Distribution of shallow water delta sand bodies and the genesis of thick layer sand bodies of the Triassic Yanchang Formation, Longdong Area, Ordos Basin

LIU Hanlin,QIU Zhen,XU Liming,WANG Fengqin,TONG Qiang,LIN Jiahao,YIN Shuai,WANG Wenqiang

Fig. 3. Sedimentary characteristics of shallow water delta of Chang 82 sub-member in Longdong area, Ordos Basin. (a) Well Y68, 2080.5 m, trough cross bedding; (b) Well L28, 1675.0 m, parallel bedding; (c) Well N197, 1600.3 m, scour surface and mud gravel; (d) Well C105, 2122.6 m, wavy bedding; (e) Well Y51, 2182.9 m, wormhole; (f) Well C40, 2171.0 m, shallow water shellfish fossil; (g) Well C40, 2167.4 m, fish scale; (h) Well B42, 2094.6 m, pecopteris; (i) Well L178, 2495.1 m, taeniopteris tenuinervis; (j) Well M130, 2499.0 m, neocalamites; (k) Hejiafang section in Tongchuan, central part of the lacustrine basin, two coal veins 2 cm thick in the middle and lower part of Chang 8 Member.