Dapingian-lower Darriwilian (Ordovician) stratigraphic gap in the Faraghan Mountains, Zagros Ranges, south-eastern Iran


Authors: Ghavidel-Syooki M, Popov LE, Álvaro JJ, Ghobadi Pour M, Tolmacheva TY, Ehsani M-H

Published in: Bulletin of Geosciences, volume 89, issue 4; pages: 679 - 706; Received 28 May 2013; Accepted in revised form 14 December 2013; Online 8 July 2014

Keywords: chitinozoans, conodonts, acritarchs, brachiopods, stratigraphy, Gondwana,

full text (PDF, 7.84 MB)

Export to RIS



The Lower-Middle Ordovician sediments exposed in the Faraghan Mountains, south-eastern Zagros Ranges, represent a condensed succession of siliciclastic-dominated rocks rich in palynomorph assemblages (acritarchs and subsidiary chitinozoans) and sparse shelly concentrations bearing biostratigraphically significant brachiopods and conodonts. The Lower Ordovician Zard-Kuh Formation comprises coarse-grained siliciclastic deposits rich in Cruziana ichnofossils. The lower 80 m of the overlying Seyahou Formation, late Floian to Katian in age, form a heterolithic succession composed of black and green shales, subarkoses and silty limestones. Its lower part is punctuated by a centimetric phosphoarenite that contains lingulate brachiopods (Atansoria yaseri sp. nov.) and conodonts (Baltoniodus aff. B. triangularis Lindström and Drepanoistodus sp.) that suggest a latest Floian age. The top of the condensed phosphoarenite is marked by a considerable hiatus that ranges the Dapingian and early Darriwilian interval. Overlying the hiatus, the Seyahou Formation comprises two fossiliferous levels, the oldest dated as mid-Darriwilian with chitinozoans characteristic of the Siphonochitina formosa Zone, and the youngest of the Katian Acanthochitina barbata Zone. Mid Ordovician phosphogenesis associated with starvation, reworking, resedimentation, and the onset of distinct stratigraphic gaps was a complex process recorded throughout the Arabian margin of Gondwana. In the Zagros Ranges, maximum flooding and phosphate precipitation are suggested as the counterpart of the Helskjer Drowning Event of Baltoscandia and the third-order maximum flooding surface that punctuates the Siphonochitina formosa Zone in North Africa.


Abaimova, G.P. 1971. New Early Ordovician conodonts of the south-eastern Siberian Platform. Paleontologicheskii Zhurnal 1971(4), 74-81. [in Russian]

Achab, A. 1982. Chitinozoaires de l’Arenig supérieur (Zone D) de la Formation de Uvis, Québec, Canada. Canadian Journal of Earth Sciences 19, 1295-307.View article

Achab, A. 1986. Assemblages de chitinozoaires dans l’Ordovicien Inférieur de l’Est du Canada. Canadian Journal of Earth Sciences 23, 269-94.View article

Afaghi, A. & Salek, M.M. (eds) 1977. Geological Map of Iran, South-Central Iran, sheet no. 5 (1/1,000,000). National Iranian Oil Company, Exploration and Production.

Ainsaar, L., Kaljo, D., Martma, T., Meidla, T., Männik, P, Nolvak, J. & Tinn, O. 2010. Middle and Upper Ordovician carbon isotope chemostratigraphy in Baltoscandia: A correlation standard and clues to environmental history. Palaeogeography, Palaeoclimatology, Palaeoecology 294, 189-201.View article

Albani, R. 1989. Ordovician (Arenigian) acritarchs from the Solanas Sandstone Formation, central Sardinia, Italy. Bollettino della Societa Paleontologica Italiana 28, 3-37.

