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Darriwilian shallow-marine deposits from the Sultanate of Oman, a poorly known portion of the Arabian margin of Gondwana

  • A. P. HEWARD (a1), G. A. BOOTH (a2), R. A. FORTEY (a3), C. G. MILLER (a3) and I. J. SANSOM (a4)...


The Amdeh Formation is a 3.4 km stack of sparsely fossiliferous quartzites and shales which crops out in the Al Hajar mountains near Muscat. Here we describe the uppermost member (Am5) that can be dated biostratigraphically as Darriwilian and which is the outcrop equivalent, and probably the seaward continuation, of the Saih Nihayda Formation in the Ghaba Salt Basin of northern Oman. The outcrops at Wadi Daiqa and Hayl al Quwasim consist of 690 m of quartzitic sandstones, shales and bivalve-rich shell beds. Trace fossils referable to the Cruziana and Skolithos ichnofacies abound. The member comprises storm-dominated shelf, shoreface and delta deposits. A number of new discoveries have been made in the outcrops: fragments of the arandaspid fish Sacabambaspis, ossicles and moulds of the early disparid crinoid Iocrinus, two new genera of conodont, an occurrence of the rare trinucleid trilobite Yinpanolithus, and palynological and sedimentological evidence of more continuous Floian–Darriwilian deposition than is usual in the region. Sea levels during Middle Ordovician time are estimated to have been 50–200 m above present levels and a wide, low-gradient shelf covered much of Arabia. Similar trace fossils and storm-dominated, micro-tidal, sedimentary rocks occur throughout the region. Small changes of sea level, possibly caused by the growth and melting of polar ice sheets, could lead to substantial seaward or landward shifts of facies belts. The Am5 deposits are thick compared to most equivalents in Arabia implying active subsidence and a ready supply of sediment.


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Ainsaar, L., Kaljo, D., Martma, T., Meidla, T., Männik, P., Nõlvak, 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, 189201.
Aldridge, R. J., Murdock, D. J. E., Gabbott, S. E. & Theron, J. 2013. A 17-element conodont apparatus from the Soom Shale Lagerstatte (Upper Ordovician). South Africa Palaeontology 56 (2), 261–76.
Aldridge, R. J., Purnell, M. A., Gabbott, S. E. & Theron, J. 1995. The apparatus architecture and function of Promissum pulchrum Kovacs-Endrödy (Conodonta, Upper Ordovician). Philosophical Transactions of the Royal Society of London, Series B 347, 275–91.
Al-Ghammari, M., Booth, G. A. & Paris, F. 2010. New chitinozoan species from the Saih Nihayda Formation, Middle Ordovician of the Sultanate of Oman. Review of Palaeobotany and Palynology 158, 250–61.
Al-Hadidy, A. H. 2007. Paleozoic stratigraphic lexicon and hydrocarbon habitat of Iraq. GeoArabia 12 (1), 63130.
Béchennec, F., Le Métour, J., Platel, J. P. & Roger, J. 1993. Geological Map of The Sultanate of Oman, Scale 1:1000,000. Explanatory Notes. Directorate General of Minerals, Oman Ministry of Petroleum and Minerals, 93 pp.
Bergström, S. M., Chen, X., Gutiérrez-Marco, J. C. & Dronov, A. 2009. The new chronostratigraphic classification of the Ordovician System and its relations to major regional series and stages and to δ13C chemostratigraphy. Lethaia 42, 97107.
Dalrymple, R. W. & Padman, L. 2015. Tides at high latitudes. In Hedberg Research Conference: Latitudinal Controls on Stratigraphic Models and Sedimentary Concepts, Abstract only. AAPG Datapages/Search and Discovery Article #120178.
Davies, N. S. & Gibling, M. R. 2010. Cambrian to Devonian evolution of alluvial systems: the sedimentological impact of the earliest land plants. Earth-Science Reviews 98, 171200.
Davies, N. S. & Sansom, I. J. 2009. Ordovician vertebrate habits: a Gondwanan perspective. Palaios 24, 717–22.
Donoghue, P. C. J., Purnell, M. A., Aldridge, R. J. & Zhang, S. 2008. The interrelationships of ‘complex’ conodonts (Vertebrata). Journal of Systematic Palaeontology 6, 119–53.
