Northwest Saudi Research Articles

Incidence, genetics, and clinical phenotype of permanent neonatal diabetes mellitus in northwest Saudi Arabia

Permanent neonatal diabetes mellitus (PNDM) in European population has an incidence of at least 1 in 260 000 live births and is most commonly due to mutations in KCNJ11 and ABCC8. However, data on this condition in other populations are limited. To define the incidence, genetic aetiology, and clinical phenotype of PNDM in Al-Madinah region, northwest Saudi Arabia. Patients with PNDM diagnosed between 2001 and 2010 were identified and clinically phenotyped. Sequencing of KCNJ11, ABCC8, and INS were performed initially on all subjects, and EIF2AK3, GLIS3, SLC2A2, SLC19A2, GCK, IPF1, and NEUROD1 genes were sequenced according to the clinical phenotype. In total, 17 patients from 11 consanguineous families were diagnosed with PNDM and the incidence was 1 in 21 196 live births. Six different mutations in four genes were identified, of which two GLIS3 and one SLC2A2 were novel and no patient had KCNJ11, ABCC8, or INS mutations. Fourteen (82.4%) patients had identifiable genetic aetiology and their PNDM was part of known autosomal-recessive syndromes including Wolcott Rallison (41.1%), neonatal diabetes and hypothyroidism (29.4%), Fanconi-Bickel (5.8%), and thiamine-responsive megaloblastic anaemia (5.8%). Two patients with isolated PNDM and one with intermediate developmental delay, epilepsy and neonatal diabetes had no identifiable cause. Al-Madinah region has the highest reported incidence of PNDM worldwide. In this region with high consanguinity, PNDM has different genetic aetiology and in the majority of cases presents as a part of rare familial autosomal-recessive syndrome rather than in isolation.

High incidence of childhood type 1 diabetes in Al-Madinah, North West Saudi Arabia (2004-2009)

There is a geographical variation in the incidence of childhood type 1 diabetes mellitus (T1DM) with a steady increase reported from some countries. However, data on the incidence of childhood T1DM in Kingdom of Saudi Arabia are limited. To identify the incidence rate (IR) and epidemiological trends of childhood T1DM in the largest city of northwest Saudi Arabia. All patients with newly diagnosed T1DM aged 0-12 yr living in the city between 2004 and 2009 were identified from different sources. The data were analyzed according to age, sex, and month of presentation. In total, 419 patients (249 girls) were diagnosed between 2004 and 2009 inclusive. The mean age at diagnosis was 6.9 ± 3.5 yr. The mean annual age-standardized IR was 29.0 (95% confidence interval 26.0-32.0). The incidence was significantly higher in the 10-12-yr age group than in younger children (p < 0.001) and higher in girls than in boys (33.0 vs. 22.2 per 100 000; p < 0.001). There was no significant increase in the annual incidence during the 6-yr period (p = 0.68) and more cases were diagnosed during autumn and winter months (p = 0.002). Al-Madinah city has the highest reported incidence of childhood T1DM in the Middle East and North Africa region. Further studies to identify the reasons for this high incidence are needed.

Preliminarily test of physically based models to estimate clear sky emissivity in Tabouk, Saudi Arabia

Analysis of the performance of physically based models was done using infrared sky temperature observations taken in Tabouk City, North-West Saudi Arabia, during winter 2005. The models used here are the Brutsaert model and the Prata model. Initially, the original coefficients are used, and then, the coefficients are adjusted according to the observed models’ response to the differences between the actual atmospheric vertical structure and the average standard conditions. The produced resulting corrected estimation has reduced the RMSE and MBE values, as compared to those obtained originally. The RMSE and MBE have been reduced from 10.5 and −10 to 3.8 and −1.6, respectively, as the coefficients for the Brutsaert model were adjusted. Similarly, for the Prata model, the RMSE and MBE in the sky temperature values have been reduced from 7.7 °C and −7.2 °C to 2.9 °C and −1.0 °C, respectively.

