Abstract:Many large and medium crystalline graphite deposits have been found in Northwestern Hebei Province, with good metallogenic geological conditions and prospecting potential of regional metamorphic graphite deposits. Taipingzhuang Formation and Dongjingzi Formation of the Hongqiyingzi Group and Xiabaiyao Formation of the Jining Group in the Paleoproterozoic are important metallogenic horizons in this area. This paper has carried out a detailed petrographic and geochemical study of these ore-bearing strata, and discussed the metallogenetic mechanism of graphite deposits. The research results show that the ore-bearing rock of the Hongqiyingzi Group is graphite garnet biotite plagiogneiss, and the original rock is mainly composed of mudstone, clay sandstone, sandstone and carbonate rock, which are locally rich in organic matter, indicating that the maturity of the carboniferous rocks is generally higher, and the clastic rocks have been deposited in the marine-continental interaction and shallow marine facies under the warm humid and semi-dry climate. The ore-bearing rock of Xiabaiyao Formation of the Jining Group is graphite garnet plagioclase granulite, and the proto-rock is mainly composed of mudstone, clay sandstone, sandstone and quartz sandstone with higher maturity of littoral-shallow sea-inland lacustrine sedimentary facies, and are locally rich in organic matter, and formed in the oxidation-weak oxidation sedimentary environment under the semi-dry and dry climate, accompanied by hot water in the deposition process. The carbonaceous components of graphite ore were all derived from the original organic carbon deposited in the original rock itself. The deposit was controlled by horizon, lithofacies and lithology. Through regional metamorphism, organic carbon crystallized to form graphite ore, which was exposed to the surface or near the surface under the control of faults.