Albani, R., Bagnoli, G., Maletz, J. & Stouge, S. 2001. Intergrated chitinozoan, conodont, and graptolite biostratigraphy from the upper part of the Cape Cormorant Formation (Middle Ordovician), western Newfoundland. Canadian Journal of Earth Sciences 38, 387-409.View article

Al-Hajri, S. 1995. Biostratigraphy of the Ordovician Chitinozoa of northwestern Saudi Arabia. Review of Palaeobotany and Palynology 89, 27-48.View article

Armstrong, H.A., Turner, B.R., Makhlouf, I.M., Weedon, G.P., Williams, M., Al Smadi, A. & Abu Salah, A. 2005. Origin, sequence stratigraphy and depositional environment of an upper Ordovician (Hirnantian) deglacial black shale, Jordan. Palaeogeography, Palaeoclimatology, Palaeoecology 220, 273-289.View article

Bagnoli, G. & Stouge, S. 1997. Lower Ordovician (Billingenian-Kunda) conodont zonation and provinces based on sections from Horns Udde, north Öland, Sweden. Bollettino della Societa Paleontologica Italiana 35, 109-63.

Benoît, A. & Taugourdeau, P. 1961. Sur quelques Chitinozoaires de l’Ordovicien du Sahara. Revue de l’Institut Français du Pétrole 16, 1403-21.

Bergeron, J. 1893. Notes Paléontologiques. 1. Crustacés. Bulletin de la Société géologique de France 21, 333-346.

Bergström, S.M. 1962. Conodonts from the Ludibundus Limestone (Middle Ordovician) of the Tvaren area (S. E. Sweden). Arkiv för Mineralogi och Geologi 3, 1-61.

Bergström, S.M. & Löfgren, A. 2009. The base of the global Dapingian Stage (Ordovician) in Baltoscandia: conodonts, graptolites and unconformities. Transactions of the Royal Society of Edinburgh, Earth and Environmental Science 99, 189-212.

Bockelie, T.G. 1980. Early Ordovician Chitinozoa from Spitsbergen. Palynology 4, 1-14.View article

Bouché, P.M. 1965. Chitinozoaires du Silurien s.1 du Djado (Sahara nigérien). Revue de Micropaléontologie 8, 151-64.

Brocke, R. 1998. Palynomorphs (Acritarchen, Prasinophyceae, Chlorophyceae) aus dem Ordovizium der Yangtze-Platform, Südwest China. 225 pp. Unpublished Ph.D. thesis, Technische Univesität Berlin.

Brocke, R., Fatka, O. & Servais, T. 1998. A review of the Ordovician acritarchs Aureotesta and Marrocanium. Annales de la Société Géologique de Belgique 120, 1-21.

Burmann, G. 1968. Diacrodien aus dem unteren Ordovizium. Paläontologische Abhandlungen, Abteilung B, Paläobotanik 2, 653-793.

Burmann, G. 1970. Weitere organische Mikrofossilien aus dem unteren Ordovizium. Paläontologische Abhandlungen, Abteilung B, Paläobotanik 3, 289-332.

Chen, X., Paris, F., Wang, X. & Zhang, M. 2009. Early and Middle Ordovician chitinozoans from the Dapingian type sections, Yichang area, China. Review of Palaeobotany and Palynology 153, 310-330.View article

Clark-Lowes, D.D. 2005. Arabian glacial deposits: recognition of palaeovalleys within the Upper Ordovician Sarah Formation, Al Qasim district, Saudi Arabia. Proceedings of the Geological Association 116, 331-347.View article

Combaz, A. & Peniguel, G. 1972. Étude palynostratigraphique de l’Ordovicien dans quelques sondages du Bassin de Canning (Australie Occidentale). Bulletin du Centre de Recherches de Pau S.N.P.A. 6, 121-167.

Cramer, F.H., Allam, B., Kanes, W.H. & Díez, M.d.C.R. 1974. Upper Arenigian to Lower Llanvirnian from the subsurface of Tadla Basin in Morocco. Palaeontographica, Abteilung B 145, 182-190.

