The Cambrian-Ordovician succession in the Ougarta Range (western Algeria, North Africa) and interference of the Late Ordovician glaciation on the development of the Lower Palaeozoic transgression on northern Gondwana


Authors: Ghienne J-F, Boumendjel K, Paris F, Videt B, Racheboeuf P, Salem HA

Published in: Bulletin of Geosciences, volume 82, issue 3; pages: 183 - 214; Received 25 June 2007; Accepted in revised form 13 September 2007;

Keywords: Cambrian, Ordovician, North Gondwana, transgression, glaciation, sequence stratigraphy,

full text (PDF, 7.15 MB)

Export to RIS


Supplementary material

Appendix 1 (3070 kB)

Fig. 8. Facies and sequence stratigraphic interpretations in the Cambrian-Ordovician succession of the Ougarta Range

Appendix 2 (5917 kB)

Dating of the Cambrian-Ordovician succession in the Ougarta Range



Depositional environments in the 1000-2000 m thick Cambrian-Ordovician succession range from inner-shelf siltstones to fluvial sandstones. Six transgressive-regressive (T-R), low-frequency (15-25 Ma) depositional sequences have been differentiated and correlated with both northern distal (Anti-Atlas, Morocco) and southern proximal (Ahnet, southern Algeria) areas. Sequence 1 (“Lower” Cambrian?) comprises fluvial deposits truncating volcanics and deformed Panafrican basement rocks. Marine strata appeared in Sequence 2 (lower and middle part of the “Middle” Cambrian) but fluvial conditions maintained to the South. Sequence 3 (upper “Middle” Cambrian) is erosionally truncated but further develops to the south, possibly comprising “Upper” Cambrian deposits. In Sequence 4 (Lower Ordovician), fluvial deposits are no longer present and inner-shelf siltstones reached southern Ougarta. Sequences 5 and 6, upper Lower-Middle Ordovician and Upper Ordovician, develop inner-shelf conditions throughout the study area at maximum flooding. Hirnantian glacial strata form a lowstand wedge in the upper part of the Sequence 6 regressive system tract. This succession designates a first-order transgression initiating in the Cambrian. It was temporarily perturbed just before its end by the Hirnantian glaciation. The related erosion led to a discontinuity, angular at basin scale, falsely suggesting a pre-glacial tectonic event. The post-glacial transgression, very fast relative to the Cambrian-Ordovician tempo, resulted in a drastic backstepping of the shorelines that shifted drastically to the south in the early Silurian. After deglaciation, the first-order inversion trend occurred between retrograding strata of the Cambrian-Ordovician succession and the prograding Siluro-Devonian wedge. This event marks in North Africa the maximum flooding of the Lower Palaeozoic megasequence.


Albani, R., Massa, D. & Tongiorgi, M. 1991. Palynostratigraphy (Acritarchs) of some Cambrian beds from the Rhadames (Ghadamis) Basin (Western Libya–Southern Tunisia). Bolletino della Societa Paleontologica Italiana 30, 255–280.

Álvaro, J.J., Van Vliet-Lanoë, B., Vennin, E. & Blanc-Valleron, M.M. 2003a. “Lower” Cambrian paleosols from the Cantabrian Mountains (northern Spain): a comparison with Neogene-Quaternary analogues. Sedimentary Geology 163, 67–84.View article

Álvaro, J.J., González-Gómez, C. & Vizcaino, D. 2003b. Paleogeographic patterns of the Cambrian-Ordovician transition in the southern Montagne Noire (France): preliminary results. Bulletin de la Société géologique de France 174/3, 23–31.

Arbey, F. 1962. Données nouvelles sur la sédimentation au Cambro-Ordovicien dans les Monts d’Ougarta (Saoura). Comptes rendus de l’Académie des sciences, Paris 254, 3726–3728.

Arbey, F. 1968. Structures et dépôts glaciaires dans l’Ordovicien terminal des chaînes d’Ougarta (Sahara algérien). Comptes rendus de l’Académie des sciences, Paris 268, 76–78.

