湖南寒婆坳矿区煤层夹矸的岩石矿物特征及其地质意义  

Mineral characteristics and geological significance of coal gangue in Hanpoao Coal Mining Area,Hunan Province

作　　者：李焕同[1,2] 张卫国 王楠[1] 潘彦宁 陈应涛 LI Huantong;ZHANG Weiguo;WANG Nan;PAN Yanning;CHEN Yingtao(College of Geology and Environment,Xi’an University of Science and Technology,Xi’an 710054,China;Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation,Xi’an 710054,China)

机构地区：[1]西安科技大学地质与环境学院,陕西西安710054 [2]陕西省煤炭绿色开发地质保障重点实验室,陕西西安710054

出　　处：《煤炭科学技术》2022年第4期206-212,共7页Coal Science and Technology

基　　金：国家自然科学基金资助项目(41502160,41802187);陕西省自然科学基础研究计划资助项目(2019JM-126)。

摘　　要：煤变质程度升高和煤层夹矸中矿物的转化与周围变形环境变化密切相关,利用偏光显微镜、X射线衍射(XRD)等测试手段,对湖南寒坡坳矿区煤层夹矸的岩石矿物学特征、伊利石结晶度等进行了研究,并探讨了黏土矿物特征直接或间接指示煤变质程度,以及对温度、压力等变化的响应。结果表明:黏土矿物这一层状结构硅酸盐矿物对研究区变形环境变化反应十分敏感,煤层夹矸中红柱石(空晶石)与伊利石、叶蜡石和绿泥石等共生,伊利石结晶度高,结晶度分布于0.14060°~0.09090°△2θ,平均晶层厚度(L_(c))大于566×10^(-1) nm;利用伊利石(001)峰面积、半高宽分别与不规则部分γ峰的面积和半高宽的比值,伊利石结晶有序度显示与煤有机结构演化一致的特征;镜质体反射率和拉曼光谱地质温度计揭示煤系石墨形成的变质温度为400~500℃或更高,指示研究区煤层遭受低级浅变质作用,煤层夹矸中伊利石为2M_(1)多型,b_(0)分布于8.8836~9.0305×10^(-1) nm,指示煤层及围岩遭受低中压的变形环境,形成的压力条件在250~400 MPa或更高;依据不同变质程度煤的XRD结构参数随形成温度的变化,显示较高的受热条件是有机质演化和夹矸中矿物转变的重要因素,但是相近温度变化区间内煤中有机质结构单元面网间距(d_(002))持续减小,指示着地质过程强烈的构造应力能明显催化石墨化进程。The increase of coal metamorphism and the transformation of minerals in the gangue are closely related to the change of the sur⁃rounding deformation environment.The mineralogy characteristics and illite crystallinity of coal gangue in Hanpoao Coal Mining Area of Hu⁃nan Province were studied by means of polarizing microscope and X-ray diffraction(XRD).The characteristics of clay minerals directly or indirectly indicate the degree of coal metamorphism and its response to temperature and pressure changes were discussed.The results show that the clay mineral,a layered silicate mineral,is very sensitive to the change of deformation environment in the study area.The andalusite(chiastolite)in the coal seam is symbiosis with illite,phyllite and chlorite,etc.The crystallinity of illite is high,and the crystal⁃linity is distributed in 0.1406°~0.0909°△2θ,the average crystal thickness(L_(c))is greater than 566×10^(-1)nm.The crystalline order de⁃gree of illite was consistent with the organic structural evolution,compared with the peak area,half height and width of illite(001)and theγpeak of irregular part.Vitrinite reflectance and Raman spectra of coal geological thermometer revealed graphite formation of the metamor⁃phic temperature of 400~500℃or higher,indicating the study area of coal seam by low-level epimetamorphism,illite in coal gangue is more than 2M_(1) model,b_(0) distributed in 8.8836~9.0305×10^(-1)nm,indicates the deformation environment of coal seam and surrounding rock under low and medium pressure,the pressure conditions formed are 250~400 MPa or higher.According to the change of XRD struc⁃ture parameters of coal with different metamorphism degree with formation temperature,it shows that higher heating condition is an impor⁃tant factor of organic matter evolution and mineral transformation in gangue.However,the d_(002)spacing of organic matter structural basic u⁃nits in coal continues to decrease in the range of similar temperature changes,indicating that the strong tectonic stress in

关 键 词：湖南寒坡坳矿区 煤层夹矸 矿物特征 伊利石 煤系石墨 

分 类 号：P571[天文地球—矿物学] P611.2[天文地球—地质学]