The main depositional systems identified in No 1 member of Xujiahe formation, which developed in early late-Triassic gulf of NW Sichuan basin, include carbonate platform, bartier island-lagoon, and braid delta, etc.

• 川西北地区上三叠统须一段形成于海湾盆地背景下,主要由碳酸盐岩台地、障壁岛-泻湖及辫状三角洲等沉积体系组成。