Characteristics of "Guangyuan-Wangcang" trough during Late Middle Permian and its petroleum geological significance in northern Sichuan Basin, SW China

WANG Xingzhi,LI Bo,YANG Xiyan,WEN Long,XU Liang,XIE Shengyang,DU Yao,FENG Mingyou,YANG Xuefei,WANG Yaping,PEI Senqi

Fig. 4. Lithological characteristics of the trough on Maokou Formation top. (a) Chejiaba profile in the northern Sichuan Basin, thin bedded dark siliceous rock interbedded with lenticular gravity flow deposit. (b) Chejiaba profile, sampling point CJBd17, siliceous rock, with siliceous radiolaria commonly, cross-polarized light; (c) Chejiaba profile, sampling point CJBd7, a large number of complete brachiopods with small body and thin shell on the siliceous rock plane. (d) Shuanghe profile in Wangcang, black siliceous rock, with well-preserved ammonite fossils on stratal surface. (e) Chejiaba profile, black siliceous rock interbedded with lenticular gravity flow deposit. (f) Chejiaba profile, sampling point CJBz5, black siliceous rock interbedded with medium-thin deep-water distal gravity flow deposit.