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Research about Kingdom of Saudi Arabia

Source-linked reports with geographic coverage including Kingdom of Saudi Arabia.

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USGS2023

Overview of the Cenozoic geology of the northern Harrat Rahat volcanic field, Kingdom of Saudi Arabia

The Harrat Rahat volcanic field, located in the west-central part of the Kingdom of Saudi Arabia, is one of the larger Cenozoic harrats among the more than 17 harrats situated upon the Arabia Plate. The map plate contained herein shows, at a scale of 1:100,000, the mapped volcanic geology of northern Harrat Rahat, which consists of the northernmost one-fifth of Harrat Rahat. Northern Harrat Rahat has an area of about 3,340 square kilometers (km 2 ), of which 2,567 km 2 is covered by Harrat Rahat volcanic rocks and deposits, and it encompasses more than 900 exposed vents (that is, craters, cryptodomes, maars, and scoria cones), 289 of which are isolated by younger volcanic deposits and have not been correlated with the 234 volcanic rock units distinguished by geologic mapping. Northern Harrat Rahat is of special interest owing to its proximity to the city of Al Madinah al Munawwarah, which sits within, and is continuing to expand southward over, the north end of the volcanic field. Al Madinah is home to an expanding population, currently at more than 2 million residents, together with the intermittent addition of approximately 3 million pilgrims during Hajj and Umrah (religious visitations). The center of Al Madinah is less than 8 km from lava flows of the only confirmed historically documented eruption, which occurred in 1256 C.E. (654 A.H.). Earlier prehistoric lava flows also encroached into the area of the present-day city limits, as demonstrated by volcanic rocks exposed widely throughout the city in roadcuts, parks, and excavations for new buildings, although no evidence has been found of any other than the 1256 C.E. lava having reached that area during times of human habitation. Geologic mapping was undertaken by the U.S. Geological Survey in collaboration with the Saudi Geological Survey. The features of primary interest within the map area are scoria cones, lava flows, lava domes, craters, and pyroclastic deposits from the Quaternary, which have compositions of basalt, hawaiite, mugearite, benmoreite, and trachyte. The geologic mapping was published by Downs and others (2019) on a single sheet at 1:75,000 scale and two detailed sheets at 1:25,000 scale, accompanied by detailed explanations of the geology. This report presents the geology on a single sheet at 1:100,000 scale and provides condensed geologic explanations for the convenience of readers of this volume. Some minor errors of nomenclature and lava source regions that do not change fundamental interpretations have been corrected herein.

Professional Paper↗
USGS2020

Geologic map of the northern Harrat Rahat volcanic field, Kingdom of Saudi Arabia

Harrat Rahat, in the west-central part of the Kingdom of Saudi Arabia, is the largest of 15 Cenozoic harrats (Arabic for “volcanic field”) distributed on the Arabian plate. It extends more than 300 km north-south and 50 to 75 km east-west, and it covers an area of approximately 20,000 km 2 , has a volume of approximately 2,000 km 3 , and encompasses more than 900 observable vents. Volcanism commenced around 10 Ma and has continued into historic time, the most recent eruption occurring in 1256 C.E. Volcanic products are dominated by alkali basalt and hawaiite lava flows, with subordinate mugearite lava flows, as well as benmoreite and trachyte lava flows, domes, and pyroclastic flows. This geologic map distinguishes 239 eruptive units that cover an area of 3,340 km 2 in northern Harrat Rahat and the adjacent city of Al-Madinah. Results are presented as a geologic map of the study area at 1:75,000 scale and of smaller regions of particular interest at 1:25,000 scale, along with interpretive text. Most units are basaltic lava flows that erupted from the broadly north-northwest-trending main vent axis that constructed the topographic crest of the volcanic field. This 300- to 400-m-high vent axis, which has a width of 6 to 10 km, lies in the eastern one-third of northern Harrat Rahat. Basalt and hawaiite lava flows can extend as far as 27 km from their vents, but most are 10 to 15 km long. Evolved products such as mugearites, benmoreites, and trachytes are less extensive; the trachytic pyroclastic flows extend as far as 9 km from their source vents, although most only reach 4 to 6 km. Vents of the evolved products are restricted to the main vent axis or its flanks. No volcanic rocks older than 1.2 Ma are exposed in the map area, and about 90 percent of the exposed volcanic rocks erupted during the past 570 thousand years. As depicted on the geologic maps, eruption ages and field relations define 12 eruptive stages for northern Harrat Rahat for the past 1.2 million years. Other important geochronological findings include (1) several late Pleistocene lava flows near Al-Madinah, which previously were interpreted as Holocene from archeological evidence; (2) the eruption age of a cluster of cinder cones and small lava flows in the western outskirts of Al-Madinah (previously ascribed to an eruption in 641 C.E.) is actually 13.3±1.9 ka, close to the Pleistocene-Holocene boundary; and (3) only two Holocene eruptions have been identified in the map area, those of the historically described basalt of Al Labah in 1256 C.E. and the dome and pyroclastic flows of the trachyte of Um Rgaibah at 4.2±5.2 ka.

