Uppermost Permian to Lower Triassic conodont successions from the Enshi area, western Hubei Province, South China

摘要

We present recent study results of the Lower Triassic conodont succession from the Ganxi and Jianshi areas of Enshi city, western Hubei Province, South China, which were situated on a carbonate ramp at the northeastern margin of the Upper Yangtze Platform. Therein, the uppermost Permian to Lower Triassic succession is well exposed and yielded abundant conodonts. A total of nine conodont zones are differentiated: (1) Clarkina yini Zone, (2) Clarkina meishanensis Zone, (3) Hindeodus changxingensis Zone, (4) Hindeodus parvus Zone, (5) Hindeodus postparvus Zone, (6) Clarkina planata Zone, (7) Neoclarkina aff. discreta Zone, (8) Neospathodus dieneri Zone, and (9) Novispathodus waageni Zone. The Ns. dieneri M1, Ns. dieneri M2, and Ns. dieneri M3 Subzones have also been distinguished within the Ns. dieneri Zone, and the Nv. waageni eowaageni and Nv. waageni waageni Subzones are recognizable within the Nv. waageni Zone in Jianshi. Most of the zones occur in succession, but the C. planata Zone is a local ecozone reflecting deeper water biofacies during H. postparvus Zone time. In the Jianshi section, the Permian-Triassic boundary is placed at Bed 136-2 based on the appearance of Hindeodus parvus immediately above the disappearance of Changhsingian taxa, while the Induan-Olenekian boundary (IOB) is drawn at Bed 225 + 40 cm based on the first appearance of Nv. waageni eowaageni within the upper range of the Ns. dieneri Zone indices. The Enshi conodont zones overall correlate well with those recognized elsewhere in South China and worldwide. (C) 2017 Elsevier B.V. All rights reserved.