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内蒙古大青山造山带中存在着一类特殊的岩石类型——极度富铝贫硅的含假蓝宝石尖晶石片麻岩。含假蓝宝石尖晶石片麻岩的岩石学和矿物学的研究表明 ,变晶序列为 Sap+Sil+Gt+Pl+Bi(早期 )→ Sp+Gt+Sil+Pl+Perth+Bi(峰期 )→ Cord+Coru+Mt+Pl+Mic+Bi(峰后 )。利用 Gibbs相律和 Schreinemakers分析方法对该岩系的矿物演化历史进行了理论推导 ,结果表明其与实际矿物的演变历史完全吻合 ,均显示为顺时针的 PT演化路径 ,矿物的演化历史表明 ,该岩系经历了早期的迅速增压 ,峰期的近等压升温和峰期后的降温降压三个演化阶段 ,这样的 PT演化史显示了大青山造山带的碰撞造山历史。该类片麻岩的典型矿物组合 Sap+Gt+Sp+Bi+Sil+Pl表明 ,其曾经历了温度下限为 85 0℃、压力大约为 0 .9GPa的高温高压动力学环境 ,生成于大青山造山带的根部带
There is a special type of rock in the Daqingshan orogen of Inner Mongolia - an extremely rich in aluminum and poor in silicon containing sapphirine spinel gneiss. Petrological and mineralogical studies of sapphirine-bearing gneiss gneisses show that the metamorphic sequences are Sap + Sil + Gt + Pl + Bi (early) → Sp + Gt + Sil + Pl + Perth + Bi ) → Cord + Coru + Mt + Pl + Mic + Bi (post-peak). The Gibbs law and Schreinemakers analysis method are used to deduce the history of mineral evolution of the rock series. The results show that they completely coincide with the evolution history of actual minerals and show the clockwise PT evolution path. The evolution history of the minerals shows that the The rock series experienced three stages of rapid pressurization in the early stage and near-equal-pressure in the peak period. The history of the PT evolution shows the history of the collision of the Daqingshan orogenic belt. The typical mineral assemblage Sap + Gt + Sp + Bi + Sil + Pl of this type of gneiss shows that it has undergone a high-temperature and high-pressure dynamic environment with a temperature lower limit of 85 0 ℃ and a pressure of about 0.9GPa. Orogenic belt root zone