Arbey, F. 1971. Glacio-tectonique et phénomenes périglaciaires dans les dépôts siluro-ordoviciens des monts d’Ougarta (Sahara algérien). Comptes rendus de l’Académie des sciences, Paris 273, 854–857.

Arbey, F. 1988. Diagéneses précoces et tardives: silicifications et roches silico-détritiques. 521 pp. These de doctorat d’état, Université de Paris-Sud, France.

Arbey, F. & Caby, R. 1966. Présence de dreikanters a la base du Cambrien de la Sebkha el Melah; remarques sur la discordance du Paléozoique et sur l’âge du soubassement dans la région des Monts d’Ougarta (Sahara algérien). Comptes rendus sommaires de la Société géologique de France, 63–64.

Avigad, D., Kolodner, K., McWilliams, M., Persing, H. & Weissbrod, T. 2003. Origin of northern Gondwana Cambrian sandstone revealed by detrital zircon SHRIMP dating. Geology 31, 227–230.View article

Avigad, D., Sandler, A., Kolodner, K., Stern, R.J., McWilliams, M., Miller, N. & Beyth, M. 2005. Mass-production of Cambro-Ordovician quartz-rich sandstone as a consequence of chemical weathering of Pan-African terranes: environmental implications. Earth and Planetary Science Letters 240, 818–826.View article

Bellini, E. & Massa, D. 1980. A stratigraphic contribution to the Paleozoic of the Southern Basins of Libya, 1–56. In Salem, M.J. & Buswell, M.T. (eds) Geology of Libya I. Academic Press, London.

Benoît, A. & Taugourdeau, P. 1961. Sur quelques chitinozoaires de l’Ordovicien du Sahara. Revue de l’Institut Français du Pétrole 16, 1403–1421.

Beuf, S., Biju-Duval, B., De Charpal, O., Rognon, P., Gariel, O. & Bennacef, A. 1971. Les gres du Paleozoique inférieur au Sahara. 464 pp. Science et Technique du Pétrole 18, Paris.

Boote, D.R.D., Clark-Lowes, D.D. & Traut, M.W. 1998. Paleozoic petroleum systems of North Africa, 7–68. In MacGregor, D.S., Moody, R.T.J. & Clark-Lowes, D.D. (eds) Petroleum Geology of North Africa, Geological Society London Special Publication 132.

Bourahrouh, A., Paris, F. & Elaouad-Debbaj, Z. 2004. Biostratigraphy, biodiversity and palaeoenvironments of the chitinozoans and associated palynomorphs from the Upper Ordovician of the Central Anti-Atlas, Morocco. Palaeogeography, Palaeoclimatology, Palaeoecology 130, 17–40.View article

Brenchley, P.J., Romano, M. & Gutiérrez-Marco, J.C. 1986. Proximal and distal hummocky cross-stratification facies on a wide Ordovician shelf in Iberia, 241–255. In Knight, R.J. & McLean, J.R. (eds) Shelf sands and sandstones. Memoir Canadian Society Petroleum Geologists II.

Brenchley, P.J., Marshall, J.D., Carden, G.A.F., Robertson, D.B.R., Long, D.G.F., Meidla, T., Hints, L. & Anderson, T.F. 1994. Bathymetric and isotopic evidence for a short-lived Late Ordovician glaciation in a greenhouse period. Geology 22, 295–298.View article

Brenchley, P.J., Carden, G.A., Hints, L., Kaljo, D., Marshall, J.D., Martma, T., Meidla, T. & Nolvak, J. 2003. High-resolution stable isotope stratigraphy of Upper Ordovician sequences: Constraints on the timing of bioevents and environmental changes associated with mass extinction and glaciation. Bulletin of the Geological Society of America 115, 89–104.View article

Burke, K. & Kraus, J.U. 2000. Deposition of immense Cambro-Ordovician sandstone bodies, now exposed mainly in north Africa and Arabia, during the aftermath of the final assembly of Gondwana. Geological Society of America Abstracts with Program 32(7), 249.

