The alternative changes of paleoenvironment favored the formation and imbedding of brine, which is the source of salt-water intrusion; and the paleochannel that formed during regressive of sea level is the path of salt-water intrusion.

• 海进时期，大面积的滨海平原被淹没，在近海平原洼地滞留的海水经过蒸发、浓缩变为卤水，成为咸水入侵的物源；海退后陆源碎屑在滨海地区沉积形成了巨厚的古河道砂层。