Stratigraphic evolution and depositional system of Lower Cretaceous Qishn Formation, Dhofar, Oman
Published:January 01, 2014
O. Salad Hersi, I. A. Abbasi, A. Al-Harthy, A. Cherchi, R. Schroeder, 2014. "Stratigraphic evolution and depositional system of Lower Cretaceous Qishn Formation, Dhofar, Oman", Tectonic Evolution of the Oman Mountains, H. R. Rollinson, M. P. Searle, I. A. Abbasi, A. I. Al-Lazki, M. H. Al Kindi
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The Barremian(?)–Aptian Qishn Formation of Dhofar (Oman) is represented by eastward (landward) thinning strata that onlap Marbat palaeohigh basin margin. The formation includes Shabon, Hinna and Hasheer members, in ascending order. The Shabon Member consists of massive and cross-bedded, locally conglomeratic arkose and quartzarenite. The Hinna Member has a lower part of rhythmically arranged bioclastic wackestones/mudstones that grade to fine crystalline dolomudstone and an upper part of cyclic units of nodular, marly, rudistic floatstone/rudstone lithofacies capped by normally grading, intraclastic, bioclastic packstone/grainstone lithofacies. Mudcracks, teepee structures and microbial laminations occur in the lower part. The member terminates with 10-m-thick discoidal orbitolinid- and rudist-bearing marls envisaged as the deepest facies of the formation. The Hasheer Member consists of partly dolomitized strata of bioclastic packstones, grainstones and rudstones. Cross-bedding and erosional surfaces are present. The overall depositional system of the formation evolved from high-energy clastic-dominated, marginal marine environment through tidal carbonate mudflat and lagoonal setting to high-energy carbonate sand shoals. The overall stratigraphic arrangement of the formation suggests a third-order transgressive-regressive system with superimposed fourth- and fifth-order cycles. Shabon and Hinna members represent lowstand to transgressive systems tracts whereas Hasheer Member represents highstand to falling stage systems tracts. Terminal platform-wide exposure resulted in an unconformity at the Qishn–Kharfot contact.
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Tectonic Evolution of the Oman Mountains
The Oman Mountains contain one of the world's best- exposed and best-understood fold–thrust belts and the largest, best-exposed and most intensively studied ophiolite complex on Earth. This volume presents new international research from authors currently active in the field focusing on the geology of the Oman Mountains, the foreland region, the carbonate platforms of Northern and Central Oman and the underlying basement complex. In addition there is a particular focus on geoconservation in the region. The volume is divided into three main sections that discuss the tectonics of the Arabian plate using insights from geophysics, petrology, structural geology, geochronology and palaeontology; the petrology and geochemistry of the Oman Ophiolite and the sedimentary and hydrocarbon systems of Oman, drawing on the geophysics, structure and sedimentology of these systems. The volume is enhanced by numerous colour images provided courtesy of Petroleum Development Oman.