Cramer, F.H. & Díez, M.d.C.R. 1976. Seven new late Arenigian species of the acritarch genus Coryphidium Vavrdová, 1972. Paläontologische Zeitschrift 50, 201-208.View article

Cramer, F.H. & Díez, M.d.C.R. 1977. Late Arenigian (Ordovician) acritarchs from Cis-Saharan, Morocco. Micropaleontology 23, 339-360.View article

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 (NW France). Palaeogeography, Palaeoclimatology, Palaeoecology 248, 339-356.View article

Dean, W.T. 1967. The correlation and trilobite fauna of the Bedinan Formation in South Eastern Turkey. Bulletin of the British Museum (Natural History), Geology 15, 83-123.

Deunff, J. 1955. Aremoricanium, genre nouveau d’Hystrichospheres du Silurien Breton. Comptes Rendus de la Société géologique de France (nouvelle série) 5, 227-229.

Deunff, J. 1959. Microorganismes planctoniques du Primaire Armoricain. I. Ordovicien du Veryhac’h (Presqu’île deu Crozon). Bulletin de la Société géologique et minéralogique de Bretagne (nouvelle série) 2, 1-41.

Deunff, J. 1961. Un microplancton a Hystrichosphéres dans le Trémadoc du Sahara. Revue de Micropaléontologie 4, 37-52.

Deunff, J., Górka, H. & Rauscher, R. 1974. Observations nouvelles et précisions sur les Acritarches a large ouverture polaire du Paléozoique Inférieur. Geobios 7, 5-18.View article

Downie, C. 1959. Hystrichospheres from the Silurian Wenlock Shale of England. Palaeontology 2, 56-71.

Dzik, J. 1983. Relationships between Ordovician Baltic and North American Midcontinent conodont faunas. Fossils and Strata 15, 59-86.

Eisenack, A. 1931. Neue Mikrofossilien des baltischen Silurs I. Palaeontologische Zeitschrift 13, 74-118.View article

Eisenack, A. 1938. Hystrichosphäriden und verwandten Formen im baltischen Silur. Z. Geschiebeforschung 14, 1-30.

Eisenack, A. 1955. Chitinozoen, Hystrichosphaeren und andere Mikrofossilien aus dem Beyrichia Kalk. Senckenbergiana lethaea 36, 157-188.

Eisenack, A. 1959. Neotypen baltischer Silur-Hystrichosphären und neue Arten. Palaeontographica, Abteilung A 112, 193-211.

Eisenack, A. 1962. Neotypen baltischer Silur-Chitinozoen und neue Arten. Neues Jahrbuch für Geologie und Paläontologie, Abhandlungen 114, 291-316.

Eisenack, A. 1963. Mitteilungen zur Biologie der Hystrichosphären und neue Arten. Palaeontographica, Abteilung A 118, 207-216.

Elaouad-Debbaj, Z. 1984. Chitinozoaires ashgilliens de l’Anti-Atlas (Maroc). Geobios 17, 45-68.View article

El-Khayal, A.A. & Romano, M. 1988. A revision of the upper part of the Saq Formation and Hanadir Shale (Lower Ordovician) of Saudi Arabia. Geological Magazine 125, 161-174.View article

Elles, G.L. & Wood, E.M.R. 1901. A monograph of British graptolites. Part 1 Dichograptidae. Monographs of the Palaeontographical Society 55, 1-54.

Fatka, O. & Brocke, R. 1999. Morphologic variability in two populations of Arbusculidium filamentosum (Vavrdová 1965). Palynology 23, 153-180.View article

Fensome, R.A., Williams, G.L., Barss, M.S., Freeman, J.M. & Hill, J.M. 1990. Acritarchs and fossil prasynophytes: an index to genera, species and intraspecific taxa. A.A.S.P. Contribution Series 25, 1-171.

Fortey, R.A., Heward, A.P. & Miller, C.G. 2011. Sedimentary facies and trilobite and conodont faunas of the Ordovician Rann Formation, Ras Al Khaimah, United Arab Emirates. GeoArabia 16, 127-152.

Ghavidel-syooki, M. 1998. Investigation of Late Palaeozoic strata on Tang-e Zakeen and introduction of Zakeen Formation in Kuh-e Faraghan, Zagros Basin, southern Iran. Geosciences Scientific Quarterly Journal 7, 54-73.

