SILURIAN – DEVONIAN BLACK SHALES IN THE ORIENTAL ALGERIAN SAHARA: implication of new field data from Tassili n'Ajjer outcrops and Berkine Basin (SE, Algeria).

The Silurian (Llandovery) and the Devonian (Frasnian) are a periods of interest because sediments and organic-rich shales were deposited in many places that form important hydrocarbon reservoirs and source rocks throughout North Africa basins and Middle East (Boot et al., 1998 ; Lüning et al., 2000). These organic-rich shales lead Algeria to hold the fourth position in terms of the estimates of technically recoverable shale oil and shale gas resources, based on major basin assessment in the world (EIA, 2013).

In the prolific Illizi and Berkine basins (western Ghadames, Algeria) a basin-wide approach is needed, especially with the new “shale gas and shale oil” frontier in the upcoming years, in order to capture regional trends and re-assessment the Siluro-Devonian successions.

Wireline-logs from more than 146 (Berkine – Illizi Basin) Algerian petroleum exploration wells have been studied (Djouder et al., 2012; Djouder et al., 2014).

In addition, a complete logging of spectacular large-scale and well exposed outcrops of the Siluro-Devonian sediments was carried out at the south margin (SE, Tassili n’Ajjer) of the Illizi-Berkine basins. The following analysis incorporates biostratigraphic, ichnological, sedimentological, magnetic susceptibility and high resolution stratigraphic data. It would allow providing a framework of deposits, ranging from offshore to deltaic deposits for the Silurian and from fluvial to normal-marine depositional conditions for the Devonian.

References cited:
Boote, D.R.D., Clark-Lowes, D.D., Traut, M.W., 1998. Palaeozoic petroleum systems of North Africa. In: Macgregor, D.S., Moo- dy, R.T.J., Clark-Lowes, D.D. (Eds.), Petroleum Geology of North Africa. Geol. Soc. London Sp. Publ., vol. 132, pp. 7–68.
Lüning, S., Craig, J., Loydell, D.K., Štorch, P., Fitches, B., 2000. Lower Silurian ‘hot shales’ in North Africa and Arabia: regional distribution and depositional model. Earth-Science Reviews, 121-200.
EIA – U.S. Energy Information Administration, 2013. Technically Recoverable Shale Oil and Shale Gas Resources: An Assessment of 137 Shale Formations in 41 Countries Outside the United States. Rapport de 730 p.
Djouder, H., Pagel, M., Murat, B., Orsingher, M., 2012. Le Silurien du Bassin de Berkine. Projet « Shale Gas » Profond. 10éme Colloque du Groupe Français des Argiles, Présentation Orale, Limoge, France 14-18 Mai 2012. http://hdl.handle.net/2268/171556
Djouder, H., Boulvain, F., Da Silva, A-C., Cornet, P., Lüning, S., 2014. Tassili n’Ajjer (Sahara Oriental Algérien) – Résultats préliminaires sur le Silurien – Dévonien : Journée Thématique de l’Association des Sédimentologistes Français (ASF) – Diagenèse : avancées récentes et perspectives, Présentation Poster, Orsay-Paris, France 04 Juillet 2014. http://hdl.handle.net/2268/171557