Southwestern Arabia Research Articles

A new polytypic species of the genus Uromastyx MERREM 1820 (Reptilia: Squamata: Agamidae: Leiolepidinae) from southwestern Arabia

We describe Uromastyx yemenensis sp. nov. from south-western Arabia, comprising two geographic subspecies, U. y. yemenensis and U. y. shobraki ssp. nov. The new species is a member of the Uromastyx ocellata species group, closely related to U. benti. It is differentiated from its sister taxon by smaller scales around midbody and smaller ventrals. The new species is restricted to the extreme south-western tip of the Arabian Peninsula. The western populations of U. yemenensis differ genetically and are constantly distinct in respect to their colour pattern and are therefore recognized as a subspecies.

The Anelastic Attenuation of Surface Waves Beneath Southwestern Arabia and the Southern Red Sea

The seismic attenuation coefficients of surface waves in southwestern Arabian Peninsula and the southern Red Sea were inves- tigated using the station ratio method. Love and Rayleigh waves data recorded by two GSN stations RAYN and ATD are used to compute Love and Rayleigh waves attenuation coefficients (γ L and γ R ), and Love and Rayleigh waves internal friction (Quality factors, Q L and Q R ) in the region between the two GSN seismic stations RAYN and ATD. RAYN lies at the center of Arabia, while ATD is located on the western coast of the southern Red Sea on the Afar depression. γ R is found to vary from a low of 4.03 × 10 -4 km -1 at 27 s and a high of 22.9 × 10 -4 km -1 at 44 s. γ L , on the other hand, varies between a mini- mum of -2.28 × 10 -4 km -1 at 6 s and a maximum of 10.81 × 10 -4 km -1 at 23 s. The average quality factors Q R and Q L for the upper crust are estimated to be 100 and 160, respectively. Surface wave attenuation below the upper crust is extremely high. The high attenua- tion of the crust and upper mantle may be explained in the frame work of the ongoing tectonic process of the Red Sea and the Afar depres- sion. High temperature associated with partial melting beneath the crust can result in increasing the attenuation which is observed at long periods, while at short periods (less than 27 s), the level of attenuation is less. However, the attenuation is remarkably high. The results of this confirm previous indications that the Arabian plate, unlike other stable regions, has unusually higher attenuation characteristics for seismic waves in the crust and upper mantle comparable to many tectonically active regions of the world.

Pursuing Nasser: The Macmillan Government and the Management of British Policy Towards the Middle East Cold War, 1957–63

In the period immediately after the Suez Crisis, Harold Macmillan continued the Eden government's previous efforts to bring down the Nasser regime in Egypt. This policy produced mixed reactions in Whitehall, although officials withheld their doubts while the new government sought to repair relations with the Eisenhower administration in 1957. The inconclusive outcome of the Jordan and Lebanon interventions in 1958 ultimately allowed the Foreign Office to push for a policy of disengagement from the wider region, although a strengthened British military posture in the Gulf and southwestern Arabia threatened renewed difficulties with local nationalists by the time Macmillan left office in 1963.

Distribution of the Yellow-lemon Tree Frog, Hyla savignyi (Audouin, 1827), in southern Arabia: updates and extensions of previous records

The distribution of the Yellow-lemon Tree Frog Hyla savignyi in southwestern Arabia is presented. This isolated distribution area is limited to the western escarpment along the Red Sea. All sites were located between 1,400 and 2,800 m above sea level. The northernmost occurrence was found near Taif in Saudi Arabia (21°16’N, 40°25’E), the southernmost near Mawah (14°13’N, 44°23’E) in Yemen.