Yardangs on the Cambro-Ordovician Saq Sandstones, North-West Saudi Arabia

Yardangs on the Cambro-Ordovician Saq Sandstones, North-West Saudi Arabia

Devonian Jauf Formation, Saudi Arabia: Orbital Second-order Depositional Sequence 28

ABSTRACTThe Devonian Jauf Formation (Huj Group) froms part of a regional transgressive-regressive depositional sequence that extends more than 1,500 km across the Arabian Platform from the Al Jawf outcrops in northwest Saudi Arabia, to the subsurface of eastern Saudi Arabia and Oman (Misfar Group). The formation ranges in thickness from 200–335 m in eastern Saudi Arabia to about 300–330 m in northwest Saudi Arabia. It disconformably (?unconformably) overlies the continental to shallow-marine Tawil Formation, and is unconformably overlain by the continental Jubah Formation. The Jauf Formation consists of five members that are apparently conformable; from base-up: Sha’iba Shale, Qasr Limestone, Subbat Shale, Hammamiyat Limestone and Murayr. In the Al-Qalibah reference section, it is divided into 21 informal units. The Early Devonian Emsian Hammamiyat Member represents the main marine flooding event; it consists of Hammamiyat units 1–6 each characterized by a clastic section that is capped by limestone.The Jauf Formation is interpreted as an orbital second-order depositional sequence (denoted DS2 28), which is bounded by two second-order sequence boundaries: SB2 28 = Jauf/Tawil (c. 407.6 Ma) and SB2 27 = Jubah/Jauf (c. 393.0 Ma). The Jauf Formation appears to consist of six third-order depositional sequences (DS3 28.1 to 28.6) that were deposited in the Early Devonian, ?Pragian and Emsian stages The Hammamiyat Member (DS3 28.4) is interpreted to consist of six fourth-order orbital cycles (DS4 28.4.1 to 28.4.6) each deposited in 0.405 million years.

Late Ordovician (Ashgillian) glacial deposits in southern Jordan

The Late Ordovician (Ashgillian) glacial deposits in southern Jordan, comprise a lower and upper glacially incised palaeovalley system, occupying reactivated basement and Pan-African fault-controlled depressions. The lower palaeovalley, incised into shoreface sandstones of the pre-glacial Tubeiliyat Formation, is filled with thin glaciofluvial sandstones at the base, overlain by up to 50 m of shoreface sandstone. A prominent glaciated surface near the top of this palaeovalley-fill contains intersecting glacial striations aligned E–W and NW–SE. The upper palaeovalley-fill comprises glaciofluvial and marine sandstones, incised into the lower palaeovalley or, where this is absent, into the Tubeiliyat Formation. Southern Jordan lay close to the margin of a Late Ordovician terrestrial ice sheet in Northwest Saudi Arabia, characterised by two major ice advances. These are correlated with the lower and upper palaeovalleys in southern Jordan, interrupted by two subsidiary glacial advances during late stage filling of the lower palaeovalley when ice advanced from the west and northwest. Thus, four ice advances are now recorded from the Late Ordovician glacial record of southern Jordan. Disturbed and deformed green sandstones beneath the upper palaeovalley-fill in the Jebel Ammar area, are confined to the margins of the Hutayya graben, and have been interpreted as structureless glacial loessite or glacial rock flour. Petrographic and textural analyses of the deformed sandstones, their mapped lateral transition into undeformed Tubeiliyat marine sandstones away from the fault zone, and the presence of similar sedimentary structures to those in the pre-glacial marine Tubeiliyat Formation suggest that they are a locally deformed facies equivalent of the Tubeiliyat, not part of the younger glacial deposits. Deformation is attributed to glacially induced crustal stresses and seismic reactivation of pre-existing faults, previously weakened by epeirogenesis, triggering sediment liquefaction and deformation typical of earthquake generated seismites. Deformation, confined to an area of not more than 4 km wide adjacent to the major fault zone, implies earthquake magnitudes of at least 6 (M o). The high authigenic chlorite content of deformed Tubeiliyat sandstones compared to undeformed ones is attributed to a post-seismic hydrothermal system driven by compactional dewatering and hydrofracturing of the bedrock which acted as a groundwater recharge area, supplied by subglacial meltwater from beneath the ice sheet. Fluid movement along glacial seismotectonically reactivated faults infiltrated the adjacent Tubeiliyat sandstones under pressure and elevated geothermal gradient, where chlorite was precipitated from solution.

