Geological Aspects of Saudi Arabia Presented By:

slide1. Geological Aspects of Saudi Arabia Presented By:<br>
slide2. Content In the following slide I am covering the following topics;
Origin, Composition and Internal Structure of the Saudi Arabia.
Plate Boundary Interaction
Active Faults
Earth Quake History
Minerals
Sedimentary Rock Deposited
Ground Water<br>
slide3. Land Location The country occupies about four-fifths of the Arabian Peninsula. It is bordered by Jordan , Iraq, and Kuwait to the north; by the Persian Gulf, Qatar the United Arab Emirates and Oman to the east; by a portion of Oman to the southeast by Yemen to the south and southwest; and by the Red Sea and the Gulf of Aqaba to the west. Long-running border disputes were nearly resolved with Yemen (2000) and Qatar (2001); the border with the United Arab Emirates remains undefined. A territory of 2,200 square miles (5,700 square km) along the gulf coast was shared by Kuwait and Saudi Arabia as a neutral zone until 1969.<br>
slide4. The Arabian Peninsula is dominated by a plateau that rises abruptly from the Red Sea and dips gently toward the Persian Gulf. In the north, the western highlands are upward of 5,000 feet (1,500 meters) above sea level, decreasing slightly to 4,000 feet (1,200 meters) in the vicinity of Medina and increasing southeastward to more than 10,000 feet (3,000 meters). Mount Sawda, which is situated near Abha in the south, is generally considered the highest point in the country. Estimates of its elevation range from 10,279 to 10,522 feet (3,133 to 3,207 meters). The watershed of the peninsula is only 25 miles (40 km) from the Red Sea in the north and recedes to 80 miles (130 km) near the Yemen border. The coastal plain, known as the Tihamah, is virtually nonexistent in the north, except for occasional wadi deltas, but it widens slightly toward the south.<br>
slide5. Introduction To The Geological Aspects Of Saudi Arabia The rocks of Saudi Arabia range in age from the Precambrian to the present day, forming part of a larger unit that includes the Arabian Peninsula and is known as the Arabian Plate.
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 evaporates (salt deposits), and volcanic rocks.<br>
slide6. The Precambrian contain most of Saudi Arabia’s known metal deposits of gold, silver, copper, zinc, iron, and magnesium. The Phanerozoic cover contains the oil resources and deposits of bauxite (the source of aluminum), phosphate, clay, limestone, silica sand, and lightweight aggregate that are of increasing importance to the industrial development of the Kingdom.<br>
slide7. Geological Features Saudi Arabia is a vast country occupying most of the Arabian Peninsula. It is bisected by the Tropic of Cancer. Climatically it is mostly dry and arid. Topographically it can be divided into the relatively fiat coastal areas between the Red Sea and the western mountain ranges and a fairly flat central plateau followed by the flat terrain of the eastern region bordering the Arabian Gulf. In the depression to the south lies the vast sand tract of Rub A1-Khali. The geology of the Arabian Peninsula is given in detail by Powers et al. (1966), A1-Sayari and Zoti (1978), Brown and Jackson (1959), Kent (1978) and others. The physical geology and climate conditions in Saudi Arabia are discussed by Oweis and Bowman (1981) and Fookes (1978).<br>
slide8. Saudi Arabia is divided into two basic geological zones. About one-third of the Kingdom is underlain by the Arabian shield (Precambrian Basement Complex) which extends from the western coast for about 500 to 600 km towards the east. The Precambrian rocks of the Arabian shield are mostly igneous and metamorphic. The rocks form a dome-shaped topography and are often covered by thin deposits of alluvial sands and gravels. The sedimentary rocks of the Cambrian and Quaternary ages of the shelf run, with a gentle dip of about one degree, towards the east to the Arabian Gulf and towards the south to the depression of Rub A1-Khali. The sedimentary rocks are mostly limestone sand and silt stones, and shales. The terrain is often covered by loose Aeolian deposits and sometimes with thick residual soils.<br>
slide9. The following is a brief description of the geological aspects and soil characteristics found in the different geographic areas of the Kingdom.
The western areas are mostly mountainous with mountains rising up to 3000 m above sea level. The western coastal plain along the Red Sea is low in elevation and fairly narrow. Owing to favorable marine and climatic conditions, coral cultures grew along the coast during recent geological times giving rise to terraces of coralline limestone.
Further east, the coastal plain rises gently and is mostly granular soils overlying tertiary rocks. In some areas they overlie soft coastal deposits or sabkha flats. he topography suddenly changes with rugged mountains rising steeply to between 2000 and 3000 m above sea level:<br>
slide10. The Tail region is an example of rugged topography with mountains composed of granite and fragments of quartz and diorite.
