Un Pachyerymnoceras arabique dans le Callovien supérieur du Dahar (Sud tunisien), nouvel élément de datation du membre Ghomrassène (formation Tataouine) ; corrélations avec l'Arabie Saoudite et le Moyen-Orient     

Raymond Enay  Khaled El Asmi  Mohamed Soussi  Charles Mangold  Pierre Hantzpergue 《Comptes Rendus Geoscience》2002,334(16):1157

The first ammonite discovered at the base of the Ghomrassène Member of the Tataouine Formation belongs to a species of Pachyerymnoceras from the Latest Callovian (Solidum Zone) of the Arabian province. The underlying Krechem el Miit Member is also dated Late Callovian, with a fauna of Pachyerymnoceras from the Lower Athleta Zone in Algeria. The associated faunas (echinids, brachiopods) are the same, as well as the faunas of the overlying Ksar Haddada Member, which is dated also Late Callovian, referring to the brachiopods faunal succession in Saudi Arabia. Correlations with other areas in Tunisia, Saudi Arabia and Middle East underline the same sedimentary evolution during a second-order transgressive half-cycle. To cite this article: R. Enay et al., C. R. Geoscience 334 (2002) 1157–1167.

Résumé

La première ammonite découverte à la base du membre Ghomrassène de la formation Tataouine est un Pachyerymnoceras de la partie supérieure du Callovien supérieur (Zone à Solidum) de la province arabique. Le membre Krechem el Miit sous-jacent est aussi daté du Callovien supérieur par des Pachyerymnoceras connus dans la partie inférieure de la Zone à Athleta en Algérie. La faune associée (échinides, brachiopodes) est la même que celle du membre Ksar Haddada sus-jacent, daté également du Callovien supérieur par référence à la succession des brachiopodes en Arabie Saoudite. Les corrélations avec les autres régions de Tunisie, l'Arabie Saoudite et le Moyen-Orient mettent en évidence une même évolution sédimentaire au cours d'un demi-cycle transgressif de deuxième ordre. Pour citer cet article : R. Enay et al., C. R. Geoscience 334 (2002) 1157–1167.  相似文献   

Hydrological considerations for dam siting in arid regions: a Saudi Arabian study     

ZEKAI ŞEN  KHALID AL-SUBA'I 《水文科学杂志》2013,58(2):173-186

Abstract

In any dam siting study in arid regions, rainfall records, runoff measurements and their greatest magnitudes are very important. Unfortunately, the data are scarce and, therefore, empirical approaches and charts obtained from similar regions in other parts of the world are necessary for complete applications. The lack of observed data presents the major problem for runoff modelling in arid regions. These regions have characteristically high rainfall intensity and consequent flash floods with large amounts of sediments. Occurrence of rainfall is sporadic, both temporally and spatially, which makes the interpretation of the rainfall-runoff relationship quite difficult. Flood estimations play a significant role in dam siting from the point of view of water availability. This paper presents the basic calculations of floods and sediment amounts that are necessary in dam siting and construction in an arid area by considering the southwestern part of the Kingdom of Saudi Arabia.  相似文献   

The shifting geopolitics of higher education: Inter/nationalizing elite universities in Kazakhstan,Saudi Arabia,and beyond     

《Geoforum》2014

This article examines recent higher education projects in two resource-rich, developmental states: Kazakhstan and Saudi Arabia. These projects are indicative of broader trend across Asia to move beyond previous national universities, toward a state-initiated model of the globally competitive university, which is designed to become an regional hub for elite education. Drawing on a range of qualitative methods, I consider the geopolitical context in which these projects have been conditioned and materialized, with a focus on how they are legitimated by policy-makers in the two case countries. By reframing discussions about the globalization of higher education in terms of a geopolitics of higher education, I argue that the cases of Kazakhstan and Saudi Arabia are not exceptions set outside of the hegemonic liberal system, but that they are ‘mirrors’ of recent internationalization agendas undertaken by elite Western universities. Through considering localized discourses of promoting knowledge-based economies, I consider how elites simultaneously work with and reconfigure globally-hegemonic discourses, and specifically how these elite university projects are part of broader authoritarian political configurations in Kazakhstan and Saudi Arabia.  相似文献   

Timing of breeding in free-ranging Ethiopian hedgehogs,Paraechinus aethiopicus,from Qatar     

《Journal of Arid Environments》2013

There is little information pertaining to the breeding behaviour and reproductive biology of free-ranging hedgehog populations outside of Europe. We monitored the seasonal changes in courtship behaviour and the presence of new young animals from a free-ranging Ethiopian hedgehog population in Qatar between 2010 and 2012. Based on frequencies of courtship behaviour and deduced frequencies of successful mating, the mating season of the Ethiopian hedgehog is believed to start in January and continue through until July with a clear peak during the February/March period. We propose the existence of two mating peaks, one in February/March and the second in June, suggesting that free-ranging Ethiopian hedgehogs breed more than twice a year in Qatar. Successful mating in late winter/early spring may be more important for the increasing the inclusive fitness of the parents based on the number of young individuals that survive beyond one month of age.  相似文献   

