| While the submarine fan system in thrust zone has been studied by many researchers,few researches have concerned of the architecture distribution pattern of submarines fan in thrust zone during different geomorphology evolution stages.This thesis take a deep water zone in thrust zone in Upper Miocene-Quaternary interval which located in west Africa continental slope as an example,using the well-logging and seismic data,to analyze submarine fan system and the evolution of architecture elements of it.Thus,the architecture distribution pattern of submarines fan in thrust zone is established.The main results are as follows.(1)Nine third-order sequence are divided in the study area.Four kind of sedimentary units,MTD,channel,lobe and shale drape,are identified in the sequence.(2)Submarine fan system presents a variety of evolution patterns in different mobile stages of thrust fault.In graded slope stage,the geomorphology is unconfined and the system is formed by the vertical combination of the high-sinuous stripe-shaped channel and the shale drape.Sandy architecture elements tend to evolve into muddy shale drape in the submarine fan system from bottom to top.In thrust fails stage,submarine fan evolves in the mini-basins which located in the hanging wall of the thrust fault.And the submarine fan perform as a combination of the lobes and MTD.Lobes in different periods gradually demise the accommodation and overlap with each other in the form of retrogradation.In the mud diapir stage,channel-lobe complexes are formed by gravity flow in two sides of the mini-basin.And the distribution patterns on two sides are different.Channels in the same periods erode and overlap with each other laterally,yet channels in different periods overlap with each other vertically.In sedimentalion-dominant stage,submarine fan system are consist of gently curving stripe-shaped channels.The evolution pattern in this stage is similar with which in graded slope stage. |
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