Donovan, S. K., Miller, C. G., Sansom, I. J., Heward, A. P. & Schreurs, J. 2011. A Laurentian Iocrinus Hall (Crinoidea, Disparida) in the Dapingian or Darriwilian (Middle Ordovician, Arenig) of Oman. Palaeontology 54, 525–33.
Droste, H. H. J. 1997. Stratigraphy of the Lower Paleozoic Haima Supergroup of Oman. GeoArabia 2 (4), 419–72.
Dzik, J. 1991. Oral evolution of conodont apparatuses in the conodont chordates. Acta Palaeontologica Polonica 36, 265323.
El-Khayal, A. A. & Romano, M. 1985. Lower Ordovician trilobites from the Hanadir Shale of Saudi Arabia. Palaeontology 28, 401–12.
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, 161–74.
Forbes, G. A., Jansen, H. S. M. & Schreurs, J. 2010. Haima Supergroup. Lexicon of Oman Subsurface Stratigraphy, pp. 171203. GeoArabia, Special Publication no. 5. Bahrain: Gulf PetroLink.
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 (4), 127–52.
Fortey, R. A. & Morris, S. F. 1982. The Ordovician trilobite Neseuretus from Saudi Arabia, and the palaeogeography of the Neseuretus fauna related to Gondwanaland in the earlier Ordovician. Bulletin of the British Museum (Natural History) 36 (1), 6375.
Fortey, R. A. & Owens, R. M. 1999. Feeding habits in trilobites. Palaeontology 42, 429–65.
Gabbott, S. E., Aldridge, R. J. & Theron, J. N. 1995. A giant conodont with preserved muscle tissue from the Upper Ordovician of South Africa. Nature 374, 800–3.
Ghavidel-Syooki, M., Popov, L. E., Álvaro, J. J., Ghobadi Pour, M., Tolmacheva, T. Y. & Ehsani, M-H. 2014. Dapingian–lower Darriwilian (Ordovician) stratigraphic gap in the Faraghan Mountains, Zagros Ranges, south-eastern Iran. Bulletin of Geosciences 89, 679706.
Ghobadi Pour, M., Popov, L. E., Kebriaee 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, 263–83.
Glennie, K. W., Boeuf, M. G. A., Hughes Clarke, M. W., Moody-Stuart, M., Pilaar, W. F. H. & Reinhart, B. M. 1974. Amdeh Quartzite Formation. In Geology of the Oman Mountains, pp. 85–6. Verhandelingen van het Koninklijk Nederlands Geologisch Mijnbouwkundig Genootschap pt. 31.
Gradstein, F. M., Ogg, J. G., Schmitz, M. D. & Ogg, G. M. (eds) 2012. The Geologic Time Scale 2012. Amsterdam: Elsevier, 1176 pp.
Haq, B. U. & Schutter, S. R. 2008. A chronology of Paleozoic sea-level changes. Science 322, 64–8.
Heward, A. P. & Penney, R. A. 2014. Al Khlata glacial deposits in the Oman Mountains and their implications. In Tectonic Evolution of the Oman Mountains (eds Rollinson, H. R., Searle, M. P., Abbasi, I. A., Al-Lazki, A. & Al Kindi, M. H.), pp. 279301. Geological Society of London, Special Publication no. 392.
Immenhauser, A. 2009. Estimating palaeo-water depth from the physical rock record. Earth-Science Reviews 96, 107–39.
Jeppsson, L., Anehus, R. & Fredholm, D. 1999.The optimal acetate buffered acetic acid technique for extracting phosphatic fossils. Journal of Paleontology 73, 957–65.
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, 367–91.
Konert, G., Afifi, A. A., Al-Hajri, S. A. & Droste, H. J. 2001. Paleozoic stratigraphy and hydrocarbon habitat of the Arabian Plate. GeoArabia 6 (3), 407–42.
Kreisa, R. D. & Bambach, R. K. 1982. The role of storm processes in generating shell beds in Paleozoic shelf environments. In Cyclic and Event Stratification (eds Einsele, G. & Seilacher, A.), pp. 200–7. Berlin: Springer-Verlag.
Lees, G. M. 1928. The geology and tectonics of Oman and parts of south-eastern Arabia. Quarterly Journal of the Geological Society of London 84 (4), 585670.
