The Baoshan region (Sibumasu Terrane) of Yunnan Province, SW China, is one of the best locations to study the Wenlock to Pridoli conodonts in China. Conodont fauna of the "Lichaiba" and Niushiping formations were preliminarily reported during the IGCP 591 Field Meeting in 2014.

Recently, a more detailed analysis of conodont collections from the Silurian strata of the Laojianshan section in the Baoshan region was carried out by Dr. CHEN Zhongyang, Prof. WANG Chengyuan and their colleagues from Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (NIGPAS), together with Dr. Peep Mannik from Tallinn University of Technology. A revised dating of the section is provided based on the conodont biostratigraphy. The results have been published online in Geological Journal.

In stratigraphically ascending order, the Pterospathodus amorphognathoides amorphognathoides Zonal Group, the Pterospathodus pennatus procerus Superbiozone, the Ozarkodina sagitta sagitta Biozone, the Kockelella ortus absidata Biozone, the Kockelella crassa Biozone, the Polygnathoides siluricus Biozone and the "Ozarkodina" eosteinhornensis s.l. Interval Biozone were recognized. Several landslides were also recognized, especially two major landslides which cover the base of the "Lichaiba" and Niushiping formations respectively.

The conodont faunas recovered indicate that the "Lichaiba Formation" corresponds to the upper Telychian–upper Wenlock, and the Niushiping Formation to the Ludlow–Pridoli. Part of the Ireviken Event, that is, from Datum 3 to Datum 4 can be recognized from the studied section. The late Telychian conodont fauna from the Laojianshan section is characteristic of distal, open-shelf depositional environments.

This research was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Science and Technology Major Project of China, the State Key Laboratory of Palaeobiology and the Eesti Teadusagentuur. This is also a contribution to the IGCP Project 652 'Reading geologic time in Paleozoic sedimentary rocks'.

Reference: Chen, Z.Y., Mannik, P., Wang, C.Y.^*, Fang, X., Chen, T.E., Ma, X., Zhang, Y.D., Silurian conodont biostratigraphy of the Laojianshan section, Baoshan, Yunnan Province, SW China. Geological Journal. https://doi.org/10.1002/gj.3813

Range chart of conodont species from the Laojianshan section

Conodonts from the "Lichaiba" Formation