论黔北──川南石炭系大竹园组

THE CARBONIFEROUS DAZHUYUAN FORMATION IN NORTHERN GUIZHOU-SOUTHERN SICHUAN

论述了贵州遵义以北至四川南川、武隆一带的含铝土矿地层。其下段为粘土岩，厚１～５ｍ；上段铝土矿一铝土岩，厚２～６ｍ。该组位于下志留统韩家店群和上石炭统黄龙组之上，下二叠统梁山组、栖霞组之下。按产出层位及孢子化石，时代应属上石炭统（相当马平阶）。建立大竹园组这个新的岩石地层单位，以便与遵义以南息烽至清镇等地的下石炭统含铝土矿的九架炉组相区别。

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.