Conodont sequences in the Upper Permian and Lower Triassic of South China and the nature of conodont faunal changes at the systemic boundary

Abstract

Introduction In the Late Permian, a large-scale regression occurred worldwide and the extent of the sea shrank enormously. As a result, there is a stratigraphic gap between Permian and Triassic rocks in many areas of the world. South China, however, possesses the most widely distributed, fairly continuous marine Permo-Triassic sequences known anywhere in the world. Thus studies of South Chinese Permian and Triassic conodonts are helpful to research on conodont biostratigraphy, biofacies, and Permo-Triassic events and a great deal of work has been done by Wang & Wang (1981, 1983), Wang & Cao (1981), Wang & Dai (1981), Ding (1983), and Yang et al ., (1987). Wang & Wang (1981) divided the Permian and Triassic of South China into 15 conodont zones, four Upper Permian and 11 Lower Triassic, and this scale provides a good basis for future research. Wang & Wang's contributions deal mostly with the determination of stratigraphic age, however, and little attention has been focused on the relationships between conodonts and sediment types or on the nature of the temporal changes in conodont faunas. The purpose of the present study is thus to discuss Permian and Triassic conodont faunas and to demonstrate that the distribution of conodonts in this interval is related to the distribution of sedimentary facies. Stratigraphy In South China, marine Permian and Triassic facies occur south of a line joining Lianyun Harbor (Jiangsu Province), Xiang Fan (Hubei Province), and Tianshui (Gansu Province). The area north of this line was continental; hence the Permo-Triassic sections considered in this report are all south of the line, on the Yangtze Platform, which lies east of the ancient Kangdian Land and west of Cathaysia.