摘要
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。
Widely developed in the Dabie complex are various disequilibrium textures which provide direct evidence for the evolution of metamorphism and late-stage uplifting history. The typical mineral assemblage in the Opx-Gt-Pl-Bi gneiss in Huangtuling, Huanggang County, HubeiProvince, is Opx (Ⅰ ) +Gt+Pl (Ⅰ ) +Bi (Ⅰ ) +Q. The corona composed of cordierite and orthopy-roxene (Ⅱ ) growing around garnets in the granulite makes it clear that there occurred the follow-ing metamorphic reaction: Gt+Q→Cd+Opx (Ⅱ ). It is estimated that the granulite-froming tem-perature (t) and pressure (p ) are 857-998℃ and 1. 18- 1. 23GPa, respectively, and the corona was formed under the following conditi0ns: t= 829- 911℃ and p =0. 53-0. 59GPa. The above re-sults indicate that there occurred a rapid and nearly adiabatic uplifting event and a decompressional metamorphism in the Dabie complex aftcr the formation of granulite. As compared with the gran-ulites worldwidely distributed in 90 locations (Harley, 1989), the Huangtuling granulite should belong to the high-pressure type, which is formed in the lower crust at a depth of more Yhan 40 kilometers.
出处
《矿物学报》
CAS
CSCD
北大核心
1996年第2期118-125,共8页
Acta Mineralogica Sinica
基金
国家自然科学基金!49472134
关键词
冠状体结构
麻粒岩
湖北
地质意义
corona texture
granulite
pressure (p) -temperature (t) vector
decompressional reaction
Dabie complex
