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1

Uranium isotopic study of artesian and pluvial contributions to the Nubian Aquifer, Western Desert, Egypt  

Microsoft Academic Search

The groundwater systems of the Nubian Aquifer beneath six major oases (Baris, Kharga, Dakhla, Farafra, Bahariya, and Siwa) in the Western Desert of Egypt have been studied to establish their sources and mixing volumes using uranium isotopes. One hundred six groundwater samples from different depths of the Nubian Aquifer have been analyzed for uranium content and 234U\\/238U activity ratio (AR).The

A. A. Dabous; J. K. Osmond

2001-01-01

2

Mesozoic rift basins in western desert of Egypt, their southern extension and impact on future exploration  

SciTech Connect

Rift basins are a primary target of exploration in east, central, and west Africa. These intracratonic rift basins range in age from the Triassic to the Neogene and are filled with lagoonal-lacustrine sand-shale sequences. Several rift basins may be present in the Western Desert of Egypt. In the northeastern African platform, the Mesozoic Tethyan strand lines were previously interpreted to have limited southern extension onto the continent. This concept, based upon a relatively limited amount of subsurface data, has directed and focused the exploration for oil and gas to the northernmost 120 km of the Western Desert of Egypt. Recent well and geophysical data indicate a southerly extension of mesozoic rift basins several hundred kilometers inland from the Mediterranean Sea. Shushan/Faghur and Abu Gharadig/Bahrein basins may represent subparallel Mesozoic basins, trending northeast-southwest. Marine Oxfordian-Kimmeridgian sediments were recently reported from wells drilled approximately 500 km south of the present-day Mediterranean shoreline. The link of these basins with the Sirte basin to the southwest in Libya is not well understood. Exploration is needed to evaluate the hydrocarbon potential of such basins.

Taha, M.A. (Conoco, Cairo (Egypt))

1988-08-01

3

Uranium isotopic study of artesian and pluvial contributions to the Nubian Aquifer, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The groundwater systems of the Nubian Aquifer beneath six major oases (Baris, Kharga, Dakhla, Farafra, Bahariya, and Siwa) in the Western Desert of Egypt have been studied to establish their sources and mixing volumes using uranium isotopes. One hundred six groundwater samples from different depths of the Nubian Aquifer have been analyzed for uranium content and 234U/ 238U activity ratio (AR). The aquifer under the Western Desert is known to have more than one source of water. At Bahariya and Farafra Oases, the Nubian artesian water migrating from the south has been augmented by local recharge during pluvial times. At Siwa Oasis in the northwestern desert, a shallower aquifer component migrating from the north or west is also present. At Dakhla, Kharga and Baris Oases in the southwestern desert, the main source is the Nubian artesian water migrating from southeast Uweinat Upland and northwest Sudan. These water masses have distinctive uranium isotopic signatures. The Nubian Aquifer water is characterized by very low U concentrations (<0.05 ppb) and a relatively high 234U/ 238U AR (>1.5). The shallow northwest aquifer water also has a high AR but a much higher U concentration. The locally recharged pluvial waters have high U concentrations (>0.1 ppb) but low ARs, near unity. A diagnostic derivative parameter is excess 234U content. The deep Nubian Aquifer water is characterized by a relatively low excess 234U (<0.02 ppb equivalent), while the shallow Siwa water has a very high excess 234U [(AR-1)(U conc.)]. The Bahariya and Farafara waters are also high in this component, probably because of pluvial water percolation through phosphate rich strata. At all oases, U isotopic mixing diagrams show that the deep aquifer sources predominate; however, the pluvial contributions are significant, ranging from about 5% at remote Baris Oasis to about 26% at the more northerly Farafra Oasis. The observed lowering of potentiometric surfaces in the Western Desert is caused not only by pumping at a rate greater than inflow from the aquifer systems, but also by the withdrawal of pluvial water which in modern times is not being replaced at all.

Dabous, A. A.; Osmond, J. K.

2001-03-01

4

A new Priabonian Chondrichthyans assemblage from the Western desert, Egypt: Correlation with the Fayum oasis  

NASA Astrophysics Data System (ADS)

While the Middle/Late Eocene marine vertebrates in Egypt have been largely reported around the Fayum oasis, few reports were made elsewhere. Here we report a new fossil site (Km55) located near the Bahariya Oasis in the Western desert of Egypt. This fossiliferous outcrop has yielded abundant fossil material of invertebrates dated to the Middle/Late Eocene and some chondrichthyan remains that testify of a Priabonian age (MK11). More than twenty Selachian taxa were recovered in one level, including " Cretolamna " twiggsensis, Misrichthys stromeri, Odontorhytis pappenheimi, ? Jacquhermania attiai, and the fauna is quite similar to some recovered from the Fayum area. However, this new association is clearly distinctive of an open marine environment during the extreme Late Eocene while the contemporaneous fossil sites farther east are deposited in shallower (e.g. Wadi Hitan) or continental environments (e.g. BQ-2). This suggests an E-W diachronous change in relative sea level on the Egyptian coastal shelf during the Late Eocene period, with a general deepening along strike to the West.

Adnet, S.; Cappetta, H.; Elnahas, S.; Strougo, A.

2011-08-01

5

Upper Cenomanian–Turonian (Upper Cretaceous) ammonoids from the western Wadi Araba, Eastern Desert, Egypt  

Microsoft Academic Search

The Cenomanian–Turonian (C–T) successions (Galala and Maghra el Hadida formations) exposed on the footwalls of the slopes of the Galala plateaus in the Wadi Araba area in the northern part of the Eastern Desert, Egypt yielded a fairly rich and moderately to well preserved ammonoid fauna. In total, 24 taxa have been identified, 17 of which are systematically described herein.

Emad Nagm; Markus Wilmsen; Mohamed F. Aly; Abdel-Galil Hewaidy

2010-01-01

6

Remote sensing and geophysical investigations of Moghra Lake in the Qattara Depression, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Western Desert covers two-thirds of the land area of Egypt and occupies one of the driest regions of the Sahara. Seven depressions within the desert - Siwa, Qattara, Fayum, Bahariya, Farafra, Dakhla, and Kharga - may represent parts of old drainage systems with deflation, extensive erosion, and possibly, some tectonic activity. Oases with freshwater exist in these depressions. Geological and geophysical investigations in the Qattara Depression indicate the presence of buried fluvial channels with southeast to northwest flow directions from the highland areas. The origin of these fluvial systems, as well as the origin of the depressions themselves, is still unresolved, and many ideas have been suggested. Moghra Lake at the northeastern tip of the Qattara basin may be a remnant of a larger paleolake, including the mouth of a paleo-river. We present here the results of our recent work in this area using ALOS PALSAR radar remote sensing data, which indicated the presence of buried channels that may have fed the larger Moghra paleolake. Ground penetrating radar (GPR) data along 2D profiles were acquired; the migrated GPR sections identified a major paleochannel with numerous minor channels at its margins. GPR interpretations are verified by field observations, trenching, and stratigraphic information from outcrop data. Potential field analyses identify possible aquifers that are controlled by regional structures. Density contrasts within the sedimentary units, physical boundaries of uplifted basement blocks and depths to causative sources were also identified. This work contributes to the reconstruction of paleodrainage of this region and helps in understanding processes involved in the formation of the Qattara Depression.

Khan, Shuhab D.; Fathy, Mohamed S.; Abdelazeem, Maha

2014-02-01

7

The geochemistry of uranium and thorium isotopes in the Western Desert of Egypt  

NASA Astrophysics Data System (ADS)

The concentrations of 238U, 234U, 232Th and 228Th have been measured in the groundwaters of the Bahariya and Farafra oases of the Western Desert of Egypt. These waters are characterized by normal amounts of U, but unusually high concentrations of Th. The pattern of variation of the parent isotopes, 238U and 232Th, as well as the daughter isotopes, 234U, 230Th and 228Th, is systematic within and between the two oases. From the unusually consistent distribution of the 234U /238U activity ratios one can conclude that the samples from both oases are representative of a two-component mixing system. One component, characterized by low U content and a high 234U /238U activity ratio, is typical of deep artesian systems and probably represents flowthrough water derived from the Nubian highlands to the south. The second component is characterized by a greater U concentration and a low activity ratio. This signature is hypothesized as being derived by leaching of downward infiltrating water during pluvial times. The source of the U may be the uraniferous phosphate strata that overly the sandstone aquifer in both oasis areas. Higher Th values are associated with the artesian flow component of the mixing system and suggests that Th-bearing minerals may be abundant in the Nubian sandstone aquifer. The distribution of 230Th and 228Th in the water samples supports this interpretation.

Dabous, Adel A.

1994-11-01

8

Some aspects of land transformation in the western mediterranean desert of egypt  

NASA Astrophysics Data System (ADS)

The western Mediterranean desert of Egypt has a long history of land-use. With recent development activities, land transformation is progressing at a high rate. Monitoring of changes to allow for predictions of long-term effects of these activities is viewed at three levels: (a) quantities of ecosystem components; (b) detailed distribution of patterns of land-use, vegetation and physiography; and (c) general distribution of the salient features of land. This study provides estimates at the first (a) and second (b) levels of changes in this region due to the main land-use types: grazing rain-fed farming, and irrigated farming. Grazing had little effects on soil characters, but it resulted in lower soil stability and abundance of plants and above-soil invertebrates. Irrigation resulted in water-logging and salinization, formation of calcic horizons, decrease in soil organic matter and soluble nitrogen, and in increase of above-and below-soil biota. A comparison of the distribution of vegetation and land-use in one of the sectors in 1964 and 1981, using maps based on aerial photographs and ground-truth data, indicated remarkable changes in areas of rain-fed farming, and in vegetation composition due to over-grazing.

Ayyad, Mohamed A.

9

Remote Sensing and Shallow Geophysical Investigations on Moghra Lake in Northeastern Qattarra Depression, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Western Desert of Egypt encompasses two thirds of the land area of Egypt and constitutes one of the driest regions of the Sahara. This desert has seven depressions; Siwa, Qattara, Fayium, Bahariya, Farafra, Dakhla and Kharga. These depressions may be the manifestation of old drainage basins with extensive erosion and possibly some tectonic activity. Several oases with freshwater can be found in these depressions. Geological and geophysical investigations in Qattara Depression indicate several buried fluvial channels with flow direction from highlands in southeast to northwest. Moghra Lake at the northeastern tip of Qatarra basin may be a small remnant of a larger paleo-lake including the mouth of a paleo-river. This study probed this area for presence of buried channels that may have fed the larger Moghra paleo-lake. We have used ALOS - PALSAR radar remote sensing data to identify the surface features in this region, such as channels, channel fills, and fractures. In addition, dual polarization PALSAR data (HV, HH) allowed analysis of the near surface geology and assisted in delineating areas of interest for GPR surveys. GPR data along 2D profiles were acquired using the GSSI SIR-3000 system with a 400 MHz antenna that provided images to approximately three meters in depth. All the GPS data were processed using RADAN 6.6 software. A conventional processing flow was used for data processing: The positional correction tool removed the air wave. A range-gain balanced the amplitudes and a final band-pass (50 kHz to 500 kHz) filter was applied to the data. Deconvolution was also applied for highlighting the finer details. In addition, spatial filters were used to attenuate continuous vertical noise. The migrated sections of GPR identified a major paleochannel distributary with two minor channels at the margins. The bedrock of the studied area consists of the Lower Miocene Moghra Formation (sandstone and shale intercalations). The area around the present lake is covered by about 2 m of lacustrine sediments of post-Miocene age in the east side and by recent eolian dunes in the west. These sediments are characterized by shallowing upward, horizontal to cross-bedded with an unconformity in between. The eastern end of the paleochannel surveyed by GPR is covered by recent sand dunes followed by an ephemeral stream that feeds the current lake. Field observations suggest that the movement of sand dunes in the northeast direction may have blocked the paleo-channel. A two meters deep trench was dug to confirm the GPR findings. Regional gravity mapping of this area also shows major gravity anomalies. More work is planned to carry out additional high resolution potential field surveys in conjunction with remote sensing and GPR studies to understand the paleo-drainage of this area. Identifying the exact track of the paleo-channels will help reconstructing of paleo drainage of this region and may help in mapping groundwater, this will be very important for the development of this rapidly expanding desert area.

Khan, S. D.; Fathy, M. S.; Azeem, M. A.

2012-12-01

10

Origin of the gypsum-rich silica nodules, Moghra Formation, Northwest Qattara depression, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

Gypsum rich-silica nodules appear in two shale horizons of the Moghra Formation (early Miocene) northwestern Qattara Depression, Western Desert, Egypt. These nodules are gray to milky white in colour, mostly botroidal and rose-like in shape and range in diameter from 2 to 7.5 cm. The silica nodule-bearing shale is composed mainly of smectite with a little minor kaolinite. The silica nodules consist mainly of quartz and are composed of gypsum-free matrix and gypsum-rich megacrystalline quartz. The matrix consists of microflamboyant quartz (less than 36 ?m in diameter) and chalcedony. The megacrystalline quartz occurs as lenticular and prismatic forms (length: 90-250 ?m; width: 30-90 ?m). The microprobe, petrographic and SEM examinations confirmed the occurrence of gypsum relics (diameter; 2-16 ?m) within the megacrystalline quartz. The chalcedony and mosaic microcrystalline quartz occurs as pore-lining and pore-filling cements. The structure of the silica nodules begins with quartzine in its outer rim, then gypsum-free microcrystalline quartz in the middle part and ends with gypsum-rich lenticular to prismatic megaquartz in the center. Field study, petrographic examination and microprobe analysis reveal that the silica nodules were formed by silicification of precursor gypsum nodules deposited in a marginal sabkha environment under an arid climate. The silicification selectively affected the gypsum nodules rather than the surrounding shale and occurred both through gypsum replacement and void filling. Transformation of isopachous chalcedony into mosaic microcrystalline quartz also occurred. The texture of the silica minerals reflects the different physico-chemical conditions under which they crystallized. Spherical nodules grew chiefly by the diffusive supply of the silica, and elongated ones grew by pore water advection. The integrated effect of climate, pH, salinity, crack systems within the sediment and oscillation in the groundwater level and its chemical composition contributed to the formation of the nodules.

El Khoriby, Essam M.

2005-06-01

11

Diagenetic origin of ironstone crusts in the Lower Cenomanian Bahariya Formation, Bahariya Depression, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

In this paper, a new interpretation of the ironstone crusts of the Bahariya Formation as late diagenetic products is provided. The siliciclastic Lower Cenomanian Bahariya Formation outcropping in the northern part of the Bahariya Depression (Western Desert, Egypt) is subdivided into three informal units that are mainly composed of thinly laminated siltstone, cross-bedded and massive sandstone, fossiliferous sandstone/sandy limestone and variegated shale. Abundant ironstone crusts occur preferentially within its lower and upper units but are absent in the middle unit. The ironstone crusts show selective replacement of carbonate components, including calcretes, by iron oxyhydroxides. More permeable parts of the terrigenous beds such as burrow traces, subaerial exposure surfaces, concretionary features and soft-sediment deformation structures led to heterogeneous distribution of the iron oxyhydroxides. A variety of diagenetic minerals, where goethite and hematite are the main end-products, were characterized by mineralogical analysis (XRD), petrography and SEM observation, and geochemical determinations (EMPA). Other diagenetic minerals include Fe-dolomite/ankerite, siderite, manganese minerals, barite, silica, illite/smectite mixed-layer, and bitumen. These minerals are interpreted to be formed in different diagenetic stages. Some minerals, especially those formed during eodiagenesis, show features indicative of biogenic activity. During burial, dolomite and ankerite replaced preferentially the depositional carbonates and infilled secondary porosity as well. Also during mesodiagenesis, the decomposition of organic matter resulted in the formation of bitumen and created reducing conditions favorable for the mobilization of iron-rich fluids in divalent stage. Telodiagenesis of the Cenomanian Bahariya deposits took place during the Turonian-Santonian uplift of the region. This resulted in partial or total dissolution of Fe-dolomite and ankerite which was concomitant to iron oxyhydroxide precipitation upon mixing with shallow oxygenated water. Circulation of reducing iron-rich fluids through fractures and inter and intrastratal discontinuities is proposed as an alternative model to explain the controversial source of iron for the ironstone crusts of the Bahariya Formation. The origin of iron-rich fluids is probably related to the basement rocks. The provided model relates the fluid movements through fractures and discontinuities with the preferential replacement of carbonates. This combination of processes is consistent with the heterogeneous geometries and the wide distribution of the ironstones.

Afify, A. M.; Sanz-Montero, M. E.; Calvo, J. P.; Wanas, H. A.

2015-01-01

12

Environmental impact and natural hazards on Kharga Oasis monumental sites, Western Desert of Egypt  

NASA Astrophysics Data System (ADS)

Kharga Oasis monumental sites are important to the cultural heritage in the South Western Desert of Egypt. These sites are scattered on the floor of the oasis representing ancient civilizations. The studied sites include the Hibis, EI-Nadura, EI-Ghueita and El-Zayyan temples as well as El-Bagawat Cemetery. The present study found that natural hazards have remarkable impacts on these sites. The impact of weathering processes, encroachment of sand dunes, stability of foundation beds and shallow groundwater seepage were documented. The present study found that humidity, temperature, sunlight and water content conditions seem to be favorable for biodegradation as evidenced by the presence of algae, bat blood and bird excretions. The radioactivity levels at the investigated sites are also measured via gamma-ray spectrometry. Sand dunes in the area pose a serious natural threat to the monumental sites. Active sand dunes are rapidly encroaching upon the components of these monuments, partially covering some monuments such as El-Ghueita Temple. These dunes load wind storms with fine sand particles. This causes wind erosion through sand blasting of these sites. Some monuments, such as EI-Nadura, EI-Ghueita and El-Zayyan temples were constructed on a suitable hard sandstone ground, whereas others, such as the Hibis Temple, were constructed on unsuitable soft shale ground in relatively topographically low area. The impact of the unstable foundation and shallow groundwater levels have caused severe structural damage as evidenced by tilted columns, cracked walls and salt-crystal growth in the porous building stones. These destructive elements threaten some other temples in Kharga Oasis and will eventually cause total physical collapse. Although rain is rare in this area, it can form a real threat to mud brick monuments such as El-Bagawat Cemetery. The natural radioactivity sources resulted in an annual effective dose equivalent values averaging 0.20, 0.13, 0.09 and 0.07 mSv/year for the monumental sites at Hibis, El-Nadura, El-Ghueita and El-Zayyan, respectively.

Salman, A. B.; Howari, F. M.; El-Sankary, M. M.; Wali, A. M.; Saleh, M. M.

2010-09-01

13

Geoenvironmental assessment of the SIWIA area Oasis, Western Desert, Egypt, using geographical and hydrological information systems  

NASA Astrophysics Data System (ADS)

Overpopulation of Egypt has put pressure on the government for horizontal expansion for food security. Therefore, horizontal expansion in the desert for agricultural purposes is one of the solutions. Groundwater represents the main source of water supply in Siwa Oasis. The sedimentary succession comprises different water bearing formations. These aquifers bear groundwater ranging in its salinity from fresh water to brine one. These aquifers are the Quaternary deposits, the Miocene carbonate, the Eocene carbonate, the Upper Cretaceous, the Cretaceous Nubian sandstone beside Carboniferous, Devonian, Silurian and Cambrian-Ordovicean sandstone aquifers. The Paleozoic sandstone has brine water but the Mesozoic one (Cretaceous Nubian sandstone) has fresh one. The Cretaceous Nubian sandstone represents the source of exploited water in the area, where it recharges the overlying carbonate aquifers. Fifty seven wells are included in the present study to reveal the hydrogeologic conditions of the oasis. The fractured carbonate aquifers represent the main exploitable aquifers due to their availability for the farmers in spite the low water quality. The water of this aquifer has a wide range of salinity ranging from 2377 ppm to > 17000 ppm depending on the depth of aquifer and the nature of facies and fracturing of the rock. The Nubian sandstone aquifers represent the main source of water in the area where it bears fresh water (< 1000 ppm). The flow within the Nubian sandstone is directed to the area of high discharge, i.e. to the west. The groundwater of the Quaternary and the fractured carbonates reflects leaching processes (secondary salinity) and that of the Nubian sandstone reflects meteoric origin and recharge during the pluvial period. The groundwater resources are evaluated with respect to their suitability for different purposes. Depending on the present geomorphological and hydrogeological studies and the previous pedological studies a landuse map was constructed.

Faid, A.; Ismail, E.; Birk, S.

2012-04-01

14

Characteristics of NORM in the oil industry from eastern and western deserts of Egypt.  

