川东华蓥山二叠系/三叠系界线附近粘土层中粘土矿物的类型及成因

对川东华蓥山二叠系/三叠系界线附近粘土层中的粘土矿物进行野外采样和室内X射线衍射分析,结果表明，这些粘土矿物主要由规则混层伊利石-蒙脱石组成，其中1个样品可能含有少量不规则混层绿泥石-蒙脱石等粘土矿物。总地看来，该界线粘土层中的规则混层伊利石－蒙脱石中伊利石层的含量自下而上呈现减少的趋势，平均含量约83%，所经历的最大古地温在125～150℃之间。这些粘土矿物的构成和特征与前人在华南其他地区相同层位取得的成果总体上具有较好的一致性，显示了该粘土层成因的相同性及所具有的等时意义。不同地区粘土矿物构成的差异性（如高岭石的存在与含量）可能与二叠系/三叠系界线不整合的存在与否或间断时间有关，规则混层伊利石－蒙脱石的混层比则与埋藏历史和沉积—沉积期后的流体介质有关。

Clay minerals in the clay beds near the Permian/Triassic boundary at Huaying Mountain, eastern Sichuan, China: their types and origin

Clay minerals in the clay beds near the P/T boundary at Huaying Mountain, eastern Sichuan, were analyzed by X-ray diffraction analysis. The results show that the clay minerals are composed predominantly of ordered mixed-layer illite/montmorillonite, and that one sample possibly contains small amount of random mixed-layer chlorite/montmorillonite. Generally, the content of illite layers in the ordered mixed-layer illite/montmorillonite of the clay beds near the boundary shows a trend of decreasing from the base upward, with an average content of 83%, and the maximum paleotemperatures which they underwent ranged from 125 to 150℃. The composition and characteristics of these clay minerals are in good agreement with those at the same horizon in other areas of South China, showing that the clay minerals in the clay beds have the same origin and isochronous significance. Their differences (e.g. in the presence and content of kaolinite) in different areas may be related to whether an unconformity or hiatus exists at the P/T boundary; whereas the ordered mixed-layer illite/montmorillonite ratio is related to the burial history or depositional to post-depositional fluid medium.