川北红层系指北纬310°20′以北的中、上侏罗系及白垩系的一套紫红色陆相砂、泥岩互层。因成岩后未遭强烈的构造变动,地层多较平缓,倾角多小于30度,受愈往盆地中心,倾角愈小,甚至近于水平。岩相变化也是由盆地边缘到中心,砂岩颗粒由粗变细,泥质增加,由薄层渐变为厚层。本区西部为北东至北北东向 The red beds in northern Sichuan refer to a set of mauve terrestrial sand and mudstone interbeds in the middle and upper Jurassic and Cretaceous north of north latitude 310 ° 20 ’. After diagenesis did not suffer strong structural changes, the strata are more gentle, dip less than 30 degrees, by the more basin center, the smaller the angle of inclination, or even near the level. The lithofacies change also from the edge of the basin to the center. The sandstone particles are coarse and thin and the mudstone is increased, changing from thin to thick layer. The western part of this area is north east to northeast