Ghavidel-syooki, M. 2000. Biostratigraphy and palaeobiogeography of Late Ordovician and Early Silurian chitinozoans from Zagros Basin, southern Iran. Historical Biology 15, 29-39.View article

Ghavidel-syooki, M. 2001. Palynostratigraphy and Palaeobiogeography of the Lower Palaeozoic sequence in the north-eastern Alborz Range (Kopet-Dagh region) of Iran, 17-35. In Goodman, D.K. & Clarke, R.T. (eds) Proceedings of the IX International Palynological Congress Houston, Texas, U.S.A., 1996. American Association of Stratigraphic Palynologists Foundation.

Ghavidel-syooki, M. 2008. Palynostratigraphy and Palaeogeography of the Upper Ordovician Gorgan Schists (Southeastern Caspian Sea), Eastern Alborz Mountain ranges, Northern Iran. Comunicaçoes Geológicas 95, 123-155.

Ghavidel-Syooki, M., Álvaro, J.J., Popov, L.E., Ghobadi Pour, M., Ehsani, M.H. & Suyarkova, A. 2011. Stratigraphic evidence for the Hirnantian (latest Ordovician) glaciation in the Zagros Mountains, Iran. Palaeogeography, Palaeoclimatology, Palaeoecology 307, 1-16.View article

Ghavidel-Syooki, M. & Khosravi, M.E. 1995. Investigation of Lower Palaeozoic sediments at Tang-e Zakeen of Kuh-e Faraghan and introduction of Seyahou and Sarchahan formations in the Zagros Basin, southern Iran. Geosciences Scientific Quarterly Journal 4, 2-21.

Ghavidel-Syooki, M. & Winchester-Seeto, T. 2002. Biostratigraphy and palaeogeography of Late Ordovician chitinozoans from the northeastern Alborz Range, Iran. Review of Palaeobotany and Palynology 118, 77-99.View article

Ghobadi Pour, M. 2006. Early Ordovician (Tremadocian) trilobites from Simeh-Kuh, Eastern Alborz, Iran, 93-118. In Bassett, M.G. & Deisler, V.K. (eds) Studies in Palaeozoic palaeontology. National Museum of Wales Geological Series 25.

Ghobadi Pour, M., Popov, L.E., Kebria-ee Zadeh, M.R. & Baars, C. 2011. Middle Ordovician (Darriwilian) brachiopods associated with the Neseuretus biofacies, eastern Alborz Mountains, Iran. Memoirs of the Association of Australasian Palaeontologists 42, 263-283.

Ghobadi Pour, M., Vidal, M. & Hosseini-Nezhad, M. 2007. An Early Ordovician trilobite assemblage from the Lashkarak Formation, Damghan area, northern Iran. Geobios 40, 489-500.View article

Gorjansky, V.Y. & Popov, L.E. 1985. Morphology, systematic position and the origin of inarticulated brachiopods with carbonate shell. Paleontologicheskii Zhurnal 1985(3), 3-14. [in Russian]

Grahn, Y. 1982. Caradocian and Ashgillian Chitinozoa from the subsurface of Gotland. Sveriges Geologiska Undersökning C788, 1-66.

Grahn, Y. 1984. Ordovician Chitinozoa from Tallinn, northern Estonia. Review of Palaeobotany and Palynology 43, 5-31.View article

Grahn, Y. 2006. Ordovician and Silurian chitinozoan biozones of western Gondwana. Geological Magazine 143, 509-529.View article

Gutiérrez-Marco, J.C., Sá, A.S., García-Bellido, D.C. & Rábano, I. 2013. The extent of the Dapingian Stage (Middle Ordovician) in peri-Gondwanan Europe and North Africa: Stratigraphic record, biostratigraphic tools, and regional chronostratigraphy, 114-115. In Lindskog, A. & Mehlqvist, K. (eds) Proceedings of the 3rd IGCP 591 Annual Meeting, 9-19 June 2013. Lund University Press, Lund.

