Characterisation of the organic matter of upper Bedoulian and lower Gargasian strata in the historical stratotypes (Apt and Cassis-la-Bédoule areas, SE France)

Abstract

The Total Organic Carbon (TOC) content of the Gargasian strata studied in their historical stratotype area is rather low (0.3% on average). Only a few levels show TOC values approaching 1.2%. This small amount of preserved organic matter, associated with low hydrogen index values (10 to 115 mg hydrocarbons/g TOC), argues for deposition in fully oxic conditions. This organic content is a mixture of land-derived organic particles and deeply oxidized marine organic matter. The organic flux was strongly diluted by the autochthonous carbonate input.

Keywords

• Lower Cretaceous
• Middle Aptian
• Gargasian
• stratotype
• organic matter
• Total Organic Carbon