Relationship between Permian volcanic rocks distribution and karst paleogeomorphology of Maokou Formation and its significance for petroleum exploration in western Sichuan Basin, SW China

LIU Ran,LUO Bing,LI Ya,QIU Nansheng,WANG Wei,ZHANG Yu,HE Qinglin,PEI Senqi

Fig. 3. Weathering crust at the top of Maokou Formation revealed by drilled wells and field sections. (a) Well WY17, 1650.25-1654.29 m, the contact surface between Longtan Formation and Maokou Formation, with about 2 m thick bauxite mudstone; (b) Well MT1, log comprehensive evaluation diagram of upper Maokou Formation, the top of Maokou Formation has karst breccias and a weathering crust; (c) Mount Huaying field section, the top of Maokou Formation has a bauxite weathering crust about 3 m thick.