Burkhard, M., Caritg, S., Helg, U., Robert-Charrue, C. & Soulaimani, A. 2006. Tectonics of the Anti-Atlas of Morocco. Comptes Rendus Geosciences 338, 11–24.View article

Caby, R. 1996. Rapport de mission de terrain dans le Grand Sud-Ouest Algérien. Mémoires du Service géologique d’Algérie 8, 49–51.

Carr, I.D. 2002. Second-order sequence stratigraphy of the Palaeozoic of North Africa. Marine Petroleum Geology 25, 259–280.View article

Catuneanu, O. 2002. Sequence stratigraphy of clastic systems: concepts, merits, and pitfalls. Journal of African Earth Science 35, 1–43.View article

Catuneanu, O.,Willis, A.J. & Miall, A.D. 1998. Temporal significance of sequence boundaries. Sedimentary Geology 121, 157–178.View article

Clifton, H.E. 1976. Wave-formed sedimentary structures – a conceptual model, 126–148. In Davis, R.A., Jr. & Ethington, R.L. (eds) Beach and Nearshore Sedimentation. Society of Economic Paleontogists and Mineralogists, Special Publication 24.

Crossley, R. & McDougall, N. 1998. Lower Palaeozoic reservoirs of North Africa, 157–166. InMacGregor, D.S.,Moody, R.T.J. & Clark-Lowes, D.D. (eds) Petroleum Geology of North Africa. Geological Society London Special Publication 132.

Dabard, M.P., Loi, A. & Paris, F. 2007. Relationship between phosphogenesis and sequence architecture: sequence stratigraphy and biostratigraphy in the Middle Ordovician of the Armorican Massif (W France). Palaeogeography, Palaeoclimatology, Palaeoecology 248, 339–356.View article

Dean, W.T. 2005. Trilobites from the Cal Tepe Formation (Cambrian), near Seydisehir, Central Taurides, south-western Turkey. Turkish Journal of Earth Sciences 13, 1–71.

Dean, W.T. & Monod, O. 1990. Revised stratigraphy and relationships of Lower Palaeozoic rocks, eastern Taurus Mountains, south central Turkey. Geological Magazine 127, 333–347.View article

Denis, M., Buoncristiani, J.-F., Konaté, M., Ghienne, J.-F. & Guiraud, M. 2007. Hirnantian glacial and deglacial record in SW Djado Basin (NE Niger). Geodinamica Acta 20(3), 177–194.View article

Destombes, J. 1968a. Sur la présence d’une discordance générale de ravinement d’âge Ashgill supérieur dans l’Ordovicien terminal de l’Anti-Atlas (Maroc). Comptes rendus de l’Académie des sciences, Paris 267 D, 565–567.

Destombes, J. 1968b. Sur la nature glaciaire des sédiments du groupe du 2e Bani, Ashgill supérieur de l’Anti-Atlas, Maroc. Comptes rendus de l’Académie des sciences, Paris 267 D, 684–686.

Destombes, J. & Feist, R. 1987. Découverte du Cambrien supérieur en Afrique (Anti-Atlas, Maroc). Comptes rendus de l’Académie des sciences, Paris 304, 719–724.

Destombes, J., Hollart, H. & Willefert, S. 1985. Lower Paleozoic rocks of Morocco, 291–325. In Holland, C.H. (ed.) Lower Paleozoic Rocks of northwest and west Central Africa. John Wiley, New York.

Deynoux, M. 1985. Terrestrial or waterlain glacial diamictites? Three case studies from the Late Precambrian and Late Ordovician glacial drifts in West Africa. Palaeogeography, Palaeoclimatology, Palaeoecology 51, 97–141.View article

Deynoux, M., Sougy, J.&Trompette, R. 1985. Lower Paleozoic rocks of West Africa and the western part of Central Africa, 337–495. In Holland, C.H. (ed.) Lower Paleozoic Rocks of northwest and west Central Africa. John Wiley, New-York.