Even in Taif with the granite base there are geotechnical problems, where subsurface conditions change abruptly within short distances from residual soil into granite .The mountain ranges continue further south to Abha and Najran. In the Abha area, the steep slopes of the escarpment consist of greenstone lava with schists.<br>
slide11. Origin, Composition and Internal Structure of the Saudi Arabia. A self‐consistent regional‐scale model of the crust and upper mantle for the southern Arabian Shield and Red Sea paar has been constructed from an integrated interpretation of seismic deep refraction, regional gravity, aeromagnetic, heat flow, and surface geologic data. The Shield consists of two 20‐km‐thick layers of crust with an average compressional wave velocity in the upper crust of about 6.3 km/s and in the lower crust of about 7.0 km/s. This crust thins abruptly to less than 20 km near the southwestern end of the transect, where Precambrian outcrops abut the Cenozoic rocks, and to 8 km beneath the Farasan Islands.<br>
slide12. The data over the Red Sea westward of Precambrian outcrop are fit satisfactorily by an oceanic crustal model. The major velocity discontinuities occur at about the same depth across the entire shield and indicate horizontal metamorphic stratification of the Precambrian crust. Several lateral inhomogeneities in bulk physical properties have been identified in both the upper and lower crust of the shield, indicating bulk compositional variations. The sub crustal portion of the model is composed of a hot, low‐density lithosphere and Asthenosphere beneath the Red Sea which is systematically cooler and denser to the northeast. This model provides a mechanism that explains the observed topographic uplift, regional gravity anomaly pattern, heat flow, and mantle seismic velocities. Such a lithosphere could be produced by upwelling of hot Asthenosphere beneath the Red Sea which then flows laterally beneath the lithosphere of the Arabian plate<br>
slide13. Plate Boundary Interaction The southern boundary of the Eurasian tectonic plate is characterized by a broad, complex zone of convergence, extending for >15 000 km (>1/3 of the circumference of the Earth) from Gibraltar to westernmost China. The wide boundary zone accommodates the northward motion of the Nubia, Arabia, Indian/Capricorn and Australian plates since >150 Ma, via northward subduction of the Neotethys oceanic lithosphere. This region is among the most seismically active on the Earth, the hazards from which are exacerbated by much of the boundary being subject to great earthquakes,<br>
slide14. with many occurring at shallow depths within the interior of the Eurasian land mass Rates of convergence with respect to Eurasia for the Nubian (NU), Arabian (AR), Indian/Capricorn (IN/CAP) and Australian (AUS) plates (note that the AUS plate east of 130°E converges with the W Pacific plate system). Triangles show the locations of Euler poles with respect to Eurasia. Blue lines show main plate boundaries, dashed where inferred or distributed. The boundaries of the Capricorn Plate are not well defined. Plate name abbreviations: SOM, Somalia; AN, Anatolia; ANT, Antarctica; PAC, Pacific; SA, South America.<br>
slide15. Present-day and long-term relative plate motions The following figure shows velocities and 1-sigma confidence ellipses for GPS sites on Arabia and adjacent plates with respect to a non-rotating Eurasian Plate 
The present-day motion of Arabia and Nubia are well described by an Arabia–Nubia Euler vector (31.5 ± 0.6°N, 25.2 ± 0.7°E, 0.393 ± 0.005° Myr–1), indicating coherent motion of both plates
At the level of present geodetic observations [i.e. ∼1 mm yr–1 or <10 per cent of the rate of Arabia motion with respect to Nubia. The Arabia–Nubia geodetic Euler vector is equal within 1-sigma uncertainties to a plate tectonic Euler vector (31.5 ± 1.2°N, 23.0 ± 2.7°E, 0.40 ± 0.05° Myr–1) derived from magnetic anomalies in the Red Sea<br>
slide16. Motion of a point on the Arabia–Africa plate as a function of time since 59 Ma compared to the geodetic rates extrapolated to this time. Geodetic and plate tectonic rates are equal within uncertainties for Arabia (AR) to >21 Ma and Nubia (NU) to >11 Ma. The convergence rates for NU–EU for different periods are indicated in the inset and illustrated graphically in the following figure.<br>
slide17. The Najd strike-slip fault system The Najd strike-slip fault system extends over the northeastern Arabian Shield in a zone >1200 km in length and >300 km wide. Faults trend NW-SE with strike lengths >500 km but small sinistral displacements of <25 km. Cumulative displacement across the zone is >240 km. Najd faults were active in the late Proterozoic and post-date cratonization of the Shield.
In the southwest of the Najd system, near Zalm, initial faulting was dextral and began earlier than formerly thought. Emplacement of a plutonic complex was controlled by Najd fractures of dextral geometry and displacements.<br>
slide18. The same fractures were active before and after deposition of a group of volcano sedimentary rocks in grabens orientated consistently with development in a dextral strike-slip regime.
