From End Member to Continuum:Review of fluvial facies model research

Key words: 
• river /
• fluvial sedimentology /
• fluvial channel /
• architectural element /
• facies model /
• review

Abstract: This paper reviewed recent development in the areas including river pattern classification, channel evolution and transformation, fluvial channel architectural elements distribution, overbank deposition, ephemeral river and distributive fluvial system, fluvial facies models, and new technologies for fluvial sedimentological research. The authors concluded that fluvial sedimentology has witnessed significant improvement in the theory and the methodology since the past two decades. Some geomorphologists, sedimentologists, and engineers recognize a continuum of channel forms rather than only several tens of end members. Channel transitions are controlled by river bed gradient, variations in river discharge, composition of river bank materials, climate, vegetation and tectonic activities along their courses. Vertical profile analysis has great difficulties in differentiating ancient fluvial channel pattern in rock record. Therefore, macro-form geometrical reconstruction based on analysis of architectural element may be the right way to recognize ancestral river pattern and construct fluvial facies model. Overbank deposits record most complete information regarding ancient floods and palaeoenvironmental, palaeoclimatic and palaeontological information of a river. Ephemeral, seasonal, and strong monsoon-affected tropical and sub-tropical rivers have unique sedimentary structures and architectural elements. Distributive fluvial system (DFS) has been received more attentions though it has some doubts. Chinese fluvial sedimentologists need to investigate more modern rivers to observe their geomorphological characteristics and depositional processes, and should refer the quantitative methods of river evolution research and integrate them with sedimentological methods. We should build up the database in fluvial architectural element by using outcrop anatomy, 3D seismic and GPR technology. We should improve our research about overbank and floodplain processes, as well as the depositional regime of rivers in different climate zones. We need to develop new techniques, strengthen research team and laboratory construction, and enhance international exchange and cooperation. The ultimate objective is to make Chinese fluvial sedimentology to provide more strong and effective support for national social and economic development, and to make our own contributions to the development of fluvial sedimentology in the world.