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太古界集宁群地层在研究区广泛分布,西起内蒙的卓资、和林格尔经集宁、兴和南延入山西大同、阳高,东延至河北省的怀安县一带,构成一个走向为北东的大复背斜,其核部位于大同北—葛胡窑—马市口一带,麻粒岩十分发育。本区区域变质作用上部P—T界限约为800-900℃,11—13千巴,埋藏深度相当于38—44公里,地热梯度21—20℃/公里,属中压相系的麻粒岩。本文试图在野外工作基础上,通过室内岩相学和岩石化学等方面的研究,对本区变质岩系的原岩进行恢复,并对其地球化学特征作了初步的探讨。
The Archean Jijiing Group strata are widely distributed in the study area. From west Zhumenzi in Inner Mongolia and Linglin Passing Jining and Xinghe South to Huai’an County in Shanxi Datong, Yanggao and East China, forming a trend For the North East anticline, its core is located in Datong North - Gehu kiln - Ma Shikou area, granulite is well developed. The upper P-T boundary of the metamorphism in this area is about 800-900 ℃ and 11-13kpa, the burial depth is equivalent to 38-44km and the geothermal gradient is 21-20 ℃ / km. It belongs to the middle-pressure facies granulite . Based on the field work, this paper attempts to recover the original rocks of the metamorphic rocks in this area through the study of indoor petrography and petrochemistry, and makes a preliminary study of their geochemical characteristics.