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湖北黄冈黄土岭麻粒岩的矿物组合为斜方辉石(Ⅰ)+石榴子石+斜长石(Ⅰ)+石英。在石榴子石的边部出现堇青石+斜方辉石(Ⅱ)组成的冠状体,它揭示曾发生如下变质反应:石榴子石±石英→英青石+斜方辉石(Ⅱ)。温压估计结果表明,麻粒岩的形成温压分别为857~998℃和1.18~1.23GPa;而堇青石+斜方辉石(Ⅱ)冠状体的形成温压分别为829~911℃和0.53~0.59GPa。上述结果显示麻粒岩形成后大别杂岩曾发生一次近绝热的快速隆升减压退变过程。该地麻粒岩的温压条件与Harley(1989)给出的世界90个麻粒岩产地的温压条件相比属于高压类型[1],代表该岩石曾达40km以上的下地壳深度。
The mineral assemblage of the Huangtuling granulite in Huanggang, Hubei province is orthopyroxene (Ⅰ) + garnet + plagioclase (Ⅰ) + quartz. A corolla of cordierite + orthopyroxene (II) appears on the edge of garnet, revealing the following metamorphic reactions: garnet + quartz + quartz + ettringite (II). The temperature and pressure estimation results show that the temperature and pressure of granulite formation are 857-998 ℃ and 1.18-1.23GPa, respectively. The formation pressure of cordierite and orthopyroxene (Ⅱ) is about 829-911 ℃ and 0.53 ~ 0.59GPa. The above results show that a nearly adiabatic rapid uplift and depressurization process occurred in the Dabie complex after the granulite was formed. The temperature and pressure conditions of this granulite are high pressure type compared with the temperature and pressure conditions of 90 granulite producing areas in the world given by Harley (1989) [1], which represent the lower crust depth where the rock has reached over 40 km.