布朗意──蒙索盆地煤相研究

Coal Facies Study in Stephanien Basin of Blanzy-Montceau, France

本文以布郎意－蒙索盆地厚度达４０ｍ的第一煤层为单元，根据煤样光片光泽、色彩及组构划分出八类煤相。用有机岩石学方法及热解分析法详细研究了这些煤相。结果表明该煤层主要为微异地－异地沉积，生源输入以木本植物为主；煤层内部也存在类似煤系地层那样的旋回沉积，其原因推测为泥炭非均一性引起差异压缩；煤相的变化主要由水动力条件及水平面高低引起．这种变化明显影响了显微组合的物理一化学性质，如镜质体反射率、孢子体荧光及煤相的氢指数。该研究还指出了各种沉积环境标志物的可靠性。

The Blanzy-Monctceau coal basin is an intramontaine rift located in North-East of massif centre of France. This paper cleals with the organo-facies in the first coal seam of basin, which is variable both in thickness and in quality.Macroscopically, the seam is largely dominated by clarain. The vertical variations in lustre, brightness and texture on polished section allow to subdivide the sample into many intervals and thus to be classified as coal facies. Eight facies are thus idendified.Detailled analyses have been performed for these coal facies by organic petrology approach and pyrolysis Rock-Eval. Facies A is telocollinite-rich and mineral-poor, contain much inertunte (fusinite) and low to very low percentages of exinite, whereas facies B is vitrinite-rich (telocollinite and desocollinite) and mineral-poor, with median percentages of exinite and low to very low percentages of inertinite. Facies C is vitrinite-rich (phyllovitrinite and desmocollinite) and mineral-poor, with much exinite and low to very low percentage of inertinite. Facies D contain more telocollinite and vitrodetrinite and high percentage of mineral(quartz and clay). Facies E contain more desmocollinite than telocollinite, with median percentage of mineral (pyrite). Facies F contain high percentage of corpocollinite and mineral (clay). Facies G and H is mineralrich, but different in occurrence.Use of the macerals as botanical markers and the texture (particle size, form, psephicity, gradation intensity etc. ) as environment markers allow one to attribute each coal facies to different depositional environment ; on the other hand, consideration of spatial distribution of facies in coal seam allows one to reconstruct the processes of coal formation. This coal seam is majoy allocthnous, with arborecent input.Within the coal seam, it exsists a cyclic deposit constructed by four major facies(facies A,G,B or C), similar to cyclothem present in coal-bearing formation.It is probably due to differential compaction in peat. Variation in coal facies is caused predominantly by water dynamic condition and water level and finally influences the physichemical properties of maceral, such as vitrinite reflectance, exinite fluorescence and hydrogen index of facies.