Deynoux, M. & Ghienne, J.-F. 2004. Late Ordovician glacial pavements revisited – a reappraisal of the origin of striated surfaces. Terra Nova 16, 95–101.View article

Deynoux, M., Affaton, P., Trompette, R. & Villeneuve, M. 2006. Pan-African tectonic evolution and glacial events registered in Neoproterozoic to Cambrian cratonic and foreland basins of West Africa. Journal of African Earth Science 46, 397–426.View article

Donzeau, M. 1971. Etude structurale dans le Paléozoique des Monts d’Ougarta. 100 pp. These de doctorat, Faculté des Sciences, Orsay, France.

Donzeau,M. 1974. L’Arc Anti-Atlas – Ougarta (Sahara nord-occidental, Algérie-Maroc). Comptes rendus de l’Académie des sciences, Paris 278, 417–420.

Donzeau, M. 1983. Tectonique des monts d’Ougarta, 118–120. In Fabre, J. (ed.) Afrique de l’Ouest, Introduction Géologique et termes stratigraphiques. Lexique stratigraphique international, Nouvelle série 1. Pergamon Press, Oxford.

Dumas, S. & Arnott, R.W.C. 2006. Origin of hummocky and swaley cross-stratification – The controlling influence of unidirectional current strength and aggradation rate. Geology 34, 1073–1076.View article

Elaouad-Debbaj, Z. 1987. Acritarches et Chitinozoaires de l’Ordovicien du Maroc. Systématique, Biostratigraphie, corrélations. 310 pp. These de doctorat, Université de Rennes I (unpublished).

Elaouad-Debbaj, Z. 1988. Acritarches et chitinozoaires du Tremadoc de l’Anti Atlas central (Maroc). Revue de micropaléontologie 31, 85–128.

Embry, A.F. 1995. Sequence boundaries and sequences hierarchies: problems and proposals, 1–11. In Steel, R.J., Felt, V.L., Johannesen, E.P. & Mathieu, C. (eds) Sequence stratigraphy on the Northwest European Margin. Norwegian Petroleum Society, Special Publication 5.View article

Ennih, N. & Liégeois, J.-P. 2001. The Moroccan Anti-Atlas: the West African passive margin with limited Pan-African activity. Precambrian Research 112, 289–302.View article

Eschard, R., Abdallah, H., Braik, F. & Desaubliaux, G. 2005. The Lower Paleozoic succession in the Tasilli outcrops, Algeria: sedimentology and sequence stratigraphy. First Break 23, 27–36.

Fabre, J. 1988. Les séries paléozoiques d’Afrique: une approche. Journal of African Earth Science 7, 1–40.View article

Fabre, J. 2005. Le Précambrien terminal – Cambrien: glaciation et enterrement d’une chaîne panafricaine, 117–144. In Fabre, J. (ed.) Géologie du Sahara occidental et central. Tervuren African Geoscience Collection 108. Musée Royal de l’Afrique Centrale, Tervuren.

Fabre, J. & Kazi-Tani, N. 2005. Ordovicien, Silurien, Devonien, Permo-Carbonifere, 147–360. In Fabre, J. (ed.) Géologie du Sahara occidental et central. Tervuren African Geoscience Collection 108. Musée Royal de l’Afrique Centrale, Tervuren.

Fabre, J., Ait-Kaci, A., Bouima, T. & Moussine-Pouchkine, A. 1988. Le cycle molassique dans le rameau trans-saharien de la chaîne panafricaine. Journal of African Earth Science 7, 41–55.View article

Faik, F., Belfoul, M.A., Bouabdelli, M. & Hassenforder, B. 2001. Les structures de la couverture Néoprotérozoique terminal et Paléozoique de la region de Tata, Anti-Atlas centre occidental, Maroc: deformation polyphasée, ou interactions socle/couverture pendant l’orogenese hercynienne. Journal of African Earth Science 32, 765–776.View article

Fekirine, B. & Abdallah, H. 1998. Palaeozoic lithofacies correlatives and sequence Stratigraphy of the Sahara Platform, Algeria, 97–108. In MacGregor, D.S., Moody, R.T.J. & Clark-Lowes, D.D. (eds) Petroleum Geology of North Africa. Geological Society London Special Publication 132.

