四川盐边凹路、力马、红果及米易二滩、金龙山等地的二滩组上、下部均为细砂岩、粉砂岩、铁铝质粘土岩夹赤铁矿和铝土矿透镜体,底部常见砾岩,顶部为灰黑色碳质页岩夹劣质煤透镜体,中部为微晶生物灰岩夹粗粒白云质钙质石英砂岩。以富含腕足化石为特色,还可见珊瑚、虫筵、非虫筵有孔虫、介形虫、三叶虫、苔藓虫、腹足类等生物化石。沉积二滩组时期,研究区处于泥坪、混合坪、不稳定碳酸盐台地及潮坪沼泽等环境,代表一次较大的海进海退过程。二滩组与梁山组、树河组在岩性特征、所含生物面貌及时间跨度等方面存在显著差异。新建二滩组相当于研究区原石炭系与原梁山组之和,其时代为早二叠世栖霞期至茅口早期 Upper and lower parts of Ertan Formation in Sichuan Province, Yanbian Pass, Lima, Hongguo, Miyi Ertan and Jinlongshan are fine sandstone, siltstone, iron-aluminum clayey rock, hematite and bauxite lens , The bottom of the common conglomerate, the top of gray-black carbonaceous shale folder inferior coal lens body, the middle of the microcrystalline bio-limestone coarse grained dolomitic calcareous quartz sandstone. Fascia is rich in brachiopod, but also see coral, pest feast, non-festoon foraminifera, ostracods, trilobites, bryozoans, gastropods and other biological fossils. Sediment Ertan period, the study area is in the mud Ping, mixed ping, unstable carbonate platform and tidal flat marsh environment, representing a larger sea into the process of retired. Ertan Formation and Liangshan Formation and Shuhe Formation have significant differences in lithology characteristics, biological aspects and time span. The new Ertan Formation is equivalent to the sum of the original Carboniferous and the original Liangshan Formation in the study area. Its age is from Early Permian Qixia Period to Early Maokou