New Depositional Model of Shallow Water Delta — An Example from Modern Yellow River Delta, Bohai Bay, Northeast China

The uniformitarianism is the basal method of geological research. The modern river mouth delta such as Mississippi, Ural, Yellow River and Ganjiang River has a significant inspiration in ancient delta study. This paper analyzes the sedimentation in river mouth of Yellow River with satellite photographs, modern water conservancy and sedimentology. We think that shallow water depth, smooth terrain, low gradient and river controlling with wave alteration are the main sedimentary setting features. Then the depositional characteristics are concluded, the depositional model of similar delta is investigated, and summarization is made on the genesis and shape of the delta. At present there have been reported 5 types of shallow water delta sedimentary model, i.e. narrow delta plain and broad delta front with developed levees, narrow delta plain and broad delta front with developed branch channels, narrow delta plain and broad delta front with developed branch channels and mouth bars, broad delta plain and broad delta front , broad delta plain and narrow delta front with mouth bars. And the modern Yellow River delta is considered as a new type of shallow water delta. The historical channel changes of Yellow River, silt deposition and migration are discussed, the new formation mechanism is presumed, and the sedimentary features are depicted. Then the new model of delta sedimentation is built up. The new model thinks that the delta lobe is formed not by many branch channels but only one channel and that more than 3/5 of modern Yellow River delta is delta plain which has been constructed mainly by branch channel, flood plain and swamp. The delta front is narrow. Bank, bar and sand sheet can be seen in delta front. Underwater channel branch extends near the bank and mouth bar is usually destroyed.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California