LAWRENCE, AMY, BEN KNELLER, and BILL McCAFFREY
School of Earth Sciences, University of Leeds, Leeds, LS2 9JT, England

Abstract: 3D Facies Distribution within a Confined Turbidite Basin, Peira Cava, South-East France

The Peira Cava outlier is a sub-basin of the Eocene/Oligocene Annot turbidite system, in the Maritime Alps, southeast France The sub-basin contains deep-marine sheet sand turbidites. Large surge-type turbidity currents were confined by the basin margins - as shown by distinctive onlap facies including reflected turbidites.

A total of over 2 km of sedimentary log was compiled from four road sections of which two intersected relatively proximal deposits and two intersected more distal deposits. Each road section contained both slope and offslope sections. Photomontages were constructed of the intervening ground. A combination of correlation techniques, including walking out of individual turbidite beds has allowed correlations to be made throughout the outlier. Subsequent statistical analysis of field data including sand and shale thicknesses, 'net-to-gross' and the presence of traction and/or erosion structures yield insights into the proximal-to-distal and slope-to-offslope distribution of facies; e.g. average sand thickness decreases from the proximal base of slope - off-slope by 86% over 1.1 km, and distally by 79% over 6.2 km.

The outlier is 12 km long by 10 km wide with up to 1km of turbidite fill and is thus comparable in volume to many turbidite systems that host hydrocarbon reservoirs. Understanding the 3D spatial distribution of sedimentary facies and the controls upon their distribution can aid the modelling of analogous hydrocarbon reservoirs.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas