Late Cretaceous Sub-Marine Fan System in Batain Mélange Zone, the Fayah Formation in Northeastern Oman

Iftikhar Ahmed Abbasi, Abdulrahman Al-Harthy, Yahya Khalifa Al-Subhi

Abstract


The Batain coast along the northeastern margin of Oman between Ra’s Al-Hadd and Ra’s Jibsch, is comprised of Permian to Late Cretaceous complex stratigraphy in a tectonically deformed area recording Permian rifting to late Cretaceous Tethys closure events. These rocks are thrust over Mesozoic and older autochthonous sedimentary cover in the form of a major nappe structure known as the Batain Nappe. The uppermost part of the Batain nappe is comprised of isolated outcrops of early Maastrichtian siliciclastic Fayah Formation dominated by gravity flow deposits. The Fayah Formation in the Jabal Fayah area is over four hundred meters thick and comprised of five distinct facies associations; namely, i) coarsening-up sandstone, ii) conglomerate, iii) debris- flow, iv) turbidite, and v) inter-bedded sandstone and shale lithofacies. These lithofacies associations are repeated many times in the section. The sandstone lithofacies association exhibits a coarsening-upward trend making sequences tens of meters thick in various parts of the formation. Waterscape structures are common along with occasional sandstone dykes and convolute bedding, reflecting fluidized conditions of deposition. The conglomerate lithofacies association is comprised of a series of interbedded coarsening-upward pebble to gravel size conglomerates containing chert, limestone, granite and volcanic clasts ranging a few mm to cm in diameter. Occasionally these are interbedded with sandstone lithofacies. The conglomerate lithofacies was deposited by a high-energy channelized flow in a sub-aqueous setting. The debris-flow lithofacies association is a matrix supported chaotic mixture of clay and boulders of granite, limestone and volcanic rocks, some of which are meter-sized in diameter, and possibly derived from the nearby basement rocks such as the Jabal Ja’alan basement rocks. It constitutes the most dominant part of the formation. These sediments were deposited along a slope setting, possibly as olistostrome formed due to submarine slumping and sliding. The turbidite lithofacies association is comprised of monotonous grayish-green to brown coloured clays tens of meters thick interbedded with thin, clean, well-sorted sandstone. The Interbedded sandstone and shale lithofacies association is comprised of a half to one meter thick cross-bedded, burrowed arkosic sandstone and plane laminated shale. The sandstone constitutes about 25% of the association with ripple lamination in the upper part of the unit indicating a fining-upward trend. Dewatering structures are common. This association constitutes the upper 100m of the formation. These sediments were deposited in shallow water conditions by channelized flows. Based on the lithofacies associations described above, especially the dominance of debris-flow units and turbidites, the greater part of the Fayah Formation are interpreted as having been deposited under a sub-marine fan setting. Only the upper part of the formation was deposited in a shallow water setting before the onset of overlying carbonate deposits. The sub-marine fan system was active during the last stages of the Tethys Ocean closure at the time of onset of the Batain nappe. 

 

 

 

 


Keywords


Batain Mélange; Late Cretaceous; Jabal Fayah; turbidite; sub-marine fan.

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References


Shackleton, R.M. & RIES, A.C. 1990. Tectonics of the Masirah fault zone and eastern Oman. In The Geology and Tectonics of the Oman Region (eds A. H. F. Robertson, M.P. Searle and A. C. Ries), Geological Society of London Special Publication 49, 715–24. London.

Shackleton, R.M., RIES, A.C., BIRD, P.R., Filbrandt, J.B. LEE, C.W. & Cunningham, G.C. 1990. The Batain Melange of NE Oman. In The Geology and Tectonics of the Oman Region (eds A. H. F. Robertson, M.P. Searle and A.C. Ries), Geological Society of London Special Publication 49, 673–96. London.

Immenhauser, A., Schreurs, G., Gnos, E., Oterdoom, H.W. & Hartmann, B. 2000. Late Palaeozoic to Neogene geodynamic evolution of the

northeastern Oman margin. Geol. Mag. 137 (1), 1–18.

Immenhauser, A., Schreurs, G., Peters, T., Matter, A., Hauser, M. & Dumitrica, P. 1998. Stratigraphy, sedimentology and depositional environments of the Permian to uppermost Cretaceous Batain Group, East-Oman. Eclogae Geologicae Helvetiae 91, 217–35.

Glennie, K.W., Hughes-Clarke, M.W., Boeuf, M.G., Pilaar, W.F., Reinhardt, B.M. 1974. Geology of the Oman Mountains. Verhandelingen Koninklijk Nederlands Geologisch Mijnbouwkundig Genootschap, 31, 423p.

Graham, G.M. 1980. Evolution of a passive margin and nappe emplacement in the Oman Mountains. Proceedings of the International Ophiolite symposium, Nicosia Cyprus, 414-423.

Loosveld, R.J.H., Bell, A., Terken J.J.M. 1996. The tectonic evolution of interior Oman. GeoArabia 1(1): 28–51.

Reading, H.G. 1996. Sedimentary Environments: Processes, Facies and Stratigraphy, 3rd Edition Wiley-Blackwell, London, 704 pp.

Reineck, H.E. and Singh, I.B. 1973. Depositional Sedimentary Environments. With Reference to Terrigenous Clastics. Springer Verlag, Berlin, Heidelberg, New York: 439 pp.

Ries, A.C. and Shackleton, R.M. 1990. Structures in the Huqf–Haushi Uplift, east Central Oman. In The Geology and Tectonics of the Oman Region (eds A. H. F.Robertson, M.P. Searle and A.C. Ries), Geological Society of London Special Publication 49. 653–664. London

Walker, R.G. 1992. Turbidites and submarine fans. In Facies Models: Response to sea-level changes (eds R.G. Walker and N.P. James) GeoText1 Canada, 239-263.

Roger, J., Béchennec, F., Janjou, D., LE Métour, J., Wyns, R. and Beurrier, M. 1991. Explanatory Notes to the Geological Map of Ja’alan, Sheet NF 40–8E, Scale:1:250,000. Muscat, Oman Directorate General of Minerals, Oman Ministry of Petroleum and Minerals, 84 pp.

Gnos, E., Immenhauser, A. and Peters, T. 1997. Late Cretaceous/Early Tertiary collision between the Indian and Arabian plates recorded in ophiolites and related sediments. Tectonophysics 271, 1–19.

Abbasi, I.A., Salad-Hersi, O., AL-Harthy, A. 2014. Late Cretaceous Conglomerates of the Qahlah Formation, north Oman. In Tectonic Evolution of the Oman Mountains (eds Rollinson, H.R., Searle, M. P., Abbasi, I. A., Al-Lazki, A. and Al Kindi, M.H), Geological Society London Special Publication 392, 325–341, London.

Normark, W.R. 1978. Fan valleys, channels and depositional lobes on modern submarine fans: Character for recognition of sandy turbidite environment. American Association of Petroleum geologists Bulletin, v. 62, 912-931.




DOI: http://dx.doi.org/10.24200/squjs.vol19iss1pp64-73

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