Heydari, E. 2008. Tectonic versus eustatic controls on supersequences of the Zagros Mountains of Iran. Tectonophysics 451, 56-70.View article

Hints, O., Nolvak, J., Viira, V. & Mens, K. 2004. New palaeontological finds from the Tremadocian of Kadriorg, Tallinn, northern Estonia, 43-44. In Hints, O. & Ainsaar, L. (eds) WOGOGOB-2004 Conference Materials, Abstracts and Field Guide Book. Tartu University Press, Tartu.

Husseini, M.I. 1989. Tectonic and depositional model of Late Precambrian-Cambrian Arabian and adjoining plates. AAPG Bulletin 73, 1117-31.

Husseini, M.I. 1990. The Cambro-Ordovician Arabian and adjoining plates: a glacio-eustatic model. Journal of Petroleum Geology 13, 267-288.View article

Jachowicz, M. 1995. Ordovician acritarch assemblages from central and northwestern Saudi Arabia. Review of Palaeobotany and Palynology 89, 19-25.View article

Jardiné, S., Combaz, A., Magloire, L., Peniguel, G. & Vichy, G. 1974. Distribution stratigraphique des acritarches dans le Paléozoique du Sahara Algérien. Review of Palaeobotany and Palynology 18, 99-129.View article

Jenkins, W.A.M. 1967. Ordovician Chitinozoa from Shropshire. Palaeontology 10, 436-488.

Jenkins, W.A.M. 1969. Chitinozoa from the Ordovician of Viola and Fernvale limestones of the Arbuckle Mountains, Oklahoma. Palaeontology, Special Paper 5, 1-44.

Jeppsson, L., Anehus, R. & Fredholm, D. 1999. The optimal acetate buffered acetic acid technique for extracting phosphatic fossils. Journal of Paleontology 73, 957-965.

King, W. 1846. Remarks on certain genera belonging to the class Palliobranchiata. Annals and Magazine of Natural History, Series 1 18, 26-42.

Konert, G., Al-Afifi, A.M. & Al-Hajri, S.A. 2011. Paleozoic stratigraphy and hydrocarbon habitat of the Arabian Plate. GeoArabia 6, 407-422.

Le Hérissé, A., Al-Ruwaili, M., Miller, M. & Vecoli, M. 2007. Environmental changes reflected by palynomorphs in the early Middle Ordovician Hanadir Member of the Qasim Formation, Saudi Arabia. Revue de Micropaleontology 50, 3-16.View article

Li, J. 1987. Ordovician acritarchs from the Meitan Formation of Guizhou province, south-west China. Palaeontology 30, 613-634.

Li, J., Servais, T., Yan, K. & Zhu, H. 2004. A nearshore-offshore trend in acritarch distribution from the Early-Middle Ordovician of the Yangtze Platform, South China. Review of Palaeobotany and Palynology 130, 141-161.View article

Lindström, M. 1955. Conodonts from the lowermost Ordovician strata of south-central Sweden. Geologiska Foreningens i Stockholm Förhandlingar 76, 517-604.View article

Lindström, M. 1971. Lower Ordovician conodonts of Europe. Geological Society of America Memoir 127, 21-61.

Loeblich, A.R. Jr. 1970. Morphology, ultrastructure and distribution of Paleozoic acritarchs. Proceedings of the American Paleontological Convention in Chicago, Illinois 1969 (G) 2, 705-788.

Loeblich, A.R. Jr. & MacAdam, R.B. 1971. North American species of the Ordovician acritarch genus Aremoricanium. Palaeontographica, Abteilung B 135(1-2), 41-47.

Loeblich, A.R. Jr. & Tappan, H. 1976. Some new and revised organic-walled phytoplankton microfossil genera. Journal of Paleontology 50, 301-308.

Lu, L.C. 1987. Acritarchs from Dawan Formation (Arenigian) of Huanghouchang in Yichang western Hubei. Acta Micropalaeontologica Sinica 4, 87-102.