Origin of Lower Cretaceous (‘Nubian’) sandstones of North‐east Africa and Arabia from detrital zircon U‐Pb SHRIMP dating     

KEREN KOLODNER  DOV AVIGAD  TREVOR RUSSELL IRELAND  ZVI GARFUNKEL 《Sedimentology》2009,56(7):2010-2023

Lower Cretaceous sandstones of the type exposed in Israel, deposited over much of North Africa and Arabia as widespread sandstone sheets, typically are mineralogically and texturally mature. Previous petrographic examinations suggested that the Lower Cretaceous sandstones are at least partly a product of recycling and the present study supports this notion. The results of U‐Pb Sensitive High Resolution Ion Micro‐Probe (SHRIMP) dating of detrital zircons from the Lower Cretaceous section exposed in Israel indicate that they are dominated by detrital zircons of Neoproterozoic age, mainly concentrated in the 0·55 to 0·65 Ga interval, with various amounts of older (pre‐Neoproterozoic) zircons (of 0·95 to 1·10, 1·7 to 2·0 and 2·6 to 2·65 Ga age groups). The overall age signal is similar to detrital zircon age spectra previously obtained from the Cambrian–Ordovician sections of Israel and Jordan. Remarkably, the detrital zircon spectra remained almost unchanged for nearly 400 Myr. Thus, the most probable provenance of the Lower Cretaceous sandstone is the recycling of relatively proximal Palaeozoic sandstone. Since first unroofed from above pan‐African terranes closer to the secession of orogeny, the ensuing siliciclastics were recycled repeatedly throughout the Phanerozoic with little additional basement denudation. The Lower Cretaceous sandstone comprises quartz sand that was first eroded from above pan‐African orogens ca 400 Myr prior to deposition.  相似文献   

Metavolcanic host rocks,mineralization, and gossans of the Shaib al Tair and Rabathan volcanogenic massive sulphide deposits of the Wadi Bidah Mineral District,Saudi Arabia     

John C. Volesky  Robert J. Stern  Jan M. Peter  Daniel Layton-Matthews  Sarah Rice 《International Geology Review》2017,59(16):1975-2002

The Wadi Bidah Mineral District of Saudi Arabia contains more than 16 small outcropping stratabound volcanogenic Cu–Zn–(Pb) ± Au-bearing massive sulphide deposits and associated zones of hydrothermal alteration. Here, we use major and trace element analyses of massive sulphides, gossans, and hydrothermally altered and least altered metamorphosed host rock (schist) from two of the deposits (Shaib al Tair and Rabathan) to interpret the geochemical and petrological evolution of the host rocks and gossanization of the mineralization. Tectonic interpretations utilize high-field-strength elements, including the rare earth elements (REE), because they are relatively immobile during hydrothermal alteration, low-grade metamorphism, and supergene weathering and therefore are useful in constraining the source, composition, and physicochemical parameters of the primary igneous rocks, the mineralizing hydrothermal fluid and subsequent supergene weathering processes. Positive Eu anomalies in some of the massive sulphide samples are consistent with a high temperature (>250°C) hydrothermal origin, consistent with the Cu contents (up to 2 wt.%) of the massive sulphides. The REE profiles of the gossans are topologically similar to nearby hydrothermally altered felsic schists (light REE (LREE)-enriched to concave-up REE profiles, with or without positive Eu anomalies) suggesting that the REE experienced little fractionation during metamorphism or supergene weathering. Hydrothermally altered rocks (now schists) close to the massive sulphide deposits have high base metals and Ba contents and have concave-up REE patterns, in contrast to the least altered host rocks, consistent with greater mobility of the middle REE compared to the light and heavy REE during hydrothermal alteration. The gossans are interpreted to represent relict massive sulphides that have undergone supergene weathering; ‘chert’ beds within these massive sulphide deposits may be leached wall-rock gossans that experienced silicification and Pb–Ba–Fe enrichment from acidic groundwaters generated during gossan formation.  相似文献   

Lithologic characteristics and diagenesis of the Devonian Jauf sandstone at Ghawar Field, Eastern Saudi Arabia     

Khalid A. Al-Ramadan  Mahbub Hussain  Badrul Imam  Salih Saner 《Marine and Petroleum Geology》2004,21(10):1221-1234