Gatinski, G., Klotchki, V.P., Rozman, K.S. & Trofimov, D.M. 1966. Nouvelles données sur la stratigraphie des dépôts paléozoiques du Sahara méridional. Doklady Akademii nauk SSSR 170, 1154–1157.

Ghienne, J.-F. 2003. Late Ordovician sedimentary environments, glacial cycles, and post-glacial transgression in the Taoudeni Basin, West Africa. Palaeogeography, Palaeoclimatology, Palaeoecology 189, 117–145.View article

Ghienne, J.-F. & Deynoux, M. 1998. Large-scale channel fill structures in Late Ordovician glacial deposits in Mauritania, western Sahara. Sedimentary Geology 119, 141–159.View article

Ghienne, J.-F., Le Heron, D., Moreau, J., Denis, M. & Deynoux,M. In press. The Late Ordovician glacial sedimentary system of the North Gondwana platform. In Hambrey, M., Christoffersen, P., Glasser, N., Janssen, P., Hubbard, B. & Siegert, M. (eds) Glacial sedimentary processes and products. International Association of Sedimentologists, Special Publication 39. Blackwells, Oxford.

Gomez Silva, M., Pacaud, M. & Wiel, F. 1963. Contribution a l’étude du Cambro-Ordovician des chaînes d’Ougarta (Sahara algérien). Bulletin de la Société géologique de France 7, 134–141.

Gutiérrez-Marco, J.C., Destombes, J., Rábano, I., Acenolaza, G.F., Sarmiento, G.N. & San José, M.A. 2003. El Ordovícico Medio del Anti-Atlas marroquí: paleobiodiversidad, actualización bioestratigráfica y correlación. Geobios 36, 151–177.View article

Hampson, G.J. 2000. Discontinuity surfaces, clinoforms, and facies architecture in a wave-dominated, shoreface-shelf parasequence. Journal of Sedimentary Research 70, 325–340.View article

Haq, B.U. & Al-Qahtani, A.M. 2005. Phanerozoic cycles of sea-level change on the Arabian Platform. GeoArabia 10, 127–160.

Haq, B.U., Hardenbol, J. & Vail, P.R. 1987. Chronology of fluctuating seal levels since the Triassic. Science 235, 1156–1166.View article

Harms, J.C., Southard, J.B. & Walker, R.G. 1982. Structures and sequences in clastics rocks. Society for Sedimentary Geology (SEPM) Short Course 9, 1–253.View article

Hart, B.S. & Plint, A.G. 1989. Gravelly shoreface deposits; a comparaison of modern and ancient facies sequences. Sedimentology 36, 551–557.View article

Helland-Hansen, W. & Gjellberg, J.G. 1994. Conceptual basis and variability in sequence stratigraphy: a different perspective. Sedimentary Geology 92, 31–52.View article

Hervouet, Y. & Duee, G. 1996. Analyse morphostructurale par imagerie satellitaire et coupes structurales modélisées des monts d’Ougarta (Sahara occidental, Algérie): une chaîne hercynienne chevauchante a plis passifs. Mémoires du Service géologique de l’Algérie 8, 127–173.

Hirst, J.P.P., Benbakir, A., Payne, D.F.&Westlake, I.R. 2002. Tunnel valleys and density flow processes in the upper Ordovician glacial succession, Illizi Basin, Algeria: influence on reservoir quality. Marine Petroleum Geology 25, 297–324View article

Kichou-Braîk, F., Samar, L., Fekirine, B. & Legrand, P. 2006. Découverte de graptolites d’âge Caradocien dans quelques sondages du Tinrhert (Sahara algérien). Comptes Rendus Palevol 5(5), 675–683.View article

Kilian, C. 1922. Aperçu général de la structure des Tassilis, des Ajjers. Comptes rendus de l’Académie des sciences, Paris 175, 825–827.