Martin, F. 1969. Les acritarches de l’Ordovicien et du Silurian belges. Mémoires de l’Institut Royal des Sciences naturalles de Belgique 160, 1-175.

Martin, F. 1972. Les acritarches de l’Ordovicien de la Montagne Noire (Hérault, France). Bulletin de l’Institut Royal des Sciences naturelles de Belgique 48, 1-61.

Martin, F. 1984. New Ordovician (Tremadoc) acritarch taxa from the middle member of the Survey Peak Formation at Wilcox Pass, southern Canadian Rocky Mountains, Alberta. Geological Survey of Canada Paper 84-1A, 441-448.

Menke, C.T. 1828. Synopsis methodica Molluscorum generum omnium et specierum earum, quae in Museo Menkeano adservantur. 91 pp. Sumtibus auctoris, typis Henrici Gelpke, Pyrmonti.View article

Molyneux, S.G. 1988. Late Ordovician acritarchs from northeast Libya, 45-59. In Ei-Arnauti, A., Owens, B. & Thusu, B. (eds) Subsurface Palynostratigraphy of Northeast Libya. Garyounis University, Benghazi.

Molyneux, S.G., Osterloff, P., Penny, R. & Spaak, P. 2006. Biostratigraphy of the Lower Paleozoic Haima Supergroup, Oman; its application in sequence stratigraphy and hydrocarbon exploration. GeoArabia 11, 17-48.

Nielsen, A.T. 2004. Ordovician sea level changes: a Baltic perspective, 84-93. In Webby, B.D., Paris, F., Droser, M.L. & Percival, I.G. (eds) The Great Ordovician Biodiversification Event. Columbia University Press, New York.

Oterdoom, W.H., Worthing, M. & Partington, M. 1999. Petrological and tectonostratigraphic evidence for a Mid Ordovician rift pulse on the Arabian Peninsula. GeoArabia 4, 467-500.

Paris, F. 1981. Les Chitinozoaires dans le Paléozoique du Sud-Ouest de l’Europe. Bulletin de la Société géologique et minéralogique de Bretagne 26, 1-412.

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

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

Paris, F., Grahn, Y.Y., Nestor, V. & Lakova, I. 1999. A revised chitinozoan classification. Journal of Paleontology 73, 549-70.

Paris, F., Le Hérissé, A., Monod, O., Kozlu, H., Ghienne, J.F., Dean, W.T., Vecoli, M. & Gunay, Y. 2007a. Ordovician chitinozoans and acritarchs from southern and southeastern Turkey. Revue de Micropaléontologie 50, 81-107.View article

Paris, F., Verniers, J. & Al-Hajri, S. 2000, Ordovician chitinozoans from Central Saudi Arabia. GeoArabia Special Publication 1, 42-56.

Playford, G. & Martin, F. 1984. Ordovician acritarchs from the Canning Basin, Westem Australia. Alcheringa 8, 187-223.View article

Popov, L.E. 2000. Late Ordovician linguliformean microbrachiopods from north-central Kazakhstsan. Alcheringa 24, 257-75.View article

Puente, G.S. de la 2010. Floian Chitinozoans (Lower Ordovician) from Santa Victoria area, Cordillera Oriental, northwestern Argentina: Systematics. Ameghiniana 47, 217-38.View article

Quintavalle, M. & Playford, G. 2008. Stratigraphic distribution of selected acritarchs in the Ordovician subsurface, Canning Basin, Western Australia. Revue de Micropaléontologie 51, 23-37.View article

Raevskaya, E.G. 1999. Early Arenig acritarchs from the Leetse Formation (St Petersburg region, northwest Russia) and their palaeogeographic significance. Bollettino della Societa Paleontologica Italiana 38, 247-256.

Rickards, R.B., Booth, G.A., Paris, F. & Heward, A.P. 2010. Marine flooding events of the Early and Middle Ordovician of Oman and the United Arab Emirates and their graptolite, acritarch and chitinozoan associations. GeoArabia 15, 81-120.

