Geology of the Ruwais 1:100 000 map sheet, 100-28, United Arab Emirates

Goodenough, K.M.; Farrant, A.R.; Thomas, R.J.; Ellison, R.A.; Lee, J.R.; Newell, A.J.. 2012 Geology of the Ruwais 1:100 000 map sheet, 100-28, United Arab Emirates. Nottingham, UK, British Geological Survey, 53pp.

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This Sheet Description describes the geology of the Ruwais 1:100 000 scale geological map. The Ruwais district includes a strip of the UAE mainland along the Gulf coast, extending from Ras al Quilja in the east to beyond Jebal Dhanna in the west, and the island of Sir Bani Yas. This district is particularly important for its exposures of two Hormuz Complex salt domes (Jebal Dhanna and Sir Bani Yas) and for its extensive outcrops of Miocene bedrock, including the type section for the Hamra Member of the Baynunah Formation. The oldest rocks in the area are those of the Neoproterozoic Hormuz Complex, exposed on Jebal Dhanna and Sir Bani Yas. The islands are cored by salt domes with excellent outcrops of the Hormuz breccias. These were mapped at 1:25 000 scale and larger clasts (those 10 m or more across) have been shown on the map (as igneous and sedimentary megaclasts). Both islands contain a range of clasts from <1 cm to over 500 m in size, including limestone, dolomite and both mafic and felsic igneous rocks. These clasts are set in a brecciated evaporitic matrix that varies from massive to well-layered. Away from the salt domes, much of the Ruwais district is underlain by Miocene rocks of the Shuwaihat and Baynunah formations. The lower, Shuwaihat Formation is characterised by red sandstones with subordinate green mudstones and grey pedogenic beds. It typically comprises a number of cyclical sequences deposited in a mixed aeolian-fluvial-sabkha environment. It is overlain by the Baynunah Formation, of which both the Barakah and Hamra members are well-developed in this area. The lower, fluvial, Barakah Member, with its basal bone bed, forms a low plateau to the south of Ruwais. The overlying Hamra Member is only exposed in scattered jebals, with its type section on the coast in the western margin of the district. This member comprises interbedded carbonate siltstones, siltstones and fine sandstones, laid down in a low-energy fluvio-lacustrine system. Quaternary sediments are present throughout much of the area. The Jebal Dhanna Formation, which outcrops only on the salt domes of Jebal Dhanna and Sir Bani Yas, comprises cream-coloured carbonate grainstones and dark-coloured gravels sourced from the underlying Hormuz breccias. The Ghayathi Formation, which is made up of dune-bedded, moderately cemented, carbonate-dominated aeolian sandstones, occurs as isolated areas of outcrop resting on Miocene bedrock throughout the district. Areas of unconsolidated aeolian sand and sand veneer are found across the district. On the coast, deposits of the Abu Dhabi Formation are found in the subtidal, intertidal and supratidal zones, forming a complex suite of spits, bars, tidal flats and lagoons. Inland, along the coastal plain are extensive areas of sabkha.

Item Type: Publication - Book
Programmes: BGS Programmes 2010 > BGS Corporate
ISBN: 9780852727355
Funders/Sponsors: Ministry of Energy United Arab Emirates
Additional Information. Not used in RCUK Gateway to Research.: This item can be purchased from
NORA Subject Terms: Earth Sciences
Date made live: 02 Aug 2012 14:38 +0 (UTC)

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