Scientific Investigations Map↗
USGS1981

Status of Regional Gravity Project, Kingdom of Saudi Arabia, as of 1 January, 1979

Regional gravity data have now been obtained for approximately 33 percent of the area of the Arabian Shield, associated harrat areas, and the Red Sea coastal plain. Virtually no surveys have been done on the Phanerozoic platform around the edges of the shield, and although regional gravity coverage is available for the Eastern Province from the Arabian American Oil Company, it is confidential. Approximately 4,500 more gravity stations at 10 km spacing are needed to complete the coverage of the shield, and 5,250 are needed on the Phanerozoic platform to the north and east of the shield. The initial gravity maps compiled from the regional gravity project will be along the "geophysical strip", a band approximately 150 km wide across the shield from Al Qawayiyah to the Farasan Islands. As more data become available, additional maps will be compiled at 1:500,000 scale covering the same areas as the USGS Miscellaneous Investigations Maps 1-700-A to I-220-A. Computer software development and implementation for gravity data reduction, storage, retrieval, and display are 80 percent complete. Development and implementation of software for routine semi-quantitative and quantitative interpretation are 50 percent complete. If the Directorate General of Mineral Resources were to commit full support for the regional gravity project, phase 1 (data acquisition) and phase 2 (data reduction and publication of maps and principal facts) could be completed and phase 3 (interpretation) could be about 50 percent completed by the end of the Third Five Year Development Plan (1985).

Open-File Report↗
USGS1981

Paleomagnetic study of the As Sarat volcanic field, southwestern Saudi Arabia

Four stratigraphic sections through alkali basalt flows of Oligocene-Miocene age (24 to 29 m.y.) in the As Sarat volcanic field, southwestern Saudi Arabia, were sampled for paleomagnetic study. Forty-two magnetically acceptable flows (139 samples) yield a mean direction of magnetization of D=-4.7°, 1=15.2° ( α 95=4.3°), which defines a paleomagnetic pole at 78.8°N, 247.8°E. Of these acceptable flows, 24 are normally magnetized and 18 are reversed. Parts of two sections of flows erupted apparently during the early phases of a polarity reversal of the earth's field. Although the mean paleomagnetic directions determined from each flow do not collectively define a strict Fisherian distribution, the fact that the mean directions for each of the four sections are nearly identical indicates that the overall paleomagnetic pole position is reliable. The magnetostratigraphy can be only generally correlated from one section to another apparently because of a lateral thickening and pinching out of many flows between sections. The dispersion of directions due to secular variation of the upper Oligocene and lower Miocene field (standard angular deviation = 16.2°) is about the same as that produced by the recent field. If the rate of secular change during the time of As Sarat eruption was approximately that of the present, the rate of eruption during several sequences of As Sarat flows is estimated to be one flow about every 100 years. The fact that the mean direction derived from 24 normally magnetized flows is significantly different from that derived from the 18 reversed flows supports the hypothesis of a displaced dipole source for the earth's field in late Oligocene to early Miocene time. The results from As Sarat, as well as those from Aden, compared with paleomagnetic results from Late Tertiary rocks in Africa indicate with 95 percent confidence that the Red Sea has opened at least 2° in the past 5 m.y., and at least 4° in the past 25 m.y. The paleomagnetic results also indicate that the Arabian Peninsula was more equatorial in late Oligocene to early Miocene time than it is now, by an amount compatible with the opening of the Gulf of Aden.

