The Hujianshan Area is dominated by fluvial and lacustrine-fluviolacustrine delta sediments in Yanchang Formation,which locates in the south extensional of delta system of Anbian.

• 胡尖山地区延长组主要以河流、湖泊一河湖三角洲沉积为主,属于安边三角洲体系向南部延伸部分。