An Early Stage Faulting Along the Altun Mountain Range——Microstructural Evidences  

作　　者：Liu Junlai, Pan Hongxun, Ye Huiwen, Ge Xiaohong and Liu Yongjiang (Changchun Univ. Sci & Tech., 130026, Changchun, China) 

出　　处：《Global Geology》1999年第2期160-165,共6页世界地质（英文版）

基　　金：FoundedbyNSFCNo .49772157&No .49872071

摘　　要：Structural, microstructural analysis is done on the Altun fault zo ne and fault rocks. The major characteristics of faulting are summarized. Micros tructural observation reveals a complicated evolution of the fault zone. Much at tention is paid to the microstructural observation and dynamic analysis of fault ing. The occurrence of phengite grains suggest abnormally high pressure conditio ns during ductile deformation and metamorphism, while the occurrence of muscovit e-chlorite mineral assemblage suggest a low temperature and low pressure condit i on. Micro-component analysis on the inter-grown muscovite and chlorite grains gives similar information. It is concluded that the first deformation along the Altun fault zone is a type of ductile shearing, forming mylonites and mylonitic rocks along the fault zone. A post-Jurassic deformation is primarily suggested by the involvement of the l atest tectonic units (Jurassic) in the ductile deformation.The early tectonic ev ent involves deformation and metamorphism under conditions in the upper crust, w ith T-P conditions varying to a large extent (T-270℃ ～350℃; P-0.005GPa～0. 43GPa), which may be attributed to the extra tectonic stresses.Structural, microstructural analysis is done on the Altun fault zo ne and fault rocks. The major characteristics of faulting are summarized. Micros tructural observation reveals a complicated evolution of the fault zone. Much at tention is paid to the microstructural observation and dynamic analysis of fault ing. The occurrence of phengite grains suggest abnormally high pressure conditio ns during ductile deformation and metamorphism, while the occurrence of muscovit e-chlorite mineral assemblage suggest a low temperature and low pressure condit i on. Micro-component analysis on the inter-grown muscovite and chlorite grains gives similar information. It is concluded that the first deformation along the Altun fault zone is a type of ductile shearing, forming mylonites and mylonitic rocks along the fault zone. A post-Jurassic deformation is primarily suggested by the involvement of the l atest tectonic units (Jurassic) in the ductile deformation.The early tectonic ev ent involves deformation and metamorphism under conditions in the upper crust, w ith T-P conditions varying to a large extent (T-270℃ ～350℃; P-0.005GPa～0. 43GPa), which may be attributed to the extra tectonic stresses.

关 键 词：the Altun fault zone MYLONITES DUCTILE deformation T -P conditions 

分 类 号：P534[天文地球—古生物学与地层学]