THE CARBONIFEROUS DAZHUYUAN FORMATION IN NORTHERN GUIZHOU-SOUTHERN SICHUAN

The Dazhuyuan Formation is represented by bauxite-bearing strata distributed in an area from north of Zunyi to Nanchuan-Wulong,Sichuan province.Its lower member consists of claystone,1-5 m thick;while its upper member,bauxite-aluminous, 2-6 m thick.This formation is underlain by the Lower Silurian Hanjiadian Group and Upper Carboniferous Huanglong Formation and overlain by the Lower Permian Liangshan Formation and Qixia Formation. Its contact relationships with the overlying and underlying strata are disconformable.According to its stratigraphic position and spores collected,its age should be Late Carboniferous（equivalent to the Maping Stage）.The purpose of establishing the Dazhuyuan Formation is to distinguishing the strata in the study area from the Lower Carboniferous bauxite-bearing Jiujialu Formation in an area from south of Zunyi to Xifeng-Qingzhen.