Saudi Arabia is geologically divided into four distinct and extensive terrains: (1) the Precambrian Proterozoic Arabian Shield, comprising metamorphosed volcanosedimentary successions intruded by granite and gabbro: (2) the Phanerozoic Arabian platform (cover rocks) of clastic, calcareous and evaporitic successions dipping gently eastward away from the shield: (3) the Tertiary "harrats" (extensive basalt plateaus) mainly overlying the shield: and (4) the narrow Red Sea coastal plain of Tertiary and Quaternary sedimentary rocks and coral reefs.
The sedimentary rocks to the east and north of the Precambrian Proterozoic Arabian Shield cover almost two-third of the total area of Saudi Arabia. The younger rocks in Saudi Arabia belong to the Paleozoic (540-250 Ma), Mesozoic (250-65 Ma), and Cenozoic (65 Ma to Recent) (collectively referred to as Phanerozoic cover), and crop out as relatively flat lying beds of sedimentary rocks such as sandstone, siltstone, limestone, and evaporites (salt deposits), and volcanic rocks. The rocks were deposited unconformably on the underlying Precambrian basement, in riverbeds, in glacial valleys, and in shallow seas, or were extruded from subaerial volcanoes. The rocks north and east of the Arabian shield are referred to as the Arabian Platform; those on the shield are mainly harrat (fields of Cenozoic flood basalt); and those west of the shield are Cenozoic rocks that occupy the Red Sea basin. The youngest deposits in the region include coral limestone and unconsolidated sand, silt, gravel, and sabkha, which accumulated in the sand seas of Ar Rub al Khali and An Nafud, filled dried-up lake beds and wadis, and fringed the coastlines.
Simplified geological map showing the main sedimentary rock main types in the eastern and
the northern parts of the kingdom of Saudi Arabia
Sedimentary geology is a one of the core business of the Saudi Geological Survey. The Sedimentary Geology Section in SGS prepares geologic maps of the continental shelf of the Kingdom of Saudi Arabia, which is bordering the eastern edge of the Arabian shield, and is fully covered of Phanerozoic sedimentary rocks.
The general geological map of the Arabian Peninsula
It is a science used to examine rock formations. It helps to determine the types, classification, criteria, geologic age of rocks, their contents of Phanerozoic fossils.
Moreover, it helps to determine the areas of geologic hazards are inherent characteristics of solution features exist in carbonate and evaporite formation terrains that may be caused by dissolution karst phenomena, including sinkholes, caves, and regional depressions of subsidence phenomena caused by interstratal dissolution of evaporite beds in the 'Arab and Hit Formations land slide or land subsidence.
The Saudi Geological Survey is the only body in the country that conducts studies and research related to the stratigraphic column, and is responsible for updating it continuously, based on new discoveries that may be achieved through the completion of implemented series of geological maps, with scale 1: 250 000. Handled by the SGS since its establishment, SGS chairs the National Committee for the Stratigraphic Column of the Kingdom, which includes representatives of Saudi universities as well as Saudi Aramco.
SGS is doing emulation studies, in the field of sedimentary rock geology, located within the territory of the Kingdom. The study is on rocks located in the territory, and are extending in the neighboring countries, to identify the extensions and variations on both sides of the border with these countries. SGS is participating in a regional project with the Jordanian Natural Resources Authority to carry out emulation studies on the geology and fossils in the area overall border between the two countries.
The Section is in the process of completing a series of maps on sedimentary rocks in the remaining quadrangles with scale 1: 250, 000. These quadrangles contain Phanerozoic rocks, that lie in an area of about one degree wide, and one and a half degree long. The formations may be covered also with Proterozoic rocks existing at the edges of the eastern Arabian Shield. Besides, the study shall cover the geologic characteristics of the formations. Usually, locations of mineral and industrial rocks are shown on these maps.
Studies of structural features that have direct relations with subsidence and caving phenomena caused by interstratal dissolution of evaporite beds formations and karstification of carbonate beds formations, and may pose danger for humans and their property. SGS also provides oil companies in the Kingdom with the results of these studies.
All these types of studies, maps, and technical reports are available for the scientific centers, universities, and government agencies.
Key elements of sedimentary geology:
- Completion of a series of geological maps on sedimentary cover at scale of 1: 250, 000.
- Determination of sedimentary layers age, through the study of what might contain fossilized remains.
- To prepare and develop the stratigraphic column of the Kingdom of Saudi Arabia.
- To print and publish geological maps in digital and hard copies.
