信阳-舒城断裂带西段石榴云母片岩中石榴石的矿物学特征及其构造意义

桐柏山地区信阳-舒城断裂带西段石榴云母片岩中石榴石变斑晶保留了较多岩石形成过程中的变形-变质信息,它真实地反映了中国南北两大板块缝合带的形成条件和演化历史.石榴石探针成分分析结果表明其属于铁铝榴石,反映出经受中级区域变质作用的特征.在Nadi石榴石成分与变质带的关系图上主要投影在略偏石榴石带的蓝晶石带内,显示岩石遭受了...

Mineralogy feature and tectonic significance of garnet from garnet-mica schist at the west section of Xinyang-Shucheng fault belt

At the western part of the Xinyang Shucheng fault of Tongbai Mountain，garnet porphyroblast in garnet mica schist retained many deformation and metamorphic information during the process of rock formation.It is a true reflection of formation conditions and evolution history of plate suture zone of Chinas two major plates.Garnet microprobe analysis shows that it belongs to almandine，and reflects it had experienced mid level regional metamorphism.In Nadi garnet composition and metamorphic belt diagram，it majorly falls in kyanite belt with clients tends to garnet belt，showing that the rock had suffered epidote amphibolite facies amphibolite facies metamorphism.Compositional zoning of garnet shows that the rocks had experienced progressive metamorphism.First metamorphic environment was continuous temperature pressure，and in mid term there were two non synchronous transient cooling and decompression process，and finally underwent decompression and warming process of the thermal relaxation environment，not subjected to significant retrograde metamorphism.Dislocations of garnet observed through TEM are mainly edge dislocations and dislocation walls.Free dislocation density ρ=614×108/cm2，these dislocation features show a plastic deformation in medium temperature conditions.Formation conditions of garnet mica schist is estimated：temperature is 562 ℃～617 ℃，and the pressure is （077～102） GPa.