Evolution And Main Controlling Factors Of The Continental Shelf-slope System Of Rio Muni Basin

The study of the evolution of the shelf continental slope sedimentary system and its controlling factors is an important research direction of deep-water sedimentary theory.The research work on the shelf continental slope sedimentary system not only has rich theoretical significance such as sequence stratigraphy,marine sedimentology,etc.,but also has guiding significance for the prediction of deep-water reservoirs.Based on the 3D seismic data of the Rio Muni Basin research area,this paper uses seismic sedimentology to conduct qualitative and quantitative research on the target layer of the Rio Muni Basin research area.The numerical simulation software is used to explore the main controlling factor of the shelf continental slope sedimentary distribution in the research area.First,the vertical evolution process of the shelf-edge migration trajectory since 16.5 Ma in the Rio Muni Basin research area was divided and its lateral evolution differences were compared,and its relationship with the clinoforms was discussed in depth.Second,the evolution characteristics of the deep-water geomorphic unit were described,And the influence of the shelf-edge migration trajectory on it.Finally,a systematic study was made on the control of the deep-water sedimentation ratio by supply and accommodation.The following results have been achieved:(1)The migration trajectory of the shelf-edge in the study area can be divided into three types: low-angle descending type,high-angle rising type and ultra-high-angle rising type.The shelf-edge migration trajectory at different evolution stages is proportion trend to the topography of clinoforms.(2)Three typical shelf-edge deltas configurations are mainly developed in the study area.The top-bottom thickness relationship(TT / BT)and top layer vertical thickness(TT)are respectively related to the shelf-edge migration trajectory angle(?)and migration trajectory progradation(P)negative linear correlation;(3)The evolution of migration channel width(B),curvature(SI),and lateral migration and vertical aggradation ratio(Lm / Va)in the study area are all affected by the migration trajectory of the shelf-edge;(4)Numerical simulation results show that,compared with the amplitude(A)and frequency(F)of sea level change,the shelf width(W)is the main controlling factor for shelf continental slope sedimentary distribution.(5)The study area from 16.5 Ma to Quarternary shelf continental slope sedimentary system can be divided into two types of sediment dispersion systems: supply-based(16.5-5Ma)and accommodation-based(5 Ma to recent),two sediment decentralized system is bounded by SASR = 0.075.