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石榴辉石麻粒岩主要产在北大别 ,以团块状 ,沿铁镁质超基性岩块走势分布。它们的主要矿物成分由石榴石、透辉石、紫苏辉石、斜长石等组成 ,在石榴石边部分别形成角闪石 +斜长石 ,紫苏辉石 +斜长石或透辉石 +斜长石后成合晶结构。通过矿物温度压力计计算 ,高峰期变质温度 740℃～ 890℃ ,压力 0 .8～ 1.5 2 GPa ;退变质期温度 70 0℃～ 86 2℃ ,压力 0 .6 9～0 .79GPa,表明石榴辉石麻粒岩 PT轨迹为等温降压顺时针轨迹。通过主量元素 D(X)函数及有关图解判别 ,表明原岩相当基性火成岩或火山岩。稀土元素 ,微量元素地球化学特征显示上述岩石具有大洋中脊拉斑玄武岩及岛弧、火山弧玄武岩元素分布特征。将 REE数据投影到 (L a/ Sm) - L a关系图中 ,投影点沿部分熔融斜线分布 ,提示原岩岩浆是地幔岩部分熔融产物。本区石榴辉石麻粒岩 ,位于大别山北部 ,华北 -扬子板块俯冲 -碰撞结合部 ,根据上述岩石形成的温压条件 ,表明是在板块碰撞过程产生挤压 ,地壳增厚 ,高压麻粒岩相条件下形成的
Garnet pyroxene granulite is mainly produced in the North Dabie, with clumps, along the trend of the distribution of iron magnesian ultrabasic rocks. Their main mineral components from garnet, diopside, peridotite, plagioclase and other components, respectively, in the edge of the garnet formed amphibole + plagioclase, peridotite + plagioclase or huihui Stone + plagioclase after into the crystal structure. Through the calculation of mineral temperature and pressure gauge, the peak metamorphic temperature is 740 ℃ ~ 890 ℃ and the pressure is 0.8 ~ 1.5 2 GPa; the degenerative temperature is 70 ℃ ~ 86 ℃ and the pressure is 0.69 ~ 0.79GPa, Pyroxenite PT trajectory is isothermal buck clockwise trajectory. By the main element D (X) function and the relevant graphic judgment, that the original rock rather basic igneous or volcanic rocks. The REE and trace element geochemical characteristics show that these rocks have the features of mid-ocean ridge mottled basalt, island arc and volcanic arc basalts. The REE data are projected onto the (L a / Sm) - L a diagram, and the projection points are partially distributed along the melting slope, suggesting that the protolith magma is a partial melting product of mantle rocks. In this area, garnet pyroxene granulites are located in the northern part of the Dabie Mountains and the North China-Yangtze Plate subduction-collision combination. According to the temperature and pressure conditions of the above rocks, it is indicated that crustal granulite is crushed during plate collision, crustal thickening and high-pressure granulite Formed under the conditions