The current status of the mapping projects at scale of 1 : 250.000
The published digital geological maps:
1) Geologic map of the Wadi as Sirhan quadrangle, sheet 30 C, Kingdom of Saudi Arabia: Saudi Geologic Survey Geoscience Map GM-127, 27 p., scale 1:250, 000. Wallace, C.A., Dini, S.M., and Al- Farasani., A.A, 2000a,
2) 2. Geologic map of the Thaniyat Turayf quadrangle, sheet 29 C, Kingdom of Saudi Arabia: Saudi Geological Survey Geoscience Map GM-129C, 32 p., scale 1:250, 000. Wallace, C.A, Dini, S.M, and AL- Farasani., A.A, 2000b,
3) Geologic map of the Jibal at Tubayq quadrangle, sheet 29B Kingdom of Saudi Arabia: Saudi Geological Survey Geoscience Map GM-133C, 36 p., scale 1:250, 000. Wallace, C.A., Dini, S.M., and Al-Farasani, A.A., 2001.
4) Geologic map of the Hizm al Jalamid quadrangle sheet 31 D, and part of the Markaz 'Anazah quadrangle, sheet 32D, Kingdom of Saudi Arabia: Saudi Geological Survey Geoscience Map GM-124C, 34 p., scale 1:250, 000. Wallace, C.A., Dini S.M., and Al-Farasani, A.A., 2002.
5) Geologic map of parts of the Judayyidat 'Ar'ar quadrangle, sheet 31 E, and of the Faydat al Adyan quadrangle, sheet 31F, Kingdom of Saudi Arabia: Saudi Geological Survey Geoscience Map GM- 140C, 45 p., scale 1:250, 000. Dini, S.M., Al-Khattabi, A.F., Wallace, C. A., Banakhar, A.S., Al-Kaff, M.H., and Garni, S.M, 2007.
6) Geological map of the As Sulayyil quadrangle, sheet 20 H, Kingdom of Saudi Arabia: Saudi Geological Survey Geoscience Map GM-141C, 64 p., scale 1:250, 000. Dini, S.M., Wallace, C.A., Halawani, M.A., Al-Sobhi, S.A., Kashgari, W.A., and Al- Ghamdi, A.S., 2009.
Digital geological maps under production processes
1) Geologic map of the 'Ar'ar quadrangle, sheet 30 E, Kingdom of Saudi Arabia: Saudi Geological Survey Geoscience Map GM-142C, scale 1:250, 000. Al-Khattabi, A.F., Dini, S.M., Wallace, C. A., Banakhar, A.S. and Al-Kaff, M.H., 2011.
2) Geologic map of the Hawtat Bani Tamim quadrangle, sheet 23 I, Kingdom of Saudi Arabia: Saudi Geological Survey Geoscience Map GM-143C, scale 1:250, 000. Memesh, A.M., Dini, S.M., Wallace, C. A., Al-Amoudi, S.A., Al-Sobhi, S., A., and Al-Juaid, A., J., 2011.
3) Geologic map of the Markaz 'Adhfa' quadrangle, sheet 29 E, Kingdom of Saudi Arabia: Saudi Geological Survey Geoscience Map GM-144C, scale 1:250, 000. Banakhar, A.S., Al-Zahrani, A., M., Al-Juaid, A., J., Dini, S.M., Wallace, C. A., Al-Kaff, M.H., and Al-Tassan, A., A., 2011.
4) Geologic map of the Rumah quadrangle, sheet 25 I, Kingdom of Saudi Arabia: Saudi Geological Survey Geoscience Map GM-145C, scale 1:250, 000. Memesh, A.M., Dini, S.M., Bamousa, A. O., Al Amoudi, S.A., Al Juaid, A.J., and Al-Tassan, A.A, 2012.
The draft geological map of the 'Ar'ar quadrangle, sheet 30 E, Kingdom of Saudi Arabia (under production).
Projects under implementation:
1) Preparation of a geologic map of Al Artawiyah quadrangle.
Al Artawiyah quadrangle is located in the Riyadh region bounded by lat 26° 00' N and 27° 00' N., and long 45° 00' E and 46° 30' E.
The project is also designed to complete a geologic map, covering the sedimentary rocks of the Mesozoic and Cenozoic eras in the Kingdom area, and to determine the occurrences of industrial minerals (silica sand, gypsum, pure limestone for cement production etc.).
2) Preparation of a geologic map of Linah Quadrangle :
Linah quadrangle is located in the north of Saudi Arabia in the northern frontier region, bounded by lat. 28° 00' N and 29° 00' N., and long 43° 30' E and 45° 00' E.