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 Micropaléontologie 50, 316.
Le Métour, J., Villey, M. & De Gramont, X. 1986. Geological Map of Qurayat, Sheet NF 40-4D, Scale 1:100,000. Explanatory Notes. Directorate General of Minerals, Oman Ministry of Petroleum and Minerals, 72 pp.
Löfgren, A. & Tolmacheva, T. 2008. Morphology, evolution and stratigraphic distribution of the Middle Ordovician conodont genus Microzarkodina . Earth and Environmental Science Transactions of the Royal Society of Edinburgh 99, 2748.
Lovelock, P. E. R., Potter, T. L., Walsworth-Bell, E. B. & Wiemer, W. M. 1981. Ordovician rocks in the Oman Mountains: the Amdeh Formation. Geologie en Mijnbouw 60, 487–95.
MacEachern, J. A., Pemberton, S. G., Gingras, M. K. & Bann, K. L. 2010. Ichnology and facies models. In Facies Models 4 (eds James, N. P. & Dalrymple, R. W.), pp. 1958. Geological Association of Canada, GEOtext 6.
Mángano, M. G. & Droser, M. L. 2004. The ichnology record of the Ordovician radiation. In The Great Ordovician Biodiversification Event (eds Webby, B. D., Paris, F., Droser, M. L. & Percival, I. G.), pp. 369–79. New York: Columbia University Press.
Männik, P. & Aldridge, R. J. 1989. Evolution, taxonomy and relationships of the Silurian conodont Pterospathodus. Palaeontology 32, 893906.
Männik, P., Miller, C. G. & Hairapetian, V. 2015. A new early Silurian prioniodontid conodont with three P elements from Iran and associated species. Acta Palaeontologica Polonica 60, 733–46.
Martin, F. 1996. Systematic revision of the acritarch Ferromia pellita and its bearing on Lower Ordovician stratigraphy. Review of Palaeobotany and Palynology 93, 2334.
Millson, J. A., Quin, J. G., Idiz, E., Turner, P. & Al-Harthy, A. 2008. The Khazzan gas accumulation, a giant combination trap in the Cambrian Barik Sandstone Member, Sultanate of Oman: implications for Cambrian petroleum systems and reservoirs. American Association of Petroleum Geologists Bulletin 92, 885917.
Molyneux, S. G. & Al-Hajri, S. 2000. Palynology of a problematic lower Palaeozoic lithofacies in the central Arabian basin, Saudi Arabia. In Stratigraphic Palynology of the Palaeozoic of Saudi Arabia (eds Al-Hajri, S. & Owens, B.), pp. 1841. GeoArabia Special Publication no. 1. Bahrain: Gulf PetroLink.
Molyneux, S. G., Osterloff, P., Penney, R. A. & Spaak, P. 2006. Biostratigraphy of the Lower Palaeozoic Haima Supergroup, Oman; its application in sequence stratigraphy and hydrocarbon exploration. GeoArabia 11 (2), 1748.
Mount, V. S., Crawford, R. I. S. & Bergman, S. C. 1998. Regional structural style of the Central and Southern Oman Mountains: Jebel Akhdar, Saih Hatat and the Northern Ghaba Salt Basin. GeoArabia 3 (4), 475–90.
Munnecke, A., Calner, M., Harper, D. A. T. & Servais, T. 2010. Ordovician and Silurian sea-water chemistry, sea level, and climate: a synopsis. Palaeogeography, Palaeoclimatology, Palaeoecology 296, 389413.
Partington, M., Faulkner, T., McCoss, A. & Hoogerduijn Strating, E. 1998. The seismic stratigraphy of the Ghudun/Safiq (Ordovician and Silurian) of North Oman. GeoArabia 3 (1), GEO’98 Abstracts, 139–40.
Pilgrim, G. E. 1908. The geology of the Persian Gulf and the adjoining portions of Persia and Arabia. Memoirs of the Geological Survey of India 34 (4), 177 pp.
Posamentier, H. W. & Morris, W. R. 2000. Aspects of the stratal architecture of forced regressive deposits. In Sedimentary Responses to Forced Regressions (eds Hunt, D. & Gawthorpe, R. L.), pp. 1446. Geological Society of London, Special Publication no. 172.
