论文部分内容阅读
大别杂岩中发育麻粒岩相岩石,主要分布在罗田、麻城等地,构成一个高级变质岩区。其中罗田黄土岭的紫苏石榴黑云片麻岩,是大别山具代表性的下地壳岩石露头。它含有较多锆石,目组成不均匀,至少可划分出4种主要类型。应用锆石Pb逐层蒸发法对这一岩石中不同晶形和颜色的锆石进行了9次同位素分析,给出年龄范围为1992～2814 Ma,可划分为晚太古代和古元古代两组。锆石电镜研究揭示了复杂的变质增生特证,因分了原岩锆石和麻粒岩相变质锆石。分别在中国地质大学(武汉)和宜昌地质矿产研究所实验室测定褐黄色自形—半自形锆石,分析结果分别为2811±27 Ma和2814±29 Ma,两者完全一致,也说明测定结果可信度高。这组数据是目前大别山区得到的最大的可信的年龄,可能反映了大别基底或大别古
Dabie complex granulite facies rock development, mainly in Luotian, Macheng and other places, constitute a high-grade metamorphic rock area. Among them, the Perilla pumice garnet biotite gneiss from Loess Plateau is the representative lower crust rock outcrop in the Dabie Mountains. It contains more zircons, head composition is not uniform, at least four major types can be divided into. Nine zircon isotope analyzes of zircons with different crystal forms and colors in this rock were carried out by zircon Pb lead evaporation method. The age range was from 1992 to 2814 Ma, which can be divided into two groups: Late Archean and Paleoproterozoic. Zircon electron microscopy revealed a complex metamorphism and proliferation of special evidence, because of the original rock and granulite zircon metamorphic zircon. The yellow-brown autoroute-authigetic zircons were determined in the laboratories of China University of Geosciences (Wuhan) and Yichang Institute of Geology and Mineral Resources respectively. The results were 2811 ± 27 Ma and 2814 ± 29 Ma, respectively, which were in good agreement with each other The result is credible. This set of data is currently the largest credible age in the Dabie Mountains, probably reflecting the Dabie base or Dabie