Catha edulis (Khat) Induces Cell Death by Apoptosis in Leukemia Cell Lines

Khat is the Celastraceus edulis plant, a flowering evergreen tree or large shrub, which grows in the Horn of Africa and southwestern Arabia. Khat use has been associated with development of oral cancer, but its molecular effects remain controversial. This study describes a novel cytotoxic effect of whole khat extract on three leukemia cell lines. Cells were exposed to khat extract and harvested for analysis by fluorescent and electron microscopy, trypan blue exclusion, as well as immunoblotting to characterize the mode of cell death. In a separate series, cells were pretreated with a panel of caspase inhibitors for possible inhibitory effects. Khat induced a rapid cell death effect in HL-60, Jurkat, and NB4 cells that occurred within 2 h of exposure. The treated cells retained their ability to exclude trypan blue dye, a key feature in the apoptotic process. Exposed cells consistently developed morphological features of manifest apoptosis. Z-VAD, a pan-caspase inhibitor, completely inhibited toxic activity for up to 8 h, with partial inhibition by other caspase-specific agents. Western blot analysis showed specific cleavage of caspase-3 in khat-exposed cells. This study shows that khat induces cell death by apoptosis in a process sensitive to inhibition by caspase inhibitors, suggesting that subcellular interactions could be of particular relevance for the biological effects of khat in the cell death process and possibly carcinogenesis.

TWO NEW SPECIES OF OSTEOSPERMUM (COMPOSITAE–CALENDULEAE) FROM SOUTHWESTERN CAPE PROVINCE, SOUTH AFRICA

The tribe Calenduleae of the Compositae (Asteraceae) has a pronounced centre of diversity in South Africa, particularly in Cape Province. The largest genus, Osteospermum L., contains c.50 species in Africa and southwestern Arabia, including about 40 in Cape Province. Two new species are described here, both narrowly endemic in southwestern Cape Province. Osteospermum australe is confined to lowland coastal limestone areas in Bredasdorp district, whereas Osteospermum burttianum has a restricted distribution in the Langebergen mountains in Heidelberg district.

Epiphytic bryophyte communities of southwestern Arabia - phytosociology, ecology and life strategies

Epiphytic bryophyte communities of southwestern Arabia - phytosociology, ecology and life strategies

Type localities of amphibian and reptile species collected by Hemprich and Ehrenberg in southwestern Arabia and Eritrea

Type localities of amphibian and reptile species collected by Hemprich and Ehrenberg in southwestern Arabia and Eritrea

Dispersion of the Afar plume: Implications from the Spatiotemporal Distribution of the Late Miocene to Recent Volcanics, Southwestern Arabian Peninsula

Forty-three new K-Ar dates from the Yemen inland volcanic fields (Amran-Sana'a, Dhamar-Rada, and Marib-Sirwah field) in the southwestern Arabian Peninsula reveal a progression that can be divided into four stages: Stage 1: 6.4-5.2 Ma, Stage 2: 3.6-2.9 Ma, Stage 3: 2.2-1.7 Ma and Stage 4: <1.3 Ma. It is clear from the data that the volcanic activity shifted northeastward, overlapping partly during Quaternary time. A similar shift has been recognized along the Aden Volcanic Line from Perim Island to the Aden volcanic field (10-5 Ma) [Mallick et al., 1990]. This study shows that the northeastward or eastward shift for the late Miocene to recent volcanic activity on southwestern Arabian Peninsula is about 3-5 cm/year (average: 4.1 cm/year). The rate of shift may reflect the rate of dispersion of an Afar plume head which impinged at 15 Ma on the base of the Arabian plate. We refine and further develop the Afar plume dispersion model proposed by Schilling et al. [1992]; we consider that two Afar plumes impinged on Afar province at 38 Ma and 15 Ma and that they are continuing to disperse under the Arabian lithosphere. The refined dispersion model we propose is consistent with the known geochemical and mantle tomographical features in the Afar-Arabian province and with the spatiotemporal distribution of late Miocene to recent volcanics in the southwestern Arabian Peninsula.

The stratigraphy, depositional environments and periods of deformation of the Wajid outcrop belt, southwestern Saudi Arabia