Purnell, M. A. 1995. Microwear in conodont elements and macrophagy in the first vertebrates. Nature 374, 798800.
Purnell, M. A., Donoghue, P. C. J. & Aldridge, R. J. 2000. Orientation and anatomical notation in conodonts. Journal of Paleontology 74, 113–22.
Quintavalle, M., Tongiorgi, M. & Gaetani, M. 2000. Lower to Middle Ordovician acritarchs and chitinozoans from Northern Karakorum Mountains, Pakistan. Rivista Italiana di Paleontologie e Stratigrafia 206 (1), 318.
Rickards, B. R., 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 (4), 81120.
Sansom, I. J., Miller, C. G., Heward, A. P., Davies, N. S., Booth, G. A., Fortey, R. A. & Paris, F. 2009. Ordovician fish from the Arabian Peninsula. Palaeontology 52, 337–42.
Searle, M. P., Warren, C. J., Waters, D. J. & Parish, R. R. 2004. Structural evolution of the Arabian continental margin, Saih Hatat region, Oman Mountains. Journal of Structural Geology 26, 451–73.
Seilacher, A. 2007. Trace Fossil Analysis. Berlin: Springer-Verlag, 226 pp.
Senalp, M. & Al-Duaiji, A. A. 2001. Qasim Formation: Ordovician storm- and tide-dominated shallow-marine siliciclastic sequences, Central Saudi Arabia. GeoArabia 6 (2), 233–68.
Sepkoski, J. J. 1982. Flat-pebble conglomerates, storm deposits and the Cambrian bottom fauna. In Cyclic and Event Stratification (eds Einsele, G. & Seilacher, A.), pp. 371–85. Berlin: Springer-Verlag.
Servais, T. 1997. The Ordovician Arkonia-Striatotheca acritarch plexus. Review of Palaeobotany and Palynology 98, 4779.
Simmons, M. D., Sharland, P. R., Casey, D. M., Davies, R. B. & Sutcliffe, O. E. 2007. Arabian Plate sequence stratigraphy: potential implications for global chronostratigraphy. GeoArabia 12 (4), 101–30.
Torsvik, T. H. & Cocks, L. R. M. 2009. The Lower Palaeozoic palaeogeographical evolution of the northeastern and eastern peri-Gondwanan margin from Turkey to New Zealand. In Early Palaeozoic Peri-Gondwana Terranes: New Insights from Tectonics and Biogeography (ed. Basset, M. G.), pp.321. Geological Society of London, Special Publication no. 325.
Turner, B. R., Armstrong, H. A., Wilson, C. R. & Makhlouf, I. M. 2012. High frequency eustatic sea-level changes during the Middle and early Late Ordovician of southern Jordan: indirect evidence for a Darriwilian ice age in Gondwana. Sedimentary Geology 251–252, 3448.
Vaslet, D. 1990. Histoire Géologique de la Bordure Occidentale de la Plate-forme Arabe, Vol. 1: Le Paléozoïque (Anté-Permien Supérieur) d'Arabie Saoudite. Bureau de Recherches Géologiques et Minières, Document no. 191, 210 pp.
Vavrdova, M. 1977. Acritarchs from the Sárka Formation (Llanvirnian). Vestnik Ustredniho Ustavu Geologickeho 52, 109–18.
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, 359–75.
Villey, M., Le Métour, J. & De Gramont, X. 1986. Geological Map of Fanjah, Sheet NF 40-3F, Scale 1:100,000. Explanatory Notes. Directorate General of Minerals, Oman Ministry of Petroleum and Minerals, 68 pp.
Wright, V. P. & Cherns, L. 2015. Leaving no stone unturned: the feedback between increasing biotic diversity and early diagenesis during the Ordovician. Journal of the Geological Society, London 173, 241–4.
Zhen, Y. Y. & Percival, I. G. 2003. Ordovician conodont biogeography reconsidered. Lethaia 36, 357–70.


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Darriwilian shallow-marine deposits from the Sultanate of Oman, a poorly known portion of the Arabian margin of Gondwana

  • A. P. HEWARD (a1), G. A. BOOTH (a2), R. A. FORTEY (a3), C. G. MILLER (a3) and I. J. SANSOM (a4)...


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