Arabian glacial deposits: recognition of palaeovalleys within the Upper Ordovician Sarah Formation, Al Qasim district, Saudi Arabia

Field work undertaken in 1979 with Professor Douglas Shearman in the Al Qasim district of northwest Saudi Arabia around the Sarah Ridge found evidence for the cutting and filling of large-scale palaeovalleys. This is interpreted to record major glacioeustatic sea-level fluctuations in the Late Ordovician. A new member of the ‘Tabuk Formation’ was recommended, the ‘Sarah Member’, primarily comprising glacigenic mudflow, alluvial fan and braided fluvial deposits. Between 1987 and 1989 the stratigraphy was revised and the proposed ‘Sarah Member’ was redefined as the Sarah Formation, a stratigraphic interval that is now recognized throughout northwest Arabia and interpreted to be deposited during a shortlived Ashgillian ice age. The characteristics of the Sarah Formation sandstones and diamictites have commercial significance since these Ashgillian glacial deposits represent an important reservoir target in the subsurface of North Africa as well as Arabia, potentially sourced and sealed by the rich petroleum source rocks of the stratigraphically overlying Llandoverian graptolitic shales.

Regional Distribution and Chronostratigraphy of the Qusaiba Member of the Qalibah Formation in the Nafud Basin, Northwestern Saudi Arabia: ABSTRACT

The Qusaiba Member of the Qalibah Formation (Silurian age) is a thick sequence consisting of massive dark gray shales. Only the very basal shales are black and highly organic rich. The basal {open_quote}Hot Shale{close_quote} unit is a prolific source correlated to all the Paleozoic discoveries in Central and Eastern Saudi Arabia. In the Nafud Basin, Northwest Saudi Arabia, this same sequence acts as both source and seal to the underlying Ordovician reservoir, making the understanding of this sequence essential to the current exploration program underway in the region. Acquiring high resolution blostratigraphy and detailed source rock analysis substantially contributed to the better understanding of the regional depositional setting of the seal, source, and the reservoirs in the area. Graptolites and chitinozoans zonation were utilized to fine-tune the chronostratigraphy and to further subdivide this huge basin into more manageable subbasins. Regional chronostratigraphic analysis has indicated that the early Qusaiba transgression took place swiftly and covered all of the Arabian plate during early Rhuddanian time. Only high areas not covered by the Rhuddanian transgression and areas that experienced later uplift and erosion lack the Rhuddanian deposits.

Delineation and Analysis of Drainage Pattern frdm Satellite Images of Sahl Al Matran Area, Northwest Saudi Arabia

Delineation and Analysis of Drainage Pattern frdm Satellite Images of Sahl Al Matran Area, Northwest Saudi Arabia

The Lower Silurian Qalibah Formation of Saudi Arabia: An Important Hydrocarbon Source Rock (1)

The Lower Silurian Qalibah Formation represents a distinct, lithostratigraphic, time-transgressive sequence. It is disconformably bounded below by the Upper Ordovician to possibly Lower Silurian Sarah Formation, and above by the continental to marginal-marine Lower Devonian and possibly Upper Silurian Tawil Sandstone Formation. This paper redefines the Qalibah Formation within these boundaries. In its reference section near the town of Al Qalibah in northwest Saudi Arabia, the Qalibah is 499 m thick, whereas in a subsurface composite section it reaches 955 m. The Qalibah Formation is a coarsening-upward, progradational sequence consisting of a lower Qusaiba Shale Member and an upper Sharawra Sandstone Member. The basal hot of the Qusaiba is a black, euxinic, bottomset shale (up to 70 m thick) which was deposited during the Early Silurian sea level rise following the deglaciation of Gondwana. This Paleozoic shale is organic rich and the most likely source rock of the low-sulfur, high-gravity oil, condensate, and gas discovered in recent years in the Paleozoic rocks of central and eastern Saudi Arabia. Lithologically similar Silurian sequences were deposited over most of the broad stable shelf of Gondwana from the Middle East to the African Sahara.