PubMed

Naturally occurring radionuclides (NORs) from the 232Th- and 238U-series, which are omnipresent in the earth's crust, can be concentrated by technical activities, particularly those involving natural resources. Although, a great deal of work has been done in the field of radiation protection and remedial action on uranium and other mines, recent concern has been devoted to the hazard arising from naturally occurring radioactive materials (NORM) in oil and gas facilities. NORM wastes associated with oil and gas operations from scale deposits, separated sludge and water at different oil fields in the eastern and western deserts were investigated. Concentrations of the uranium, thorium, and potassium (40K) series have been determined from high-resolution gamma-ray spectrometry. Total uranium content of samples was determined using laser fluorimetry. The levels of radioactivity were mainly due to enhanced levels of dissolved radium ions. Only minute quantities of uranium and thorium were present. The disequilibrium factor for 238U/226Ra has been determined. PMID:11339530

Shawky, S; Amer, H; Nada, A A; El-Maksoud, T M; Ibrahiem, N M

2001-07-01

15

Subsurface geology of Tertiary rocks of northeastern district of Western Desert, Egypt  

SciTech Connect

The lithofacies analysis of the Tertiary rocks reveals two ancient subbasins at the north and southeast of the northeastern district, Western Desert. The lithofacies of the Paleocene and early and middle Eocene sections are mainly calcareous. Shale predominates in the late Eocene rocks. The Paleocene rocks seem to have accumulated in a lagoonal environment of epineritic depths. The Paleocene rocks of the northern subbasin indicate accumulation on an unstable shelf. The Paleocene environmental conditions seem to have prevailed during the early and middle Eocene. During the late Eocene, rocks of shallow-water and current-agitated environments accumulated. The lower clastic layers of the Oligocene, having a sand/shale ratio less than one, indicate a clastic shoreline environment-lagoonal subenvironment. The Oligocene clastics are overlain by a basaltic sheet at the eastern part of the district. The middle Miocene lithofacies indicate rock accumulation in a contemporaneously subsiding basin under lagoonal or delta-front conditions at the southern part of the district. Marine stagnant-bottom-water conditions prevailed during the accumulation of the middle Miocene rocks at the norther parts. The Pliocene rocks seem to have accumulated in lagoons, where the inflow exceeded evaporation and alternating periods of exposure and flooding by either fresh or saline water of poor circulation prevailed. The tectonic instability of the district was initiated by volcancity during the late Oligocene.

Elzarka, M.H.; Radwan, I.A.

1983-03-01

16

3D slicing of radiogenic heat production in Bahariya Formation, Tut oil field, North-Western Desert, Egypt.  

PubMed

A 3D block of radiogenic heat production was constructed from the subsurface total gamma ray logs of Bahariya Formation, Western Desert, Egypt. The studied rocks possess a range of radiogenic heat production varying from 0.21 ?Wm(-3) to 2.2 ?Wm(-3). Sandstone rocks of Bahariya Formation have higher radiogenic heat production than the average for crustal sedimentary rocks. The high values of density log of Bahariya Formation indicate the presence of iron oxides which contribute the uranium radioactive ores that increase the radiogenic heat production of these rocks. The average radiogenic heat production produced from the study area is calculated as 6.3 kW. The histogram and cumulative frequency analyses illustrate that the range from 0.8 to 1.2 ?Wm(-3) is about 45.3% of radiogenic heat production values. The 3D slicing of the reservoir shows that the southeastern and northeastern parts of the study area have higher radiogenic heat production than other parts. PMID:23291561

Al-Alfy, I M; Nabih, M A

2013-03-01

17

Assessment of waterlogging in agricultural megaprojects in the closed drainage basins of the Western Desert of Egypt  

NASA Astrophysics Data System (ADS)

This paper investigates the development of waterlogging in the cultivated and arable areas within typical dryland closed drainage basins (e.g. the Farafra and Baharia Oases), which are located in the Western Desert of Egypt. Multi-temporal remote sensing data of the Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) were collected and processed to detect the land cover changes; cultivations, and the extent of water ponds and seepage channels. The Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) has been processed to delineate the catchment morphometrical parameters (i.e. drainage networks, catchment divides and surface areas of different basins) and to examine the spatial distribution of cultivated fields and their relation to the extracted drainage networks. The soil of these closed drainage basins is mainly shallow and lithic with high calcium carbonate content; therefore, the downward percolation of excess irrigation water is limited by the development of subsurface hardpan, which also saturates the upper layer of soil with water. The subsurface seepage from the newly cultivated areas in the Farafra Oasis has revealed the pattern of buried alluvial channels, which are waterlogged and outlined by the growth of diagnostic saline shrubs. Furthermore, the courses of these waterlogged channels are coinciding with their counterparts of the SRTM DEM, and the recent satellite images show that the surface playas in the downstream of these channels are partially occupied by water ponds. On the other hand, a large water pond has occupied the main playa and submerged the surrounding fields, as a large area has been cultivated within a relatively small closed drainage basin in the Baharia Oasis. The geomorphology of closed drainage basins has to be considered when planning for a new cultivation in dryland catchments to better control waterlogging hazards. The "dry-drainage" concept can be implemented as the drainage and seepage water can be conveyed through the inactive alluvial channels into certain abandoned playas for evaporation.

El Bastawesy, M.; Ramadan Ali, R.; Faid, A.; El Osta, M.

2013-04-01

18

Palynostratigraphy and paleoenvironmental significance of the Cretaceous succession in the Gebel Rissu-1 well, north Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

Palynological investigation of the Cretaceous Abu Roash, Bahariya, Kharita, Alamein, Alam El Bueib and Betty formations, encountered in the Gebel Rissu-1 well, north Western Desert, Egypt yielded 27 species of pteridophytic spores, 24 of gymnosperm pollen, 25 of angiosperm pollen and 11 of dinoflagellate cysts in addition to some acritarchs, foraminiferal test linings and freshwater algae. This enabled us to recognize five miospore biozones arranged from youngest to oldest as: Classopollis brasiliensis- Afropollis cf. kahramanensis- Dichastopollenites ghazalataensis Assemblage Zone (Late Cenomanian); Elaterosporites klaszii- Sofrepites legouxae- Afropollis jardinus Assemblage Zone (Middle/Late Albian-Early Cenomanian); Pennipollis peroreticulatus- Duplexisporites generalis-Tricolpates Assemblage Zone (Early Aptian-Early Albian); Tucanopollis crisopolensis- Afropollis sp. Assemblage Zone (Barremian) and Appendicisporites cf. tricornitatus- Ephedripites spp. Assemblage Zone (Late Neocomian). The Early Cretaceous Kharita, Alam El Bueib and the Betty formations encountered in the Gebel Rissu-1 well are interpreted to indicate oxic proximal and distal shelf deposits, characterized by type III/IV, V kerogen, which is gas prone but having little potential to produce hydrocarbons. The Upper Cretaceous Abu Roash and Bahariya formations are characterized by a distal suboxic-anoxic and marginal dysoxic-anoxic environment, and their kerogen type III/II indicates gas/oil prone nature. The Bahariya and Kharita Albian-Cenomanian sediments in the present study witnessed the onset of a semi-arid to arid climate, with local or seasonal humid conditions, based on the continuous high abundance of the elaterates pollen and Afropollis-producing plants that inhabited the paleotropical humid coastal plains.

El Beialy, Salah; El-Soughier, Maher; Mohsen, Sayed Abdel; El Atfy, Haytham

2011-02-01

19

Stacked, Lower Miocene tide-dominated estuary deposits in a transgressive succession, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The net transgressive Lower Miocene Moghra Formation of Egypt is a sandy estuarine complex consisting of a series of stratigraphic units that reflect repeated transgressive to regressive shoreline movements across the Burdigalian (Lower Miocene) coastal landscape. The transgressive part of each unit is preserved atop a deep erosional scour surface, and consists of tidal-fluvial sandstones with tree logs and vertebrate bones that transition up to cross-stratified, tidal estuarine channel deposits and then to open-marine, shelf mudstones and limestones. In contrast, the regressive part is thinly developed and consists of thin-bedded, fossiliferous shelf mudstones that pass upward to thin, tide-influenced delta-front deposits. Each of the nine transgressive-regressive units of the Moghra Formation is capped by a river-scour surface that severely truncates the underlying regressive half-unit. Regional tectonic subsidence and an overall decreasing influx of clastic sediment accounts for the accumulation of the Moghra Formation and its overall transgressive character. The high frequency relative base-level changes reflected by the transgressive-regressive units (averaging < 350 kyr) that punctuate the overall transgressive stratigraphic trend are thought to have been driven by (1) sea-level changes caused by recently-documented variations in East Antarctic ice-sheet volume during the Lower Miocene, and/or by (2) variation in the large-scale influx of sediment to the region (during continuous tectonic subsidence). The relative importance of the sea-level (eustatic fall) vs. supply drive (deep fluvial scour) mechanisms for producing the repeated and widespread Burdigalian incision surfaces in the Moghra succession cannot easily be determined.

Hassan, Safiya M.; Steel, Ronald J.; El Barkooky, Ahmed; Hamdan, Mohamed; Olariu, Cornel; Helper, Mark A.

2012-12-01

20

Tectono-metamorphic evolution of the Wadi Hafafit Culmination (central Eastern Desert, Egypt). Implication for Neoproterozoic  

E-print Network

Tectono-metamorphic evolution of the Wadi Hafafit Culmination (central Eastern Desert, Egypt Eastern Desert, Sudan, western Saudi Arabia, Ethiopia, Eritrea, Jordan and Yemen belong to the so.O. 530 El-Maadi, Cairo, Egypt Institut für Geowissenschaften, Universität Tübingen Sigwartstr. 10, D

Siebel, Wolfgang

21

ORIGINAL PAPER Neoproterozoic diamictite in the Eastern Desert of Egypt  

E-print Network

ORIGINAL PAPER Neoproterozoic diamictite in the Eastern Desert of Egypt and Northern Saudi Arabia in Wadi Kareim and Wadi Mobarak in the Eastern Desert of Egypt and the Nuwaybah formation in NW Saudi Desert of Egypt and in correlative exposures in NW Saudi Arabia. Because sedimentary rocks in ANS

Stern, Robert J.

22

Calcretes and palustrine carbonates in the Oligo-Miocene clastic-carbonate unit of the Farafra Oasis, Western Desert, Egypt: Their origin and paleoenvironmental significance  

NASA Astrophysics Data System (ADS)

The origin and paleoenvironmental significance of the calcretes and palustrine carbonates in the Oligo-Miocene clastic-carbonate unit that outcrops at the eastern sector of the Farafra Depression (Western Desert, Egypt) have been discussed based on field and petrographic investigations. The calcretes-palustrine carbonates assemblage occurs above a siliciclastic/distal alluvial-floodplain facies. The calcretes represent the transition from the underlying siliciclastic/distal alluvial-floodplain facies to the overlying palustrine carbonates. The calcrete-host rocks are muddy sandstones and sandy mudrocks. This study reveals the occurrence of groundwater calcretes with an upward gradational maturity pattern, ranging from incipient to nodular and to massive calcretes. The calcretes micromorphological analysis suggests that they were originated in vadose and phreatic diagenetic environments by groundwater through evaporation, degassing with no biological activity. The palustrine carbonates are also recognized above the calcrete horizons. They occur in the form of micritic limestones displaying different features that indicate their modifications during pedogenesis and subaerial exposure. These features include clotted-peloidal texture, fenestral fabric, mottling, pseudo-brecciation, desiccation cracks, pseudomicrokarst, root traces and silicification of the lime mud. The calcretes-palustrine carbonates assemblage records a progressive decrease in the terrigenous supply and a continuous rise of the groundwater table associated with local subsidence in a semi-arid to sub-humid climate. A model is suggested for the development of calcretes and palustrine carbonates in the study area.

Wanas, H. A.; Soliman, H. E.

2014-07-01

23

The contribution of geographic information systems and remote sensing in determining priority areas for hydrogeological development, Darb el-Arbain area, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Darb el-Arbain study area is in the southern Western Desert of Egypt and has been attracting increasing developmental interest in the last few decades, especially since agricultural development of the southern Baris area, where the groundwater resources of the Nubian Sandstone Aquifer System (NSAS) have been utilized for the cultivation of valuable lands. Due to the proven high potential of both groundwater and land resources, determining the priority areas for sustainable hydrogeological development becomes a necessity. A geographic information system, as a platform for geospatial modeling techniques, has been built, which depends on the recently collected data about the NSAS, in addition to the published databases. Certain criteria of practical value, like depth to groundwater, hydraulic conductivity, groundwater salinity, sodium adsorption ratio, and the safe yield of wells, were selected as decisive parameters for hydrogeological prioritization. The model pinpoints areas characterized by favorable hydrogeological conditions, which could be used for future development and implementation of an artificial storage and recovery (ASR) program. The designated priority areas for hydrogeological development occur at the southern, middle southern and some localized northern parts of the Darb el-Arbain area. The newly formed Tushka Lakes represent a suitable and excellent natural source of freshwater for implementing an ASR program.

Elewa, Hossam H.; Fathy, Rafik G.; Qaddah, Atef A.

2010-08-01

24

Characterization of magnetic spherical fractions in sand deposits for interpretation of environmental change around the El- Zayyan temple, Kharga Oasis, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

Desertification in North Africa has rapidly advanced over the last 6,000 years. Such environmental changes began in the Early Dynastic Period of Egypt (4200 - 3150 BC), and the occupation of Achaemenid Persian and Roman cultures in Egypt occurred under even drier climates. Kharga is the largest oasis of the five oases, located in the western desert of Egypt that contains a treasure trove of archaeological resources. This oasis has been highlighted to promote resource exploration and development of archaeological tourism since the 1980's. The El-Zayyan temple is located 27 km south of the central Kharga oasis. Zayyan was once called 'Tchonemyris', which has connection with the means of 'huge well' in Greek. Although major portions of the temple were rebuilt in 140 AD during the rule of the Roman Emperor Antoninus Pius, this temple is considered to be originally built in the Ptolemaic period (4c-1c BC). It is likely that the area had a sufficient water supply in the past as the El-Zayyan temple stands at the lowest point (-18 m a.s.l.) in the Kharga oasis. Furthermore, the El-Ghueita temple that stands on a hill top at 68.5 m a.s.l., 4 km northward from the El-Zayyan temple, has given name that means 'beautiful garden' in Greek. From these facts, we can imagine that the past landscape of this area contained green surroundings. The El-Ghueita temple was well known as a production centre of high quality wine since the mid-Dynastic age (2050 -1786 BC). As this area is currently arid, it is expected that there were irrigation facilities to maintain the vast farm land during the ancient period. To deepen our knowledge of how people developed their technologies and conducted their life within the natural environment of a drastic drying period, understanding the process of environmental change on a region scale is necessary. The aim of this study was to extract proxies from sand deposits in the western desert area to estimate the change in the environment. We examined the sand layers with a focus on the spherical magnetic fractions having relations with accumulation of free iron oxides, condition of water and microbial activities. The study sites were located west of the El-Zayyan temple, and six and seven samples were collected every 10 cm from the two sand profiles, Zy-R and Zy-6, respectively. AMS 14C dating was conducted using fine fractions of an organo-mineral complex; date ranges 5,000-8,400 yBP and 5,500-7,800 yBP were assigned to Zy-R and Zy-6, respectively. Spherical fractions, separated into six colored-types, were extracted using a neodymium magnet, and then characterized by SEM observation, EDX elemental analysis (FE-SEM S4700, Hitachi, Genesis, EDAX), and X-ray micro-crystal structural analysis (D8-Discover, Bruker axs) to discuss their origins. The vertical change in the density of each fraction by weight and counts in sand revealed the environmental change.

Watanabe, Makiko; Koizumi, Natsuko; Kato, Sayuri; Kikuchi, Ryohei; Kamei, Hiroyuki

2014-05-01

25

Evidence for Early and Mid-Cryogenian glaciation in the Northern ArabianNubian Shield (Egypt, Sudan, and western Arabia)  

E-print Network

over broad regions of the Central Eastern Desert of Egypt, NW Arabia and possible correlative units diamictite and BIFs of the Central Eastern Desert of Egypt and the correlative Nuwaybah diamictite and BIF (Egypt, Sudan, and western Arabia) ROBERT J. STERN1*, PETER R. JOHNSON2, KAMAL A. ALI1,3 & SUMIT K

Stern, Robert J.

26

The uppermost deposits of the stratigraphic succession of the Farafra Depression (Western Desert, Egypt): Evolution to a Post-Eocene continental event  

NASA Astrophysics Data System (ADS)

This paper gives insight into continental sedimentary deposits that occur at the uppermost part of the stratigraphic succession present in the north-eastern sector of the Farafra Depression (Western Desert, Egypt). Using space imagery to complete the field work, the geology of the area has been mapped and the presence of a N-S oriented fault system is documented. The analysis of the morphotectonic features related to this fault system allows reconstructing the structural and sedimentological evolution of the area. The study indicates that the continental deposits were accumulated in alluvial systems that unconformably overlie shale and evaporitic rocks attributable to the Paleocene-Eocene Esna Formation. The deposits of the Esna Formation show soft-sediment deformation features, which include slump associated to dish and pillar sedimentary structures and provide evidence of syndepositional tectonic activity during the sedimentation of this unit. The outcrops are preserved in two areas on separated fault-bounded blocks. Proximal alluvial fan facies crop out in a dowthrown block close to the depression boundary. The proximal facies are made up mostly by polymictic conglomerates which occasionally contain boulders. The conglomerate clasts are mainly quartz, carbonate, anhydrite satin spar vein, mudrock, ironstone and nummulite fossils. The mid-fan facies consist of trough cross-bedded, rippled and cross-laminated quartzarenites with reworked glauconite grains and carbonate rock fragments, interpreted as deposited by distributary streams. The distal alluvial fan deposits consist of sandy marls that evolve toward the top of the sections into root-bioturbated lacustrine limestone beds that are locally silicified. The limestones are biomicrites containing characea, ostracods and gastropods with fenestral porosity. A number of features, including clast provenance (mainly from marine Paleocene and Eocene rocks), the observed fractural pattern (N-S direction related to the opening of the Red Sea), and the sedimentary relationships, suggests that the continental deposits were accumulated during the Oligocene-Miocene interval.

Sanz-Montero, M. E.; Wanas, H.; Muñoz-García, M. B.; González-Acebrón, L.; López, M. V.

2013-11-01

27

Tectonic and provenance history of the Neotethyan margin in NE Africa recorded by detrital zircon (U-Th)/He thermochronometry from a borehole in the Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The subsurface of the Western Desert of Egypt contains multiple stacked sedimentary basin deposits separated by major unconformities reflecting the long-lived tectonic evolution of the Neotethyan continental margin in eastern North Africa. In this study, zircon (U/Th)/He (ZHe) data were collected from cuttings from a ~15000 ft borehole that penetrated Tertiary and Cretaceous strata and a major erosional unconformity at 13000 ft that juxtaposes Cretaceous and Cambro-Ordovician strata. A total of 56 samples spanning the borehole from 750-15400 ft yielded >200 single-grain ZHe ages in order to elucidate the thermal evolution of the borehole and constrain the thermal history of detrital provenance. ZHe ages above the unconformity are significantly older than the depositional age, suggesting detrital ZHe ages that were not reset subsequent to deposition. ZHe ages from Cambro-Ordovician strata below the unconformity are substantially younger than the minimum depositional age suggesting major cooling and resetting of zircon (>200C) during the Hercynian orogeny. In detail, ZHe ages form Cretaceous strata above the unconformity show the following trends. (1) ZHe ages from 6000-9000 ft (Aptian-Early Cenomanian) are characterized by a ZHe age peak at ~450 Ma and a minor Albian peak, (2) samples from 9000-12000 ft (Late Hauterivian-Barremian) show two major detrital ZHe age peaks at ~450 and 350 Ma, while (3) samples from 12000-13000 ft (Early Hauterivian) exhibit three dominant ZHe age components at ~450 Ma, 350 Ma, and 170-200 Ma. Additional cuttings from an offset containing complete stratigraphy yielded ZHe ages that mainly represent a strong Hercynian input as well as Late Triassic and Early Jurassic components of Tethyan related input. These ZHe age peaks display provenance characteristics typical for cooling signatures of rocks from the eroding Arabian-Nubian Shield, a North-African Hercynian source, and eroded material from exhumed fault blocks along the Triassic-Jurassic Neotethyan rifted margin. While immediately above the unconformity Hercynian ZHe ages dominate, the occurrence of Triassic or Early Jurassic suggest the presence of eroding rapidly cooled and exhumed Tethyan normal fault blocks. At decreasing depth, first Jurassic-Triassic, and then Hercynian source input disappears and the arrival of detritus from the Arabian-Nubian Shield begins to dominate the North African passive continental margin in the Western Desert in the middle to late Cretaceous. This unique data set illustrates the power of ZHe thermochronometry as a thermochronometer in boreholes with temperatures in excess of other low-temperature dating techniques and as a detrital provenance tool, not constraining crystallization ages, but rather shedding light on the cooling and exhumation history of the source terrane and the tectonic/geological environment of the basin deposits.

