机构地区:[1]西安科技大学地质与环境学院,陕西西安710054 [2]中国矿业大学(北京)地球科学与测绘工程学院,北京100083 [3]湖南省煤炭地质勘查院,湖南长沙410014
出 处:《煤炭学报》2019年第7期2206-2215,共10页Journal of China Coal Society
基 金:国家自然科学基金资助项目(41502160);中国博士后科学基金资助项目(2016M592907XB)
摘 要:煤对应力、应变和温度十分敏感,在多期次、多层次的构造-热运动下必然会留下各种应力作用(静压力和构造应力)痕迹。采用工业分析、元素分析、XRD,SEM及ICP-MS等方法,探讨了新化中生代天龙山岩体侵位对煤系变形变质、煤结构变化的构造效应以及元素迁移富集的应力-应变环境响应。研究结果表明:天龙山岩体侵位引起的岩浆热及构造应力作用,促进煤化程度升高逐渐转变为隐晶质石墨,煤及围岩出现大量热变质矿物;岩体侵位施加放射状挤压应力集中带,节理与岩组主压应力轴方位与岩体边界近于垂直,靠近岩体构造变形增强;构造应力与岩浆热变质叠加作用对煤的大分子结构影响显著,d002值、La/Lc分别随变质程度降低及远离岩体而减小。岩体附近煤层受岩浆热作用显著,岩浆侵位的构造效应(机械能、热能及化学能)造成煤岩结构破坏、变质程度升高以及元素富集、迁移,煤中REE含量增加;稀土元素球粒陨石标准化分配模式曲线特征可划分为3种类型,其中A型与C1型靠近岩体叠加了岩浆热变质作用,与泥盆纪灰岩及硅化灰岩稀土元素分配模式曲线相似,岩浆热液使围岩矿化,但局限于蚀变带。岩浆热变质作用驱使稀土元素向富轻稀土方向演化,构造应力驱使稀土元素向着富重稀土的方向演化,导致ΣL/ΣH比值偏低。Coal is sensitive to stress,strain and temperature.Under the multi-stage and multi-layer tectonic-thermal movement,there will inevitably be various traces of stress (static pressure and structural stress).This paper discusses the effect of intrusion of the Tianlongshan granite body on coal seam deformation and metamorphism,molecular structure,trace elements migration and aggregation in detail by proximate and ultimate analysis,XRD,SEM,ICP-MS methods.The results show that the coal turned itself into aphanitic graphite with the increase of coalification degree under the local stress field which was caused by Tianlongshan granite body intrusion and magmatic hydrothermalism,and the large quantities of thermal metamorphic minerals appeared in the coals and surround rock.Radial compressive stress concentration zone was applied to the rock mass emplacement,σ1orientation of joint and petrofabric was perpendicular to the granite body boundary,under the ductile-brittle deformation with low temperature,low stress,and high strain rate.The superposition of tectonic stress and magmatic thermal metamorphism had a significant effect on the macromolecular structure of the coals,and the value of d 002 and L a/ L c reduction with the decrease of metamorphism degree and away from the magmatic intrusion,respectively.The coal seam near the granite body was obviously affected by magmatic heat.Structural effects of magmatic intrusion (mechanical energy,thermal energy and chemical energy) caused structural damage to coal petrography,the increase of metamorphism degree,and element enrichment and migration,REE content obviously increased,chondrite-normalized REE patterns could be divided into three types,Type A and C1superimposed magmatic thermal metamorphism near the rock mass,similar to the distribution pattern curve of rare earth elements in Devonian limestone and silicified limestone.Magmatic hydrothermal fluid mineralized the surrounding rock,but was limited to the alteration zone.The magmatic thermal metamorphism led to an enrichmen
关 键 词:天龙山岩体 煤系变形变质 X射线衍射分析 稀土元素 构造效应
分 类 号:P55[天文地球—构造地质学]
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