Lower Silurian-Upper Ordovician Subsurface Glacial Outwash Deposits, Northern Saudi Arabia

Recently acquired seismic data reinterpreted well information in northwest Saudi Arabia extends outcropping Lower Silurian to Upper Ordovician Zarqa/Sarah glacial and periglacial deposits into the subsurface. These deposits range from northeast-trending outwash-filled channels deeply incised into the underlying Ordovician Qasim and the Cambrian-Ordovician Saq Formation in the east. A southwest source for these sediments is implied by this new data. This supports previously interpreted source directions mapped from outcrop. It also correlates with the position of the Arabian plate relative to known Gonwanaland ice caps during the Early Silurian-Late Ordovician. The recognition of glacial outwash sediments in the subsurface provides new insight into the continuity and environments of deposition of the Qasim Formation members in northwest Saudi Arabia. The hydrocarbon-prone Lower Silurian Qusaiba Member of the Qalibah Formation overlies the Zarqa/Sarah Formations. The Qusaiba represents a rapid transgression of the Paleo-Tethys Sea during the final melting of the Gondwanaland ice caps. The seal-source characteristics of the Qusaiba Member, combined with the good porosity and permeability of the underlying outwash deposits, suggest a prospective hydrocarbon exploration play. Gas is produced from this reservoir in the Risha field of eastern Jordan.

Large tectonic and lithospheric structures of the Red Sea region

Using new tectonic data regarding the timing and mechanical development of large fracture structures and a review of deep seismic data especially in relation to crustal thickness, a geodynamic evolutionary model for the Nubo-Arabian region is described. Combination of the data sets results in a 3-D picture of the crustal structure of the region and definition of problems regarding the geodynamic evolution of the Red Sea structure. Evidence from northwest Saudi Arabia, bordering the northern end of the Red Sea, suggests that rifting began around 32–30 Ma. During the Miocene, rifting intensified probably including significant lithospheric thinning. This first stage of development ended in the Middle Miocene, about 14 Ma, when the complete rift structure was about as wide as the present day Gulf of Suez. Between the Middle Miocene and the Upper Miocene/Pliocene boundary, about 10 ± 2 Ma, the Aqaba-Levant structure became active and thus the Gulf of Suez became essentially stagnant. Since this time about 70% of the total opening of the Red Sea has occurred, again probably including significant lithospheric thinning. This opening has been taken up totally by the movement along the Aqaba-Levant fault. Finally, about 5 Ma seafloor spreading began in the central axial trough of the Red Sea south of 21°N. A better knowledge of the thickness and nature of the present day Red Sea crust is still required so that the amount of opening of the Red Sea can be more accurately estimated.

Similarities in the Paleozoic Successions of North Africa and Arabia and Implications for Petroleum Exploration: ABSTRACT

From field studies in southwest Libya and northwest Saudi Arabia, the facies of the Paleozoic succession of the north African/Arabian stable cratonic margin of Gondwanaland are interpreted as fluvial, estuarine, deltaic, shallow marine, and glacial deposits. The facies of the Saq and Tabuk Formations of Saudi Arabia bear witness to a sedimentary history that is very similar to that of north Africa, the Saq Formation (Cambrian-Arenig) being equivalent to the Hassaouna Formation of Libya and the Tabuk Formation being subdivided and correlated using well-dated shale members to the following formations: Haouaz (Llanvirn-Llandeilo), Melez-Chograne (Caradoc), Memouniat (Ashgill), Tanezzuft/Acacus (Llandovery-Ludlow), and Tadrart (Gedinnian -Emsian). The Cambrian-Ordovician succession comprises Nubian-type fluvial and estuarine sandstones which pass up to regressive deltaic/shallow marine sequences overlain by Upper Ordovician glacial deposits that lie in deeply incised paleovalleys recorded from Saudi Arabia and north Africa. The Silurian succession comprises the deposits of a postglacial marine transgression of vast lateral extent and a subsequent regression, the sandstones of which are markedly diachronous. The Lower Devonian succession comprises fining-upward retrogradational deltaic (transgressive) sequences of Nubian-type sandstones (fluvial to shallow marine) which form widespread blanket sandstone bodies. The prospectivity of these strata is well known from Algeria in the westmore » to Jordan in the east, the Llandoverian oil-prone source rocks providing the key to Cambrian-Ordovician and Lower Devonian plays. The significance of underlying paleovalley-fill fluvioglacial sandstones as linear reservoir targets has yet to be fully appreciated.« less