Rickards, R.B., Wright, A.J. & Hamedi, A.M. 2000. Late Ordovician and Early Silurian graptolites from southern Iran. Records of the West Australian Museum 58, 103-122.

Robardet, M., Henry, J.L., Nion, J., Paris, F. & Pillet, J. 1972. La Formation du Pont-de-Caen (Caradocien) dans les synclinaux de Domfront et de Sees (Normandie). Annales de la Société Géologique du Nord 92, 117-137.

Rubinstein, C.V., Vecoli, M. & Astini, R.A. 2011. Biostratigraphy and paleoenvironmental characterization of the Middle Ordovician from the Sierras Subandinas (NW Argentina) based on organic-walled microfossils and sequence stratigraphy. Journal of South American Earth Sciences 31, 124-138.View article

Samuelsson, J. & Verniers, J. 2000. Ordovician chitinozoan biozonation of the Brabant Massif, Belgium. Review of Palaeobotany and Palynology 113, 105-29.View article

Seilacher, A. 1970. Cruziana stratigraphy of “non-fossiliferous” Palaeozoic sandstones, 447-476. In Crimes, T.P. & Harper, J.C. (eds) Trace Fossils 2. Geological Journal, Special Issue 3. Seel House Press, Liverpool.

Senalp, M. & Al-Duaiji, A. 2001. Qasim Formation: Ordovician storm- and tide-dominated shallow-marine siliciclastic sequences, Central Saudi Arabia. GeoArabia 6, 233-268.

Servais, T., Brocke, R. & Fatka, O. 1996. Variability in the Ordovician acritarch Dicrodiacrodium. Palaeontology 39, 389-405.

Setudehnia, A. 1975. The Palaeozoic Sequence at Zard Kuh and Kuh-e Dinar. Bulletin of the Iranian Petroleum Institute 60, 16-33.

Sharland, P.R., Casey, D.M., Davies, R.B., Simmons, M.D. & Sutcliffe, O.E. 2004. Arabian Plate sequence stratigraphy. GeoArabia 9, 199-214.

Stouge, S. 2005. Barrandegnathus n. gen. (Conodonta) from the Komstad Limestone (lower Mid Ordovician), Scandinavia, and its palaeogeographical significance. Bulletin of the Geological Society of Denmark 52, 245-255.

Stouge, S. & Bagnoli, G. 1990. Lower Ordovician (Volkhovian-Kundan) conodonts from Hagudden, northern Öland, Sweden. Palaeontographia Italica 77, 1-54.

Tappan, H. & Loeblich, A.R. 1971. Surface sculpture of the wall in Lower Paleozoic acritarchs. Micropaleontology 17, 385-410.View article

Taugourdeau, P. 1966. Les Chitinozoares, techniques d’études, morphologie et classification. Mémoire de la Société Géologique de France (nouvelle série) 45, 1-64.

Taugourdeau, P., Bouché P., Combaz, A., Magloire, L. & Millepied, P. 1967. Microfossiles organiques du Paléozoique. Les Chitinozoaires. I. Analyse biblographique illustrée. 96 pp. Centre National de la Recherche Scientifique, Paris.

Taugourdeau, P. & 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.

Tongiorgi, M., Yin, L.M. & Di Milia, A. 1995. Arenigian acritarchs from the Daping Section (Yangtze Gorges area, Hubei Province, Southern China) and their palaeogeographic significance. Review of Palaeobotany and Palynology 86, 13-48.View article

Turner, B.R., Armstrong, H.A., Wilson, C.R. & Makhlouf, I.M. 2012. High frequency eustatic sea-level changes during the Middle to early Late Ordovician of southern Jordan: Indirect evidence for a Darriwilian Ice age in Gondwana. Sedimentary Geology 251-252, 34-48.View article

Turner, B.R., Makhlouf, I.M. & Armstrong, H.A. 2005. Late Ordovician (Ashgillian) glacial deposits in southern Jordan. Sedimentary Geology 181, 73-91.View article

Vaslet, D. 1989. Late Ordovician glacial deposits in Saudi Arabia: A lithostratigraphic revision of the Early Paleozoic succession. Deputy Ministry for Mineral Resources, Ministry of Petroleum and Mineral Resources, Jiddah, Kingdom of Saudi Arabia, Professional Papers 3, 13-44.