As Sarat volcanic field↗
USGS1979

Mineralization and gossans in the Wadi Wassat-Wadi Qatan region, Kingdom of Saudi Arabia

Very large bodies of stratabound iron sulfides in volcanic rocks of the Wadi Wassat-Wadi Qatan region of Saudi Arabia are capped at surface by numerous iron oxide-rich gossan outcrops. The gossan at Hadbah overlies a low-grade nickel-bearing sulfide body, but most of the sulfide lenses are almost devoid of base metals. Supergene alteration of pyrrhotite-pentlandite has given rise, in profile, to a narrow (<5 m thick) zone of violarite-pyrite (or marcasite) beneath an oxide zone (<35 m deep) of goethite-hematite-silica. Geochemical data show that, despite intensive leaching in the upper parts of the profile, the gossans over the nickeliferous sulfides have higher contents of trace metals than do the gossans overlying pyritic bodies. Both hypogene and supergene textures are well preserved in the gossans; in particular, the presence of very fine-grained pentlandite in the primary sulfide assemblage is precisely recorded by diagnostic replica textures in the gossans.

Wadi Wassat-Wadi Qatan region↗
USGS1979

Airborne gamma-ray spectrometry survey of the Jabal Sayid area, Kingdom of Saudi Arabia

An airborne gamma-ray spectrometer survey covering 2750 km 2 in the Jabal Sayid area, Kingdom of Saudi Arabia, was flown to measure anomalous concentrations of potassium in a known mineral belt. No anomalies were detected over the Jabal Sayid copper prospect, although part of the prospect is within a radioactive, high-dispersion halo associated with the Jabal Sayid granitic pluton. Anomalous potassium concentrations were detected in several areas north of the mine at Mand adh Dhahab and over the rhyolitic rocks of the mine itself. Count-rate ratios of the potassium (K 40 ), uranium (Bi 214) and thorium (Tl 208 ), reached a high of 24:1 for K:Th, and 11.6:1 for K:U. Count-rate ratios over granitic rocks are generally much lower. Areas of anomalous potassium correlate with rhyolitic rocks in some places. Other potassium anomalies have no known explanation, but may reflect unmapped potassium-rich rocks and(or) zones of hydrothermal alteration. These anomalies are considered as potential targets for further exploration, but ground follow-up investigations will be necessary to ascertain the exact cause of the anomalies.

Jabal Sayid area↗
USGS1978

Placer gold deposits in the Mahd adh Dhahab district, Kingdom of Saudi Arabia

Placer gold deposits in the Mahd adh Dhahab district were productive during ancient times, possibly during two periods, about 950 B.C. and 750— 1258 A.D. These deposits were mapped and systematically sampled in 1973 to determine their future potential. The sampling program was facilitated by use of a backhoe which dug 1284 m of trenches and 17 pits. Five hundred and eight samples of surficial material were collected from the trenches and pits, and 78 samples were taken from bedrock exposed in the trenches. Panning tests indicate that 710,910 m 3 of gold—bearing material containing an average of 0.102 g/m 3 gold are available; the total gold content is 72,268 g. Of this volume higher grade zones containing 263,455 m 3 of auriferous detritus are available; this material averages 0.262 g/m 3 gold and contains about 69,000 g gold. This gold could be recovered with simple washing and concentrating equipment. In addition, a substantial amount of lower grade material which might be workable during times of higher gold prices is available in the district. It is concluded that the placer resources in the Mahd adh Dhahab district could form the basis for a small—scale local industry if the gold price is high.