The Wajid outcrop belt in southwestern Saudi Arabia is an area of over 22,000 square kilometers where strata of Middle(?) Cambrian through to Jurassic crop out. The Early Palaeozoic sediments in southwestern Arabia have been placed in the Wajid sandstone. This paper elevates this unit to group status and recognizes its former members as formations. The remaining Palaeozoic successions are placed in the Qalibah and Khuff formations. The Middle(?) Cambrian through to Early(?) Ordovician Dibsiyah Formation, Wajid Group, correlates with the Saq sandstone of central and northern Saudi Arabia. The ‘lower’ Dibsiyah buries a topography developed on the Arabian shield during the Late Precambrian Pan-African and/or the late Early Cambrian periods of uplift. The late Early Cambrian period of deformation is documented in southwestern Saudi Arabia and adjacent Oman by an angular unconformity which separates the Dibsiyah Formation correlative from the underlying Late Precambrian-Early Cambrian Lower Haima Group. The ‘lower’ Dibsiyah was deposited in a northward prograding fluvial apron. The ‘upper’ Dibsiyah was deposited in intertidal to shallow subtidal marine settings during a period of coastal onlap. The Late(?) Ordovician Sanamah Formation overlies the Dibsiyah Formation in angular and/or erosional unconformity. This unconformity was developed during a period of regional uplift which began near the close of the Middle Ordovician. The Sanamah Formation was deposited in broad valley complexes excavated in fluvial settings. The Early Silurian Qusaiba Member of the Qalibah Formation unconformably overlies the Sanamah. The Qalibah Formation was deposited in shallow marine to mid-shelf settings during a major period of coastal onlap. The angular unconformity to disconformity, which separates the Qalibah Formation from underlying units, resulted from diastrophism of Late Ordovician to earliest Silurian age. The Early Devonian to Middle(?) Carboniferous Khusayyayn Formation unconformably overlies the Qalibah Formation. The Khusayyayn Formation was deposited in shallow marine, lagoonal, eolian and fluvio-deltaic settings. The unconformity separating the Khusayyayn Formation from the Qalibah Formation documents a period of regional diastrophism of late Early Silurian to late Early Devonian age. Unconformably overlying the Khusayyayn is the Middle Carboniferous through Early Permian Juwayl Formation. This unit was deposited in broad valley complexes excavated in fluvial settings. The base Juwayl unconformity was produced by the Hercynian orogeny. The Permian Khuff Formation unconformably overlies the Juwayl and the former deposited in shallow marine settings. The base Khuff Formation unconformity resulted from a period of major coastal onlap. The Early Triassic Sudair shale succeeds the Khuff and the former was deposited during a period of coastal offlap in lagoonal to coastal plain settings. Near the end of the Early Triassic the Arabian Peninsula underwent another period of tectonism. In central and southwest Saudi Arabia this event is reflected by the erosion of the Sudair shale and older units from the higher portions of reactivated fault blocks and the syndepositional thickening of the Jilh Formation on the down thrown sides of these fault blocks.

The ecology of Agama yemenesis Klausewitz(Lacertilia: Agamidae) in south-western Arabia

A field study of the ecology of Agama yemenensis was carried out in DalaghanNational Park near Abha, Saudi Arabia. This lizard occurs in rocky areas of the highland in the south-west of Arabia. Emergence time, basking, thermoregulation and activity period have been determined. The body temperature of active lizards in the field is 29°C, while the selected temperatures in a thermal gradient during the day and night were 32·2°C and 26·5°C, respectively. Lizards depend on a sit-and-wait strategy, and spend little time feeding on the ground. They feed mainly on ants which are very abundant in their habitat. Seeds, leaflets, twigs and other plant materials are also an important part of their diet.

Carbonate-Evaporite Sequences of the Late Jurassic, Southern and Southwestern Arabian Gulf

The carbonate-evaporite sequences of the Upper Jurassic Arab and overlying Hith formations in the southern and southwestern Arabian Gulf form many supergiant and giant fields that produce from the Arab Formation and are excellent examples of a classic reservoir/seal relationship. The present-day sabkha depositional setting that extends along most of the southern and southwestern coasts of the Arabian Gulf provides an analog to these Upper Jurassic sedimentary rocks. In fact, sabkha-related diagenesis of original grain-supported sediments in the Arab and Hith formations has resulted in five distinct lithofacies that characterize the reservoir/seal relationship: (1) oolitic/peloidal grainstone, (2) dolomitic grainstone, (3) dolomitic mudstone, (4) dolomitized grainstone, an (5) massive anhydrite. Interparticle porosity in grainstones and dolomitic grainstones and intercrystalline porosity in dolomitized rocks provide the highest porosity in the study area. These sediments accumulated in four types of depositional settings: (1) supratidal sabkhas, (2) intertidal mud flats and stromatolitic flats, (3) shallow subtidal lagoons, and (4) shallow open-marine shelves. The diagenetic history of the Arab and Hith formations in the southern and southwestern Arabian Gulf suggests that the anhydrite and much of the dolomitization are a result of penecontemporaneous sabkha diagenesis. The character and timing of the paragenetic events are responsible for the excellent porosity of the Arab Formation and the lack of porosity in the massive anhydrites of the Hith, which together result in the prolific hydrocarbon sequences of these formations.