Stockli, D.; Glauser, T.; Bosworth, W.; Maher, T.; Clare, A.

2009-04-01

28

Pseudospherulitic fibrous calcite from the Quaternary shallow lacustrine carbonates of the Farafra Oasis, Western Desert, Egypt: A primary precipitate with possible bacterial influence  

NASA Astrophysics Data System (ADS)

Pseudospherulitic fibrous calcite (PFC) has been found as a major constituent (85-90%) within thin massive limestone beds of the Quaternary mudflat-shallow lacustrine facies association (1.5-2 m thick) that forms part of combined facies associations of the Quaternary clastic-carbonate unit (25-30 m thick) at Bir-Karawein area in the Farafra Oasis, Western Desert, Egypt. The thin massive limestone beds (2-5 cm thick) are devoid of pedogenic features and marine fossils. They form a rhythmic cyclic succession with thin massive mudrocks (5-10 cm thick). The mudflat-shallow lacustrine facies association herein occurs within a depositional sequence of distal alluvial-floodplain (6-12 m thick) and palustrine (1.5-4.5 m thick) facies associations. The PFC is a composed of loosely packed rounded to sub-rounded single low-Mg-calcite crystals (150-250 ?m-sized) with intracrystalline fibrous microfabric marked by fibers (150-250 ?m long and 10-20 ?m wide) radiating from the center of the individual crystals and displaying irregular internal growth with lobate pattern. The PFC crystals show non-planar to highly irregular intercrystalline boundaries. Under SEM, the individual crystal fibers group of PFC form ellipsoid to sub-globular bodies. Each PFC crystal exhibits successive zones of thick non-luminescence and thin brightly orange to dull luminescence. The matrix (10-15%) between the PFC crystals is mainly a honeycomb-like smectite. The PFC is postulated to be a primary precipitate. This concept is reached because the PFC: (i) does not display the criteria of typical Microcodium structures, root-calcification, speleothem structures, calcite spherulites of laminar calcretes, and calcitization of precursor dolomite or aragonite, (ii) possesses homogenous compositional and textural characteristics, and (iii) occurs within limestone beds that lie in between impermeable massive mudrock beds that dampen diagenesis. A role for possible bacterial contribution in crystallization of the PFC is assumed in the view of its internal microfabric characteristics (pseudospherulitic and lobate internal growth patterns), and morphological features (ellipsoidal to subglobular appearance), in addition to its slightly negative values of ?13C (-0.51‰ to -2.19‰). The low concentration of Na (0.11-0.20%), Sr (70-110 ppm) and Mn (0.04-0.31%), in addition to the negative values of ?18O (-4.65‰ to -5.96‰) in the PFC reflect its deposition from oxygenated freshwater. In addition, the absence of covariance between ?13C and ?18O values (r = -0.202) of the PFC indicates precipitation in a hydrologically-open, short-lived lake setting. In summary, the PFC is of low-Mg type and formed in a hydrologically-open, short-lived, freshwater lake as a primary precipitate with possible bacterial contribution.

Wanas, H. A.

2012-04-01

29

Precambrian Research 136 (2005) 2750 The Wadi Mubarak belt, Eastern Desert of Egypt  

E-print Network

Precambrian Research 136 (2005) 27­50 The Wadi Mubarak belt, Eastern Desert of Egypt System in the Central Eastern Desert of Egypt. The belt therefore appears to be a structural feature reserved. Keywords: Central Eastern Desert; Egypt; Najd Fault System; Wadi Mubarak belt; Conjugate strike

Fritz, Harald

30

Neoproterozoic tectonothermal evolution of the Central Eastern Desert, Egypt: a slow velocity tectonic process  

E-print Network

Neoproterozoic tectonothermal evolution of the Central Eastern Desert, Egypt: a slow velocity in the Central Eastern Desert of Egypt is constraint by 40 Ar/39 Ar ages of hornblende and muscovite from Meatiq, University of Assiut, Egypt Received 10 January 2001; received in revised form 24 October 2001; accepted 25

Fritz, Harald

31

Geology of Gebel Qattar batholith, central Eastern Desert, Egypt  

Microsoft Academic Search

Using Multi-Spectral Scanner (MSS) Landsat images of bands 5 and 7, colour stretched enhancement images and aerial photographs, it was possible for the first time to identify three different types of granites within the Gebel Qattar batholith (central Eastern Desert, Egypt), named G1, G2 and G3. The last two represent two successive granitic intrusive phases, G2 being earlier. G1 represents

M. L. EL RAKAIBY; M. H. SHALABY

1992-01-01

32

Phanerozoic tectonothermal history of the ArabianNubian shield in the Eastern Desert of Egypt: evidence from fission track  

E-print Network

Phanerozoic tectonothermal history of the Arabian­Nubian shield in the Eastern Desert of Egypt were performed in the Eastern Desert of Egypt. The results provide insights into the processes driving sedimentary strata in the Eastern Desert of Egypt are largely missing. (2) The second major Phanerozoic event

Fritz, Harald

33

Silver and silver-bearing minerals at the Um Samiuki volcanogenic massive sulphide deposit, Eastern Desert, Egypt  

Microsoft Academic Search

The Um Samiuki Zn–Cu–Pb–Ag mineralisation, south Eastern Desert, Egypt is hosted by felsic volcanic rocks which form part of the 712-Ma-old, east-west-trending Shadli Volcanic Belt. Two major occurrences of massive sulphides are present at the top of rhyolitic breccia in the Western and Eastern mine areas. In each occurrence, a bornite-bearing zone is overlain by a pyrite-chalcopyrite-bearing zone and underlain

Ibrahim M. Shalaby; Eugen Stumpfl; Hassan M. Helmy; Mahmoud M. El Mahallawi; Omar A. Kamel

2004-01-01

34

Gravitational collapse origin of shear zones, foliations and linear structures in the Neoproterozoic cover nappes, Eastern Desert, Egypt  

Microsoft Academic Search

The Um Esh–Um Seleimat area lies to the west of the Meatiq Core Complex (MCC), in the Central Eastern Desert (CED), Egypt, which forms part of the Neoproterozoic Arabian–Nubian Shield in NE Africa and Western Arabia. The study area is a NW-trending zone of intensely foliated ophiolitic melange and molasse sedimentary rocks. There is a single regional foliation, S1, defined

Abdel-Rahman Fowler; Baher El Kalioubi

2004-01-01

35

Chemical and isotopic constraints on the origin of Wadi El-Tarfa ground waters, Eastern Desert, Egypt  

Microsoft Academic Search

We evaluated the use of the renewable ground water resources of the Eastern Desert to develop sustainable agriculture in Upper Egypt, an alternative that could alleviate some of Egypt's dependence on water from the Nile River. Ground water from shallow aquifers in the Eastern Desert of Egypt, near the intersection of Wadi El-Tarfa and the Nile River, was analyzed for

M. Sultan; N. C. Sturchio; Y. Abdel Hady; M. El Anbeawy

2000-01-01

36

Holocene freshwater carbonate structures in the hyper-arid Gebel Uweinat region of the Sahara Desert (Southwestern Egypt) q  

E-print Network

Desert (Southwestern Egypt) q Margarita M. Marinova a,b , A. Nele Meckler c , Christopher P. McKay b: Carbonate structures Gebel Uweinat Sahara Desert Holocene climate a b s t r a c t The eastern part region of the Sahara Desert, near the triple border of Egypt, Sudan, and Libya (N22°, E25°), re- ceives

Gilli, Adrian

37

Natural radioactivity and Rare Earth elements in feldspar samples, Central Eastern desert, Egypt  

Microsoft Academic Search

The pegmatite bodies of the Eastern Desert of Egypt are widely distributed especially along the Marsa-Alam-Idfu road. The Abu Dob area covers about 150km2 of the Arabian Nubian shield at the central part of the Eastern Desert of Egypt. Most of the pegmatite is zoned; the zonation starts with milky quartz at the core followed by alkali feldspar at the

Nadia Walley El-Dine; Amal El-Shershaby; Sofia Afifi; Amany Sroor; Eman Samir

2011-01-01

38

Formation of Neoproterozoic metamorphic complex during oblique convergence (Eastern Desert, Egypt)  

Microsoft Academic Search

Major portions of the Pan-African Orogen in the Eastern Desert of Egypt were formed by island-arc accretion in the Neoproterozoic. These areas are characterized by their lack of major crustal thickening. Metamorphic core complexes occur parallel to the strike of the Eastern Desert Orogen. These domes exhibit polyphase metamorphism and deformation in contrast to the structurally overlying nappes which include

H. Fritz; E. Wallbrecher; A. A. Khudeir; F. Abu el Ela; D. R. Dallmeyer

1996-01-01

39

Formation of Neoproterozoic metamorphic core complexes during oblique convergence (Eastern Desert, Egypt)  

Microsoft Academic Search

Major portions of the Pan-African Orogen in the Eastern Desert of Egypt were formed by island-arc accretion in the Neoproterozoic. These areas are characterized by their lack of major crustal thickening. Metamorphic core complexes occur parallel to the strike of the Eastern Desert Orogen. These domes exhibit polyphase metamorphism and deformation in contrast to the structurally overlying nappes which include

H. FRITZ; E. WALLBRECHER; A. A. KHUDEIR; F. ABU EL ELA; D. R. DALLMEYER

1996-01-01

40

Thermal Performance of Building Envelope in Very Hot Dry Desert Region in Egypt (Toshky)  

E-print Network

Toshky region is a desert region located in the south east of Egyptian western desert at the Tropical Cancer (23.5 N). The following features characterized this region during the summer season; aridity, high summer day time temperatures reaches...

Khalil, M. H.; Sheble, S. S.; Helal, M. A.; El-Demirdash, M.

2010-01-01

41

The El Mayah molasse basin in the Eastern Desert of Egypt A. Shalaby a,b,*, K. Stuwe a,*, H. Fritz a  

E-print Network

The El Mayah molasse basin in the Eastern Desert of Egypt A. Shalaby a,b,*, K. Stu¨we a,*, H. Fritz: Molasse basin; Eastern Desert of Egypt; Pan-African evolution 1. Introduction Molasse basins occur of kilometres of the East- ern Desert of Egypt. Its sedimentary record shows that deposition occurred in two

Fritz, Harald

42

MODELING POPULATION VIABILITY FOR THE DESERT TORTOISE IN THE WESTERN MOJAVE DESERT1  

Microsoft Academic Search

The desert tortoise is a threatened species living in the deserts of the Amer- ican Southwest. Using size-structured demographic models, we analyzed the status of the tortoise in the Western Mojave desert and evaluated the effectiveness of possible manage- ment measures. Our demographic analyses agree with the trends reported by field censuses in showing rapid population decline. Importantly, simulations that

DANIEL DOAK; PETER KAREIVA

1994-01-01

43

Eoradiolites liratus (Bivalvia, Radiolitidae) from the Upper Cenomanian Galala Formation at Saint Paul, Eastern Desert (Egypt)  

Microsoft Academic Search

An assemblage of the shallow-water radiolitid Eoradiolites liratus (Conrad, 1852) is described from the Upper Cenomanian Galala Formation at Saint Paul (southern Galala, Eastern Desert, Egypt). At this locality, the stratigraphically youngest rudists occur just below the latest Cenomanian ammonite Vascoceras cauvini\\/V. rumeaui Biozone. Palaeogeographically, E. liratus shows affinities with southern parts of the Mediterranean Tethyan Realm and a close

Magdy M. El-Hedeny; Ahmed M. El-Sabbagh

2005-01-01

44

From platform to basin: the evolution of a Paleocene carbonate margin (Eastern Desert, Egypt)  

Microsoft Academic Search

In this study, progradation and the subsequent retrogradation of a late Paleocene isolated carbonate platform (Galala Mountains, Eastern Desert, Egypt) is demonstrated by variations of distinct facies associations from the platform margin in the north to the hemipelagic basin in the south. A combination of a sea-level drop and tectonic uplift at around 59 Ma (calcareous nannofossil biozone NP5) favored the

C. Scheibner; J. J. G. Reijmer; A. M. Marzouk; R. P. Speijer; J. Kuss

2003-01-01

45

Diagenesis of the lower Eocene Thebes Formation, Gebel Rewagen area, Eastern Desert, Egypt  

Microsoft Academic Search

The diagenesis of lower Eocene shallow water carbonates with flint was studied in the Gebel Rewagen area, Eastern Desert, Egypt. The carbonates are mainly wackestones to packstones with benthic bioclasts embedded in a dark red luminescent micrite matrix. The studied succession displays a complex diagenetic history that involves syngenetic and late diagenetic processes. Silica, which exists either as persistent bands,

Mohamad N Shaaban

2004-01-01

46

Geochemistry and tectonic evolution of the Neoproterozoic Wadi Ghadir ophiolite, Eastern Desert, Egypt  

Microsoft Academic Search

We report new geochemical data from the Neoproterozoic ophiolite in the Wadi Ghadir area, Eastern Desert, Egypt. The Wadi Ghadir ophiolite (WGO) is composed of layered and isotropic gabbros and amygdaloidal to porphyritic pillow lavas. Both the gabbroic rocks and the pillow lavas are intruded by dike swarms with different chemical affinities and spatial orientations. The WGO occurs in an

Yasser Abd El-Rahman; Ali Polat; Yildirim Dilek; Brian Fryer; Mohamed El-Sharkawy; Shawki Sakran

2009-01-01

47

Cu Ni PGE MINERALIZATION IN THE GENINA GHARBIA MAFIC ULTRAMAFIC INTRUSION, EASTERN DESERT, EGYPT  

Microsoft Academic Search

The Genina Gharbia intrusion is a small late Precambrian mafic-ultramafic complex in the Eastern Desert of Egypt. It com- prises harzburgite, lherzolite, pyroxenite, norite and gabbro. The intrusion is not metamorphosed, but highly affected by faulting and shearing, and most of the original contacts have been obliterated. The various rocks are characterized by high modal content of magnesiohornblende and abundant

HASSAN M. HELMY

2004-01-01

48

Islamic Versus Western Conceptions of Education: Reflections on Egypt  

Microsoft Academic Search

Creating an education system based on Islamic principles while also meeting the demands of a modern, technological world is a daunting, perhaps impossible task. This paper examines the contradictions between Islamic education theory and the Western-based education systems found in most Islamically oriented countries. Egypt is used as a case study to illustrate the complex and delicate balance policy makers

Bradley J. Cook

1999-01-01

49

Clockwise rotation of the western Mojave Desert  

NASA Technical Reports Server (NTRS)

A study of paleomagnetic data from Miocene volcanic rocks in the western Mojave Desert, which suggests about 25 deg of clockwise rotation, is presented. A total of 166 oriented core samples of two types of basalt were taken from 19 sites in the region. After demagnetization to 40 or 60 mT, application of structural corrections, and inversion of reversed sites, the data yielded an average direction of 51.6 deg inclination and 15.6 deg declination. When compared with the expected direction for Miocene rocks for stable North America, the direction for these Mojave rocks shows a clockwise rotation of 23.8 deg + or - 11.3 deg and a flattening of about 2.1 deg, a rotation which agrees in direction with oroclinal bending of the southern Sierra Nevada due to right-lateral shear along the western margin of North America. Most of this rotation is constrained by other paleomagnetic and strucural information to have occurred soon after the sampled basalts were deposited (about 20 Ma) and before about 16 Ma. These clockwise declination anomalies indicate that any subsequent counterclockwise rotation is small and/or compensated by previous clockwise rotation.

Golombek, Matthew P.; Brown, Laurie L.

1988-01-01

50

Banded Iron Formations from the Eastern Desert of Egypt: A new type of Ore? KHALIL, Khalil Isaac1 and EL-SHAZLY, Aley K.2  

E-print Network

Banded Iron Formations from the Eastern Desert of Egypt: A new type of Ore? KHALIL, Khalil Isaac1 localities in an area approximately 30,000 km2 within the eastern desert of Egypt. With the exception and EL-SHAZLY, Aley K.2 1 Department of Geology, University of Alexandria, Egypt 2 Geology Department

El-Shazly, Aley

51

Soil seed bank in different habitats of the Eastern Desert of Egypt.  

PubMed

The floristic composition and species diversity of the germinable soil seed bank were studied in three different habitats (desert salinized land, desert wadi, and reclaimed land) in the Eastern Desert of Egypt. Moreover, the degree of similarity between the seed bank and the above-ground vegetation was determined. The seed bank was studied in 40 stands representing the three habitats. Ten soil samples (each 25 × 20 cm and 5 cm depth) were randomly taken per stand. The seed bank was investigated by the seedling emergence method. Some 61 species belonging to 21 families and 54 genera were identified in the germinable seed bank. The recorded species include 43 annuals and 18 perennials. Ordination of stands by Detrended Correspondence Analysis (DCA) indicates that the stands of the three habitats are markedly distinguishable and show a clear pattern of segregation on the ordination planes. This indicates variations in the species composition among habitats. The results also demonstrate significant associations between the floristic composition of the seed bank and edaphic factors such as CaCO3, electrical conductivity, organic carbon and soil texture. The reclaimed land has the highest values of species richness, Shannon-index of diversity and the density of the germinable seed bank followed by the habitats of desert wadi and desert salinized land. Motyka's similarity index between the seed bank and the above-ground vegetation is significantly higher in reclaimed land (75.1%) compared to desert wadi (38.4%) and desert salinized land (36.5%). PMID:23961181

Gomaa, Nasr H

2012-04-01

52

Platinum-Group Element Geochemistry in Podiform Chromitites and Associated Peridotites of the Precambrian Ophiolite, Eastern Desert, Egypt  

Microsoft Academic Search

The ultramafic portions of the Proterozoic ophiolite, Eastern Desert, Egypt, contain significant chromitite concentrations that are mainly located in the central and southern parts of the Eastern Desert as small and irregular bodies within a fully serpentinized dunite and harzburgite. Chromitite spinel exhibits a wide range of composition from high Cr to high Al varieties. The Cr# of chromian spinel

A. Hassan Ahmed; Shoji Arai

53

Geochemistry of lamprophyre dykes, Wadi Sikait area, South Eastern Desert, Egypt  

Microsoft Academic Search

The Wadi Sikait area lies at about 95 km southwest of Marsa Alam City along the Red Sea Coast, Eastern Desert, Egypt. It is\\u000a occupied by Precambrian rocks of ophiolitic mélange, metamorphosed sandstones (MSS), gabbros and monzogranites which were\\u000a later intruded by lamprophyre dykes and quartz veins.\\u000a \\u000a \\u000a The lamprophyre dykes were extruded in NW-SE and NE-SW trends cutting monzogranites and

Ibrahim M. El-Ahmadi; Ragab A. Ahmed

2011-01-01

54

Peculiar Feldspar And Quartz Inclusions Within Zircons From Anorthosites, North Eastern Desert, Egypt  

Microsoft Academic Search

Zircons from three anorthosite outcrops along Wadi Dib area, north Eastern Desert of Egypt contain abundant and conspicuous inclusions of quartz, feldspar, amphibole and apatite. These anorthosites, as (50-100m thick) layers, represent the top of mafic-ultramafic intrusions exhibiting rhythmic layering visible by reputation of melanocratic and leucocratic layers. Field and microscopic studies exhibit that these anorthosites were affected by the

H. A. Eliwa; M. I. Dawoud; I. M. Khalaf; J. F. Negendank; T. Itaya

2004-01-01

55

Late Neoproterozoic strongly peraluminous leucogranites, South Eastern Desert, Egypt – petrogenesis and geodynamic significance  

Microsoft Academic Search

Summary Late Neoproterozoic garnet-bearing leucogranites are developed locally along thrust faults in the South Eastern Desert, Egypt. This work presents field observations, whole rock major and trace element abundances, Rb–Sr isotope data and mineral chemistry for three occurrences in the Sikait-Nugrus area. Field observations show that the leucogranites cut the faults and their contact with the country rocks is sharp

A. M. Moghazi; M. A. Hassanen; F. H. Mohamed; S. Ali

2004-01-01

56

Barite mineralisation in the south Um Monqul area, north Eastern Desert, Egypt  

Microsoft Academic Search

The barite mineralisation in the north Eastern Desert of Egypt is hosted by Pan-African dacite, dacite porphyry and granite. The host rocks are variably altered by potassic, phyllic, phyllic-argillic, propylitic and advanced argillic alteration. The barite mineralisation is in veins trending east-northeast — west-southwest and dipping 65°–80° to the southeast. The veins are mainly of barite with subordinate quartz, accessory

Mohamed A. Wetait; Nagy S. Botros

1997-01-01

57

Geochemistry of an island-arc plutonic suite: Wadi Dabr intrusive complex, Eastern Desert, Egypt  

