黔西威宁岔河陆相二叠系—三叠系界线粘土岩研究——基于X射线衍射、扫描电镜分析  

CLAYROCKS OF THE TERRESTRIAL PERMIAN-TRIASSIC BOU- NDARY OF CHAHE SECTION,WEINING,WESTERN GUIZHOU PROVINCE,SOUTH CHINA∶BASED ON X-RAY DIFFRACTION AND SCAN ELECTRONIC MICROSCOPE

作　　者：张素新[1] 彭元桥[1] 喻建新[1] 杨逢清[1] 殷鸿福[1] 史玉芳[1] 

机构地区：[1]中国地质大学地球科学学院,湖北武汉430074

出　　处：《地质科技情报》2004年第1期21-26,共6页Geological Science and Technology Information

基　　金：国家自然科学基金资助项目(40172012;40232025);中国地质调查局宜昌地层中心项目(200113900072)

摘　　要：利用X射线衍射、扫描电镜等分析方法,对黔西威宁岔河陆相剖面二叠系—三叠系界线附近的粘土岩进行了研究。在界线粘土岩中,粘土矿物组合为伊—蒙混层矿物+蒙脱石+绿泥石;碎屑物质中有六方双锥石英和锆石,无球粒;多种化学成分在界线粘土岩中出现了异常。据此得出岔河剖面的二叠系—三叠系事件地层界线确定在第66f层比较合适;第66f和68a这两层粘土岩为此剖面的界线粘土岩;自第66f层底部至第68a层顶部这一段地层为二叠系—三叠系的界线层(组);界线粘土岩的成因可能是由于火山喷发、火山灰降落伴随正常沉积物沉积形成的。Applying the concept of the Permian-Triassic Boundary Stratigraphic Set (PTBST) to the non-marine Permian-Triassic boundary (PTB) sections in Western Guizhou Province, South China, we have found that the clayrocks of the PTB in these sections have the same origin and exhibit a remarkably similar vertical succession to similar rocks found at the marine Permian-Triassic boundary of the Meishan Section. The X-ray diffraction and scan electronic microscope studies of some clays and/or mudstones from the Chahe Section, indicate that the composition of the clays in the PTBST (beds 66f-68a) is very different from that of the clays found either under or above the PTBST beds of the same section. The clay minerals in the clayrocks of the PTBST are mainly composed of illite-montmorillonite interlayers, with few montmorillonites and chlorites. Whereas the other clayrocks and/or mudstones underlying and overlying the PTBST are made of chlorites and/or kaolinites. Some special mineral contents, such as hexagonal dipyramid quartz, zircons and few spherules, and the abnormal contents of some elements are only found in the calyrocks in the PTBST. These particular characteristics of the PTBST clayrocks are attributed to their special volcanic formation and thus provide a reliable auxiliary marker for high-resolution demarcation of the terrestrial PTB.

关 键 词：粘土岩 陆相 二叠系-三叠系界线 岔河剖面 

分 类 号：P588.22[天文地球—岩石学]