Abstract:

A deep trough which was more than 700 km long stretched from north tosouth in west Yunnan in the Devonian.Submarine fan of terrigenous debrisand the related deep water sediments were well developed there,thus formed theas semblage of both submarine fan model and carbonat slope wedge model.The fan is between high energy system and low energy system,but moreclose to high energy system.It can be divided into five subfacies such asinnerfan facies,central-fan facies,outer-fan facies,fan marginal facies and basin-plain facies.The carbonate sediments on base of the slope along the dis-tribution of carbonate slope,as a self-formed system,are not controlled by thefan body.It consist of all ochthonous sediments in carbonate gravity flow and autochthonous sediments in deep water.The provenance of the former is relat-ed to the submarine canyon which deeply cuts the slope,and that of the fateris the adjacent carbonate platform.Gravity sediment,especially the submarine fan show up distinct phases.Itcan be divided into embryonic stage(Shanjiang-Alengchu period,i.e.,the earlystage of the Early Devonian),prime stage(Banmandaodi period,i.e.,the latestage of the Early Devonian)and depauperation stage(the Middle Devonian).They constitute the evolution history of deep water sediments.