The Lower Devonian Jauf Formation in Saudi Arabia is an important hydrocarbon reservoir. However, in spite of its importance as a reservoir, published studies on the Jauf Formation more specifically on the reservoir quality (including diagenesis), are very few. This study, which is based on core samples from two wells in the Ghawar Field, northeastern Saudi Arabia, reports the lithologic and diagenetic characteristics of this reservoir. The Jauf reservoir is a fine to medium-grained, moderate to well-sorted quartz arenite. The diagenetic processes recognized include compaction, cementation (calcite, clay minerals, quartz overgrowths, and a minor amount of pyrite), and dissolution of the calcite cements and of feldspar grains. The widespread occurrences of early calcite cement suggest that the Jauf reservoir lost a significant amount of primary porosity at a very early stage of its diagenetic history. Early calcite cement, however, prevented the later compaction of the sandstone, thus preserving an unfilled part of the primary porosity. Based on the framework grain–cement relationships, precipitation of the early calcite cement was either accompanied or followed by the development of part of the pore-lining and pore-bridging clay cement. Secondary porosity development occurred due to partial to complete dissolution of early calcite cements and feldspar. Late calcite cement occurs as isolated patches, and has little impact on reservoir quality of the sandstones.In addition to calcite, several different clay minerals including illite and chlorite occur as pore-filling and pore-lining cements. While the pore-filling illite and chlorite resulted in a considerable loss of porosity, the pore-lining chlorite may have helped in retaining the porosity by preventing the precipitation of syntaxial quartz overgrowths. Illite, which largely occurs as hair-like rims around the grains and bridges on the pore throats, caused a substantial deterioration to permeability of the reservoir. Diagenetic history of the Jauf Formation as established here is expected to help better understanding and exploitation of this reservoir.  相似文献   

Green Laboratories: University Campuses as Sustainability “Exemplars” in the Arabian Peninsula     

Natalie Koch 《社会与自然资源》2018,31(5):525-540

ABSTRACT

Like many universities in the West, universities across the Arabian Peninsula are increasingly home to various conspicuous sustainability initiatives. This article examines this trend at three of the region’s most prominent projects: NYU-Abu Dhabi in the Emirates, Qatar Foundation’s Education City, and Saudi Arabia’s King Abdullah University of Science and Technology. Based on the textual analysis and informed by fieldwork in these countries since 2012, this article joins interdisciplinary research in political geography, sustainability experimentation, and laboratory studies to understand their iconic campuses not as enclaves, but as “exemplars” of sustainability and renewable energy futures in the region. Tracing their effects beyond their walls, I argue that they have mostly been limited to symbolically injecting sustainability into public discourse. While more substantial shifts toward sustainable development in the region are underway, these have largely stemmed from market forces rather than a new environmental consciousness promoted by these three iconic universities.  相似文献   

Microbial community of cyanobacteria mats in the intertidal zone of oil-polluted coast of Saudi Arabia     

Al-Thukair AA  Abed RM  Mohamed L 《Marine pollution bulletin》2007,54(2):173-179

Cyanobacterial mats are found at various locations along the coast of the Eastern Province of Saudi Arabia. Those mats were affected by severe oil pollution following 1991 oil spill. In this study, samples from Abu Ali Island were collected at three selected sampling sites across the intertidal zone (Lower, Middle, and Upper) in order to understand the effect of extreme environmental conditions of high salinity, temperature and desiccation on distribution of cyanobacteria along the oil polluted intertidal zone. Our investigation of composition of cyanobacteria and diatoms was carried out using light microscopy, and Denaturant Gradient Gel Electrophoresis (DGGE) technique. Light microscopy identification revealed dominant cyanobacteria to be affiliated with genera Phormidium, Microcoleus, and Schizothrix, and to a lesser extent with Oscillatoria, Halothece, and various diatom species. The analysis of DGGE of PCR-amplified 16S rRNA fragments showed that the diversity of cyanobacteria decreases as we proceed from the lower to the upper intertidal zone. Accordingly, the tidal regime, salinity, elevated ambient air temperature, and desiccation periods have a great influence on the distribution of cyanobacterial community in the oil polluted intertidal zone of Abu Ali Island.  相似文献   

Late Quaternary history of the coastal Wahiba Sands,Sultanate of Oman     

Frank Preusser  Dirk Radies  Frauke Driehorst  Albert Matter 《第四纪科学杂志》2005,20(4):395-405

Continental sediments and geomorphological features of the coastal Wahiba Sands, Sultanate of Oman, reflect environmental variability in southeastern Arabia during the late Quaternary. Weakly cemented dune sands, interdune deposits and coastal sediments were dated by luminescence methods to establish an absolute chronology of changes in sedimentary dynamics. The dating results confirm previous assumptions that during times of low global sea level sand was transported by southerly winds from the exposed shelf onto the Arabian Peninsula. Two prominent phases of sand accumulation in the coastal area took place just before and after the last glacial maximum (LGM). A final significant period of dune consolidation is recognised during the early Holocene. However, no major consolidation of dunes appears to have occurred during the LGM and the Younger Dryas. In the northern part of the Wahiba Sands, these two periods are characterised by substantial sand deposition. This discrepancy is explained by the lack of conservation potential for dunes in the coastal area, probably caused by a low groundwater table due to low sea level and decreased precipitation. While the times of aeolian activity reflect arid to hyper‐arid conditions, lacustrine and pedogenically altered interdune deposits indicate wetter conditions than today caused by increased monsoonal circulation during the Holocene climatic optimum. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献