New records of the Bald Ibis (Geronticus eremita) from Saudi Arabia

24 Bald Ibises (Geronticus eremita) in four groups were recorded during 1991 in an area of only approx. 8 km2, close to Taif in southwestern Saudi Arabia. These observations lead to the conclusion that the eastern population of the Bald Ibis is not yet extinct, as was believed up to now, and that colonies do still exist, either in Asia Minor or in southwestern Arabia. All records from Arabia are presented and the status of the eastern Bald Ibis is discussed.

Age of initial oceanic magmatism in the Late Proterozoic Arabian Shield

Research Article| September 01, 1992 Age of initial oceanic magmatism in the Late Proterozoic Arabian Shield A. Kröner; A. Kröner 1Institut für Geowissenschaften, Universität Mainz, Postfach 3980, 6500 Mainz, Germany Search for other works by this author on: GSW Google Scholar J. S. Pallister; J. S. Pallister 2U.S. Geological Survey, Box 25046, Denver, Colorado 80225 Search for other works by this author on: GSW Google Scholar R. J. Fleck R. J. Fleck 3U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Search for other works by this author on: GSW Google Scholar Author and Article Information A. Kröner 1Institut für Geowissenschaften, Universität Mainz, Postfach 3980, 6500 Mainz, Germany J. S. Pallister 2U.S. Geological Survey, Box 25046, Denver, Colorado 80225 R. J. Fleck 3U.S. Geological Survey, 345 Middlefield Road, Menlo Park, California 94025 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1992) 20 (9): 803–806. https://doi.org/10.1130/0091-7613(1992)020<0803:AOIOMI>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation A. Kröner, J. S. Pallister, R. J. Fleck; Age of initial oceanic magmatism in the Late Proterozoic Arabian Shield. Geology 1992;; 20 (9): 803–806. doi: https://doi.org/10.1130/0091-7613(1992)020<0803:AOIOMI>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Lead isotopic data for zircons from a dacite clast in a volcanic breccia of the oldest oceanic assemblage (immature arc or oceanic plateau) of the southwestern Arabian Shield (Baish group), acquired with the single-grain evaporation technique, yielded a mean 207Pb/206Pb age of 842 ±17 Ma. Earlier published Rb-Sr data for Baish rocks yielded a three-point isochron of 1165 ±110 Ma. This age has been repeatedly cited as evidence for pre-1 Ga arc magmatism in the Arabian Shield. However, more recent Rb-Sr data and zircon ages for clastic metasedimentary rocks are in agreement with our new zircon age, suggesting that initial oceanic magmatism in the Arabian Shield did not begin until after 900 Ma and was coeval with arc evolution in the southern Red Sea Hills of the Sudan. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Evolution of Pan-African island arc assemblages in the southern Red Sea Hills, Sudan, and in southwestern Arabia as exemplified by geochemistry and geochronology

We report RbSr whole-rock and zircon ages for metavolcanic and plutonic associations in the southeastern part of the Red Sea Hills, Sudan, and show that these rocks constitute one of the earliest Pan-African arc assemblages within the Arabian-Nubian shield. The remarkable similarity in geochemistry and age between these and comparable rocks in southwestern Arabia suggests that the southeastern Red Sea Hills and the Al-Lith area of Arabia probably formed part of one large arc complex that was probably accreted to the African continent about 720 Ma ago. The Erkowit and nearby Dahand plutons SW of Suakin yield ages of 850–870 Ma and intrude older metavolcanic suites; one of these, exposed in Khor Ashat, provides an imprecise RbSr age of 860 ± 101 Ma. Several rhyolite suites from the hills SE of Tokar and near the border with Ethiopia yield variable RbSr ages between ∼ 670 and 770 Ma that we relate to partial resetting, whereas single zircons from these rocks gave 207Pb/ 206Pb ages of ∼ 840–855 Ma. An early syn-tectonic granite infolded with the Tokar metavolcanic assemblage has a 207Pb/ 206Pb age of 827 ± 33 Ma, while a post-tectonic granite, probably resulting from intracrustal melting after arc/continent collision, was dated at 652 ± 14 Ma.