Vaslet, D. 1990. Upper Ordovician glacial deposits in Saudi Arabia. Episodes 13, 147-161.

Vavrdová, M. 1965. Ordovician acritarchs from central Bohemia. Věstník Ústředního ústavu geologického 40, 351-357.

Vavrdová, M. 1966. Palaeozoic microplankton from central Bohemia. Časopis pro mineralogii a geologii 11, 409-414.

Vavrdová, M. 1972. Acritarchs from the Klabava Shales (Arenig). Věstník Ústředního ústavu geologického 47, 79-86.

Vavrdová, M. 1990. Early Ordovician acritarchs from locality Myto near Rokycany (late Arening, Czechoslovakia). Časopis pro mineralogii a geologii 35, 239-50.

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., Tongiorgi, M., Abdesselam-Roughi, F., Benzarti, R. & Massa, D. 1999. Palynostratigraphy of Upper Cambrian-Upper Ordovician intracratonic clastic sequences, North Africa. Bollettino della Societa Paleontologica Italiana 38, 331-341.

Videt, B., Paris, F., Rubino, J.L., Boumendjel, K., Dabard, M.P., Loi, A., Ghienne, J.F., Marante, A. & Gorini, A. 2010. Biostratigraphical calibration of third-order Ordovician sequences on the northern Gondwana platform. Palaeogeography, Palaeoclimatology, Palaeoecology 296, 359-375.View article

Villas, E. 1995. Caradoc through Early Ashgill brachiopods from the Central-Iberian Zone (Central Spain). Geobios 28, 49-84.View article

Waagen, W. 1883. Salt Range fossils, vol. I, part 4. Productus Limestone fossils, Brachiopoda. Memoirs of the Geological Survey of India, Palaeontologia Indica (series 13) 2, 391-546.

Wang, X.F., Stouge, S., Chen, X.H., Li, Z.H. & Wang, C.S. 2009. Dapingian Stage: standard name for the lowermost global stage of the Middle Ordovician Series. Lethaia 42, 377-380.View article

Wang, X.F., Stouge, S., Erdtmann, B.D., Chen, X.H., Li, Z.H., Wang, C.S., Zeng, Q.L., Zhou, Z.Q. & Chen, H.M. 2005. A proposed GSSP for the base of the Middle Ordovician Series: the Huanghuachang section, Yichang, China. Episodes 28, 105-117.

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

Winchester-Seeto, T., Foster, C. & O’Leary, T. 2000. Chitinozoans from the Middle Ordovician (Darriwilian) Goldwyer and Nita formations, Canning Basin (Western Australia). Acta Palaeontologica Polonica 45, 271-300.

Yan, K., Li, J. & Liu, J. 2005. Biodiversity of Early-Middle Ordovician acritarchs and sea level changes in South China. Chinese Science Bulletin 50(20), 2362-2368.View article

Yin, L., Di Milia, A. & Tongiorgi, M. 1998. New and emended acritarch taxa from the lower Dawan Formation (lower Arenig, Huanghuachang Section, South China). Review of Palaeobotany and Palynology 102, 223-248.View article

Zhen, Y.Y. 1985. The biostratigraphic significance of the chitinozoans from the Meitan Formation at Honghuayuan, Northern Guizhou. Scientia Geologica, Sinica 4, 375-379. [in Chinese with English summary]

Zhen, Y.Y., Percival, I.G., Cooper, R.A., Simes, J.E. & Wright, A.J. 2009. Darriwilian (Middle Ordovician) conodonts from Thompson Creek, Nelson Province, New Zealand. Memoirs of the Association of Australasian Palaeontologists 37, 25-53.

Zhen, Y.Y., Percival, I.G. & Webby, B.D. 2003. Early Ordovician conodonts from western New South Wales, Australia. Records of the Australian Museum 55, 169-220.View article