Microsoft Academic Search

The Wadi Dabr intrusive complex, west of Mersa-Alam, Eastern Desert, Egypt ranges in composition from gabbro to diorite, quartz diorite and tonalite. The gabbroic rocks include pyroxene-horn blend e gabbro, hornblende gabbro, quartz-hornblende gabbro, metagabbro and amphibolite. Mineral chemistry data for the gabbroic rocks indicate that the composition of clinopyroxenes ranges from diopside to augite and the corresponding magma is

Fawzy F. Abu El-Ela

1997-01-01

58

Ocellar lamprophyre dyke bearing mineralization, Wadi Nugrus, Eastern Desert, Egypt: Geology, mineralogy and geochemical implications  

Microsoft Academic Search

The ocellar lamprophyre dyke (ENE-WSW) is recorded at Wadi Nugrus, Eastern Desert, Egypt. It cuts porphyritic biotite granites\\u000a and varies in thickness from 0.5 to 1.5 m and up to 3 km in length. The lamprophyre dyke has been altered, and it is characterized\\u000a by porphyritic and panidiomorphic textures with plagioclase, olivine, and augite constituting the porphyritic phase in a

M. E. Ibrahim; G. M. Saleh; N. A. Dawood; G. M. Aly

2010-01-01

59

Measurement of natural radioactivity and its significant hazards of some hematite samples in Eastern Desert, Egypt  

Microsoft Academic Search

Using high-resolution ?-ray spectroscopy, the activity concentration of naturally occurring radionuclides 226Ra, 232Th and 40K was determined in hematite mineral samples from two different areas, Abu Aggag and Um Gereifat areas, in Eastern Desert of Egypt. The results indicated that all samples under investigation contain 226Ra and 232Th whereas 40K could not be detected. The mean activity concentration values were

N. K. Ahmed; A. M. El Arabi; H. M. Mahmoud; K. Salahel-din

2007-01-01

60

Geochemistry of accessory minerals associated with radioactive mineralisation in the central Eastern Desert, Egypt  

Microsoft Academic Search

Prominent shear zones in the low Ca granitic plutons of El-Missikat and El-Erediya, central Eastern Desert of Egypt trend northwest-southeast, north-south and northeast-southwest. The shear zones are filled with jasper containing uraniferous mineralisation with accessory uranophane, pitchblende and uraninite, accompanied by pyrite, galena, magnetite-titanomagnetite, ilmenite, hematite, rutile, titanite, fluorite, zircon, monazite, apatite and tourmaline. It is possible to discriminate between

A. M. El-Kammar; N. El-Hazik; M. Mahdi; N. Aly

1997-01-01

61

Chemistry of columbite-tantalite minerals in rare metal granitoids, Eastern Desert, Egypt  

Microsoft Academic Search

Paragenetic, textural, and chemical characteristics of columbite-tantalite minerals are examined as steps towards identifying the metallogenetic processes of their host granitoids. Columbite-tantalite-bearing granitoids of the Eastern Desert province of Egypt can be categorized into: (i) metaluminous alkali granites; (ii) peraluminous Li-albite granites; and (iii) metasomatized biotite and\\/or muscovite granite (i.e. apogranites). Columbite of the alkali granite is of FeNb206 composition

H. M. Abdalla; H. A. Helba; F. H. Mohamed

1998-01-01

62

The Sukari Gold Mine, Eastern Desert—Egypt: structural setting, mineralogy and fluid inclusion study  

Microsoft Academic Search

The Sukari gold mine (18.8 Mt @ 2.14 g\\/t Au) is located 15 km west of the Red Sea coast in the southern central Eastern Desert of Egypt. The vein-type deposit is hosted in Late Neoproterozoic granite that intruded island-arc and ophiolite rock assemblages. The vein-forming process is related to overall late Pan-African shear and extension tectonics. At Sukari, bulk NE–SW strike-slip deformation

Hassan M. Helmy; Reinhard Kaindl; Harald Fritz; Jürgen Loizenbauer

2004-01-01

63

Melonite group minerals and other tellurides from three Cu–Ni–PGE prospects, Eastern Desert, Egypt  

Microsoft Academic Search

Melonite group minerals and other tellurides are described from three Cu–Ni–PGE prospects in the Eastern Desert of Egypt: Gabbro Akarem, Genina Gharbia and Abu Swayel. The prospects are hosted in late Precambrian mafic–ultramafic rocks and have different geologic histories. The Gabbro Akarem prospect is hosted in dunite pipes where net-textured and massive sulfides are associated with spinel and Cr-magnetite. Michenerite,

Hassan M. Helmy

2005-01-01

64

Abu Hamamid Neoproterozoic Alaskan-type complex, south Eastern Desert, Egypt  

Microsoft Academic Search

Abu Hamamid (AH) Neoproterozoic (Sm\\/Nd model age of ?770±20Ma) mafic–ultramafic intrusion lies along a NE–SW fracture zone in the Shadli Metavolcanic Belt, south Eastern Desert, Egypt. AH intrusion is concentrically zoned with cumulate clinopyroxene-bearing dunite core mantled by olivine clinopyroxenite, hornblende clinopyroxenite and hornblende gabbroic rim. The observed crystallization sequence is olivine (+spinel)-clinopyroxene–hornblende. Orthopyroxene is an extremely rare phase in

E. S. Farahat; H. M. Helmy

2006-01-01

65

Neoproterozoic (835–720 Ma) Serpentinites in the Eastern Desert, Egypt: Fragments of Forearc Mantle  

Microsoft Academic Search

Most Neoproterozoic ophiolites of the Arabian-Nubian Shield show compositions consistent with formation in a suprasubduction zone environment, but it has not been clear whether this was in a forearc or back-arc setting. Ophiolitic serpentinites are common in the Eastern Desert of Egypt, but their composition and significance are not well understood. Here we report new petrographic, mineral, chemical, and whole-rock

2007-01-01

66

Geochemical and petrographic studies of Ta mineralization in the Nuweibi albite granite complex, Eastern Desert, Egypt  

Microsoft Academic Search

The Nuweibi albite granite is one of 14 known Sn-Ta-Nb bearing granitoids in the Eastern Desert region of Egypt. The granite\\u000a is a highly leucocratic, albite-rich rock with accessory columbite-tantalite, cassiterite, microlite and ixiolite as well\\u000a as topaz, garnet and white mica. Ages of 450–600 Ma were obtained from zircons by the 207Pb\\/206Pb evaporation method. Great uncertainty is caused by

H. Helba; R. B. Trumbull; G. Morteani; S. O. Khalil; A. Arslan

1997-01-01

67

Listvenite–lode association at the Barramiya gold mine, Eastern Desert, Egypt  

Microsoft Academic Search

Several occurrences of gold-bearing quartz veins are situated along the east–northeast-trending Barramiya–Um Salatit ophiolitic belt in the central Eastern Desert of Egypt. In the Barramiya mine, gold mineralization within carbonaceous, listvenized serpentinite and adjacent to post-tectonic granite stocks points toward a significant role of listvenitization in the ore genesis. The mineralization is related to quartz and quartz–carbonate lodes in silicified\\/carbonatized

Basem Zoheir; Bernd Lehmann

2011-01-01

68

Pan-African Younger Granitoids of the Southern Eastern Desert, Egypt: Geology, Geochemical Constraints, and Mineralization  

Microsoft Academic Search

Younger granitoids of the Gabal El Farayid—Gabal El Marafawy district in the southern Eastern Desert, Egypt are compositionally syenogranites. Based on petrological and geochemical studies, they are classified as two distinct types: the biotite-hornblende subsolvus El-Marafaway I-type syenogranite; and the biotite-bearing hypersolvus El-Farayid A-type syenogranite. The subsolvus El-Marafawy syenogranite is characterized by low Rb\\/Sr ratios and high field strength element

Gehad M. Saleh

2006-01-01

69

Talc mineralization of ultramafic affinity in the Eastern Desert of Egypt  

Microsoft Academic Search

Petrographical and petrochemical studies of the talc host rocks of Rod Umm El-Farag and Wadi Thamil in the Eastern Desert\\u000a of Egypt reveal that they consist mainly of metavolcanic rocks, whilst the geology, petrography, mineralogy, chemistry and\\u000a quality of the enclosed talc lenses reveal that the ore has ultramafic affinity. The setting of the talc ore is similar to\\u000a that

M. F. El-Sharkawy

2000-01-01

70

Late Proterozoic older granitoids from the North Eastern desert of Egypt: petrogenesis and geodynamic implications  

Microsoft Academic Search

Major, trace, and REE data for three localities of calc–alkaline older granitoid rocks exposed in the north Eastern Desert\\u000a of Egypt are presented. These rocks were selected to cover wide compositional spectrum of the Egyptian older granitoid varieties.\\u000a They are petrographically represented by granodiorite, tonalite, quartz–diorite, and quartz–monzodiorite. The rocks are comparable\\u000a with the peraluminous, unfractionated calc–alkaline suites and fall

Mahmoud M. El Mahallawi; A. F. Ahmed

71

Remote sensing observations of sand movement in the Bahariya Depression, Western Egypt  

NASA Technical Reports Server (NTRS)

Aerial photographs taken in the 1940's have been used in combination with recent Landsat MSS and TM data to study dune movement in the Western Desert of Egypt. The El-Ghorabi dunes track northwest to southeast along the eastern edge of the Bahariya Depression. These dunes are of complex longitudinal form with well-defined, lag-covered interdune corridors. Studies using both aerial coverage and multitemporal MSS and TM image data reveal little or no net southward extension or movement of the seifs, although field measurements and remote sensing data indicate small-scale lateral migration of dune crests and interdune corridors through time. The primary process of sand transport for these dunes seems to be in response to seasonal shifts in dominant wind direction, as reflected in the development and rapid response of sand shadows leeward of the main dune masses.

Maxwell, Ted A.; Jacobberger, Patricia A.

1987-01-01

72

Age constraints on the formation and emplacement of Neoproterozoic ophiolites along the AllaqiHeiani Suture, South Eastern Desert of Egypt  

E-print Network

­Heiani Suture, South Eastern Desert of Egypt K.A. Ali a,d, , M.K. Azer b , H.A. Gahlan c , S.A. Wilde d , M., Richardson, TX 75080, USA b Geology Department, National Research Centre, Dokki-Cairo, Egypt c Geology Department, Faculty of Science, Assiut University, Assiut 71516, Egypt d Department of Applied Geology

Stern, Robert J.

73

Soil seed bank in different habitats of the Eastern Desert of Egypt  

PubMed Central

The floristic composition and species diversity of the germinable soil seed bank were studied in three different habitats (desert salinized land, desert wadi, and reclaimed land) in the Eastern Desert of Egypt. Moreover, the degree of similarity between the seed bank and the above-ground vegetation was determined. The seed bank was studied in 40 stands representing the three habitats. Ten soil samples (each 25 × 20 cm and 5 cm depth) were randomly taken per stand. The seed bank was investigated by the seedling emergence method. Some 61 species belonging to 21 families and 54 genera were identified in the germinable seed bank. The recorded species include 43 annuals and 18 perennials. Ordination of stands by Detrended Correspondence Analysis (DCA) indicates that the stands of the three habitats are markedly distinguishable and show a clear pattern of segregation on the ordination planes. This indicates variations in the species composition among habitats. The results also demonstrate significant associations between the floristic composition of the seed bank and edaphic factors such as CaCO3, electrical conductivity, organic carbon and soil texture. The reclaimed land has the highest values of species richness, Shannon-index of diversity and the density of the germinable seed bank followed by the habitats of desert wadi and desert salinized land. Motyka’s similarity index between the seed bank and the above-ground vegetation is significantly higher in reclaimed land (75.1%) compared to desert wadi (38.4%) and desert salinized land (36.5%). PMID:23961181

Gomaa, Nasr H.

2012-01-01

74

Origin and recharge rates of alluvial ground waters, Eastern Desert, Egypt.  

SciTech Connect

Stable isotope and tritium analyses of shallow ground waters in the Eastern Desert of Egypt showed that the waters were derived largely by evaporation of regional precipitation and at least partly from precipitation in the past 45 y. To estimate the ground water recharge rate, we developed an integrated hydrologic model based on satellite data, geologic maps, infiltration parameters, and spatial rainfall distribution. Modeling indicated that during a severe 1994 storm, recharge through transmission loss in Wadi El-Tarfa was 21% of the precipitation volume. From archival precipitation data, we estimate that the annual recharge rate for the El-Tarfa alluvial aquifer is 4.7 x 10{sup 6} m{sup 3}. Implications for the use of renewable ground waters in arid areas of Egypt and in neighboring countries are clear.

Sultan, M.; Gheith, H.; Sturchio, N. C.; El Alfy, Z.; Danishwar, S.

2002-04-12

75

Neoproterozoic SHRIMP U–Pb zircon ages of silica-rich Dokhan Volcanics in the North Eastern Desert, Egypt  

Microsoft Academic Search

Chronology of Neoproterozoic volcanosedimentary successions remains controversial for many regions of the Arabian–Nubian Shield, including the Dokhan Volcanics of NE Egypt. New U–Pb zircon SHRIMP ages have been obtained for 10 silica-rich ignimbrites and two subvolcanic dacitic bodies, mapped as Dokhan Volcanics, from the North Eastern Desert of Egypt. Crystallization ages range between 592±5 and 630±6Ma (Early Ediacaran). Apparently, the

Christoph Breitkreuz; Hassan Eliwa; Ibrahim Khalaf; Khaled El Gameel; Benjamin Bühler; Sergei Sergeev; Alexander Larionov; Mamoru Murata

2010-01-01

76

Wall rock alteration, Atud gold mine, Eastern Desert, Egypt: processes and P?T?X CO 2 conditions of metasomatism  

Microsoft Academic Search

The Atud gold mine, central Eastern Desert of Egypt, is located in an intrusive metagabbro-diorite complex that abutts the conglomerate-greywacke-slate series of the Pan-African Belt in Egypt. Gold-bearing quartz veins occur as fracture filling in the Neoproterozoic dioritic rocks and along their contacts with the metagabbro. Gold mineralisation is associated with discrete metasomatic alteration zones around shear zones and quartz-carbonate

Hassan Z. Harraz

1999-01-01

77

Mineral chemistry and geochemical aspects of Gebel Filat granites, South Eastern Desert, Egypt  

Microsoft Academic Search

Gebel Filat granites form one of Egyptian younger granite intrusions in Wadi Allaqi region, South Eastern Desert of Egypt.\\u000a They are perthitic monzogranites composed mainly of K-feldspars, plagioclase, and quartz with minor biotite. Plagioclase feldspars\\u000a are Na-rich and have low anorthite content (An2–3). Potash feldspars are mainly perthitic microcline and have chemical formula as (Or96–96.6 Ab3.4–4 An0). Biotite is Mg-rich

N. M. Moghazy; A. A. Emam; E. M. Abdel Rahman

2011-01-01

78

Repeated magmatic pulses in the East African Orogen in the Eastern Desert, Egypt: An old idea supported by new evidence  

Microsoft Academic Search

This paper presents U–Pb ID-TIMS geochronological data from granitoids in the Hafafit area in the Central and South Eastern Desert, Egypt. It dates several Neoproterozoic magmatic pulses and metamorphic events, and constrains one episode of U, Nb and Ta mineralisation along the Nugrus Shear Zone, part of the Eastern Desert Shear Zone, to 608±1Ma. The data testify to the localized

Anders Mattias Lundmark; Arild Andresen; Mohamed A. Hassan; Lars Eivind Augland; Gamal Yehia Boghdady

79

Neoproterozoic post-collisional granitoids in the Central Eastern Desert of Egypt: Petrological and geochemical constraints  

NASA Astrophysics Data System (ADS)

The Um Had and Um Effein (UHUE), Central Eastern Desert of Egypt, are elliptical and circular bodies of monzogranite to syenogranite with subordinate alkali feldspar granite. The UHUE granites are quite evolved (SiO2 = 67-74 wt.%), and have characteristics of high-K calc-alkaline peraluminous rocks. They are relatively enriched in K, Ba, La, Rb, Zr and total REEs, while are depleted in Sr, Y, Ti, HREE. The rocks have LREE-enriched patterns with significant negative Eu anamolies suggesting post-collision granites. The gradual increase of Rb/Sr and Rb/Ba ratios from the monzogranite to the alkali feldspar granites indicates that these granites are genetically related. The various geochemical discrimination diagrams strongly suggest that the studied granitoids were generated from crustal sources through fractional crystallization with some crustal contamination which have played a major role during the magmatic evolution of the plutons. These granites display transitional character from orogenic calc-alkaline arc-type up to subsequent anorogenic within-plate environments, suggesting continuous crystallization of magma in a transitional “post-collision” tectonic setting. This transition from compression to extension was controlled mainly by lithospheric delamination following continental collision in the Eastern Desert of Egypt.

Osman, Ali F.; El Kalioubi, Baher A.

2014-11-01

80

Genetic Aspects of Gold Mineralization at Some Occurrences in the Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The Eastern Desert of Egypt is well known as a gold-mining area since ancient times, there're more than 95 gold deposits and occurrences spread the whole area covered by the basement rocks of Precambrian age. The basement rocks of the Eastern Desert of Egypt constitute the Nubian Shield that has formed a continuous part of the Arabian-Nubian Shield before the opening of Red Sea (Oligocene-Early Miocene). Commonly, the system of gold-bearing quartz veins in the Eastern Desert is clearly structural controlled related to brittle-ductile shear zones that mostly developed during late deformational stages of the evolution history for basement rocks in the Eastern Desert. This running study principally aims to contribute the mineral resource potential of the gold deposits in Egypt, so particularly Fatira, Gidami and Atalla occurrences have been involved into a comprehensive study based on field, structural, mineralogical, geochemical and genetic investigations. It is intended to better understanding for the characteristics, distribution controls, conditions and age of mineralization in relation to the age of the hosting rocks intrusion to find if there're genetic links between the gold mineralization and the evolution of the host intrusive complex. Several authors suggested that the gold mineralization was related to the intrusion of the (postorogenic) Younger granites. Other authors interpret these deposits as products of hydrothermal activity induced either by metamorphism or cooling effects of early Paleozoic magmatism or as combined metamorphic/magmatic episodes. The prime focus will be directed to the ore itself and the associated hydrothermal alteration zones based on detailed maps and well-distributed samples network and geochemical anomalies distribution. The laboratory studies included microscopic examination (reflecting and transmitting microscopy) to allow for determination of the hosting rocks types and mineralogical changes related to the gold mineralization in each area and revealing the ore mineralogy and the ore textures, geochemical analyses (including rare earth elements) are to be used in order to determine the tectonic setting and magmatic evolution of the host intrusions, scanning electron microscope, microprobe analysis, stable isotopes and fluid inclusions will serve as a new part of this study in detection of the origin and the physico-chemical conditions (P-T condition) for the gold precipitation, Age dating of the host intrusion and mineralization will be based on K-Ar for dating potassium-bearing minerals in fresh host rocks and hydrothermal mineral phases.

Abd El Monsef, M.; Slobodník, M.; Salem, I. A.