Kolodner, K., Avigad, D., McWilliams, M., Wooden, J.L., Weissbrod, T. & Feinstein, S. 2006. Provenance of north Gondwana Cambrian-Ordovician sandstone: U-Pb. SHRIMP dating of detrital zircons from Israel and Jordan. Geological Magazine 143, 367–391.View article

Landing, E., Geyer, G. & Heldmaier, W. 2006. Distinguishing eustatic and epeirogenic controls on Lower-“Middle” Cambrian boundary successions in West Gondwana (Morocco and Iberia). Sedimentology 54, 899–918.View article

Laskar, J. 1999. The limits of Earth orbital calculations for geological time-scale use. Philosophical Transactions of the Royal Society of London A 357, 1735–1759.View article

Leckie, D.A. 1988. Wave-formed, coarse-grained ripples and their relationship to hummocky cross-stratification. Journal of Sedimentary Petrology 58, 607–622.View article

Ledru, P., Autran, A. & Santallier, D. 1994. Lithostratigraphy of Variscan terranes in the French Massif Central: a basis for paleogeographical reconstruction, 226–288. In Keppie, J.D. (ed.) Pre-Mesozoic geology in France and related areas. Springer, Berlin.View article

Le Heron, D.P., Sutcliffe, O.E.,Whittington, R.J. & Craig, J. 2005. The origins of glacially related soft-sediment deformation structures in Upper Ordovician glaciogenic rocks: implication for ice sheet dynamics. Palaeogeography, Palaeoclimatology, Palaeoecology 218, 75–103.View article

Legrand, P. 1964. Un graptolite intéressant de l’Arénigien supérieur du Sahara algérien: Didymograptus v-fraactus wieli nov. subsp. Comptes rendus sommaires de la Société géologique de France 9, 360–363.

Legrand, P. 1966. Précisions biostratigraphiques sur l’Ordovicien inférieur et le Silurien des chaînes de l’Ougarta (Sahara algérien). Comptes rendus sommaires de la Société géologique de France 97, 243–245.

Legrand, P. 1974. Essai sur la paléogéographie de l’Ordovicien du Sahara algérien. Compagnie Française des Pétroles, Notes et Mémoires 11, 121–138.

Legrand, P. 1985. Lower Palaeozoic rocks of Algeria, 5–89. In Holland, C.H. (ed.) Lower Paleozoic Rocks of northwest and west Central Africa. John Wiley, New York.

Legrand, P. 1988. The Ordovician-Silurian boundary in the Algerian Sahara, 139–143. In Cocks, L.R.M. & Rickards, R.B. (eds) A global analysis of the Ordovician-Silurian boundary. Bulletin of the British Museum (Natural History), Geology 43.

Legrand, P. 2003. Paléogeographie du Sahara algérien a l’Ordovicien terminal et au Silurien inférieur. Bulletin de la Société géologique de France 174, 19–32.View article

Legrand, P. & Nabos, G. 1962. Contribution a la stratigraphie du Cambro-Ordovicien dans le bassin saharien occidental. Bulletin de la Société géologique de France 7, 123–131.

Lessertisseur, J. 1971. L’énigme du Daedalus (Daedalus Rouault, 1850). Ichnofossilia. Bulletin du Muséum national d’histoire naturelle (Paris) 20, 37–66.

Long, D.G.F. 2004. Precambrian rivers, 660–663. In Eriksson, P.G., Altermann, W., Nelson, D.R., Mueller, W.U. & Catuneanu, O. (eds) The Precambrian Earth: Tempos and events (Developments in Precambrian geology) 12. Elsevier, Amsterdam.

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 49, 121–200.View article

MacNaughton, R.B., Dalrymple, R.W. & Narbonne, G.M. 1997. Early Cambrian braid-delta deposits, MacKenzie Mountains, north-western Canada. Sedimentology 44, 587–609.View article

Menchikoff, N. 1933. La série primaire de la Saoura et des chaînes d’Ougarta. Bulletin du Service de la Carte géologique d’Algérie 11, 109–123.

