The geology of the United Arab Emirates includes very thick Paleozoic, Mesozoic and Cenozoic marine and continental sedimentary rocks overlying deeply buried Precambrian. The region has extensive oil and gas resources and was deformed during the last several million years by more distant tectonic events. [1]
Atop the crystalline and igneous metamorphic basement rock of the Arabian Shield, Huqf Group clastics, carbonates and evaporites are the oldest sedimentary rocks in the UAE. Throughout the Paleozoic, the region experienced mainly clastic deposition. Carbonates are rare, except from the Cambrian, early-middle Devonian and early-middle Carboniferous. Jebel Dhanna in Abu Dhabi and the offshore islands of Dalma, Arzana, Zirkouh and Das have some of the oldest surface exposures: dolomite, shale and volcanic rocks brought to the surface by salt tectonics. The Hercynian orogeny affected the Middle East Craton in the Late Carboniferous, driving erosion and warping. Clastics deposited on the unconformity left by the erosion through the Permian, principally sandstone, siltstone, anhydrite and dolomite. [2]
With the formation of the supercontinent Pangea, the area became more arid in the Permian into the Triassic. Shallow water carbonates and evaporites belonging to the Khuff Formation deposited during a marine transgression, with microcrystalline dolomite, limestone and anhydrite up to 2.9 kilometres (1.8 miles) thick and recording five marine regressions. With the westward uplifting of the region, it was succeeded by the Sudair Formation (dolomite, argillaceous limestone, shale and anhydrite) and the Gulailh and Jilh formations (offshore and on-shore in Abu Dhabi respectively). A full scale marine regression is recorded in the clastic lacustrine sandstones and limestones of the Minjur Formation.
A very large carbonate platform took shape during a major marine transgression in the Jurassic, leaving behind the Hamlah Formation greywacke and mudstone from the early Jurassic, the middle Jurassic Araej Formation and the oolite dominated Asab Formation in the east. In the 1960s and 1970s, oil companies described the Thamama Group.[ citation needed ]
The early Cretaceous is marked by the fossil-bearing Shuaiba Formation, which contains breccia and mollusk-rich limestone as well as ammonite fossils. The Middle Cretaceous Wasia Group, including the Nahr Umr, Salbikh and Mishrif formations occurs between Abu Dhabi and Qatar and deposited during a time of moderate uplift and erosion. As a result, the Nahr Umr Formation contains glauconite sands, shale, small phosphates and some limestone. However, a marine transgression took place by the time of the Mauddud Member deposition. The thick limestone sequence of the Mishrif Formation deposited in the Shilaif Basin, with a thickness of 1,600 feet (490 metres) in the west offshore and 865 ft (264 m) in the Umm Addalkh field. The packstone, greywacke and limestone contains abundant rudist fossils. The Aruma Group marks two successive transgression-regression events in the late Cretaceous, with the Laffan Formation argillaceous limestone and the Halul Formation calcareous shale and lime-mudstone from the first event and the marl-shale-mudstone Fiqa Formation and greywacke-dolomite Simsima Formation from the second event. [3]
A disconformity appeared with a drop in sea level in the Cenozoic. In the Paleogene, the Qatar Arch was comparatively stable and Abu Dhabi was at the edge of the Rub al Khali and Pabdeh-Gurpi (centered in the North Emirates) basins. The Hasa Group includes Umm Er Radhuma, Rus and Dammam formations. The Pabdeh Formation is largely offshore and contains 2,200 feet (670 metres) of shale and argillaceous limestone.
The Umm Er Radhuma Formation ranges from 1150 feet in the northwest to 2300 in the east with limestone, dolomite, argillite, sabkha cycles, shale and anhydrite. Evaporite formed in the early Eocene leaving the 200 to 840 foot Rus Formation which also includes minor argillaceous limestones. A return to lower salinity and shallow marine conditions in the Middle Eocene deposited the nummulitic carbonates of the Dammam Formation, as well as dolomite and subordinate shales. Uplift and erosion affected the region into the Oligocene. The partially dolomite, and fossiliferous limestone dominated Asmari Formation emplaced in the far east, followed by the 400 to 2,800 feet (120 to 850 metres) Gachsaran Formation from the early Miocene, with anhydrite and dolomite, ascending to dolomite, limestone, anhydrite, shale, marl and other carbonates. The Gachsaran depocenter was located in onshore Abu Dhabi.
During the late Miocene and into the Pliocene, the Alpine Orogeny which uplifted the Alps and the Himalayas affected the region, uplifting the Omani and Zagros Mountains and driving significant erosion. Muds, sabkha deposits, windblown sand, conglomerate limestone, beach gravel and silt are all defining sediments of the past 2.5 million years of the Quaternary. [4]
On the country's eastern border with Oman are the Western Hajar Mountains: [5]
The highest mountains in the Emirates, located entirely within its territory, or with its peak located exactly on the border with Oman, are the following:
The United Arab Emirates is situated in the Middle East and West Asia, bordering the Gulf of Oman and the Persian Gulf, between Oman and Saudi Arabia; it is at a strategic location along the northern approaches to the Strait of Hormuz, a vital transit point for world crude oil. The UAE lies between 22°50′ and 26° north latitude and between 51° and 56°25′ east longitude. It shares a 19 km (12 mi) border with Qatar on the northwest, a 530 km (330 mi) border with Saudi Arabia on the west, south, and southeast, and a 450 km (280 mi) border with Oman on the southeast and northeast.