2012-04-01

81

Distribution of Radioelements and its Relation to Uranium Migration, El-Erediya Exploratory Tunnels, Central Eastern Desert, Egypt  

Microsoft Academic Search

Uranium mineralization, connected mainly to jasperoid veins, occupying shear and fracture zones, was discovered in 1970 at El-Erediya post-tectonic granitic mass, Central Eastern Desert, Egypt. Exploratory tunnels were excavated, at wadi (valley) level, following these shear zones, in order to determine extensions of the mineralized parts and evaluate their potentiality. Excavation works revealed the presence of massive and disseminated pitchblende,

ALI ABU-DEIF; HELMY S. O. ABOUELNAGA; HAMDY I. E. HASSANEIN

2001-01-01

82

DISCRIMINATIONS OF YOUNGER GRANITIC MASSES AT GABAL QATTAR AREA, NORTH EASTERN DESERT, EGYPT, USING REMOTE SENSING TECHNIQUES  

Microsoft Academic Search

Gabal Qattar area is located in the north Eastern Desert of Egypt between Latitudes 26° 52´ and 27° 08´ N, and Longitudes 33° 13´ and 33° 25´ E. The exposed rock units, there, from the oldest to the youngest, are metavolcanics; granodiorites- diorite complex; Hammamat sediments and younger granites. Most of the area is densely traversed by felsic and mafic

S. A. Wasfi; E. L. Iliase; M. I. Mousa

83

Stability of remanence and paleomagnetic studies of some chromite ores from Barramiya and Allawi occurrences, Eastern Desert, Egypt  

Microsoft Academic Search

Rock magnetic investigations were carried out on natural Precambrian chromite ore at two occurrences in the Eastern Desert, Egypt. A medium\\/high coercivity component of remanence of reversed polarity can be defined. The mean direction of the five sites studied is D = 198°, I = -44°, with k = 55 and alpha95 = 10°. Ore microscopic and magnetic examinations indicate

E. Refai; Nadia A. Wassif; A. Shoaib

1989-01-01

84

Magmatic unmixing in spinel from late Precambrian concentrically-zoned mafic–ultramafic intrusions, Eastern Desert, Egypt  

Microsoft Academic Search

Spinel is widespread in the ultramafic core rocks of zoned late Precambrian mafic–ultramafic complexes from the Eastern Desert of Egypt. These complexes; Gabbro Akarem, Genina Gharbia and Abu Hamamid are Precambrian analogues of Alaskan-type complexes, they are not metamorphosed although weakly altered. Each intrusion is composed of a predotite core enveloped by pyroxenites and gabbros at the margin. Silicate mineralogy

Ahmed Hassan Ahmed; Hassan Mohamed Helmy; Shoji Arai; Masako Yoshikawa

2008-01-01

85

Stratigraphy, facies architecture, and palaeoenvironment of Neoproterozoic volcanics and volcaniclastic deposits in Fatira area, Central Eastern Desert, Egypt  

Microsoft Academic Search

Fatira area in the Central Eastern Desert, Egypt, is a composite terrane consisting of Neoproterozoic volcanics and sediments laid down in submarine to subaerial environment, intruded by voluminous old to young granitic rocks. The various lithofacies of the study area can be grouped in three distinct lithostratigraphic sequences, which are described here in stratigraphic order, from base to top as

Ezz El Din Abdel Hakim Khalaf

2010-01-01

86

Diversity of platinum-group minerals in podiform chromitites of the late Proterozoic ophiolite, Eastern Desert, Egypt: Genetic implications  

Microsoft Academic Search

Podiform chromitites are frequently distributed as lensoidal pods in the central and southern parts of the Eastern Desert, Egypt. They are, in most cases, hosted by fully serpentinized peridotite which is a part of dismembered ophiolite complexes of the Pan–African belt of Late Precambrian age. Serpentinites are the predominant components in the ophiolitic mélange, either as matrix or as variably

Ahmed Hassan Ahmed

2007-01-01

87

Neoproterozoic tectonothermal evolution of the Central Eastern Desert, Egypt: a slow velocity tectonic process of core complex exhumation  

Microsoft Academic Search

Regional cooling in the course of Neoproterozoic core complex exhumation in the Central Eastern Desert of Egypt is constraint by 40Ar\\/39Ar ages of hornblende and muscovite from Meatiq, Sibai and Hafafit domes. The data reveal highly diachronous cooling with hornblende ages clustering around 580 Ma in the Meatiq and the Hafafit, and 623 and 606 Ma in the Sibai. These

Harald Fritz; David R. Dallmeyer; Eckart Wallbrecher; J U Urgen Loizenbauer; Georg Hoinkes; Peter Neumayr; Ali A. Khudeir

2002-01-01

88

Structural analysis of the main uraniferous chalcedony vein at G. El Missikat environs, Central Eastern Desert, Egypt  

Microsoft Academic Search

This study deals with the structural analysis of joints in the uranium-bearing vein deposits and the surrounding enclosing granite rocks in G. El Missikat pluton, Central Eastern Desert, Egypt. The study includes the different structural features such as the intensity of joints, their opening and length for the different sets taken on a systematic pattern through and along the upper

F. S. BAKHIT; M. E. MOSTAFA

1987-01-01

89

Pattern of the main tectonic trends from remote geophysics, geological structures and satellite imagery, Central Eastern Desert, Egypt  

Microsoft Academic Search

The area under study lies in the Central Eastern Desert of Egypt and is covered by exposed Precambrian basement rocks to the east and Phanerozoic cover sediments to the west. The technique of using the autocovariance function was applied to remote geophysics (aeromagnetic and aeroradiometric data), and statistical trend analysis was conducted on data of geological structures and satellite imagery.

Said I. Rabie; Ahmed A. Ammar

1990-01-01

90

Supra-subduction affinity in the Neoproterozoic serpentinites in the Eastern Desert, Egypt: Evidence from mineral composition  

Microsoft Academic Search

Serpentinites in the Eastern Desert (ED) of Egypt represent integral components of the ophiolites. Metamorphic textures of the serpentinites preserve the complex mineralogical evolution from primary peridotite through metamorphism, and late-stage hydrothermal alteration. Two textural types are distinguished in the olivines of the present serpentinized peridotites, namely (a) highly-strained olivine grains with kink bands, as in the deformed mantle tectonites

A. E. S. Khalil; M. K. Azer

2007-01-01

91

The Neoproterozoic Kolet Um Kharit bimodal metavolcanic rocks, south Eastern Desert, Egypt: a case of enrichment from plume interaction?  

Microsoft Academic Search

Neoproterozoic metavolcanic rocks of Kolet Um Kharit (KUKh) in the southern Eastern Desert of Egypt have been traditionally regarded as a bimodal island-arc sequence. However, geological and geochemical arguments presented here make this interpretation doubtful. Geochemically, these rocks are classified into mafic (tholeiitic basalts) and felsic (high-K rhyodacites to rhyolites) groups. Both the KUKh mafic and felsic metavolcanic rocks show

E. S. Farahat

2006-01-01

92

An example of application of factor analysis on geochemical stream sediment survey in Umm Khariga Area, Eastern Desert, Egypt  

Microsoft Academic Search

Geochemical reconnaissance survey of Wadi Umm Khariga in the southern part of the Eastern Desert of Egypt was carried out in an area of 30 Km2. The results of 79 stream sediment samples analyzed for Co, Cr, Cu, Fe, K, Li, Mn, Ni, Pb, Rb, Ti, and Zn after hot extraction with aqua regia were treated with simple and multivariate

Mohamed A. Morsy

1993-01-01

93

Influence of the alteration processes on the origin of uranium and europium anomalies in trachyte, central Eastern Desert, Egypt  

Microsoft Academic Search

El Atshan mining area, central Eastern Desert, represents one of the uranium occurrences related to alkaline volcanic rocks in Egypt. Based on the plot of total alkali elements versus silica, these rocks are classified as trachytes. The U and Eu anomalies appear to be derived from trachyte exposed to a long period of alteration and rock–fluid interaction. The trachyte has

Y. H. Dawood; H. H. Abd El-Naby; A. A. Sharafeldin

2004-01-01

94

PLEISTOCENE BIRD FAUNA FROM BIR TARFAWI (EGYPTIAN WESTERN DESERT)  

Microsoft Academic Search

Boche?ski, Z. 1991. Pleistocene bird fauna from Bir Tarfawi (Egyptian Western Desert). Ostrich 62: 29–34.At Bir Tarfawi, an archaeological site in the Egyptian Sahara dated to about 135000 years (before present), 202 bone fragments were identified as belonging to 24 bird species or genera. Most of the material is apparently from owl pellets. The birds represent aquatic and terrestrial forms

Zygmunt Boche?ski

1991-01-01

95

The Sha’it–Nugrus shear zone separating Central and South Eastern Deserts, Egypt: A post-arc collision low-angle normal ductile shear zone  

Microsoft Academic Search

The northerly dipping Sha’it–Nugrus shear zone (SNSZ) is the boundary separating the Central Eastern Desert from the South Eastern Desert of Egypt. The hangingwall of this shear zone is composed of low-grade metavolcanics and ophiolitic nappes of the Central Eastern Desert, while the footwall consists of South Eastern Desert high-grade metapsammitic gneisses (Migif-Hafafit gneissic complex). The SNSZ is about 700m

A. Fowler; A. F. Osman

2009-01-01

96

Geochemistry of the Banded Iron Formations and their Host Rocks in the Eastern Desert of Egypt BACKUS, Ethan L.1, GAGNON, Kelli E.1, EL-SHAZLY, Aley K.1, and KHALIL, Khalil Isaac2  

E-print Network

Geochemistry of the Banded Iron Formations and their Host Rocks in the Eastern Desert of Egypt over 30,000 km2 in the central Eastern Desert of Egypt. The deposits most resemble Algoma-type iron University, Egypt Sponsored by NSF-OISE-1004021 Session 92:T3. Sigma Gamma Epsilon Undergraduate Research

El-Shazly, Aley

97

Silver and silver-bearing minerals at the Um Samiuki volcanogenic massive sulphide deposit, Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Um Samiuki Zn Cu Pb Ag mineralisation, south Eastern Desert, Egypt is hosted by felsic volcanic rocks which form part of the 712-Ma-old, east-west-trending Shadli Volcanic Belt. Two major occurrences of massive sulphides are present at the top of rhyolitic breccia in the Western and Eastern mine areas. In each occurrence, a bornite-bearing zone is overlain by a pyrite-chalcopyrite-bearing zone and underlain by a disseminated, Cu-depleted zone. In the massive sulphide ore, sphalerite, chalcopyrite, pyrite, galena, bornite and tetrahedrite tennantite are major minerals, whereas arsenopyrite, pyrrhotite, molybdenite and magnetite are accessory phases. Covellite and digenite are common secondary minerals. Bornite, tetrahedrite tennantite and covellite contain high amounts of silver (averages of 1.97, 1.39 and 1.82 wt% respectively). Based on mineralogical balance calculations, bornite and covellite accommodate 80% of silver in the Um Samiuki deposit. Ag was incorporated in the crystal structure of the early-crystallised copper sulphides and sulphosalts and silver minerals. The temperature, sequential precipitation of the fluids and the structure of the crystallising phases control the distribution of silver. Post-depositional deformation and metamorphic processes caused liberation, remobilisation and redeposition of silver within the massive sulphides.

Shalaby, Ibrahim M.; Stumpfl, Eugen; Helmy, Hassan M.; El Mahallawi, Mahmoud M.; Kamel, Omar A.

2004-10-01

98

Elemental content of feldspar from Eastern Desert, Egypt, determined by INAA and XRF.  

PubMed

Instrumental neutron activation analysis (INAA) and HPGe detector gamma-spectroscopy were used to determine a total of 16 elements qualitatively and quantitatively for the first time from feldspar rock samples collected from Gabel El Dubb, Eastern desert, Egypt. The elements determined are (Na, Mg, K, Sc, Ga, Cr, Fe, Co, Zn, Nb, Ba, Ce, Eu, Hf, Th and U). The samples were properly prepared together with their standard reference material and simultaneously irradiated by thermal neutrons at the TRIGA Mainz research reactor at a neutron flux of 7x10(11)n/cm(2)s. XRF was also used. Comparison of the results obtained by both techniques showed good agreement for such elements as K, Na, Fe, Mg, Ba and Cr. PMID:20185321

El-Taher, A

2010-06-01

99

Natural radioactivity and rare earth elements in feldspar samples, Central Eastern desert, Egypt.  

PubMed

The pegmatite bodies of the Eastern Desert of Egypt are widely distributed especially along the Marsa-Alam-Idfu road. The Abu Dob area covers about 150km(2) of the Arabian Nubian shield at the central part of the Eastern Desert of Egypt. Most of the pegmatite is zoned; the zonation starts with milky quartz at the core followed by alkali feldspar at the margins. The feldspars vary in color from rose to milky and in composition from K-feldspar to Na-feldspar, sometimes interactions of both types are encountered. Thirteen feldspar samples were collected from different locations in the Abu Dob area for measuring the natural radioactivity of (238)U, (232)Th and (40)K using an HPGe detector. The variation in concentration of radionuclides for the area under investigation can be classified into regions of high, medium and low natural radioactivity. The average concentration in BqKg(-1) has been observed to be from 9.5 to 183675.7BqKg(-1) for (238)U, between 6.1 and 94,314.2BqKg(-1) for (232)Th and from 0 to 7894.6BqKg(-1) for (40)K. Radium equivalent activities (Ra(eq)), dose rate (D(R)) and external hazard (H(ex)) have also been determined. In the present work, the concentration of rare earth elements are measured for two feldspar samples using two techniques, Environmental Scanning Electron microscope XIL 30 ESEM, Philips, and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS). The existence of rare earth elements in this area are very high and can be used in different important industries. PMID:21324705

Walley El-Dine, Nadia; El-Shershaby, Amal; Afifi, Sofia; Sroor, Amany; Samir, Eman

2011-05-01

100

Extensional collapse along the Sevier Desert reflection, northern Sevier Desert basin, western United States  

NASA Astrophysics Data System (ADS)

Newly released and previously published seismic reflection data from the northern Sevier Desert basin provide a complete seismic transect between the tilted western margin of the basin and the eastern breakaway zone. When tied to well and surface age data, the transect delineates a continuum of extensional fault and basin fill geometries that developed between late Oligocene and Pleistocene time across the basin. A minimum of 18 km of top-to-the-west normal displacement is estimated across the Sevier Desert from only the most conspicuous growth geometries and offsets across listric normal faults that sole downward into the Sevier Desert reflection (SDR). The SDR clearly marks a normal fault zone beneath the entire basin, where stratal truncations are imaged for 50% of the 39 km length of the reflection east of the Cricket Mountains block. Restoration of extensional displacement along this entire 39 km fault length is necessary to reconstruct the pre-Oligocene configuration and erosion level of Sevier thrust sheets across the Sevier Desert area. The SDR normal fault zone underlies the former topographic crest of the Sevier orogenic belt, where it accommodated extensional collapse after cessation of regional contractile tectonism.

Coogan, James C.; Decelles, Peter G.

1996-10-01

101

Classification and origin of the Neoproterozoic ophiolitic mélanges in the Central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The Eastern Desert of Egypt is part of the Neoproterozoic Arabian-Nubian Shield and displays different occurrences of Neoproterozoic ophiolitic mélanges. The mélanges contain exotic and native blocks and fragments of variable sizes and types set in a sheared and schistose volcaniclastic matrix. The main exotic blocks are ophiolitic and include metamorphosed ultramafic rocks, metagabbros, massive and pillowed metabasalts and pelagic sedimentary rocks. Based on the mode of occurrences of the ophiolitic components and the processes of mélange formation, the ophiolitic mélanges of the Central Eastern Desert are classified and mapped into tectonic mélange, olistostrome and olistostromal mélange. The whole rock associations of these mélanges were subjected to two different events of deformation (D1 and D2) and contemporaneous metamorphism (M1 and M2). The metagreywackes of the mélange matrix are similar to oceanic island arc sandstone and appear to have been deposited in a back-arc or inter-arc basin. The blocks of ophiolitic metabasalts within the mélange show tholeiitic affinity and have back-arc basin (BAB) tectonic origins. Metamorphosed ultramafic blocks in the mélange display both mid-ocean ridge (MOR) and suprasubduction zone (SSZ) affinities. The ophiolitic components represent fragments of oceanic lithosphere that formed in a back-arc/arc environment, and were incorporated into the mélange through tectonic and/or sedimentary processes. Both tectonic and sedimentary processes played a major role during mélange formation in a back-arc or inter-arc setting.

El Bahariya, Gaafar A.

2012-09-01

102

Mapping of serpentinites in the Eastern Desert of Egypt by using Landsat thematic mapper data  

SciTech Connect

Serpentinites in the Eastern Desert of Egypt were mapped from Landsat thematic mapper (TM) data by using procedures that take advantage of the distinctive spectral reflectance of these rocks caused by the abundance of antigorite, lizardite, clinochrysotile, and magnetite. The method employs a threshold classifier based on three reflectance ratios: (1) band 5/7 for estimating the abundance of hydroxyl-bearing phases, (2) band 5/1 for magnetite content, and (3) the calculated value of reflectance for band 4, based on a linear interpolation between bands 3 and 5, divided by the observed band-4 reflectance. The third ratio was used to identify rocks in iron-bearing aluminosilicates and thereby to distinguish mafic rocks containing substantial amounts of magnetite and hydroxyl-bearing phases from serpentinites. The method was first successfully tested over the Meatiq dome and Wadi Ghadir areas, where serpentinites and ophiolitic melanges dominated by serpentinites have been mapped during the course of field work. A TM-based map was then generated; the map covered about 60,000 km/sup 2/ in the Eastern Desert. Results demonstrate that TM data can be used with reliability to distinguish serpentinites from surrounding rocks in arid regions and to generate detailed maps over wide regions by using quantitative, reproducible mapping criteria. Possibilities for locating suture zones over the less well known parts of arid continents are clear.

Sultan, M.; Arvidson, R.E.; Sturchio, N.C.

1986-12-01

103

Significance of SHRIMP UPb dating of the Imperial Porphyry and associated Dokhan Volcanics, Gebel Dokhan, north Eastern Desert, Egypt  

Microsoft Academic Search

SHRIMP U-Pb zircon dating was undertaken on two samples of Dokhan Volcanics from the type area at Gebel Dokhan, north Eastern Desert, Egypt. A quartz andesite from the Imperial Porphyry unit has a weighted 206Pb\\/238U age of 593 ± 13 Ma (2?). A sample of grey andesite, from ~450 m lower in the succession, has a weighted 206Pb\\/238U age of

S. A. Wilde; K. Youssef

2000-01-01

104

Medium-to high-pressure garnet-amphibolites from Gebel Zabara and Wadi Sikait, south Eastern Desert, Egypt  

Microsoft Academic Search

Garnet-amphibolites from Gebel Zabara and Wadi Sikait in the southern Eastern Desert of Egypt occur as highly flattened metamorphosed basic volcanic bands enclosed within garnetiferous metasediments. Samples from both localities have almost the same metamorphic assemblage of garnet-amphibole-plagioclase-ilmeniterutile. An electron microprobe study indicates that garnet, amphibole and plagioclase are cryptically zoned only in samples from Wadi Sikait. The composition of

Adel A. Surour

1995-01-01

105

The paleomagnetism of certain late precambrian and early paleozoic rocks from the Red Sea Hills, Eastern Desert, Egypt  

Microsoft Academic Search

A stable remanence was isolated from three groups of rocks collected in the Eastern Desert of Egypt. Two groups of dikes, one collected orth of the Qena-Safaga road and the other about 20 km to the south near the Um Rus gold mine, gave paleomagnetic pole positions of 87°N, 304°E and 86°N, 185°E, respectively. Both have K\\/Ar ages in the

J. Davies; A. E. M. Nairn; R. Ressetar

1980-01-01

106

Facies development of upper cretaceous—Lower tertiary sediments from the monastery of St. Anthony\\/Eastern Desert, Egypt  

Microsoft Academic Search

Summary  Facies development (supported by microfacies analysis of the limestones) is described in an Upper Cretaceous mixed siliciclastic\\/carbonate\\u000a sequence from the Eastern Desert of Egypt. It is overlain by diagenetically altered Lower Tertiary limestones, yielding good\\u000a fauna only from one horizon. The occurrence of marine Campanian and Maastrichtian sediments, without phosphates emphasizes\\u000a the importance of this section. Stratigraphic distribution of benthic

Jochen Kuss

1986-01-01

107

Post-orogenic and anorogenic A-type fluorite-bearing granitoids, Eastern Desert, Egypt: Petrogenetic and geotectonic implications  

Microsoft Academic Search

The present study focuses on four A-type fluorite-bearing granitic plutons in the Eastern Desert of Egypt which are classified into post-orogenic subsolvus (Homrit Waggat, 535Ma; Homer Akarem, 541Ma and Ineigi, 571Ma) and anorogenic hypersolvus (Gabal Gharib, 476Ma) granites. All the granites are Si- and alkali-rich and MgCaTi poor. Whereas both granite types appear relatively homogeneous in terms of most of

Fathy H. Mohamed; Mohamed M. El-Sayed

2008-01-01

108

Thrusting and multiple folding in the Neoproterozoic Pan-African basement of Wadi Hodein area, south Eastern Desert, Egypt  

Microsoft Academic Search

Detailed field mapping and structural studies of the area around the mouth of Wadi Hodein, some 20km west of Shalatein at the Red Sea coast in the south Eastern Desert of Egypt, revealed four phases of structural deformation (D1–D4) affecting the Neoproterozoic Pan-African basement rocks. D1 is related to arc–arc collision and is represented by ENE–WSW oriented megascopic upright open

M. M. Abdeen; M. F. Sadek; R. O. Greiling

2008-01-01

109

Thrusting and transpressional shearing in the Pan-African nappe southwest El-Sibai core complex, Central Eastern Desert, Egypt  

Microsoft Academic Search

The Wadi El-Shush area in the Central Eastern Desert (CED) of Egypt is occupied by the Sibai core complex and its surrounding Pan-African nappe complex. The sequence of metamorphic and structural events in the Sibai core complex and the enveloping Pan-African nappe can be summarized as follows: (1) high temperature metamorphism associated with partial melting of amphibolites and development of

Mohamed A. Abd El-Wahed

2008-01-01

110

Stratigraphic modelling of carbonate platform-to-basin sediments (Maastrichtian to Paleocene) in the Eastern Desert, Egypt  

Microsoft Academic Search

In the Galala Mountains of the Eastern Desert, Egypt, carbonate platform and basin deposits have excellent exposure. These exposures show a late Campanian–early Paleocene rimmed platform evolving into a late Paleocene distally steepened ramp. We modelled the evolution of the platform–basin transition from the Maastrichtian to Selandian (68.7–59 Ma) with the 2-D stratigraphic simulation program PHIL and compared the modelled

C. Scheibner; J. Kuss; R. P. Speijer

2003-01-01

111

Genesis of the gold mineralization at the Dungash gold mine area, Eastern Desert, Egypt: a mineralogical–microchemical study  

Microsoft Academic Search

The Au-deposit of the Dungash gold mine area, Eastern Desert of Egypt, is situated in an EW-trending quartz vein along a shear zone in metavolcanic and metasedimentary host rocks. Petrographic and micro-chemical analyses show that the style of alterations (chloritization, sericitization, carbonatization and silicification) and mineralization (formation of sulphides and gold) are not limited to only the auriferrous quartz ore

Khalil I Khalil; Hossam A Helba; Arno Mücke

2003-01-01

112

Paleocene–Early Eocene ostracodes from the Southern Galala Plateau (Eastern Desert, Egypt): Taxonomy, impact of paleobathymetric changes  

Microsoft Academic Search

Ostracode faunas obtained from nine sections spanning the Paleocene–Early Eocene interval from a platform–basin transect in the Southern Galala Plateau area (Eastern Desert, Egypt) have been investigated. The study focuses on taxonomy and biostratigraphy of the ostracode assemblages across the P\\/E boundary, with supporting comments on paleoecology and paleobiogeography. The studied nine sections yielded 60 taxa belonging to 39 genera.