Miall, A.D. 1997. The geology of stratigraphic sequences. 433 pp. Springer-Verlag, Berlin.View article

Moreau, J. 2005. Architecture stratigraphique et dynamique des dépôts glaciaires ordoviciens du Bassin de Murzuk (Libye). 192 pp. These de doctorat, Université Louis Pasteur, Strasbourg, France (unpublished).

Nielsen, A.T. 2004. Ordovician sea level changes: A Baltoscandian perspective, 83–94. In Webby, B.D., Paris, F., Droser, M. & Percival, I. (eds) The Great Ordovician diversification event. Columbia University Press, New York.

Nio, S.-D. & Yang, C.-S. 1991. Diagnostic attributes of clastic tidal deposits: a review, 3–28. In Smith, D.G., Reinson, B., Zaitlin, B.A. & Rahmani, R.A. (eds) Clastic tidal sedimentology. Canadian Society of Petroleum Geologists Memoir 16.

ORGM (Office National de la Recherche Géologique) 2000. Kerzaz. Carte géologique de l’Algérie a 1/200.000. Service géologique de l’Algérie, Boumerdes.

Oulebsir, L. & Paris, F. 1995. Chitinozoaires ordoviciens du Sahara algérien: biostratigraphie et affinités paléogéographiques. Review of Palaeobotany and Palynology 86, 49–68.View article

Paris, F. 1990. The Ordovician chitinozoan biozones of the Northern Gondwana Domain. Review of Palaeobotany and Palynology 66, 181–209.View article

Paris, F., Elaouad-Debbaj, Z., Jaglin, J.C., Massa, D. & Oulebsir, L. 1995. Chitinozoans and Late Ordovician glacial events on Gondwana, 171–176. In Cooper, D., Droser, M.L. & Finney, S. (eds) Ordovician Odyssey, Short papers for the seventh international symposium on the Ordovician System. SEPM, Fullerton, California.

Paris, F., Deynoux, M. & Ghienne, J.-F. 1998. Chitinozoaires de la limite Ordovicien-Silurien en Mauritanie. Comptes rendus de l’Académie des sciences, Paris 326, 499–504.

Paris, F., Boumendjel, K., Dabard, M.P., Ghienne, J.-F., Loi, A., Tang, P., Videt, B. & Achab, A. 2007. Chitinozoan-based calibration of Early-Mid Ordovician transgressive events on northern Gondwana. Acta Palaeontologica Sinica 46, 370–375.

Pillola, G.L., Leone, F. & Loi, A. 1998. The Cambrian and Early Ordovician of SW Sardinia. Giornale di Geologia (Spec. Issue ECOS VII – Sardinia Guidebook) 60, 25–38.

Posamentier, H.W. 2001. Lowstand alluvial bypass systems: incised vs. unincised. Bulletin American Association Petroleum Geologist 85, 1771–1793.

Poueyto, A. 1952. Rhyolites et Gres d’Ougarta, Terrains Gothlandiens, 25–47. In Alimen, H., Le Maître, D., Menchikoff, N., Petter, G. & Poueyto, A. (eds) Les Chaînes d’Ougarta et la Saoura, Monographies Régionales 15. XIX Congres Géologique International, Alger.

Powell, R.D. 1990. Sedimentary processes at grounding line fans and their growth to ice-contact deltas, 53–77. In Dowdeswell, J.A. & Scourse, J.D. (eds) Glacimarine environments: processes and sediments. Geological Society London Special Publication 53.

Prigmore, J.K., Butler, A.J. & Woodcock, N.H. 1997. Rifting during separation of Eastern Avalonia from Gondwana: evidence from subsidence analysis. Geology 25, 203–206.View article

Robin, C., Rouby, D., Granjeon, D., Guillocheau, F., Allemand, P. & Raillard, S. 2005. Expression and modelling of stratigraphic sequence distortion. Sedimentary Geology 178, 159–186.View article

Ross, J.R.P. & Ross, C.A. 1992. Ordovician sea-level fluctuations, 327–336. InWebby, B.D. & Laurie, J.R. (eds) Global perspectives on Ordovician geology. Balkema, Rotterdam.

