Abstract:

 Thecoarse-graineddelta,developedinsteepslopebeltofariftbasin,usuallyplaysanimportantroleinoilandgas exploration.Basedontheanalysisofcore,loggingandseismicdata,twotypesoffandeltasarerecognizedinsteepslopebeltinthe FulaSub-basin,MugladBasin,Sudan.Thetaper-shapedfandeltainJakeAreaiscomposedofrelativelycoarse-grainedsandstoneand conglomeratewithmorethicknessandwidedistribution.Thesortingandgroundingarepoorinthistypeoffandeltadeposition.Onthe contrary,thegrainismuchfinerintheplatyfandeltainKeyiAreawhilethesortingandgroundingarerelativelygood.Thesandbody isthinandlimitedspread.ThesourceissufficientinJakeAreabutinsufficientinKeyiAreaduringtheEarlyCretaceous.Thispaper bringsthetheoryofsource-to-sinksystemintothefandeltaresearch.Throughthestudyaboutclasticsupplying,transportingand accumulating,theexplanationofthesetwotypesoffandeltasaregiven,andthedepositionalmodelsarebuilt.Onlyberegardedasa whole,thesource-to-sinksystemstudycanbeutilizedtopredictthefandeltadepositioninsteepslopebeltoftheriftbasin.

Key words: sourcetosinksystem；riftbasin；steepslopebelt；fandelta；FulaSub-basin