论文部分内容阅读
中缅边界首次发现的麻粒岩相变质基性岩经历了两期变质作用的改造，依据共生矿物组合和矿物电子探针分析判定早期的变质作用的压力下限是０．８～１．０ＧＰａ，温度是７５０℃～８６０℃，为麻粒岩相变质作用；后期变质作用的温压是０．５９～０．８０ＧＰａ、６５０℃～７２０℃，为高角闪岩相变质作用。变质作用ＰＴ演化轨迹呈现降温减压的特点，指示俯冲作用和碰撞造山作用的大地构造背景。区域地质背景显示变质基性岩的早期变质作用与密支那古洋壳俯冲作用有关。构造分析得出后期的变质变形作用与研究区约２３．０８～０．６３Ｍａ前后的右行逆冲走滑剪切作用有关，是俯冲带上驮板片前缘强烈抬升的记录。那邦麻粒岩相变质岩的发现对滇西腾冲地块大地构造属性的研究、与密支那缝合带相关的板片俯冲、俯冲板片的裂离、俯冲带上驮板片前缘的抬升和变形研究具有重要意义。
The granulite-facies metamorphic metamorphic rocks first discovered on the Sino-Burmese boundary have undergone two alterations of metamorphism. The lower pressure limit of early metamorphism determined by symbiotic mineral assemblages and mineral electronic probe analysis is 0.8-1.0 GPa, The temperature is 750 ℃ ~ 860 ℃, for the granulite facies metamorphism; Late metamorphism temperature pressure is 0.59 ~ 0.80GPa, 650 ℃ ~ 720 ℃, is amphibolite facies metamorphism. The metamorphic PT evolutionary trajectory shows the features of cooling and depressurization, tectonic setting indicating the tectonic subduction and collision orogeny. The regional geological background shows that the early metamorphism of metamorphic basic rocks is related to the subduction of the Myzotonian oceanic crust. The tectonic analysis shows that the metamorphism and deformation of late stage are related to the right-lateral thrust strike-slip shear before and after about 23.08 ~ 0.63 Ma in the study area, which is a record of intense uplift of the front plate of the delamination belt. The discovery of Na Bang granulite facies metamorphism of the tectonic attribute of the Tengchong block in western Yunnan, the subduction of the plate associated with the Myintina suture, the detachment of the subducting slab, the uplifting of the leading edge of the subducting belt And deformation research is of great significance.