焦作地区太原组层状硅质岩中叶蜡石的发现及其成因意义  

DISCOVERY AND ITS GENETIC SIGNIFICANCE OF PYROPHYLLITE IN THE BEDDED SILICEOUS ROCKS OF THE TAIYUAN FORMATION IN JIAOZUO AREA

作　　者：曹高社[1,2] 徐光明[1] 周红春[3] 杜忠[1] 张松[1] 

机构地区：[1]河南理工大学资源环境学院,河南焦作454000 [2]中原经济区煤层(页岩)气河南省协同创新中心,河南焦作454000 [3]河南省地质矿产勘查开发局第四地质勘查院,河南郑州450001

出　　处：《矿物岩石》2015年第4期43-50,共8页Mineralogy and Petrology

基　　金：全国油气资源战略选区调查与评价(1211302108023-2);两权价款项目(20111-36-8)

摘　　要：焦作地区太原组层状硅质岩中新发现了叶蜡石矿物,该矿物具有典型叶蜡石的光性特征,X衍射图谱中,叶蜡石的主要特征峰d0020.917nm、d0040.459nm、d0060.306nm清晰存在,主、次、第三峰对应良好。差热图谱中,具有叶蜡石脱羟基的典型吸热谷726℃,760℃。岩石薄片和扫描电镜分析表明,叶蜡石赋存在具有两组方向的微裂隙中,[001]面平行于微裂隙的边部,含量达20%。对硅质岩准同生变形分析和沉积期表生地球化学分析表明,叶蜡石是在硅质岩原岩硅化作用的晚期,由火山灰水解产生的Al_2O_3胶体和体系外部提供的H_4SiO_4胶体一同进入到由地震冲击荷载造成的微裂隙中经过合成作用形成的,所需要的温度由地震滑动产生的能量提供,所必需的还原和酸性环境由层状硅质岩的原岩当时的沉积环境提供。华北陆块太原组底部普遍存在有火山灰沉积作用和冲击荷载反映的地震作用,共同揭示了太原组沉积时期可能伴随着一个大的构造事件,这一构造事件可能是潘吉亚大陆形成的响应。Pyrophyllite in the bedded siliceous rocks of the Taiyuan Formation in Jiaozuo area has typical optical feature of pyrophyllite. X-ray diffraction pattern show that the peak d0020. 917 nm,d0040. 459 nm,d0060. 306 nm is in accordance with the main characteristic peaks of pyrophyllite. Differential thermal spectrum yields 726 ℃ and 760 ℃ heat-absorption valley which represents typical pyrophyllite dehydroxylation. Al2O3 colloid derived from the hydrolysis of volcanic ash and the H4 SiO4 colloid from the external system at the end of the protolith silicification of silicalite. The necessary temperature of the formation of pyrophyllite was provided by the energy produced by earthquake slip. Meanwhile, the essential reductive and acidic condition for forming pyrophyllite was supplied by the sedimentary environment of protolith of the siliceous rocks. The widespread deposition of volcanic ash and seismicity reflected by shock load at the period of the Taiyuan Formation sedimentation in the North china Block possibly reveals an important tectonic event,which is correspond to the formation of Pangaea.

关 键 词：太原组 硅质岩 叶蜡石 火山灰 

分 类 号：P571[天文地球—矿物学] P542[天文地球—地质学]