Different Styles Of Canyon Infill Related To Gravity And Bottom Current Processes : Examples From The Upper Slope Of The Se Brazilian Margin

Abstract

A series of modern submarine canyons were examined in the south-eastern Brazilian margin in order to identify<br>the different styles of canyon filling and their relationship with sedimentary processes and sea-level changes.<br>Such study should be considered as a predictive tool in order to estimate the presence of reservoir-like<br>deposits. Four seismic facies related to intra-canyon depositional patterns were individualised in this study:<br>clinoform prograding lateral accretion (Cp), cahotic fill (Ch), parallel-to-divergent aggradation (Pd) and<br>horizontal strata (Pl). Relationship between these styles and sea-level changes was attempted and results<br>indicate a complex interaction between hydrodynamic conditions, position of sediment source and sediment<br>availability. Coriolis Effect seems to play a minor role in controlling the downcanyon flow/erosion processes.<br>Lateral accretion is mainly related to the southward flowing Brazil Current. Aggradation and horizontal strata are<br>related to a relative decrease in the Brazil Current action and to an increase in gravity flows activity.