宣东矿区下花园组岩矿、煤岩及孢粉组合特征

Petrology,Mineralogy,Lithotype and Palynological Assemblage Characteristics in Xiahuayuan Formation,Xuandong Mining Area,Hebei Province

河北宣东矿区含煤地层为中侏罗统下花园组,含有5个煤组,煤层多,标志层不发育,煤层对比较为困难。钻孔岩、煤心样品的岩矿、煤岩鉴定和孢粉分析等成果资料揭示:①长石砂岩主要赋存于Ⅲ煤组岩段及其以上地层,Ⅴ煤组岩段分布极少;安山岩屑砂岩集中分布在Ⅴ煤组顶底板附近,Ⅲ煤组岩段及其以上岩段未见;泥化安山岩屑砂岩仅分布在Ⅴ煤组岩段的下部;石英砂岩分布在Ⅴ煤组岩段底部与煤系基底地层接触处;鲕状粘土岩仅分布于Ⅴ煤组岩段下部,并常为煤组底板。②Ⅰ、Ⅱ、Ⅲ煤组显微煤岩类型以微镜煤、微亮煤为主;Ⅳ、Ⅴ煤组多为角质微亮煤、微亮暗煤及丝炭微暗煤。③Ⅰ、Ⅱ煤组的裸子植物花粉含量丰富,占孢粉总数的40%～60%;Ⅲ煤组低于Ⅰ、Ⅱ煤组;Ⅴ煤组除克拉梭粉及苏铁粉含量占15%左右外,其它松科花粉少见。该结论可作为矿区岩、煤组(层)划分和对比的依据,对指导煤矿开采生产和邻区的勘查工作具有实际意义。

The coal-bearing strata in the Xuandong mining area,Hebei belong to middle Jurassic Xiahuayuan Formation,contain 5 coal groups,multiple coal seams with undeveloped marker beds,thus difficult coal seams correlation.The borehole rock and coal core samples petrological,mineralogical,lithoype identifications and sporo-pollen analysis information revealed that：① Arkose is mainly hosted in coal group III section and above,very rare in coal group V;andesitic lithic sandstone concentrated near the top and bottom of coal group V,unseen in coal group III section and above;argillized andesitic lithic sandstone only distributed in lower part of coal group V section,quartzose sandstone distributed at the contact between coal group V section bottom and coal measures basement strata,oolitic claystone only distributed in bottom part of coal group V section.② Coal microlithotypes of coal groups I,II and III are mainly vitrite and clarite,IV and V mostly cuticoclarite,clarodurite and fusitodurite.③ Gymnospermous pollens in coal groups I and II are abundant,about 40%～60% in pollen total,in coal group III lower than in I and II,in coal group V except Classopollis and Cycadopites account for about 15%,other Pinaceae pollens are rare.The result can be the basis to divide and correlate rock and coal group（seam） in the mining area and has valuable significance in guidance of coalmine production and neighboring area exploration.