Sedimentary Composition Of Shelf Margin Sedimentary System And Palaeogeomorphology Shelf-break Zone Of Lower Zhujiang Formation On The Southeast Of Panyu Low Uplift

The southeast margin of Panyu low uplift is located in the center part of Pearl River Mouth basin,the lower part of Zhujiang formation of its strata developed in the shelf slope break belt.Study on the lowstand distribution and composition of shelf break system will be of great significance benefit in deepening in theory of shelf margin and carrying on deep water exploration to search for favourable traps.Comprehensive application in the theory of Sequence Stratigraphy,Sedimentology,Seismic Sedimentology and Seismic Geomorphology and based on well-seismic data,the third-order sequences of Zhujiang Formation is setted up.Its in the research area is divided into four third-order sequences(SQzj1?SQzj2?SQzj3?SQzj4).In SQzj2 lowstand systems tract(LST),early and late periods of lowstand systems tract are recognized based on seismic reflection characteristic,log presentation and seismic attributions.Identified the depositional systems of LST in the chronostratigraphic framework,were described which includes shelf edge delta(SED)and canyon-channel depositional system.The SED developed in the west area display the lowstand wedge in seismic profile and the small area in the plan view.In the early LST,the channels developed primarily in west area that most of them are depositional bypass.In the late LST,the incised channels exist in the northeast area.The canyon channel system can be divided into two types:cutting the shelf edge and source supply directly and uncutting the shelf edge.Restoration of SQzj2(21.0Ma)of Zhujiang formation shelf-break zone palaeogeomorphology,The paleo-slope can be divided into four steps that steep gradient,flat gradient,flat-steep double gradient and fault-controlled gradient.It revealed that shelf trajectory along the strike near WE distributed in west area PY35-2 well district and gradually become near NE distributed in the eastward direction.The steepest gradient part is in the middle area of shelf break zone caused by fault-controlled shelf break developed and the slope gradient gradually become flat in both eastward and westward.In the late LST,the shelf edge delta had been developed in the PY35-2 district,and the factor that influence shelf-break zone palaeogeomorphology is the shelf edge delta and the growth fault have a great effect on the shelf margin strike.The classification of shelf-break zone traps are three types that predelta slope turbidite stratigraphic trap,delta-shore structure-stratigraphic compound trap and structural trap belt.The three favorable sand bodies are predicted in the lowstand system tract.