New progress in the study of the early Early Carboniferous conodonts biostratigraphy from Nandong, Guangxi

Abstract: Abundant conodonts fossils from the Late Devonian-early Early Carboniferous Wuzhishan Formation to the Early Carboniferous Baping Formation were examined and studied in this paper. The phylogenetic evolution of the conodonts fossils from 20th to 30th layer of the Baping Formation along the Nandong section is very similar to that of rapidly evolutionary taxa described by Sandberg & Ziegler et al. (1978). Due to the vertical distribution and FAD of the conodonts, ten conodont interval zones were recognized from the bottom upward, i.e., Siphonodella duplicate sensu Hass, S. cooperi moephotype 1, S. obosoleta, S. sandbergi, S. quadruplicata, S. lobata, S. crenulata, S. isosticha，Gnathodus delicates, Protognathus preadelicatus, respectively. Among them, Siphonodella duplicate sensu Hass, S. cooperi moephotype 1, S. obosoleta, S. quadruplicata, S. lobata, S. isosticha，Gnathodus delicates, and Protognathus preadelicatus interval zones are newly established in this paper. Furthermore, the vertical distribution and zone taxon FAD of the early Early Carboniferous S. sandbergi, S. crenulata, S. isosticha, Gnathodus delicatus, Protognathus preadelicatus interval zones in Nandong area of Guangxi were revised and confirmed. The results achieved by the authors supply more detail information for delicate stratigraphic correlation.