黄河三角洲下三角洲平原沉积环境

现代黄河三角洲活动叶瓣上河口附近发育着决口扇沉积物,潮汐影响不明显。两侧发育着具有进积潮滩特点的沉积物。叶瓣废弃后由于压实下沉和波浪作用海岸后退,形成退积潮滩。在废弃河口侧部发育较好。那里高潮线处没有侵蚀陡坎,海岸后退是由于压实下沉引起的。废弃河口附近侵蚀作用明显,高潮线处发育侵蚀陡坎,潮间带变窄。

DEPOSITIONAL ENVIRONMENT OF LOWER DELTA PLAIN OF YELLOW RIVER DELTA

The lower delta plain of the modern Yellow (Huanghe) River Delta is composed of two parts: the lower delta plain of active lobe and the lower delta plain of abandoned lobes. In the present active lobe, crevasse splay deposits, which rarely show influence of tide, are developed near the distributary mouth; in the area to the north of the distributary mouth, deposits characteristic of tidal flat lie on the crevasse splay; in the area to the south of the distributary mouth, deposits are similar to typical tidal-flat ones. After delta lobe being abandoned, retrograded tidal-flat deposits occur on the retreated coast because of subsidence and marine reworking. Cliffs at high-tide limit are formed near the abandoned distributary mouth, where the tidal deposits are coarse in grain size and comparatively thin. There are no cliffs but a wide tidal flat in the lateral areas of the abandoned distributary mouth, and the deposits are comparatively thick and fine in grain size.