Conodont Sequences and Their Lineages in the Permian-Triassic Boundary Strata at the Meishan Section, South China

摘要

This paper deals in detail with the conodont sequences and the evolution of Clarkina lineage and Hindeodus-Isarcicella lineage on the basis of the Upper Permian -Lower Triassie Conodonts from the Meishan section, Changxing. Zhejiang Province, South China, Which is proposed as a Candidate of the Global Stratotype Section and Point of the Permian-Triassic boundary. Three Upper Permian-Lower Triassie Conodont Zones are defined in ascending order, as follows. Clarkina changxingensis Zone, Hindeodus Parvus Zone, and Isarcicella isarcica Zone, The Clarkina changxingensis Zone is subdivided into three faunas, the Clarkina changxingensis-C. dleflecta-C. subcarinata fauna, the Hindeodus latidentatus-Clarkina meishanensis fauna and the Hindeodus typicalis fauna. It is very important that the conodont sequences established in the Permian-Triassic boundary strata at the Meishan section make a complete zonation and correlation over the world. This significantly helps the precise definition of the Permian-Triassic boundary at the Meishan section. The Clarkina stock at section D of Meishan, Changxing, appeared only in the Upper Permian and represented the descendant of the Eurasian stock. It is mainly Composed ofClarkina orientalis (Barskov and Koroleva), C. subcarinata (Sweet), C. v/angi (Zhang), C. changxingensis (Wang and Wang), C. deflecta (Wang and Wang), C. carinata (Clark) and C, dicerocarinata (Wang and Wang). Clarkina orientalis is the ancestor of C. subcarinata. C. subarinata diverged into three branches, i.e., C. Changxingensis, C. deflecta and C. carinata. C. deflecta further developed into C. dicerocarinata. The evolution of Clarkina v/angi is unsettled. The evolution o￡Hindeodus-Isarcilella stock at the Meishan section, Changxing, is Hindeodus latidentatus-H. parvus-Isarctcella turgida-L isarcica.