Dynamics and genetic grids of sapphirine-bearing spinel gneiss in Daqing Mountain orogen zone, Inner Mongolia.

• Main Authors: Liu, JZ, Qiang, XK, Liu, XS, Ouyang, ZY
• Format: Article in Journal/Newspaper
• Language: Chinese
• Published: SCIENCE PRESS 2000
• Subjects: sapphirine; spinel; Daqing Mountain; orogen zone; Geology; HIGH-PRESSURE GRANULITE; ORTHO-PYROXENE; ENDERBY LAND; METAMORPHIC EVOLUTION; ANTARCTICA; GARNET; QUARTZ; STABILITY; HISTORY; COMPLEX; Antarc*; Antarctica; Enderby Land
• Online Access: http://ir.ieecas.cn/handle/361006/11966

A special kind of rock which is sapphirine-bearing spinel gneiss from Daqing Mountain orogen tenet Inner Mongolia has been reported. This kind of rock is characterised by abundant AI-rich minerals and its chemical composition is alumina-rich and silica-undersatuated. The study of metamorphic minerals and crystalloblastic sequences indicates that evolution of crystalloblastic sequences in typical mineral assemblages of sapphirine-bearing spinel gneiss is Sap + Sil + Gt + Pl + Bi --> Sp + Gt + Sil + Pl + Perth + Bi --> Cord + Coru + Mt + Pl + Mic + Bi. By means of genetic grids,the crystalloblastic sequence of the main minerals assemblages in rock is inferred theoretically. The result is well consistent to the actual assemblages. According to crystalloblastic sequence and characteristics of assemblages formation of different stages of mineral development in rock, a clockwise P-T-t path is set up by studying genetic grids. The model of metamorphism is interpreted as follows: in the early stage of orogenics, the crust was thickened rapidly leading to pressure increase to peak and then crust was heated near isodar and temperature reached to peak condition, at last. Crust was lifted up and P-T fell down. In the course of oregenics sapphirine-bearing spinel gneiss wes formed in orogen root zone. The dynamic conditions are P>0. 85GPa, T>850 degrees C.