New cognition of the Devonian-Carboniferous contact relationship in Shidian area, western Yunnan Province

The Late Paleozoic strata are extensively exposed in Baoshan massif of western Yunnan. Research work has been relatively in detail and, as a result, many achievements have been obtained. However, the Devonian-Carboniferous boundary was previously considered to be of pseudoconformity contact. In recent years, through 1∶50000 regional geological survey in Shidian area, we collected a large number of Famennian-Tournaisian conodonts in upper Heyuanzhai Formation which was previously assigned to Middle-Late Devonian and confirmed that the sequence of sedimentary facies between Heyuanzhai Formation and overlying Xiangshan Formation is a gradual transition relationship. Therefore, the authors propose for the first time that the Devonian-Carboniferous contact relationship is conformable contact, and this result will provide the latest information for the tectonic evolution of Baoshan massif.