Abdel-Mohsen M. Morsi; Christian Scheibner

2009-01-01

113

ORIGIN OF MAGNESITE VEINS IN SERPENTINITES FROM MOUNT EL-RUBSHI AND MOUNT EL-MAIYIT, EASTERN DESERT, EGYPT  

Microsoft Academic Search

Serpentinite-hosted magnesite veins have been studied in Mt. El-Rubshi and Mt. El- Maiyit, Eastern Desert, Egypt, in order to elucidate the origin of this type of ore. The studied cryptocrystalline magnesite veins were formed as the fracture fillings from ascending CO2-rich hydrothermal solutions. These solutions were brought from deeper- seated horizons upwards to a shallower zone, where due to the

MOHAMED F. GHONEIM; IBRAHIM A. SALEM; MOHAMED M. HAMDY

114

Application of ground geophysical data to uranium mineralization in the El-Missikat area, central Eastern Desert, Egypt  

Microsoft Academic Search

The El-Missikat prospect lies in the Eastern Desert of Egypt, 85 km from Qena along the river Nile. The area of the prospect is covered by pink granites of the Gabal (G.) El-Missikat pluton from the south and quartz diorite from the north, as well as wadi alluvium at Wadi El-Missikat, which passes through the study area from south to

Elsayed M. Elkattan; Hassan M. Abdulhadi; Said I. Rabie; Hamdy I. E. Hassanein

1996-01-01

115

Stable isotope stratigraphy across the K\\/T boundary, and isotopic investigations of an ‘Ignored’ worm bed, Eastern Desert, Egypt  

Microsoft Academic Search

Summary  Oxygen and carbon stable isotope profiles of the Dakhla sequence at the Eastern Desert, Egypt, reveal that the negative isotopic\\u000a excursion commonly observed at the K\\/T boundary in sections showing continuous deposition around the world (e.g. El Kef section\\u000a at Tunisia,Perch-Nielsen et al.; 1982 and at Zumaya, Spain;Mount et al., 1986) is missing in this Egyptian study area. However, several

Mohamed N. A. Shaaban

1997-01-01

116

U–Pb TIMS age constraints on the evolution of the Neoproterozoic Meatiq Gneiss Dome, Eastern Desert, Egypt  

Microsoft Academic Search

Ages are used to constrain the temporal evolution of the Meatiq Gneiss Dome, Eastern Desert, Egypt, by dating (ID-TIMS) pre-,\\u000a syn-, and post-tectonic igneous rocks in and around the dome. The Um Ba’anib Orthogneiss, comprising the deepest exposed structural\\u000a levels of the dome, has a crystallization age of 630.8 ± 2 Ma. The overlying mylonites are interpreted to be a thrust sheet\\/complex\\u000a (Abu

Arild Andresen; Mohamed Ali Abu El-Rus; Per Inge Myhre; Gamal Y. Boghdady; Fernando Corfu

2009-01-01

117

Neoproterozoic tholeiitic arc plutonism: petrology of gabbroic intrusions in the El-Aradiya area, Eastern Desert, Egypt  

Microsoft Academic Search

Gabbroic intrusions of the El-Aradiya area are a part of the Neoproterozoic basement cropping out in the central Eastern Desert of Egypt. They are composed mainly of gabbroic cumulates (diopside-plagioclase cumulate and plagioclase-augite cumulate) and fine-grained noncumulate gabbro. Mineral chemistry data indicate that the plagioclase core compositions of the gabbroic cumulates range between An90 and An60, whereas fine-grained noncumulate gabbro

Fawzy F. Abu El-Ela

1999-01-01

118

Late precambrian volcanism at Wadi Allaqi, south Eastern Desert, Egypt: evidence for transitional continental arc\\/margin environment  

Microsoft Academic Search

The Dokhan volcanics at Wadi Allaqi, situated in the south Eastern Desert of Egypt, range in composition from basaltic-andesite to dacite. Geochemically, they have a transitional character from low K-tholeiite to calc-alkaline with a relatively high ZrY ratio that characterises a continental arc\\/margin setting. The most basic sample has extremely low Mg# (40) and Ni (55 ppm) values, indicating significant

Said A. El-Nisr

1997-01-01

119

Structural and tectonic evolution of the Umm Gheig\\/El-Shush region, central Eastern Desert of Egypt  

Microsoft Academic Search

The rocks of the Wadi Umm Gheig\\/El-Shush area in the central Eastern Desert of Egypt form part of the Nubian Shield, a component of the Neoproterozoic Pan-African Orogeny. The rocks have been divided into three units: (i) low-grade metamorphosed rocks, which consist of metavolcanic rocks interleaved with slices of ophiolitic melange; (ii) high-grade metamorphic rocks, which consist of syn-tectonic granitoids;

S. Ibrahim; J. Cosgrove

2001-01-01

120

Multistage emerald formation during Pan-African regional metamorphism: The Zabara, Sikait, Umm Kabo deposits, South Eastern desert of Egypt  

Microsoft Academic Search

The genesis of gem-quality deep green emeralds of Zabara, Sikait and Umm Kabo (South Eastern Desert, Egypt) is to date a controversial topic. The emerald-bearing biotite schists and quartz lenses are interpreted alternatively as a product of (i) thrust-fault-shear zone – controlled large scale alkali-metasomatism driven by post-magmatic fluid flow or of (ii) a large scale interaction between syntectonic pegmatitic

G. Grundmann; G. Morteani

2008-01-01

121

Technologies Applied in the Toshka Project of Egypt  

ERIC Educational Resources Information Center

The Toshka Project, located in Egypt, involves excavating a canal to carry about 380 billion ft[supercript 3] of water every year from Lake Nasser to the Toshka Depression, southwest of Aswan. This will eventually create a new valley to the River Nile in the western desert of Egypt in addition to the currently existing prehistoric river course.…

Wahby, Wafeek S.

2004-01-01

122

Petrogenesis of selected A-type granitic intrusions from Central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The Pan-African orogeny in the Arabian-Nubian Shield was terminated by intrusion of A-type granites (~ 595 Ma; Greenberg, 1981) and its volcanic equivalents. Subsequent to the intrusions of these granitic bodies the shield was exhumed. Eroded A-type granite pebbles were found in the molasse sediments that were deposited in intermountain basins. Therefore the A-type granites provide information about the last stage of the Pan-African geochemical system. Preliminary whole-rock geochemical data of three granitic intrusions (Kadabora, Um Naggat and El shiekh Salem) from the Central Eastern Desert of Egypt; indicate that all of them are peraluminous and with A-type characteristics. These intrusions show low CaO content (average 0.43 %wt), high FeOT/MgO ratio (10.46-121.88), high Na2O+K2O (average 8.04 %wt), marked enrichment of high field strength elements (Y, Nb and Ga except Zr), depletion in MgO (0.01-0.11 %wt) and with low concentration of Sr and Ba. The studied granitoids were emplaced in within plate tectonic regime. References: Greenberg, J.K. (1981): Characteristic and origin of Egyptian younger granites. Bull. Geol. Soc. Am. Part 1, v.92: 224-232.

Hassan, Tharwat; Asran, Asran; Amron, Taha; Hauzenberger, Christoph

2014-05-01

123

Sequence stratigraphy of the Cenomanian Galala Formation, north Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The sequence stratigraphic framework of the Cenomanian Galala Formation (north Eastern Desert, Egypt) is estimated on the basis of the Sedimentological and obtainable biostratigraphic data, in addition to the regional correlation of the studied sections. Five sequence boundaries are identified. The first sequence boundary separates between the Galala and Malha formations. The second, third and fourth sequence boundary exhibit a differentiated nature. It is noticed that such sequence boundaries in Gebel El-Zeit are mainly represented by paleosols and caliche, while those of the Northern Galala, Gebel Ataqa and Gebel Shabraweet are mostly typified by emergence horizons of dolomites and dedolomites. The fifth (last) sequence boundary separates the Galala Formation from the overlying El-Khashm Formation at Gebel El-Zeit, the Northern Galala and Gebel Ataqa and from Maghra El-Hadida Formation at Gebel Shabraweet. The Galala Formation in the study area is subdivided into four depositional sequences, which are built up of three systems tracts; the lowstand (LST), transgressive (TST) and highstand (HST) systems tracts. The LSTs are realized only from Gebel El-Zeit, where they are made up of clastic facies organized in coarsening- and fining-upward parasequences. The TSTs form a series of aggradational-retrogradational, shallowing-upward parasequences, which transgress across the ramp till the point of maximum flooding is reached. The HSTs are built up of aggradational-progradational, shallowing-upward parasequences of shallow subtidal to peritidal facies.

Khalifa, M. A.; Abu El-Ghar, Mohamed S.; Helal, S. A.; Hussein, A. W.

2014-01-01

124

Remobilization of gold from a chalcopyrite-pyrite mineralization Hamash gold mine, Southeastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

Pyrite, chalcopyrite, and gold occur in quartz veins in granitic rocks and as scattered and disseminated impregnations in shear zones of the highly altered metavolcanics in the Hamash area, Southeastern Desert, Egypt. The minerals are associated in part with pyrrhotite, digenite, tetrahedrite, chalcocite, bornite, and covellite. Pyrite occurs in two forms: (1) idio- to hypidiomorphic coarse crystals with inclusions of preexisting sulfides, and (2) fine-crystalline aggregates. Chalcopyrite occurs in three forms: (1) idiomorphic coarse crystals, (2) fine-crystalline microinclusions, and (3) xenomorphic relicts. Three genetic phases of sulfide mineralization were identified. They are related to the successive cooling of the crystallizing solutions. Gold was hosted in the older sulfide minerals during a high-temperature disorder phase. Native gold was formed during the latest, decreasing-temperature phase through remobilization of auriferous pyrite. Microprobe analysis confirmed that gold and copper are relatively enriched in the late pyrite. Identified surface-alteration products include goethite, limonite, gold, carbonates, and sulfates of iron and copper.

Hilmy, M. Ezzeldin; Osman, A.

1989-10-01

125

Kinematic analysis of the Migif area in the Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The use of porphyroclasts rotating in a flowing matrix to estimate mean kinematic vorticity number (Wm) is important for quantifying the relative contributions of pure and simple shear in penetratively deformed rocks. The kinematic vorticity number determined for high temperature mylonitic gneisses in the Migif area in the Eastern Desert of Egypt range from ?0.6 to 0.9. The results from vorticity and strain analyses indicate that deformation in the area deviated from simple shear. It is concluded that nappe stacking occurred early during the thrusting event, probably by brittle imbrications, and that ductile strain was superimposed on the nappe structure at high-pressure as shown by a penetrative subhorizontal foliation is developed subparallel to the tectonic contacts with the under- and overlying nappes. The accumulation of ductile strain during underplating was not by simple shear but involved a component of vertical shortening, which caused the subhorizontal foliation in the Migif area. In most cases, this foliation was formed during thrusting of the nappes onto each other, suggesting that nappe stacking was associated with vertical shortening.

Kassem, Osama M. K.

2014-11-01

126

Holocene Paleoecology of the Western Tenere Desert, Niger, Africa  

NASA Astrophysics Data System (ADS)

Multiple paleontological, sedimentological, and isotopic/ionic geochemical indicators permit reconstruction of the Holocene ecology of the western Tenere Desert (southern Sahara hyper-desert). Modern precipitation is highly erratic, averaging 25 mm yearly, and vegetative cover is negligible. From the early to middle Holocene, however, grassland-shrublands and seasonal to permanent lakes and wetlands predominated, supporting diverse limnic, riparian, and upland communities. Annual precipitation probably was comparable to that of the modern southern Sahel, exceeding 350 mm. Coarse-grained sediment washed into the large lacustrine basin from exposures of metamorphic, plutonic, and volcanic rocks in the nearby Air Massif highland. Lake margins fluctuated in response to runoff and limited ground-water discharge. The water was non-saline and there is no evidence of evaporite deposition. Aquatic and riparian macrophytes thrived, as did an extensive lacustrine-palustrine macrofauna. A Sahelian flora of mixed grasses, thorn shrubs, and perhaps some larger woodland species occupied the contiguous uplands, supporting resident and migratory mammalian and avian faunas. Lake levels were high until 6300 to 5200 BP, possibly as late as 4800 BP locally. Deflation of lacustrine deposits during a subsequent dry period provided finer-grained eolian sediment accreting as proximal dunes. The composition of mineral sediment within the middle to late Holocene dunes is different from, but clearly a subset of the lacustrine deposits. Organic matter reworked from the lake sediment was deposited in the dunes and oxidized in situ, generating CO2 that dissolved in soil moisture, producing bicarbonate. The bicarbonate reacted with calcium from weathered minerals, producing calcic cementation about 5100 BP. The resulting petrocalcic horizon was later exposed, weathered, and colonized by sparse terrestrial vegetation for one or more brief periods. A late phase of pedogenesis concurrent with or closely post-dating plant colonization produced secondary porosity and metallic oxide cementation. The metallic oxide cement preserved minute quantities of organic matter from the terrestrial flora and invertebrate microfauna. Regional ecology was controlled by global post-Pleistocene deglaciation, sea-level changes, and establishment of zonal weather systems. The modern Okavango Delta of Botswana is, in part, a suitable analog for the late Pleistocene to early/middle Holocene environment of the western Tenere Desert, as are smaller, lesser-known, extant wetlands in Niger.

Sereno, P. C.; Caran, S. C.; Housh, T. B.

2007-12-01

127

Greenstone-hosted lode-gold mineralization at Dungash mine, Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The auriferous quartz ± carbonate veins at Dungash mine, central Eastern Desert of Egypt, are confined to ?E-trending dilation zones within variably foliated/sheared metavolcanic/volcaniclastic rocks. The vein morphology and internal structures demonstrate formation concurrent with a dextral shear system. The latter is attributed to flexural displacement of folded, heterogeneous rock blocks through transpression increment, late in the Neoproterozoic deformation history of the area. Geochemistry of the host metavolcanic/metavolcaniclastic rocks from the mine area suggests derivation from a low-K, calc-alkaline magma in a subduction-related, volcanic arc setting. In addition, chemistry of disseminated Cr-spinels further constrain on the back-arc basin setting and low-grade metamorphism, typical of gold-hosting greenstone belts elsewhere. Mineralogy of the mineralized veins includes an early assemblage of arsenopyrite-As-pyrite-gersdorffite ± pyrrhotite, a transitional pyrite-Sb-arsenopyrite ± gersdorffite assemblage, and a late tetrahedrite-chalcopyrite-sphalerite-galena-gold assemblage. Based on arsenopyrite and chlorite geothermometers, formation of gold-sulfide mineralization occurred between ?365 and 280 °C. LA-ICP-MS measurements indicate the presence of refractory Au in arsenian pyrite (up to 53 ppm) and Sb-bearing arsenopyrite (up to 974 ppm). Abundant free-milling gold associated with the late sulfide assemblage may have been mobilized and re-distributed by circulating, lower temperature ore fluids in the waning stages of the hydrothermal system. Based on the isotopic values of vein quartz and carbonate, the calculated average ?18OH2O values of the ore fluids are 5.0 ± 1.4‰ SMOW for quartz, and 3.3 ± 1.4‰ for vein carbonate. The measured carbonate ?13C values correspond to ore fluids with ?13CCO2 = -6.7 ± 0.7‰ PDB. These results suggest a mainly metamorphic source for ore fluids, in good agreement with the vein morphology, textures and hydrothermal alteration. The calculated ?34SH2S values for early, transitional, and late sulfide assemblages define three distinct ranges (?1.5-3.6‰), (?0.4-1.0‰), and (-3.7‰ to -1.9‰), respectively. The systematic evolution towards lighter ?34S values may be attributed to recrystallization, or to ore fluid buffering under variable physicochemical conditions. The shear zone-related setting, mineralogy and isotopic characteristics of gold mineralization in Dungash mine are comparable with other orogenic gold deposits in the region (e.g., Barramiya deposit), which may suggest a regional setting controlling gold metallogeny of the region. This setting should guide future exploration programs in the central Eastern Desert province.

Zoheir, Basem; Weihed, Pär

2014-11-01

128

Chemical and isotopic constraints on the origin of Wadi El-Tarfa ground waters, Eastern Desert, Egypt.  

SciTech Connect

We evaluated the use of the renewable ground water resources of the Eastern Desert to develop sustainable agriculture in Upper Egypt, an alternative that could alleviate some of Egypt's dependence on water from the Nile River. Ground water from shallow aquifers in the Eastern Desert of Egypt, near the intersection of Wadi El-Tarfa and the Nile River, was analyzed for chemical compositions, stable isotope ratios, and tritium activities. The ground water has a range in total dissolved solids of 300 to 5000 mg/L. Values of {delta}D and {delta}{sup 18}O range from -10 to +34 %o and -2 to +5.2 %o, respectively, and defines a line having a slope of 5.7 that intersects the meteoric water line at about {delta}D = -15% on a plot of 8D versus {delta}{sup 18}O. These findings indicate that the water might have been derived by a combination of evaporation of and salt addition to regional precipitation. Only one sample could have been derived directly by evaporation and transpiration of modern Nile River water. Salinization of the ground water could have occurred through dissolution of marine aerosol dry fallout, carbonate minerals, gypsum, and other trace evaporitic minerals at and near the ground surface. Tritium activities ranged from 0.04 to 12.9 TU (tritium unite), indicating that all but one of the samples were derived at least partly from precipitation that occurred within the last 45 years. These data indicate that Nubian Aquifer paleowater is not a significant component of the shallow aquifers of this portion of the Eastern Desert. The most likely source of this ground water is sporadic flash flood events yielding locally voluminous recharge that accumulates in coarse sediments and fractured rock beneath alluvial channels. The magnitude of this renewable ground water resource and its potential for supporting sustainable agriculture require further investigation.

Sultan, M.; Sturchio, N. C.; Abdel Hady, Y.; El Anbeawy, M.; Environmental Research; Cairo Univ.

2000-10-01

129

Gabbro Akarem mafic-ultramafic complex, Eastern Desert, Egypt: a Late Precambrian analogue of Alaskan-type complexes  

Microsoft Academic Search

Summary  ¶Gabbro Akarem is a Late-Precambrian concentrically-zoned mafic-ultramafic intrusion located along a major fracture zone trending\\u000a NE-SW in the Eastern Desert of Egypt. It intruded low-grade metasedimentary rocks, and has a contact metamorphic aureole a\\u000a few meters wide. This intrusion comprises a dunite core enveloped by clinopyroxene hornblende-bearing lherzolite, olivine-hornblende\\u000a clinopyroxenite and plagioclase hornblendite. The contacts between the rock types are

H. M. Helmy; M. M. El Mahallawi

2003-01-01

130

The role of the Najd Fault System in the tectonic evolution of the Hammamat molasse sediments, Eastern Desert, Egypt  

Microsoft Academic Search

The Hammamat molasse sediments of the Eastern Desert of Egypt were deposited in isolated basins formed during an initial stage\\u000a of orogen parallel N–S extension (650–580 Ma) in the Neoproterozoic time. Supply of sediments to the molasse basins began\\u000a after the eruption of Dokhan volcanics (602–593 Ma), exhumation of core complexes (650–550 Ma), and intrusion of late tectonic\\u000a granites (610–550 Ma). The late Neoproterozoic

Mohamed A. Abd El-Wahed

2010-01-01

131

Desert  

NSDL National Science Digital Library

Become an expert on the Desert habitat!! Begin your search for information by reading below. You can click on the underlined words to take you to the website you want to go to. Have fun! Read carefully. Visit the Desert to learn all about the desert! All about the desert also has lots of important facts about deserts. This site includes animals in the desert. Desert Facts is a great place to find lots of different facts about the desert! Kenley, you can click on "desert animals" to find a list of animals ...

