Study On The Characteristics Of Jurassic Coal In Ordos Basin

Based on the analysis on a large number of coal data in the North China, especially the study on the characteristics of coal from the Jurassic coal beds in the Ordos basin, the data collection and the micro-characteristics observation of coal, the coal characteristics have been known well and the comparative study has been carried out between the coal samples from the Ordos basin and the Huainan coalfield.The sedimentary condition of Jurassic in the Ordos is terrestrial facies, mainly developing fluvial facies, lake delta facies and so on. In this thesis, the sedimentation features and the coal gathering laws of the Jurassic Yan’an formation of the Xiyuanlingwu area, Ordos basin. have been taken as an example to elaborate the sedimentation conditions and the coal gathering features. There exist great differences in the coal macro-features, the micro-features and the distribution laws between the samples from Jurassic coal of Ordos basin and the Permian coal of Huainan coalfield.In the Jurassic coal of Ordos basin, the macroscopic maceral is mainly fusite, the bright coal and glossy coal take the second place, and anthraxylon the least; semi-splint coal and dull coal are the main Micro-features and the semibright coal and glossy coal are less. Concerning the macerals, inertinite content is more than vitrinite content. Vitrinite content in the mining sites of Jurassic coal, Ordos basin, is between the 32%—60% and its high value ( >90% ) only occurs in certain mining sites(RujiGou of Ningxia, Huating of Gansu and so on). Inorganic substances are mainly clay minerals, commonly the calcite, carbonate minerals, sideritic kernels or their combination and rarely pyrite.In the Permian coal beds of Huainan coalfield, the macroscopic maceral is mainly bright coal and glossy coal, a little bit of anthraxylon bands and fusite. The macroscopic coal types are mainly semi-splint coal and the semibright coal. The main reasons of their differences are the different micro-contents resulted by their different sedimentation environments and coal gathering periods. The Jurassic coal of Ordos basin develops mainly in the inland lake detla—fluvial facies, which belongs to the Oxidizing environment with low extent of water cover. During the sedimentation of Permian period, it is the epeiric sea, the transitional facies of terrestrial and marine which is reducing—weak reducing environment.