Caracterización geoquímica de los niveles ricos en materia orgánica de los sedimentos turbidíticos del Eoceno, Pirineo Oriental

Abstract

The occurrence of or ganic-rich levels in the turbiditic sediments of the Vallfogona Fm (Cadí thrust sheet) in the South-Eastern Pyrenees allowed us the determination of organic matter types, richness and oil potential, and highlighted the importance of organic matter sedimentation in turbiditic environments. Two types of samples were differentiated based on organic geochemistry and organic petrography. Type A samples were deposited in a carbonated environment (even/odd n-alkanes predominance and Pr/Ph<1), under hypersaline conditions (presence of gammacerane, Ts/Tm >1). Type B samples suggest a more shaly marine environment, which is corroborated by the predominance of odd n-alkanes, Pr/Phe»1, Ts/Tm<1, the absence of gammacerane and the similar content of the C27 and C29. Therefore, turbidite facies can be regarded as an environment where organic sedimentation occurs although with heterogeneities in type and amount of organic matter. Thus, in turbidite systems reservoir and source could exist simultaneously