Ms. Ryan

2013-02-12

132

Detailed gravimetric geoid for the Egyptian south-western desert  

NASA Astrophysics Data System (ADS)

Different gravimetric geoid solutions were carried out for the south-western Egyptian desert. A set of 2682 measured gravity stations were available for this investigation. The discrete gravity data are reduced to the geoid through the free-air reduction. Also terrain reduction is performed using a set of fine 30? × 30? and coarse 3? × 3? Digital Height Models for the test area. Different earth's geopotential models were used for the removing of the reference field. The geoid computations were performed in the space domain using the discrete Stokes integration technique and in the spectral domain using the spherical 2-D FFT technique. For both techniques, the reduced gravity anomalies are gridded on a 3? × 3? geographical grid using the least-squares interpolation technique with local covariance functions. A broad comparison among the different geoid solutions is made. The effect of the inner zone densification is in the order of about 2 cm. The effect of the spherical 2-D FFT approximation is mostly less than 1 cm.

Abd-Elmotaal, H. A.

133

Pd-BISMUTHOTELLURIDES and Other Tellurides from Some Cu-Ni-PGE Deposits, Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

Pd-bismuthotellurides and other tellurides are described from three Cu-Ni-PGE deposits in the Eastern Desert, Egypt: Abu Swayl, Genina Gharbia, Gabbro Akarem. The deposits are hosted in Late Precambrian mafic-ultramafic rocks and have different geologic histories. The Abu Swayel deposit occurs in conformable, lens-like mafic-ultramafic rocks in metasediments. Mineralization and host rocks are metamorphosed (amphibolite facies; 550-650ºC, 4-5 kbar) and syn-metamorphically sheared. Metamorphism and associated fluid regimes resulted in remobilization and transport of Cu-sulfides and PGE, and development of hydrosilicates. Michenerite, merenskyite, Pd-Bi-melonite, (NiPdBi)Te2, melonite, hessite, altaite and joséite-B occur as inclusions in mobilized sulfides and along cracks in garnet and plagioclase. The Genina Gharbia and Gabbro Akarem deposits are hosted in concentrically zoned, Alaskan-type, complexes; neither is metamorphosed. At Genina Gharbia, ore forms either disseminations in peridotite or massive patches in hornblende-pyroxenite in the vicinity of metasediments. Important petrographic features are a dominance of hornblende, biotite and chlorapatite and alteration of plagioclase to epidote. Disseminated and network sulfide ores are dominated by po, pn, cp and minor py; accessories are cobaltite, molybdenite and valleriite. Sulfide textures and host rock petrography suggest a prolonged late-magmatic hydrothermal event. Michenerite, merenskyite, Pd-Bi-melonite, altaite, hessite, tsumoite and native-Te are mainly present at sulfide-silicate contacts. The Gabbro Akarem deposit is hosted in dunite pipes where net-textured and massive sulfides are associated with spinel and Cr-magnetite. Michenerite, merenskyite, Pd-Bi-melonite and hessite occur mainly as inclusions in sulfides. Typical magmatic textures indicate the limited role of late- and post-magmatic hydrothermal processes. Different geological history of the different deposits enables examination of the role played by late-magmatic and post-magmatic metamorphic fluids in the diversity of tellurides. High Te-activities, indicated by various tellurides at Abu Swayel and Genina Gharbia, relate to participation of solutions generated during metamorphism and late-magmatic hydrothermal activity respectively. The limited role of hydrothermal fluids in the Gabbro Akarem deposit is responsible for low Te activity. It is suggested that hydrothermal fluids introduced by late- and post-magmatic processes largely control Te-activity in Cu-Ni-PGE deposits in mafic-ultramafic rocks. Involvement of a sedimentary component either early, during magma contamination or later, during metamorphism, significantly increases Te-activity.

Helmy, H. M.

2003-04-01

134

Genesis of the Abu Marawat gold deposit, central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

Gold mineralisation at the Abu Marawat mine, central Eastern Desert of Egypt, is related to a system of massive and sheared, milky quartz veins cutting a sequence of Neoproterozoic island arc metavolcanic/volcaniclastic rocks and related banded iron formation (BIF). Sulphide-bearing quartz veins and related hydrothermal breccia bodies display a range of textures including sheared, boudinaged and recrystallised quartz, open space filling and microbreccia. These variable textures imply a complex history of crack-seal mechanism characterising the relation between mineral deposition and a major N-S-trending shear zone, during a late brittle-ductile deformation event which affected the area at about 550 Ma. Gold-base metal mineralisation is associated with brecciation and fracturing of the iron ore bands, close to silicified shears and related quartz veins. The auriferous quartz lodes are characterised by the occurrence of visible pyrite-chalcopyrite ± pyrrhotite ± sphalerite ± galena mineralisation. Gold is refractory in pyrite and chalcopyrite, but rare visible gold/electrum and telluride specks were observed in a few samples. Hydrothermal alteration includes pervasive silicification, pyritisation, sericitisation, carbonatisation confined to a delicate set of veins and altered shears, and a more widespread propylitic alteration assemblage (quartz + chlorite + pyrite + calcite ± epidote). Fluid inclusion petrography and microthermometric studies suggest heterogeneous trapping of a low-salinity (1.4-6.7 wt.% eq. NaCl) aqueous solution and a carbonic fluid. Evidence for fluid immiscibility during ore formation includes variable liquid/vapour ratios in inclusions along individual trails and bulk inclusion homogenisation into liquid and occasionally to vapour at comparable temperatures. The trapping conditions of intragranular aqueous-carbonic inclusions approximate 264-378 °C at 700-1300 bar. Similar temperature estimates have been obtained from Al-in-chlorite geothermometry of chlorite associated with sulphides in the mineralised quartz veins. Fracturing enhanced fluid circulation through the wallrock and related BIF, allowing reaction of the S-bearing ore fluid with iron oxides. This caused pyrite formation and concomitant Au precipitation, enhanced by fluid immiscibility as H 2S partitioned preferentially into the carbonic phase. The ore fluids may have originated from granitoid intrusions (likely the post-Hammamat felsites, whereas gold and base metals might have been leached from the Abu Marawat basic metavolcanics.

Zoheir, Basem A.; Akawy, Ahmed

2010-06-01

135

Mineralogy and fluid inclusion studies of the Au-Cu quartz veins in the Hamash area, South-Eastern Desert, Egypt  

Microsoft Academic Search

Summary Field relations, petrographic observations and fluid inclusion data are used to characterize the mineralizing fluids of gold-copper bearing quartz veins, which are spatially associated with a granite-porphyry, metavolcanics and metagabbro in the Hamash area, South Eastern Desert of Egypt. Four generations of genetically related quartz veins occur in the Hamash mine area. Two types of alteration are developed in

H. M. Helmy; R. Kaindl

1999-01-01

136

The northern dome of Wadi Hafafit culmination, Eastern Desert, Egypt: Structural setting in tectonic framework of a scissor-like wrench corridor  

Microsoft Academic Search

Although the gneissic domes in Eastern Desert of Egypt have been studied recently in a considerable detail; their origin remains controversial. Basically four schools of thought exist: one argues for an origin parallel crustal extension, a second suggests emplacement within antiformal stacks, a third envisages young emplacement within a core of a sheath fold and finally some authors believe that

Ahmed Shalaby

2010-01-01

137

El Sibai gneissic complex, Central Eastern Desert, Egypt: Folded nappes and syn-kinematic gneissic granitoid sheets – not a core complex  

Microsoft Academic Search

The El Sibai area of the Central Eastern Desert (CED) of Egypt consists of an ophiolitic association of arc metavolcanics, ophiolitic rocks, mélange, metasediments and minor mafic intrusions; and a gneissic association of amphibolite, gneissic diorite, tonalite, granodiorite and granite. Previous studies of the El Sibai area have identified the gneissic association as a lower crustal infrastructure in sheared contact

Abdel-Rahman Fowler; Hossam Khamees; Hamed Dowidar

2007-01-01

138

Carbonate-orthopyroxenite lenses from the Neoproterozoic Gerf ophiolite, South Eastern Desert, Egypt: The first record in the Arabian Nubian Shield ophiolites  

Microsoft Academic Search

Carbonate-orthopyroxenites (classic sagvandites) are reported in the Gerf ophiolite, South Eastern Desert, Egypt: the first finding from the Arabian Nubian Shield (ANS) ophiolites. They form massive lenses at the southern tip of the Gerf ophiolite, along the contact between the Shinai granite and Gerf serpentinized peridotites. The lenses show structural concordance with the neighboring country rocks and the granite contact.

Hisham A. Gahlan; Shoji Arai

2009-01-01

139

Moving Water to Move People The Toshka Project in Egypt A Water Forum Contribution  

Microsoft Academic Search

The purpose of this paper is to provide an initial assessment of Egypt's plan to resettle population from the Nile Valley to the Western Desert. Known popularly as the Toshka Project, it is formally titled the National Project for the Development of Upper Egypt (NPDUE). The resettlement scheme is entirely dependent on the provision of a reliable source of freshwater.

Steve Lonergan; Aaron T. Wolf

2001-01-01

140

Neoproterozoic ophiolitic peridotites along the Allaqi-Heiani suture, South Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Wadi Allaqi ophiolite along the Egyptian-Sudanese border defines the southernmost ophiolitic assemblage and suture zone in the Eastern Desert. Ophiolite assemblages comprise nappes composed mainly of mafic and ultramafic rocks that were tectonically emplaced and replaced by serpentine and carbonates along shear zones probably due to CO2-metasomatism. Serpentinites, altered slices of the upper mantle, represent a distinctive lithology of dismembered ophiolites of the western YOSHGAH suture. Microscopically, they are composed of more than 90 % serpentine minerals with minor opaque minerals, carbonate, brucite and talc. The mineral chemistry and whole-rock chemical data reported here indicate that the serpentinized peridotites formed as highly-depleted mantle residues. They show compositions consistent with formation in a suprasubduction zone environment. They are depleted in Al2O3 and CaO similar to those in fore-arc peridotites. Also, high Cr# (Cr/ (Cr+Al)) in the relict chrome spinels (average ~0.72) indicates that these are residual after extensive partial melting, similar to spinels in modern fore-arc peridotites. Therefore, the studied serpentinites represent fragments of an oceanic lithosphere that formed in a fore-arc environment, which belongs to an ophiolitic mantle sequence formed in a suprasubduction zone.

Azer, M. K.; Samuel, M. D.; Ali, K. A.; Gahlan, H. A.; Stern, R. J.; Ren, M.; Moussa, H. E.

2013-10-01

141

Single quartz grain electron spin resonance (ESR) dating of a contemporary desert surface deposit, Eastern Desert, Egypt  

Microsoft Academic Search

Signal resetting by sunlight prior to burial is a crucial assumption in electron spin resonance (ESR) dating of sediments. This resetting process is expected to be completed to a greater extent in arid than in fluvial environments. The present paper investigates the natural and artificially irradiated signal intensity of Ti related centres in single quartz grains collected from the desert

Koen Beerten; André Stesmans

2005-01-01

142

Deserts  

NSDL National Science Digital Library

Deserts, one of the four major terrestial biomes, cover about one-fifth of Earth's land area. This interactive slide presentation shows some aspects of deserts, including dunes, desert-adapted plants, oases, and sculpted rock formations. There is also a map showing the distribution of the world's deserts. A background essay and discussion questions are included.

143

Habitat Invasibility and Dominance by Alien Annual Plants in the Western Mojave Desert  

Microsoft Academic Search

Patterns of habitat invasibility and alien dominance, respectively measured as species richness and biomass of alien annual\\u000a plants, were evaluated in association with four habitat factors at the Desert Tortoise Research Natural Area (DTNA) in the\\u000a western Mojave Desert, USA. Habitat factors varied in levels of disturbance outside (high) and inside (low) the DTNA, and\\u000a in levels of soil nutrients

Matthew L. Brooks

1999-01-01

144

Origin of Neoproterozoic ophiolitic peridotites in south Eastern Desert, Egypt, constrained from primary mantle mineral chemistry  

NASA Astrophysics Data System (ADS)

The ophiolitic peridotites in the Wadi Arais area, south Eastern Desert of Egypt, represent a part of Neoproterozoic ophiolites of the Arabian-Nubian Shield (ANS). We found relics of fresh dunites enveloped by serpentinites that show abundances of bastite after orthopyroxene, reflecting harzburgite protoliths. The bulk-rock chemistry confirmed the harzburgites as the main protoliths. The primary mantle minerals such as orthopyroxene, olivine and chromian spinel in Arais serpentinites are still preserved. The orthopyroxene has high Mg# [=Mg/(Mg + Fe2+)], ~0.923 on average. It shows intra-grain chemical homogeneity and contains, on average, 2.28 wt.% A12O3, 0.88 wt.% Cr2O3 and 0.53 wt.% CaO, similar to primary orthopyroxenes in modern forearc peridotites. The olivine in harzburgites has lower Fo (93-94.5) than that in dunites (Fo94.3-Fo95.9). The Arais olivine is similar in NiO (0.47 wt.% on average) and MnO (0.08 wt.% on average) contents to the mantle olivine in primary peridotites. This olivine is high in Fo content, similar to Mg-rich olivines in ANS ophiolitic harzburgites, because of its residual origin. The chromian spinel, found in harzburgites, shows wide ranges of Cr#s [=Cr/(Cr + Al)], 0.46-0.81 and Mg#s, 0.34-0.67. The chromian spinel in dunites shows an intra-grain chemical homogeneity with high Cr#s (0.82-0.86). The chromian spinels in Arais peridotites are low in TiO2, 0.05 wt.% and YFe [= Fe3+/(Cr + Al + Fe3+)], ~0.06 on average. They are similar in chemistry to spinels in forearc peridotites. Their compositions associated with olivine’s Fo suggest that the harzburgites are refractory residues after high-degree partial melting (mainly ~25-30 % partial melting) and dunites are more depleted, similar to highly refractory peridotites recovered from forearcs. This is in accordance with the partial melting (>20 % melt) obtained by the whole-rock Al2O3 composition. The Arais peridotites have been possibly formed in a sub-arc setting (mantle wedge), where high degrees of partial melting were available during subduction and closing of the Mozambique Ocean, and emplaced in a forearc basin. Their equilibrium temperature based on olivine-spinel thermometry ranges from 650 to 780 °C, and their oxygen fugacity is high (?log ƒO2 = 2.3 to 2.8), which is characteristic of mantle-wedge peridotites. The Arais peridotites are affected by secondary processes forming microinclusions inside the dunitic olivine, abundances of carbonates and talc flakes in serpentinites. These microinclusions have been formed by reaction between trapped fluids and host olivine in a closed system. Lizardite and chrysotile, based on Raman analyses, are the main serpentine minerals with lesser antigorite, indicating that serpentines were possibly formed under retrograde metamorphism during exhumation and near the surface at low T (<400 °C).

Khedr, Mohamed Zaki; Arai, Shoji

2013-10-01

145

Mineralogical and structural characterization of alteration zones detected by orbital remote sensing at Shalatein District, SE Desert, Egypt  

NASA Astrophysics Data System (ADS)

In the Shalatein district, Eastern Desert of Egypt, Landsat Thematic Mapper (TM) data and fieldwork were combined with mineralogical and geochemical investigations in order to detect and characterize alteration zones within Pan-African rocks. The processing of Landsat TM data using ratioing (bands 5/7, 4/5, 3/1 in red, green, blue) showed two different types of alteration zones (type 1 and 2). Type 1 is close to the ophiolitic ultramafic rocks at Wadi Hodein and Wadi Beida areas, whereby type 2 is located within island-arc related metavolcanic rocks at Wadi Beida and Gabal El Qurun areas. Both of these alteration types are concordant with the main NW-SE structural trend. Mineralogical studies indicate that the type 1 alteration consists mainly of calcite, ankerite, magnesite, dolomite and quartz. Chromian spinel, pyrite, and Ni-bearing sulphides (gersdorffite, pentlandite and polydymite) are the main ore minerals within this type. Type 2 alteration is strongly potassium-enriched and pyrophyllite, kaolinite, illite, gypsum and quartz occur. The brecciated quartz-veins, which are associated with these alteration zones, consist of quartz, Fe-hydroxides, hematite and native gold. The gold content reaches up to 5 g/t in the alteration zone, while it extends up to 50 g/t in the quartz veins. This study presents a mineralogical characterization of such alteration zones and demonstrates the utility of orbital remote sensing for finding unknown alteration zones in the Eastern Desert of Egypt and other arid areas with similar host rock lithologies.

Ramadan, Talaat M.; Kontny, Agnes

2004-09-01

146

Potential Impacts of Climate Change on Modern Recharge in the Eastern Desert and Sinai Peninsula of Egypt  

NASA Astrophysics Data System (ADS)

Aquifers in Egypt (e.g., Nubian Sandstone, shallow alluvial) were primarily recharged in previous wet climatic periods in the Quaternary. Previous studies have shown that both aquifers are receiving modern recharge under the current drier climatic conditions. The validity of these advocated models was tested using geophysical (conventional Electrical Resistivity, [ER]) and isotopic (O, H) data, and estimates for modern recharge were obtained using continuous rainfall-runoff modeling over the period 1998-2007. First-order estimates of the average annual modern recharge for the NSS aquifer (~13.0 x 10^6m^3/yr) and the shallow Alluvial aquifers in the Sinai Peninsula for the investigated watersheds (456 x 10^6m^3/yr) and the shallow Alluvial aquifers in the Eastern Desert (147 x 10^6m^3/yr) were computed using the SWAT (Soil Water Assessment Tool) model and readily available global remote sensing data sets (e.g., TRMM). Projections of climate change over North Africa from three of the leading general circulation models (GCMs) (GISS, GFDL, and UKMO) indicate a potentially high degree of vulnerability in the future precipitation amounts in Egypt. For each of the major watersheds and the Nubian Sandstone outcrops, we ran the calibrated model over the investigation period (1998-2007) using the obtained average annual precipitation and additional values of 10, 50, 100, and 150 mm. The SWAT model outputs were then used to extract relationships describing variations in runoff, recharge, and evaporation in relation to average annual precipitation amounts. Using developed tools on a web-based GIS interface we described these relationships under various climatic trends. Using a 10% decrease in rainfall in Egypt results in decreasing the average annual recharge to the shallow Alluvial aquifers in the Sinai Peninsula (384 x 10^6m^3/yr) and in the Eastern Desert (111 x 10^6m^3/yr). The observed differences between the watersheds in the partitioning of precipitation and in their response to increasing precipitation, is largely related to the variations in their lithologic characteristics. Findings bear on the sustainable exploitation of the Nubian Sandstone and shallow Alluvial aquifers, where the aquifer is being locally recharged, and on the exploitation of similar extensive aquifers largely recharged in previous wet climatic periods yet are still receiving modest modern meteoric contributions.

Milewski, A.; Sultan, M.; Becker, D.; Soliman, F.; Yan, E.; Becker, R.; Chouinard, K.

