Source Rock Potential of the Organic Rich Turonian – Upper Campanian Carbonates of Northern Lebanon

Upper Cretaceous chalks, marls, and shales are arguably the most prolific petroleum source rocks in the eastern Mediterranean region. 209 core samples from the Turonian – Upper Campanian rock succession in north Lebanon were collected and analyzed for their organic matter (OM) content, quality, and maturity. The total organic carbon (TOC) measurements revealed a very good source rock potential for a 150 m interval within the Upper Santonian – Upper Campanian, with an average of 2% TOC. High HI values (average 707 mg/g TOC) characterize these source rocks as type I kerogen and reflect a very good preservation of the organic matter. Tmax values (average 421°C) match the other maturity parameters such as vitrinite reflectance (average 0.35%), and all point towards immature organic matter. The equivalent Upper Cretaceous in the offshore Levant basin has enough overburden to have reached maturity. However, the accurate extrapolation of the organic matter quality and quantity to the offshore is yet a challenge with the data at hand. Introduction Recent gas discoveries in the eastern Mediterranean brought back the attention towards this region and triggered a new phase of exploration, making out of the Levant Basin a new frontier hydrocarbon province. Substantial questions are still unanswered concerning the types and distribution of source rocks. The Upper Cretaceous chalks, marls, and shales are among the best petroleum source rock candidates potentially charging reservoirs in the Levant Basin and Margin (Gardosh et al., 2006; Inan et al., 2010; Nader, 2011). The elevated organic matter content in the Upper Cretaceous succession is attributed to an increase in primary productivity induced by an extensive coastal upwelling that operated during the Late Cretaceous along the SE Tethys margin (Almogi-Labin et al., 1993, 2012; Ashckenazi-Polivoda et al., 2010, 2011; Schneider-Mor et al., 2011). A pre-existing anticlinalsynclinal basin architecture resulting from the early pulses of the Syrian Arc compression lead to a considerable variation in the thickness, organic matter content, and lithofacies of the Upper Cretaceous rock succession (Bein et al., 1990; Almogi-Labin et al., 2012). Hence, quantifying those variations and characterizing the various organofacies exposed onshore, is vital for reconstructing the contemporaneous paleogeographic setting, and anticipating the distribution of these major source rocks within the Levant Basin and Margin. Material and methods In this study 209 core samples from the Turonian – Upper Campanian rock succession in north Lebanon (Fig. 1) were collected and analyzed for their organic matter (OM) content, quality, and maturity. This work provides a contribution to the relatively scarce geochemical information available for the eastern Mediterranean and discusses its implication on future petroleum exploration. Total organic carbon (TOC) content was measured for all the samples using a liquiTOC II analyzer. Rock-Eval pyrolysis (Espitalie et al., 1977) was performed on a selection of 33 representative samples from the upper Santonian ─ upper Campanian, having TOC>1%,