Mahd adh Dhahab district↗
USGS1978

Mineral exploration in the Wadi Bidah district, 1972-1976, Kingdom of Saudi Arabia

Four deposits in the Wadi Bidah district of southwestern Saudi Arabia were explored during the period 1972-1974. The work consisted of geologic, geochemical, and geophysical investigations and diamond drilling in the subsurface. Thirteen holes were drilled, aggregating a length of 2,397 m. Drilling at three of the deposits, Gehab, Sha'ab El Tare, and Rabathan, indicated mineralized reserves aggregating 6,341,000 tons, the average grade of which is 0.95 percent copper. The deposits are strata-bound in volcaniclastic rocks of the Baish Group and in quartz porphyry, all of which are Precambrian in age. The bodies are lenticular in strike and dip, and are offset and broken by postmineral faults.

Wadi Bidah district↗
USGS1978

Raw materials for structural clay products in the Abha-Khamis Mushayt area, Kingdom of Saudi Arabia

Abha and Khamis Mushayt, rapidly growing twin cities in southwestern Saudi Arabia, would benefit greatly by having an indigenous source of structural clay products. Conventional sources of high-quality raw materials, i.e., clay and shale, are lacking in the dominantly igneous and metamorphic terrain. Although not of high quality, colluvium and wadi silts are the most probable sources of raw material for hollow ware. The thick, widespread wadi silts near Hamdah are the largest potential source of raw material, but are 125 km from the market area. The siliceous kaolinite in the As Sarat laterite might be beneficiated to a suitable raw material for ceramic tile by grinding and possibly by addition of kaolinite from near Suleiman.

Abha-Khamis Mushayt area↗
USGS1978

Aggregate resources of the Abha-Khamis Mushayt area: A preliminary report, Kingdom of Saudi Arabia

The area within 30 km of Abha and Khamis Mushayt in the Asir province of the Kingdom of Saudi Arabia is experiencing rapid growth and a corresponding strong demand for construction materials, including aggregate. The major source of aggregate at present is wadi gravels, supplemented by shallow pits in bedrock. A vast quantity of coarse aggregate as yet untouched is readily available near Abha and Khamis Mushayt in the granite, gabbro, and gneiss bedrock that underlie the area. Fine aggregate of high quality is readily available in the major wadis.

Abha-Khamis Mushayt area↗
USGS1978

Preliminary sulfur isotope investigations of mineral deposits in the Precambrian shield, Kingdom of Saudi Arabia

Massive sulfide deposits and sulfide-bearing veins in Saudi Arabia show a wide range in δ 34 S values from very negative to strongly positive and cover almost the entire range observed for ore deposits in nature. Massive sulfide deposits that have very negative values (Wadi Wassat and Wadi Qatan) formed as syngenetic sedimentary deposits in stagnant, euxinic basins. Deposits that have large positive values (Khnaiguiyah and Al Amar) were formed by sea water hydrothermal systems. Gold- and silver-bearing veins whose δ 34 S values fall near 0 permil (Mand adh Dhahab and Samrah) are believed to have derived both sulfur and metals from magmatic sources. Massive sulfide deposits whose δ 34 S values range from slightly negative to slightly positive (Kutam, Al Masane, Wadi Bidah, and Jabal Sayid) are thought to have been formed largely from sea water hydrothermal systems, though deep-seated contributions of sulfur cannot be ruled out. Some deposits in this group (Nuqrah and AT Ridayniyah) appear to have derived their sulfur from volcanic exhalative sources.