Ras Al Khaimah (RAK) is the northernmost of the seven emirates that make up the United Arab Emirates. The city of Ras Al Khaimah, abbreviated to RAK or RAK City, is the capital of the emirate and home to most of the emirate's residents. It is linked to the Islamic trading port of Julfar. Its name in English means "headland of the tent". The emirate borders Oman's exclave of Musandam, and occupies part of the same peninsula. It covers an area of 2,486 km2 (960 sq mi) and has 64 km (40 mi) of beach coastline. As of 2023, the emirate had a population of about 400,000.
The Musandam Peninsula, locally known as Ruus Al Jibal, is a peninsula that forms the northeastern point of the Arabian Peninsula.
Jabal Hafeet is a mountain in the region of Tawam, on the border of the United Arab Emirates and Oman, which may be considered an outlier of the Hajar Mountains in Eastern Arabia. Due to its proximity to the main Hajar range, the mountain may be considered as being part of the Hajar range. To the north is the UAE city of Al Ain, in the Eastern Region of the Emirate of Abu Dhabi, and the adjacent Omani town of Al-Buraimi.
Jabal Al-Mebraḥ, also known by the name Jabal Yibir, is a 1,527 m (5,010 ft) tall mountain in the Emirate of Fujairah, the U.A.E.
The Haynesville Shale is an informal, popular name for a Jurassic Period rock formation that underlies large parts of southwestern Arkansas, northwest Louisiana, and East Texas. It lies at depths of 10,500 to 13,000 feet below the land’s surface. It is part of a large rock formation which is known by geologists as the Haynesville Formation. The Haynesville Shale underlies an area of about 9,000 square miles and averages about 200 to 300 feet thick. The Haynesville Shale is overlain by sandstone of the Cotton Valley Group and underlain by limestone of the Smackover Formation.
Jebel Jais is a mountain of the North-Western Hajar range in the Musandam Governorate of Oman and also in Ras Al Khaimah, United Arab Emirates. The summit has an elevation of 1,934 m (6,345 ft). The summit is located on the Omani side, but a high point west of this peak is considered the highest point in the United Arab Emirates, at 1,892 m (6,207 ft) above sea level, and with around 10m of prominence. Since the summit is on the Omani side, Jabal ar Raḩraḩ, at 1,892 m (6,207 ft), is the highest peak in the UAE, with significant prominence.
The Hajar Mountains are one of the highest mountain ranges in the Arabian Peninsula, shared between northern Oman and eastern United Arab Emirates. Also known as "Oman Mountains", they separate the low coastal plain of Oman from the high desert plateau, and lie 50–100 km (31–62 mi) inland from the Gulf of Oman.
Jabal Ar Rahrah is a peak in the Hajar Mountains, northeast of the United Arab Emirates, in the Emirate of Ras Al Khaimah. It has a height of 1,691 metres, and is situated entirely within the United Arab Emirates, at the coordinates 25.94419°N, 56.15219°E.
Jabal Rahabah, is a peak in the Hajar Mountains, northeast of the United Arab Emirates, in the Emirate of Ras Al Khaimah. At 1,543 m (5,062 ft), it is one of the highest peaks in the UAE, located entirely within the territory of the Emirates
The Wadi Jib is a valley or dry river, with intermittent flow, which flows almost exclusively during the rainy season, belonging to the drainage basin of Wadi Bih, north-east of the United Arab Emirates (UAE), in the Emirate of Ras Al Khaimah.
The Wadi Litibah is a valley or dry river, with intermittent flow, flowing almost exclusively during the rainy season, located northeast of the United Arab Emirates, in the Emirate of Ras Al Khaimah.
The Wadi Arus is a valley or dry river, with intermittent flow, which flows almost exclusively during the rainy season, belonging to the river basin of Wadi Bih, north-east of the United Arab Emirates (UAE), in the Emirate of Ras Al Khaimah.
Jabal Al Harim or Jebel Al Harim is a peak located in the Hajar Mountains range, north of the Sultanate of Oman, in the Musandam Governorate.
The Wadi Khabb Shamsi, is a valley or dry river, with ephemeral or intermittent flow, flowing almost exclusively during the rainy season, located west of the Musandam Governorate, in the Sultanate of Oman.
Jebel Qihwi or Jabal Qa'wah, along with the Jabal Al Harim and Jabal Bil Ays / Jebel Jais, are the three highest and most representative mountains of the Musandam Governorate, in Oman.
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