Structures in the Zalm area occur throughout the Najd system and the consistent chronology of older dextral structures dislocated and deformed by younger sinistral faults suggests a reversal in the sense of motion of the Najd system as a whole.<br>
slide19. Seismic Zone of Saudi Arabia Arabian peninsula to obtain a preliminary seism tectonic map of the region. The results of the probabilistic seismic hazard assessment indicate that the highest relative predicted ground‐motion occurs near the northwestern border neighboring the Gulf of Aqaba and also near the southwestern border, neighboring Yemen. Based on iso‐acceleration map for 10% probability of being exceeded in 50 years, for the seismic design purposes the Kingdom was delineated into four seismic zones.<br>
slide20. Earth Quakes History Kingdom records 63,000 earthquakes in the past 6 years.
A sequence of shallow earthquakes of magnitudes ≤5.1 took place in 2004 on the eastern flank of the Red Sea rift, near the city of Tabuk in northwestern Saudi Arabia. The earthquakes could not be well located due to the sparse distribution of seismic stations in the region, making it difficult to associate the activity with one of the many mapped faults in the area and thus to improve the assessment of seismic hazard in the region. 
The number of tremors detected by seismic monitors in Saudi Arabia since 2010, until the end of 2015, stood at 62,900, of which, six were strong tremors felt during the years 2011 and 2012, according to the economic reports unit at Al-Eqtisadiah newspaper.Last year, the Kingdom witnessed 5,450 earthquakes compared to 11,000 in 2014, a decline of 54 percent.<br>
slide21. In terms of magnitude, about 95 percent of the total number of the earthquakes witnessed in the region from 2010 until 2015 were less than a 1-2 magnitude on the Richter scale, which means that almost 59,700 earthquakes were not felt on the surface, but were nonetheless registered on seismic devices. A proportion of 4 percent of the earthquakes, about 2,670, were of a magnitude of 2-3 on the Richter scale and people closest to the epicenters felt them.
Meanwhile, 311 earthquakes, measuring 3-4 on the Richter scale, were small tremors felt by those closest to the epicenter, and mostly they did not wreak any havoc or cause damages. WHEN EARTH SHAKES: The five-mile-long (8-km-long) rupture produced by the May 19, 2009, earthquake in Saudi Arabia<br>
slide22. Saudi Arabia Mineral Resources Mineral deposits in Saudi Arabia are widespread and of many types, ranging from gold to lightweight aggregate. The bulk of metallic mineral resources are contained in Precambrian rocks of the Arabian shield, in the western part of the country.
Non-metallic resources are contained in both Precambrian rocks and Phanerozoic rocks that overlie the Arabian shield in the central and northern parts of the Kingdom..
 The chief metallic mineral resources include:
Gold 
Zinc 
Copper 
Tin-Tungsten<br>
slide23. The chief non-metallic resources include:
  Phosphate 
High-grade silica sand 
Feldspar and nepheline syenite      Kaolin      Basalt and scoria      Gypsum and anhydrite      Limestone and dolomite      Ornamental stone      Quartz<br>
slide24. Saudi Arabia's Great Thirst/ Ground Water Recourses DRAINED DRY:
When intensive modern farming started, there was a staggering 120 cubic miles (500 cubic kilometers) of water beneath the Saudi desert, enough to fill Lake Erie in the U.S. But in recent years, up to 5 cubic miles (21 cubic kilometers) has been pumped to the surface annually for use on the farms. Virtually none of it is replaced by the rains, because there effectively are none. The Saudis were on track to use up at least 96 cubic miles (400 cubic kilometers) of their aquifers by 2008. Experts estimate that four-fifths of the Saudis' "fossil" water is now gone.<br>
slide25. FARMING THE DESERT
There are no rivers or lakes or areas of abundant natural vegetation because rainfall is scant to non-existent. Over the centuries, through oases and then desalination plants, the Saudi people have found enough water to support their daily lives. But a relatively recent national effort has brought changes to the desert and created much greater demands for water resources. Zooming in on certain areas shows that there are indeed regions of intense greenery that nature did not create. Saudi men visit the Ain Zubaida archaeological site in the Muslim holy city of Mecca on October 22, 2012. The wells of Ain Zubaida served Muslim pilgrims for hundreds of years as an essential water source in the desert region<br>
slide26. Groundwater in Gulf countries is running out because they have some of the highest levels of water consumption per capita in the world, Saudi newspaper Al-Watan Arabic daily reported. Daily water per person is reported to be 265 liters in Saudi Arabia, double the EU average.<br>
slide27. The End<br>