The project aims at the completion of the geologic maps covering the sedimentary rocks of the continental shelf of the Mesozoic and Cenozoic in the Kingdom, and to determine the presence of industrial minerals (such as silica sand, gypsum, limestone suitable for the manufacture of pure cement and other mineral resources).
3) A Review of the biostratigraphy and lithostratigraphy of the Phanerozoic rock units along the border between the Kingdom of Saudi Arabia, and the Hashemite Kingdom of Jordan.
The project aims to correlate the rock units and divisions of geological terms of age and content of the rock and fossils, and to unify the classification bases of these units in the Kingdom of Saudi Arabia and the Hashemite Kingdom of Jordan. The duration of the project is three years from 2009 to 2011.
The study has so far resulted in identifying a number of geological formations, which were not, previously, known in the stratigraphic records of the two countries.
Satellite image, showing the joint area of the geological correlation project, along the border strip between the Kingdom of Saudi Arabia and the Hashemite kingdom of Jordan.
4) In the study of the stratigraphic sequence of the Kingdom, the report of the Paleozoic rocks has been completed, and is now under the process of technical review.
The study area of the reviewing of the biostratigraphy and lithostratigraphy of the Phanerozoic rock units
between the Kingdom of Saudi Arabia, and the Hashemite Kingdom of Jordan
Draft of the Geological Compilation Digital Map of Saudi Arabia at scale of 1 : 1,000,000
The aim of this project is creating the first compiled map of the entire Saudi Arabia in digital form at scale of 1 : 1,000,000. The previous digital map at scale of 1:1000,000 of the Arabian shield published by Dr. Peter Johnson (2006) will be used as an essential map for the Arabian shield that covering the western part of the Saudi Arabia, and the old published digital map at scale of 1:2,000,000 that produces by USGS (1972) will be used partly and temporally to fill full the Phanerozoic stratigraphy unites that covering the remaining parts of Saudi Arabia.
The Published digital maps for the Phanerozoic stratigraphy and sediments at scale of 1:250,000 will be particularly comprehensive for the main target of this compilation and will draw heavily on the use of computer-bases methods of data retrieval, remote sensing, and Arial photos for correlation and compilation using particularly the Geographic Information System (GIS) techniques to generalized the litho-stratigraphic unites to match the produced map scale.
The goal of this work, which will occur as ongoing efforts, will yield a series of updated information delivered from this compiled data of the 1:250,000 scale maps products to aid in the recognition and update of the geological Phanerozoic environments of known stratigraphic unites, and substituted the old data of the older USGS Map.
It is hoped that this compilation, and the consequence versions products that will be generated form the foundation of new information that will be available from the upcoming mapping projects of the Panerozoic stratigraphy, and will organize and prepare the required data infrastructure to produce the first national geological map of Saudi Arabia at scale of 1 : 1,000,000.
The effort has been inspired since more than 15 years that was the launch date of the creation of the digital geological maps that covering the Arabian shield at scales of 1:500,000 and 1,000,000 by Peter Johnson (2006), and the launch date of creating the Phanerozoic stratigraphic digital maps at scale of 1:250,000, which was the culmination of more than 35 years of mapping activities in the Saudi Arabia, and which included contributions from DMMR, USGS, BRGM, and SGS.
SGS will be the principal funding organization for this sub-project over its operating time, and will provide considerable human and other resources, with the goal of producing a product at 1:1,000,000 scale, in both digital and hard copy formats. The geologic map sub-project is the result of the initiative of the SGS ongoing and the upcoming geological mapping projects of the current and the coming fifth national plans.
The map will be a unique product in that it will depict the distribution of the Litho-stratigraphy for the entire Kingdom of Saudi Arabia. All possible stratigraphic unit that applicable for this scale will be shown on the map, and will be compiled digitally, making use of Geographic Information Systems (GIS) techniques. The database model will consist of various data layers, and will include topography, structure, and lithological information as well as information on the major Kingdom’s mines and mineral deposits. Aside from the scientific and cultural value of the geological map of the Kingdom, the data contained in the map and database will assist to attract any new information into the continent’s geological survey sector and will contribute to scientific and economic development and integration.
The work of this project has been concentrated on integrating, assembling, matching, and linking implemented digital information of geological maps, which were produced during the previous periods of already implemented projects. Those projects are designed for the production of a series of digital maps, and to transform existing paper maps into digital ones. The end goal of this process is to produce the first digital map for the Kingdom with scale 1:1, 000, 000.
