unified organic process. The author proposes that both time and space, should be considered concurrently in the investigation of orogenic metamorphism, and thus a pressure-temperature-space-time (PTSt) model will be constructed.