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大别山东段超高压变质带中变质花岗岩富硅、贫钙、贫铝 ,属偏碱性花岗岩 ,围岩为含榴辉岩包体的超高压副片麻岩。变质花岗岩稀土元素总量多在 (10 0～ 2 0 0 )× 10 - 6,具有较大的负铕异常 ,其原岩应为壳源型花岗岩。元素地球化学特征表明变质花岗岩原岩与古造山作用有关。变质花岗岩中存在大量由岩浆型内核和变生型边缘构成的变质增生锆石。结合锆石U Pb年龄资料认为 ,变质花岗岩应由古老花岗岩变质形成 ,而不是超高压变质作用之后部分地壳岩石重熔的产物。岩石中有富锰和贫锰两种石榴子石 ,通过富锰石榴子石 黑云母、贫锰石榴子石 多硅白云母等矿物对的温压计算可知变质花岗岩在 4 0 0～ 5 0 0℃、0 .6～ 0 .8GPa条件下经历过变质作用。但几种间接证据反映出变质花岗岩可能经历过超高压变质作用。
The metamorphic granites in the ultrahigh-pressure metamorphic belt in the eastern part of the Dabie Mountains are rich in silicon, poor in calcium and poor in aluminum, belong to alkaline granites, and are surrounded by eclogite enclaves. The total amount of rare earth elements in the metamorphic granites is more than (10 0 ~ 2 0 0) × 10 - 6, with a large negative Eu anomaly. The original rocks should be crust-derived granites. Elemental geochemical characteristics indicate that metamorphic granite protoliths are related to paleo-orogenic activities. There are a large number of metamorphic and proliferated zircons in the metamorphic granites, which are composed of magmatic cores and metamorphic edges. According to zircon U Pb age data, the metamorphic granites should be formed by the ancient granite metamorphism instead of the partial crustal remelting after the UHP metamorphism. The rocks are rich in manganese and lean manganese two kinds of garnet, through the rich manganese garnet biotite, poor manganese garnet and other silicate mica and other mineral pairs of the temperature and pressure calculation shows that the metamorphic granite in 400 ~ 500 ℃, 0 .6 ~ 0 .8 GPa under the conditions of metamorphism. However, several indirect evidences show that metamorphic granites may have undergone UHP metamorphism.