贵州海相二叠—三叠纪界线层基本特征及两纪界线的选择

Basic Features of Boundary Layers and Boundary Sections of Uppermost Permian and Lowermost Triassic Marine Facies in Guizhou

本文基于丰富的实际材料,讨论二叠—三叠纪界线层基本特征及两系界线位置。提出华南长兴阶与苏联外高加索多拉萨姆阶为晚二叠世晚期同时异相地层单位。其标志化石Pseu-dotirolites和Paratiroliles均为二叠纪最高菊石带代表。在贵州,其上存在以Hypophiceras-Otoceras-Anchignathodus和以Ophiceras-Claraia wangi-Isarcicella isarcica为代表的两个生物层序,分别为国际格里斯巴赫早期和晚期的标志。贵州和华南的P—T过渡层,具独自岩相、生物及物、化特征,是两纪间沉积环境连续过渡—骤变之产物。按岩相,其底为两个沉积单元急变转折处;按化石,为两纪生物分界线;按物、化异常,为事件发生的位置。因些,过渡层是岩石、生物、事件三者重合标志,其底为二叠—三叠系界线最佳位置。

Based on a large number of prataical data, this paper mainly discusses the basic features and the boundary locations of Uppermost Permian and Lowermost Triassic boundary layers and suggests the Changxin Stage in South China and the Dorashamian stage of Transcaucasus in Russia be the Stratigraphical units of synchonous different facies of Late Permian, With Pseuialmlites and Paratirolites as symbol fossils of the uppermost ammonoid zones of Permian. In Guizhou, there are two biological sequences represented by Hypojhioeras - Otocceras- Anclagnalhodus paws and Ophscenas - Claraia wangi-Isarcieella isarcim. The two sequences are separately the symbols of the early and the late Gries- bachian Period, The P-T transitional layer in Guizhou and South China with unique rock facies, biological, physical and chemical features is the product of continuous transition and abrupt change of sedimentary environments of Permian and Triassic. According to the lithofacies, the bottom of the P-T transitional layer is the abrupt turning place of two sedimentary units?according to the fossils, it is the biological demarcation line of Permian and Triassic; according to the physical and chemical differentiations, it is the place where events occurred. Therefore, the transitional stratigraphy is the coinciding symbol of rocks, organism and events, and the bottom is the best position of the demarcation line of Permian and Triassic.