Abstract: Organic Facies Variations of mixed siliciclastic-carbonate shelfal environments: Example from the Kimmeridgian-Tithonian of France

BAUDIN, FRANCOIS, PIERRE HANTZPERGUE, and ROGER JAN DU CHENE

The Kimmeridgian-Tithonian series were intensely studied in open marine siliciclastic environments of the North Sea and surrounding areas because of their significant contribution to the genesis of hydrocarbons.

The Kimmeridgian-Tithonian deposits are also well-represented along the Atlantic coast in France over a distance of 500 km passing through the Boulonnais, Normandy, Charentes and Quercy regions. This transect allows to follow the facies from the proximal mixed siliciclastic-carbonate neritic environment from Boulonnais to the patch-reef middle-shelf environment from Charentes and the intra-shelf carbonate facies from Quercy.

Within a precise biostratigraphic framework based on ammonites (dating precision: 250 000 years), the studied sections are interpreted in term of sequence stratigraphy using field observations, stratonomy, vertical variations of macro- and microfacies. Within this sequence stratigraphic framework followed throughout the different studied areas, trends in the distribution of organic matter are analyzed using both bulk geochemical (Rock-eval) and palynofacies data.

Models for an idealized organic matter distribution are proposed within each depositional sequence and systems tract and their implication to the prediction of marine petroleum source rock is discussed.

AAPG Search and Discovery Article #90942©1997 AAPG International Conference and Exhibition, Vienna, Austria