Abstract
The Jebel Oust region (north-eastern Tunisia) recorded two levels of marine black shale in the Lower Cretaceous marly series. Geodynamic evolution, biostratigraphic and Rock–Eval analysies allow classifying those black shales as unconventional shale oil resource systems that were deposited during two oceanic anoxic events: the Middel Barremian Event "MBE" and the Early Aptian Event "OAE1a". Paleogeographic evolution highlights two transgressive–regressive cycles: the first one is Valanginian-Early Barremian, and the second is Late Barremian–Early Aptian. Each black shale deposit occurs at the end of the transgression that coincides with the highest sea level. During the Barreman–Aptian interval, sedimentation was controlled by extensional faults in a system of tilted fault blocks which were reactivated several times. Kerogen is of type I, II origin in black shales and of type III origin in marls. Tmax values indicate "oil window" stage. Average transformation ratio is around 67% and 82%, respectively, in the Lower Aptian and Middel Barremian source rock related to the relatively high thermal maturity degree due to the deep burial of the later. Estimated initial hydrocarbon generation potential is moderate to high. Oil saturation index records an "oil crossover" indicating expelled and migrated hydrocarbons from the organic-rich to the organic-poor facies. The petroleum system of the two mature source rocks with a high hydrocarbon generation potential enclose all elements characterizing a "shale oil hybrid system with a combination of juxtaposed organic-rich and organic-lean facies associated with open fractures".
Highlights
The Middel Barremian Event (MBE) black shales were detected in the north Tethyan margin and took place during a short episode (Coccioni et al 1992, 2003, 2006; Sprovieri et al 2006; Godet et al 2006; Bodin et al 2009; Malkoc and Mutterlose 2010; Yilmaz et al 2012)
This study presents the first recording of the oceanic anoxic event of Mid-Barremian outcrops in the southern Tethyan margin
The bottom of the section begins with gray marls that are surmounted by alternations of consolidated marls, limestones and clayey limestones with gray marls intercalation which contain the following planktic foraminifera: Gorbachikella kugleri and Praehedbergella sigali and benthic foraminifera: Lenticulina ouachensis ouachensis, L. ouachensis bartensteini L. nodosa, L. eichenbergi, Gavelinella barremiana, Dentalina oligostegia, Praedorothia hechti, Epistomina sp with rare ostracods, radiolarian and echinoderms
Summary
The Middel Barremian Event (MBE) black shales were detected in the north Tethyan margin and took place during a short episode (Coccioni et al 1992, 2003, 2006; Sprovieri et al 2006; Godet et al 2006; Bodin et al 2009; Malkoc and Mutterlose 2010; Yilmaz et al 2012). This study presents the first recording of the oceanic anoxic event of Mid-Barremian outcrops in the southern Tethyan margin. A geochemical and biostratigraphic approach is used to invest organic compounds distribution through the source rocks as well as characterizating and dating the two oceanic anoxic events MBE and OAE1a recorded in the Barremian–Aptian series which outcrop in the locality of Jebel Oust (NE Tunisia) (Fig. 1). Geodynamical and Journal of Petroleum Exploration and Production (2021) 11:1559–1575
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
