The basin's Late Triassic coal-bearing strata are the major coal-bearing horizon in central Yunnan and southwestern Sichuan.
其中的晚三叠世含煤岩系是滇中与川西南重要含煤层位。
2
The Youganwo Formation is the main mining horizon where the oil shale lies on the top of coal beds. The sedimentary environment of the oil shale belongs to a moderate deep lake system.