Work has started on this project during the year 2008. Its estimated duration is five years, taking into account the work of the continuous process needed to update such information.
Geotechnical structure of the project, with respect to maps of the continental shelf in Saudi Arabia:
- Outputs of the implementation of a series of the geologic maps of the continental shelf at 1: 250, 000 scale.
- Outputs of studies and correlation of geologic maps produced from both sides of the border between Saudi Arabia and Jordan.
- Outputs of works of updating the stratigraphic column of the Kingdom.
- Outputs of the geomorphologic directory of the territory of the Kingdom
- Output of conversion of paper maps into digital ones.
The Accomplished Works:
- During 2009, the work was concentrated on completing the Standard Attribution Table, which will cover the technical information of the compilation map of the Kingdom, which will include the full information related to rocks and geologic formations of the Precambrian Arabian Shield, the geologic formations of the Panerozoic sedimentary cover rocks, and the lava flows of the Tertiary-Quaternary age.
- Rock unit edges were fully cleaned after identification of a number of technical errors, seen in the overlap and the intersection of the edges of some geologic formations over the edges of other formations, since such cases may result in technical problems during the stages of merging and generalization. These are subsequent operations necessary for the conversion of the large scales to smaller scales, which is the case in this project.
- A table of updating Litho_Code was made for the whole Phanerozoic rock units. This table shall be used during the operations of merging and compilation for the final product as it is present in the original map, in order to facilitate reference to it at any time.
- A preliminary generalization process was made for the compilation of rock units, in accordance with the Litho_Code which depended in its denotation on the period, and formation only and ignored the members, the parts and levels of some formations such as (Upper, Middle, and Lower). This is an optional experimental stage made only for testing its suitability with the targeted scale. i.e. 1:1, 000, 000. This process requires additional effort, and an in-depth study by experts. It was scheduled to take place during 2010. Because there are some units that may be neglected or may have a scientific or an economic importance, or may be having spaces and extensions of appropriate area that may appear and suit the targeted can appear and commensurate with the scale target scale,
- The work on some parts of the Phanerozoic cover rocks, that were not yet mapped, were completed by making a digital map of the Arabian peninsula, produced by the U.S. Geological Survey (1972), at scale 1: 2,000,000 . They were obtained in digital form from the site of the (Saudi) Department of Survey.
- Due to the lack of a comprehensive table of descriptive information for the above-mentioned map, a technical treatment was made by deducing the guides of these codes with other similar sedimentary rock maps, and the missing information was filled in. This is a very critical job, and must be noted in the final report, due to the high rate and level of mistakes in it. However, this may be a normal thing due to the small size of the scale. It is a temporary stage, which may be corrected continuously, with the continuation of projects of the sedimentary cover rock maps prepared by SGS to replace this information.
- A linking process, of the map of the edges of the Arabian Shield, with the corresponding rock and sedimentary rocks units of the sedimentary cover, was made. in accordance with the available data, and this linking process will be reviewed and revised during the next year, since they need technical studies, and field trips by specialists from the project members, to complete the linking process to suit the scale target.
- Correlation tables were prepared to compare the nomenclature, and Litho_Code symbols of sedimentary rock units with the original nomenclature from their sources in the topographic maps, and from those of the Encyclopedia of the names of places in the Kingdom (Mohammad Rashed, Abdullah Onaizan)
- During the year 2009, a merge or link of all information of the digital maps available until the end of year 2009, was made in a geologic map and a single scale of 1: 1, 000, 000. This is a preliminary map for the project, as a result of the integration of information of the digital maps which are currently available at the SGS.
Part of the attribution table elements for the digital compilation map project
The primary draft geological map layout of Saudi Arabia at scale of 1 : 1,000,000
The work program also includes the preparation and the following work details:
- Updating and compiling the newer geosciences data (tectonic, structure, lithology, genesis ….etc.)
- Treat and generalized the large scale maps of the Phanerozoic to be part of the Geological compilation map of the Kingdom of Saudi Arabia at scale of 1 : 1,000,000.
- Remapping quadrangles in the northern east of the edge of Arabian shield, located between latitude 26° 00¢N -30° 00¢N, longitude 34° 30¢E - 40° 30¢ E
- Preparation of the required basemap (topographic, geologic base, … etc.)
- Creating the legend of the compiled litho-stratigraphic Map (geologic base legend, symbols, .. etc.)
A map slices showing the mismatching units at the boundary between the completed geological map
of the Arabian Shield and the adjacent Phanerozoic GM maps in the northern part.