黔西地区晚二叠世煤层变质规律及机理研究

Pattern and mechanism of metamorphism of late permian coal in western Guizhou

在煤镜质组反射率测试的基础上,结合大量的煤田勘探资料分析,总结了黔西地区晚二叠世煤层变质规律,综合区域构造演化背景、野外地质、微观构造和流体包裹体测试分析对煤层变质机理进行了深入探讨。研究结果表明:黔西地区晚二叠世煤层煤种齐全,变质程度普遍偏高,整体上具有南北高中间低、东部高西部低的特点,分别以盘关向斜和水城两个低变质区域为中心向四周递增;黔西地区晚二叠世煤层深成变质作用是其主控类型,J3-K1期间叠加了区域岩浆热变质作用,燕山运动作用下形成的不同的构造形态决定了煤层的不同的埋藏深度,进而决定了煤层的变质程度,水城-紫云断裂等深大断裂只是形成于上地壳的脆性变形构造,并且处于强烈的挤压应力场中,并非岩浆侵入通道,岩浆侵入煤系促进煤层变质只存在于局部地区。

Based on the test of coal vitrinite reflectivity,combined with abundant data of exploration,the pattern and mechanism of metamorphism of late permian coal seam in western Guizhou was summarized.Through the compositive analysis of the tectonic evolution background,the observation of field geology,the microstructures and the test of fluid inclusion,the metamorphism mechanism of coal in western Guizhou was deeply discussed.The research results indicate that the coal rank is complete in western Guizhou coalfield,the metamorphic grade is generally higher and characterized by north-south higher,middle lower and west higher,east lower,and increasing outward around the two lower grade areas,Panguan syncline and Shuicheng;the plutonic metamorphism is the main type to the late permian coal seam,and the rank raises by the regional magmatic thermal metamorphism in J3-K1,the structure formed in Yanshan movement decides the buried depth and further controlled the metamorphic grade of coal,and metamorphism pattern is established in western Guizhou.The discordogenic faults such as Shuicheng-Ziyun fault are ductile deformation of the upper crust and in compressional stress field,so they are not the channel of magma except sporadic areas.