Kaijiang-Liangping trough controls the distribution of platform edge oolitic shoal in the Feixianguan Fm in northern Sichuan basin. It is found from the seismic section that the eastern boundary to be a breakpoint

while the western boundary appears as an onlap point. In respect of sedimentary petrography

basin and slope facies are developed between the two boundaries mentioned above

which are represented by thin bedded marl and debris flow sediment

respectively. The earliest platform edge oolitic shoal deposit is located along Jiangyou-Zitong-Nanchong-Linshui-Dianjiang. The Feixianguan Fm is of basin facies on the western side of the trough with sediments of over 600 m thick and on the eastern side of the trough with sediments of over 500 m thick. Based on various evidences

the western boundary of the trough is basically determined to be approximately along Qinglin 1 well-Bailong 1 well-Si 1 well-Longhui 1 well

while its eastern boundary is a-long Tiandong 10 well-Chuanyue 83 well-Chuanfu 82 well. The trough is bounded by faults in the east

so the boundary location has only a little change in the course of the closing of the trough

while the western boundary is composed of slopes and the boundary location has gradually changed along with the closing of the trough. It is predicted that the area of platform edge oolitic shoal can be up to 3?10

4

km

2

in the northern Sichuan basin. On the west side of the trough

the platform edge oolitic shoal is mainly distributed in the area encircled by Jiangyou

Guangyuan

Liangping and Linshui; while on the east side of the trough

it is mainly distributed in Yunyang

Wanxian and Lianghekou (of Tongjiang).