Open-File Report↗
USGS1978

Asbestos occurrences in serpentinites of the Hamdah area, Kingdom of Saudi Arabia

A cluster of serpentinite bodies centered at 19°00'N. and 43°45'E., near the village of Hamdah, contain many occurrences of the fibrous asbestos minerals chrysotile and anthophyllite. In the south-central part of the area, near the ancient Hajr gold mine (18°54'45"N. and 43°40'30"E.), the fiber is of fair quality and grade but the estimated quantity is too small to be of commercial interest. Elsewhere in the Hamdah area the serpentinite contains some small concentrations of anthophyllite but only traces of chrysotile.

Hamdah area↗
USGS1977

The Jabal Guyan ancient gold mine, Wadi Malahah quadrangle (sheet 18/43D), Kingdom of Saudi Arabia

Gold occurs in quartz veins and associated altered country rocks at the Jabal Guyan ancient mine in southern Saudi Arabia. The gold-bearing veins follow northwest-trending fault zones which cut the Precambrian metavolcanic rocks of the area. The veins are brecciated, and gold may have been remobilized during cataclasis. A second generation of unbrecciated, barren quartz cements the earlier quartz and also occurs in north-northeast-trending veins. Gold values are greater in waste in the mine area than in vein quartz remaining in the ancient workings, and it is believed that considerable gold was extracted from high-grade ore by the ancient miners. Exploration drilling to determine if veins and alteration zones persist at depth at the Jabal Guyan mine and examination of other ancient mines in the region are recommended.

Wadi Malahah quadrangle↗
USGS1974

Summary of activities, U.S. Geological Survey Saudi Arabian project, 1950 to 1974

The U. S. Geological Survey (USGS) first began work in the Kingdom of Saudi Arabia in 1950 under the sponsorship of the Ministry of Finance and National Economy. The basic objective of the work was to investigate the mineral and water resource potential in western Saudi Arabia, but little was known of the region and it therefore was necessary to prepare geographic and geologic maps. Aerial photographs were taken and controlled mosaics produced, some paid for by the USGS but most paid for by the Saudi Arabian government, and reconnaissance geologic mapping was undertaken until the USGS team left Saudi Arabia in 1955. This mapping, in cooperation with mapping of the Arabian American Oil Company, was compiled as a series of scale 1:500,000 geographic and geologic maps in Arabic and English covering all of Saudi Arabia. A total of 42 of these maps were prepared. Three scale 1:2,000,000 geographic and geologic maps in Arabic and English, covering the Arabian Peninsula, also were prepared from this work. All of the maps were printed in the United States and published by the USGS, the last in 1963. Other work done by the USGS between 1950 and 1955 included locating and examining ancient mines, indentifying the Wadi Fatima oolitic iron deposit and other iron deposits in northwest Saudi Arabia, and advising on many water supply problems including those for Riyadh, Qizan, Qunfudhah, Rabigh, Yenbo, Umm Lejh, and Al Wajh. The mapping work and the geologic investigations laid the groundwork for the more detailed studies that followed.

Open-File Report↗
USGS1974

Nonglacial origin for conglomerate beds in the Wajid Sandstone of Saudi Arabia

Conglomerate beds containing sparse boulders in the upper part of the Wajid Sandstone of Permian or older(?) age have been interpreted as Gondwana glacial deposits (Helal, 1965). These beds, exposed in the Bani Khatmah area near the southeastern edge of the Arabian Shield of Saudi Arabia, contain normally graded polymictic conglomerate, commonly in fluvial channels cut into mature quartz sandstone. None of the features observed suggest deposition in a glacial environment. The conglomerate beds constitute a laterally and vertically restricted facies about 150 km wide in the quartz-sand facies of the Wajid. Recent palynological evidence suggests that the Wajid Sandstone is of Cambrian or Ordovician age. The conglomerate of the Wajid is probably derived from locally uplifted Precambrian rocks in the southern part of the Arabian Peninsula. This is in contrast with an otherwise extensive, stable, deeply weathered, and low-lying Precambrian Shield that was the source of the predominant quartz sandstone of the Wajid during early Paleozoic time.

Open-File Report↗