Runkel, A.C., McKay, R.M. & Palmer, A.R. 1998. Origin of a classic cratonic sheet sandstone: stratigraphy across the Sauk II–Sauk III boundary in the Upper Mississippi Valley. Geological Society of America Bulletin 110, 188–210.View article

Sharland, P.R., Archer, R., Casey, D.M., Davies, R.B., Hall, S.H., Heward, A.P., Horbury, A.D. & Simmons, M.D. 2001. Arabian plate sequence stratigraphy. GeoArabia Special Publication 2, 1–371.

Sharland, P.R., Casey, D.M., Davies, R.B., Simmons, M.D. & Sutcliffe, O.E. 2004. Arabian plate sequence stratigraphy – Revisions to SP 2. GeoArabia 9, 199–214 (chronostratigraphic chart available at

Stampfli, G.M. & Borel, G.D. 2002. A tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrones. Earth Planetary Science Letters 196, 17–33.View article

Štorch, P. 2006. Facies development, depositional settings and sequence stratigraphy across the Ordovician-Silurian boundary: a new perspective from the Barrandian area of the Czech Republic. Geological Journal 41, 163–192.View article

Sutcliffe, O.E., Dowdeswell, J.A., Whittington, R.J., Theron, J.N. & Craig, J. 2000. Calibrating the Late Ordovician glaciation and mass extinction by the eccentricity cycles of Earth’s orbit. Geology 28, 967–970.View article

Takherist, D. 1990. Structure crustale, subsidence mesozoique et flux de chaleur dans les bassins nord-sahariens (Algérie): apport de la gravimétrie et des données de puits. 207 pp. These de doctorat, Université de Montpellier (unpublished).

Taugourdeau, P. & de Jekhowsky, B. 1960. Répartition et description des Chitinozoaires siluro-dévoniens de quelques sondages de la C.R.E.P.S., de la C.F.P.A. et de la S.N. Repal au Sahara. Revue de l’Institut Français du Pétrole 15, 1199–1260.

Vail, P.R., Audemard, F., Bowman, S.A., Eisner, P.N. & Perez-Cruz, C. 1991. The stratigraphic signatures of tectonics, eustasy and sedimentology – an overview, 617–659. In Einsele, G., Ricken, W. & Seilacher, A. (eds) Cycles and events in stratigraphy. Springer-Verlag, Berlin.

Vecoli, M. 1999. Cambro-Ordovician palynostratigraphy (acritarches and prasinophytes) of the Hassi-R’Mel area and northern Rhadames Basin, North Africa. Palaeontographia Italica 86, 1–112.

Vecoli, M., Albani, R., Ghomari, A.,Massa, D. & Tongiorgi, M. 1995. Précisions sur la limite Cambrien-Ordovicien au Sahara Algérien (Secteur de Hassi-R’mel). Comptes rendus de l’Académie des sciences, Paris 320, 515–522.

Vecoli, M. & Le Hérissé, A. 2004. Biostratigraphy, taxonomic diversity and patterns of morphological evolution of Ordovician acritarchs (organic-walled microphytoplankton) from the northern Gondwana margin in relation to palaeoclimatic and palaeogeographic changes. Earth Science Reviews 67, 267–311.View article

Vecoli, M., Paris, F. & Videt, B. 2007. “Middle” Cambrian non-marine organic walled microfossils from the Algerian Sahara and their implications for the debate on the nature and origin of cryptospores. Geophysical Research Abstracts 9. EGU General Assembly 2007, Vienna, Austria.

Wade, B.S. & Pälike, H. 2004. Oligocene climate dynamics. Paleoceanography 19(4), PA4019.View article

Webby, B.D., Cooper, R.A., Bergström, S.M. & Paris, F. 2004. Stratigraphic framework and time slices, 41–47. In Webby, B.D., Paris, F., Droser, M. & Percival, I. (eds) The Great Ordovician diversification event. Columbia University Press, New York.