Conodont Biostratigraphy and Age of the Early Triassic Fish-Bearing-Nodule Levels from Nanjing and Jurong, Jiangsu Province, South China

Abstract

Fish-bearing nodules are found in Early Triassic marine strata in many regions, including East Greenland, East Spitsbergen, Northwest Madagascar, Canada, Angola, and South China. A new Olenekian (Early Triassic) conodont biostratigraphic study for stratum that contains fish-bearing nodule levels is conducted based on the Longtan (LT) Section of Nanjing City and the Qingshan (QS) Section of Jurong County, Jiangsu Province, South China. A total of 101 samples were collected at the two sections and three conodont zones were recognized: in ascending order, they are Scythogondolella (Sc.) milleri Zone, Novispathodus (Nv.) pingdingshanensis Zone, and Triassospathodus (Tr.) aff. homeri Zone. The Scythogondolella milleri Zone is globally recognized as the uppermost conodont zone of the Smithian and the base of the Novispathodus pingdingshanensis Zone was previously suggested as the marker of the Smithian-Spathian boundary in the Yangtze region. The fish-bearing-nodule levels of Nanjing and Jurong are within the conodont Scythogondolella milleri Zone, laterally correlated well with the upper part of the Novispathodus waageni Zone in Chaohu of Anhui Province that also contains fish-bearing-nodule levels. The conodont biostratigraphic correlation confirms the Early Triassic fish-bearing-nodule levels in the Lower Yangtze region are coeval, with an end-Smithian in age.