Primary Productivity Studies In The South Western Arabian Sea

Primary Productivity Studies In The South Western Arabian Sea

Distribution of the African armyworm,Spodoptera exempta(walker) (Lepidoptera: Noctuidae), and the frequency of larval outbreaks in Africa and Arabia

AbstractSpodoptera exempta(Walker) occurs very widely in Africa south of the Sahara and in south-western Arabia, and more intermittently in the eastern Indian Ocean and Pacific areas. Throughout its range, the extent and frequency of its attacks have increased markedly, especially in the last 10–15 years. In parts of Africa and in south-western Arabia it is now regularly a seasonally important pest; examples are given of monthly distribution maps of the frequency of its attacks in this region. Maps such as these provide a useful and wide-based perspective for those concerned with prediction, survey and control ofS. exemptain a more limited area and with little or no access to information from other territories. Year to year variations within the general patterns derived from many years' records are illustrated by the distribution of outbreaks in three recent seasons, in all of which there were outbreaks in at least seven countries of central and eastern Africa, in two years in Arabia, and in one year also in southern and western Africa.

On The Meaning of Chewing The Significance of Qāt (Catha Edulis)in the Yemen Arab Republic

So writers the British administrator Harold Ingrams about the chewing of leaves from the qāt tree in Yemen. Qāt is the Arabic term for Catha edulis, a species of the Celastracae cultivated in the highlands of southwestern Arabia for at least the last six centuries. The leaves of this tree are chewed as a stimulant, producing a feeling of euphoria followed by depression.

Saudi Arabian seismic-refraction profile: A traveltime interpretation of crustal and upper mantle structure

The crustal and upper mantle compressional-wave velocity structure across the southwestern Arabian Shield has been investigated by a 1000-km-long seismic refraction profile. The profile begins in Mesozoic cover rocks near Riyadh on the Arabian Platform, trends southwesterly across three major Precambrian tectonic provinces, traverses Cenozoic rocks of the coastal plain near Jizan, and terminates at the outer edge of the Farasan Bank in the southern Red Sea. More than 500 surveyed recording sites were occupied, and six shot points were used, including one in the Red Sea. Two-dimensional ray-tracing techniques, used to analyze amplitude-normalized record sections indicate that the Arabian Shield is composed, to first order, of two layers, each about 20 km thick, with average velocities of about 6.3 km/s and 7.0 km/s, respectively. West of the Shield-Red Sea margin, the crust thins to a total thickness of less than 20 km, beyond which the Red Sea shelf and coastal plain are interpreted to be underlain by oceanic crust. A major crustal inhomogeneity at the northeast end of the profile probably represents the suture zone between two crustal blocks of different composition. Elsewhere along the profile, several high-velocity anomalies in the upper crust correlate with mapped gneiss domes, the most prominent of which is the Khamis Mushayt gneiss. Based on their velocities, these domes may constitute areas where lower crustal rocks have been raised some 20 km. Two intracrustal reflectors in the center of the Shield at 13 km depth probably represent the tops of mafic intrusives. The Mohorovičić discontinuity beneath the Shield varies from a depth of 43 km and mantle velocity of 8.2 km/s in the northeast to a depth of 38 km and mantle velocity of 8.0 km/s depth in the southwest near the Shield-Red Sea transition. Two velocity discontinuities occur in the upper mantle, at 59 and 70 km depth. The crustal and upper mantle velocity structure of the Arabian Shield is interpreted as revealing a complex crust derived from the suturing of island arcs in the Precarnbrian. The Shield is currently flanked by the active spreading boundary in the Red Sea.

Weeds of Southwestern Arabian Peninsula

Abstract A list of weeds and their maximum intensity of infestation observed in agricultural areas in the southwestern Arabian Peninsula is presented.