2011-12-01

147

Holocene environmental changes in the Gebel Umm Hammad, Eastern Desert, Egypt  

Microsoft Academic Search

Gebel Umm Hammad in the Red Sea Mountains east of Quseir, Egypt, today enjoys small but irregular amounts of winter rain, enabling the widening of joint controlled openings in the Thebes Limestone. Cavities are especially affected by flaking, while rock fragmentation is more active on the outside. The sedimentological and botanical study of fan deposits at the outlet of a

Jan Moeyersons; Pierre M. Vermeersch; Hans Beeckman; Philip Van Peer

1999-01-01

148

Petrology and petrogenesis of the older and younger granitoids of Wadi Beizah area, Central Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The studied granitoids of Wadi Beizah area, Central Eastern Desert, Egypt, are represented by older arc-granitoids intruded by a post-collisional stock of younger pink granite. The arc-granitoids (I-type) cover a wide compositional spectrum from meladiorites, diorites, quartzdiorites/monzodiorites and tonalites, to leucogranodiorites. Their distribution pattern is unimodal dominated by diorites. They are of low-K calc-alkaline character and represent the plutonic rocks of the mature, ensimatic island arc stage. Three models for the geotectonic environment of the younger granites of the Eastern Desert of Egypt have been suggested: (1) Within-plate, rifting, tensional environment similar to the Oslo Rift of Norway (Greenberg, 1981) Stern et al., 1984, 1986), (2) Extensive crustal anatexis during collisional tectonics, compression, thickening of the crust and thrust imbrication (Hussein et al., 1982; Ragab, 1987b), (3) Active continental margin geotectonic environment (Abdel-Rahman and Martin, 1987). These three models are discussed in detail. The present workers believe that the Younger Granites in general are the products of extensive crustal anatexis at the culmination of the Pan-African orogenic cycle when arc-arc suturing is complete. Recent studies revealed a low-angle thrust event in the Central Eastern Desert followed the initial arc-arc collision and continued after the deposition of the molasse-type sediments (Ries et al., 1983; El-Ramly et al., 1984; Greiling et al., 1984; Habib et al., 1985; Greiling and El-Ramly, 1985) which indicate thickening of the crust and compression regime at the time of emplacement of the Younger Granites. The dominance of ?granite minimum? composition of these late orogenic granites suggests extensive crustal anatexis. Their low Nb-content (< 40 ppm) precludes within-plate hot-spot related magma, in comparison with: (1) The post-Pan-African (400-100 M.a.) granitic rocks from the NE Sudan which on a geochemical evidence are the products of within-continental plate ?hot-spot? magmatism with Nb-content of about 50-300 ppm (Gass, 1979); (2) The Oslo Rift within-plate granites with Nb-content of 226 ppm (Pearce et al., 1984). A post-collision model showing the formation of the ?petrotectonic assemblage? of this stage (molasse-type sediments deposited in fault-bounded troughs, and calc-alkaline bimodal intermediate and felsic magmas) as well as the heat sources in the geotectonic environment of thrust imbrication and the mode of formation of the Younger Granites by crustal anatexis is suggested. K/Ar dating of a younger granite sample gave an age of 584 ± 5 M.a. which is compatible with several similar ages of younger pink granites in the Eastern Desert of Egypt. An older granite sample gave an age of 591 ± 7 M.a. (K/Ar method) indicating resetting of its isotopic clocks probably as a result of the extensive crustal anatexis event.

Ragab, A. I.; Menesy, M. Y.; Diab, M. M.

149

Sr-Nd isotopes and geochemistry of granite-gneiss complexes from the Meatiq and Hafafit domes, Eastern Desert, Egypt: No evidence for pre-Neoproterozoic crust  

Microsoft Academic Search

Neoproterozoic gneisses at Meatiq and Hafafit in the Eastern Desert of Egypt give Rb-Sr and U-Pb zircon ages of 600-750 Ma. These gneisses are interpreted by different workers to represent deeper levels of juvenile Neoproterozoic crust or Archaean\\/Palaeoproterozoic crust that was remobilized during Neopro- terozoic time. Geochemical and Sr-Nd isotope compositions for these gneisses reported here are remark- ably homogeneous:

Jean-Paul Liégeois; Robert J. Stern

2009-01-01

150

Geochemistry and petrogenesis of Pan-African late- to post-orogenic younger granitoids at Shalatin-Halaib, south Eastern Desert, Egypt  

Microsoft Academic Search

The younger granitoids of the Shalatin-Halaib district in the south Eastern Desert of Egypt are of syenogranite compositions. Based on petrological and geochemical studies, the syenogranites have been differentiated into two distinct types, namely biotitehornblende subsolvus syenogranite (SGR I), showing I-type affinity, and biotite-bearing hypersolvus syenogranite (SGR II) with A-type affinity. On the basis of rare earth element (REE) patterns,

S. A. El-Nisr; M. M. El-Sayed; G. M. Saleh

2001-01-01

151

Gneiss-cored interference dome associated with two phases of late Pan-African thrusting in the Central Eastern Desert, Egypt  

Microsoft Academic Search

Structural analysis of the Wadi Um Had area in the Central Eastern Desert (CED) of Egypt reveals the presence of another NW-trending elliptical gneissic and migmatitic domal structure west of Gabal Meatiq, outlined by a thick schistose and mylonitized carapace. The sheared carapace formed during a NW\\/NNW-ward thrusting event which emplaced thrust slices of ophiolitic mélange, Dokhan Volcanics and Hammamat

T. J Fowler; A. F Osman

2001-01-01

152

A genetic model for a mesothermal Au deposit: evidence from fluid inclusions and stable isotopic studies at El Sid Gold Mine, Eastern Desert, Egypt  

Microsoft Academic Search

The El Sid Au mineralisation in the Fawakhir area, Eastern Desert, Egypt, is comprised of hydrothermal quartz veins cutting a Neoproterozoic granitoid pluton. The mineralisation is divided into Au-bearing, transitional and late carbonate vug stages. Pyrite- arsenopyrite and streaky pyrite-sphalerite-galena assemblages characterise the early and late episodes of the Au-bearing stage, respectively. These sulphide minerals sometimes contain Au as inclusions.

Hassan Z. Harraz

2000-01-01

153

Origin of wehrlite cumulates in the Moho transition zone of the Neoproterozoic Ras Salatit ophiolite, Central Eastern Desert, Egypt: crustal wehrlites with typical mantle characteristics  

Microsoft Academic Search

Ultramafic cumulates, mainly crustal true wehrlites, were discovered and described in the mantle–crust transition zone (MTZ)\\u000a and the extremely lower layered gabbro sequence of the Ras Salatit ophiolite, Central Eastern Desert, Egypt. They form either\\u000a boudinaged lensoidal tabular bodies or interdigitated layers often concordant with the planolinear fabrics of the Ras Salatit\\u000a ophiolite rocks. The contact between wehrlites and the

Hisham A. Gahlan; Shoji Arai; Fawzy F. Abu El-Ela; Akihiro Tamura

154

Composition and total-Pb model ages of monazite from high-grade paragneisses in the Abu Swayel area, southern eastern desert, Egypt  

Microsoft Academic Search

Summary Monazites from high-grade metapelitic paragneisses from the southern Eastern Desert of Egypt (Abu Swayel area) were analysed with the electron microprobe mainly in an attempt to broadly constrain the metamorphic ages of the rocks by means of chemical Th(U)-Pb dating. Two samples were investigated, one showed weak signs of a greenschist facies overprint, the other one did not. For

F. Finger; H. Mo Helmy

1998-01-01

155

Sr–Nd isotopes and geochemistry of granite-gneiss complexes from the Meatiq and Hafafit domes, Eastern Desert, Egypt: No evidence for pre-Neoproterozoic crust  

Microsoft Academic Search

Neoproterozoic gneisses at Meatiq and Hafafit in the Eastern Desert of Egypt give Rb–Sr and U–Pb zircon ages of 600–750Ma. These gneisses are interpreted by different workers to represent deeper levels of juvenile Neoproterozoic crust or Archaean\\/Palaeoproterozoic crust that was remobilized during Neoproterozoic time. Geochemical and Sr–Nd isotope compositions for these gneisses reported here are remarkably homogeneous: Initial 87Sr\\/86Sr (0.70252±0.00056)

Jean-Paul Liégeois; Robert J. Stern

2010-01-01

156

Chrome-spinels in serpentinites and talc carbonates of the El Ideid-El Sodmein District, central Eastern Desert, Egypt: their metamorphism and petrogenetic implications  

Microsoft Academic Search

Serpentinites and talc-carbonate rocks of El Ideid-El Sodmein District (ISD), central Eastern Desert, Egypt, contain variably altered chrome-spinels. Back-scattered electron images and electron microprobe analyses of chrome-spinels and associated silicates are made to evaluate their textural and compositional variations with metamorphism. In most cases the chrome-spinel crystals are concentrically zoned with unaltered cores through transitional zone of ferritchromit to Cr-magnetite

E. S. Farahat

2008-01-01

157

Paleosols of the Upper Cretaceous–Lower Tertiary Maghra El-Bahari Formation in the northeastern portion of the Eastern Desert, Egypt: Their recognition and geological significance  

Microsoft Academic Search

The Upper Cretaceous\\/Lower Tertiary Maghra El-Bahari Formation at Gabal Ataqa and Gabal Shabrawet in the northeastern portion of the Eastern Desert of Egypt is subdivided into two informal lithostratigraphic parts: lower and upper. The lower part has common features of alluvial floodplain-dominated deposits with occasional occurrences of crevasse splay deposits. The upper part has sediments typical of marginal lacustrine environments.Both

H. A. Wanas; M. M. Abu El-Hassan

2006-01-01

158

Ground-water quality and geochemistry, Carson Desert, western Nevada  

USGS Publications Warehouse

Aquifers in the Carson Desert are the primary source of drinking water, which is highly variable in chemical composition. In the shallow basin-fill aquifers, water chemistyr varies from a dilute calcium bicarbonate-dominated water beneath the irrigated areas to a saline sodium chloride- dominated water beneath unirrigated areas. Water samples from the shallow aquifers commonly have dissolved solids, chloride, magnesium, sulfate, arsenic, and manganese concentrations that exceed State of Nevada drinking-water standards. Water in the intermediante basin-fill aquifers is a dilute sodium bicarbonate type in the Fallon area and a distinctly more saline sodium chloride type in the Soda Lake-Upsal Hogback area. Dissolved solids, chloride, arsenic, fluoride, and manganese concen- trations commonly exceed drinking-water standards. The basalt aquifer contains a dilute sodium bicarbonate chloride water. Arsenic concentrations exceed standards in all sampled wells. The concen- trations of major constituents in ground water beneath the southern Carson Desert are the result of evapotranspiration and natural geochemical reactions with minerals derived mostly from igneous rocks. Water with higher concentrations of iron and manganese is near thermodynamic equilibrium with siderite and rhodochrosite and indicates that these elements may be limited by the solubility of their respective carbonate minerals. Naturally occurring radionuclides (uranium and radon-222) are present in ground water from the Carson Desert in concen- tratons higher than proposed drinking-water standards. High uranium concentrations in the shallow aquifers may be caused by evaporative concentration and the release of uranium during dissolution of iron and manganese oxides or the oxidation of sedimentary organic matter that typically has elevated uranium concentrations. Ground water in the Carson Desert does not appear to have be contaminated by synthetic organic chemicals.

Lico, Michael S.; Seiler, R.L.

1994-01-01

159

Effect of ploughing on plant species abundance and diversity in the northwestern coastal desert of Egypt  

Microsoft Academic Search

This study focuses on the effect of ploughing on plant abundance,vegetation cover, species richness, and taxonomic diversity during the growingseasons (winter and spring) of 1992 and 2000 in the habitat of inland plateau(natural habitat), 21 km south of Mersa-Matrouh (Egypt).Ninety-five species belonging to 27 families were recorded. High percentages oflife-forms and a large number of species were recorded in ploughed

Sania K. Hammouda; Selim Z. Heneidy

2003-01-01

160

Plant species distribution and spatial habitat heterogeneity in the landscape of urbanizing desert ecosystems in Egypt  

Microsoft Academic Search

Information on the urban flora and vegetation in the industrial new cities in Egypt are insufficient and far from complete.\\u000a For this reason, this study was undertaken as the first attempt to fill this gap of knowledge. For two successive years (2004\\u000a and 2005), a reconnaissance survey was conducted in four new industrial cities: 6th October, El-Sadat, Burg El-Arab and

Monier Abd El-Ghani; Reinhard Bornkamm; Nadia El-Sawaf; Hamdiya Turky

161

Sulfuric acid leaching of Kab Amiri niobium–tantalum bearing minerals, Central Eastern Desert, Egypt  

Microsoft Academic Search

The ore under study was obtained from the Kab Amiri area located close to the northern boundary of the Central Eastern Desert. The ore is constituted of different kinds of refractory minerals. These are mainly represented by the niobium–tantalum rare earth-bearing minerals namely euxinite, samarsakite and fergusonite, beside the uranium refractory minerals davidite and zircon. Increasing demand for niobium, tantalum,

Omneya M El-Hussaini; Mohamed A Mahdy

2002-01-01

162

Petrogenetic and geotectonic significance of Neoproterozoic suprasubduction mantle as revealed by the Wizer ophiolite complex, Central Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

Ophiolite complexes, formed in a suprasubduction zone environment during Neoproterozoic time, are widely distributed in the Eastern Desert of Egypt. Their mantle sections provide important information on the origin and tectonic history of ocean basins these complexes represent. The geochemistry and mineralogy of the mantle section of the Wizer ophiolite complex, represented by serpentinites after harzburgite containing minor dunite bodies, are presented. Presence of antigorite together with the incipient alteration of chromite and absence of chlorite suggests that serpentinization occurred in the mantle wedge above a Neoproterozoic subduction zone. Wizer peridotites have a wide range of spinel compositions. Spinel Cr# [100Cr/(Cr + Al)] decrease gradually from dunite bodies (Cr# = 81-87) and their host highly depleted harzburgites (Cr# = 67-79) to the less depleted harzburgites (Cr# = 57-63). Such decreases in mantle refractory character are accompanied by higher Al and Ti contents in bulk compositions. Estimated parental melt compositions point to an equilibration with melts of boninitic composition for the dunite bodies (TiO2 = ~<0.07-0.22 wt%; Al2O3 = 9.4-10.6 wt%), boninitic-arc tholeiite for the highly depleted harzburgites (TiO2 = <0.09-0.28 wt%; Al2O3 = 11.2-14.1 wt%) and more MORB-like affinities for the less depleted harzburgites (TiO2 = ~<0.38-0.51 wt%; Al2O3 = 14.5-15.3 wt%). Estimated equilibrium melts are found in the overlying volcanic sequence, which shows a transitional MORB-island arc geochemical signature with a few boninitic samples. Enrichment of some chromites in TiO2 and identification of sulfides in highly depleted peridotites imply interaction with an impregnating melt. A two-stage partial melting/melt-rock reaction model is advocated, whereby, melting of a depleted mantle source by reaction with MORB-like melts is followed by a second stage melting by interaction with melts of IAT-boninitic affinities in a suprasubduction zone environment to generate the highly depleted harzburgites and dunite bodies. The shift from MORB to island arc/boninitic affinities within the mantle lithosphere of the Wizer ophiolite sequence suggests generation in a protoarc-forearc environment. This, together with the systematic latitudinal change in composition of ophiolitic lavas in the Central Eastern Desert (CED) of Egypt from IAT-boninitic affinities to more MORB-like signature, implies that the CED could represent a disrupted forearc-arc-backarc system above a southeast-dipping subduction zone.

Farahat, E. S.; Hoinkes, G.; Mogessie, A.

2011-10-01

163

Natural radionuclide concentrations in granite rocks in Aswan and Central-Southern Eastern Desert, Egypt and their radiological implications.  

PubMed

Different types of granites, used extensively in local construction, were collected from five localities in Egypt, namely: Abu Ziran (Central Eastern Desert), Gabal El Maesala (Aswan) and three areas from Wadi Allaqi, (Gabal Abu Marw, Gabal Haumor and Gabal um Shalman), in the South Eastern Desert. Granite samples were studied radiologically, petrographically and geochemically. The contents of natural radionuclides ((226)Ra, (232)Th and (40)K) were measured in investigated samples by using gamma spectrometry [NaI (Tl) 3'×3']. The activity concentrations of (226)Ra, (232)Th and (40)K in the selected granite samples ranged from 9±0.5 to 111±7, 8±1 to 75±4 and 100±6 to 790±40 Bq kg(-1), respectively. The external hazard index (H(ex)), absorbed dose and annual effective dose rate were evaluated to assess the radiation hazard for people living in dwellings made of the materials studied. The calculated radium equivalents were lower than the values recommended for construction materials (370 Bq kg(-1)). The excess lifetime cancer risks were also calculated. Petrographically, the granites studied are varied in the form of potash-feldspar, quartz, plagioclase, mica and hornblende. The accessory minerals are zircon, apatite and allanite. Geochemically, the chemical composition of the granite is studied especially for major oxides. They are characterized to have SiO(2), K(2)O, Na(2)O and Al(2)O(3) with depletion in CaO, MgO, TiO(2) and P(2)O(5). PMID:22147926

Issa, Shams A M; Uosif, M A M; Abd el-Salam, L M

2012-07-01

164

Desert landforms of southwest Egypt: A basis for comparison with Mars  

NASA Technical Reports Server (NTRS)

Geologic interpretations of The Gilf Kebir-Uweinat of Apollo-Soyuz photographs were verified. The photographs and LANDSAT images showed features reminiscent of those depicted by Mariner and Viking missions to Mars. These features were to better understand their morphologic analogs on Mars. It is indicated that climate change played a significant role in the formation of the eastern Sahara. It is also revealed that correlations between the eolian features in southwestern Egypt and the wind blown patterns on the surface of Mars result in a better understanding of eolian activity on both planets.

El-Baz, F. (editor); Maxwell, T. A. (editor)

1982-01-01

165

Late Neoproterozoic Dokhan Volcanics, North Eastern Desert, Egypt: Geochemistry and petrogenesis  

Microsoft Academic Search

Origin and tectonic setting of the late Neoproterozoic Dokhan Volcanics (ca. 610–560Ma by whole rock Rb–Sr and ca. 600–590Ma by SHRIMP U–Pb zircon) in the Egyptian Eastern Desert is debated. Debate concerns the tectonic setting they formed in, during transition between convergent to extensional, during or after collision of E and W Gondwana ?600Ma. In order to solve this problem,

H. A. Eliwa; J.-I. Kimura; T. Itaya

2006-01-01

166

Magmatic and solid state structures of the Abu Ziran pluton: Deciphering transition from thrusting to extension in the Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The 606 Ma old Abu Ziran granite of the Eastern Desert of Egypt intruded the southern margin of the Meatiq dome in a sinistral shear extensional setting. Its emplacement was enabled by a system of NW-trending sinistral shears, related Riedel shears and N-S extensional shear zones and faults. Magmatic flow was east-directed and controlled by Riedel shears that progressively rotated to an orientation favourable for extension. Strain markers that document magmatic flow show eastward decreasing strain together with strain increase from pluton centre to margins. This is explained by Newtonian flow between non-parallel plates and differences in flow velocities across the pluton. Solid state fabrics including shear fabrics, orientation of late magmatic dykes and quartz tension gashes, together with quartz C-axes distributions, document southward extensional shear within the solidified pluton and adjacent host rocks. Extensional shear is correlated with exhumation of the Meatiq dome coeval and soon after pluton solidification (585 Ma). Pressure temperature evolutionary paths, derived from fluid inclusions, show a clockwise path with exhumation by isothermal decompression in the Meatiq dome. By contrast, the overlying volcanosedimentary nappes experienced an anti-clockwise path released by temperature rise due to pluton emplacement followed by isobaric cooling. Quartz fabrics indicate high-temperature coaxial N-S flow in the northern Meatiq dome and lower-temperature, non-coaxial southward flow within the overlaying superficial nappe. This is explained by the exhumation process itself that progressively localised into simple shear domains when rocks approached higher crustal levels. Late extension at ca. 580 Ma was pure shear dominated and resulted in reversal of shear, now dextral, in the western Meatiq shear zone.

Fritz, Harald; Loizenbauer, Jürgen; Wallbrecher, Eckart

2014-11-01

167

Blackbrush shrublands occupy about three million acres of land in the western United States and they provide critical habitat for animals such as desert rodents, birds, and bighorn  

E-print Network

and they provide critical habitat for animals such as desert rodents, birds, and bighorn sheep. This blackbrush in the Western U.S. Desert: Blackbrush Shrublands Respond to a Changing Climate Standing in the Mojave Desert. But with the passage of time, change is the rule in most ecosystems, and this desert is no exception. A time

168

Groundwater quality and management in arid and semi-arid regions: Case study, Central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

This study presents a model budget for groundwater in the Central Eastern Desert of Egypt. The stable isotopic composition and hydrochemistry of groundwater samples collected from different aquifers were determined to identify recharge sources and water quality. Stable isotopic values suggest that shallow alluvial and fracture zone aquifers are recharged from seasonal precipitation, while groundwater in deeper sedimentary sub-basins is paleowater that was recharged during periods of less arid regional climate. Hydrochemical analysis indicates elevated salinity in each aquifer type, which is attributed to leaching and dissolution of terrestrial salts and to mixing with marine water. Groundwater from sedimentary sub-basin aquifers can be treated and used for drinking and domestic purposes. Groundwater from shallow alluvial and fracture zone wells is suitable for animal husbandry and mineral ore dressing. A model water budget shows that approximately 4.8 × 109 m3 of recoverable groundwater is stored in sedimentary sub-basin aquifers, or approximately 550 years of water at present utilization rates.

Amer, Reda; Ripperdan, Robert; Wang, Tao; Encarnación, John

2012-07-01

169

Banded iron formations of Um Nar, Eastern Desert of Egypt: P-T-X conditions of metamorphism and tectonic implications  

NASA Astrophysics Data System (ADS)

Banded iron formations (BIF) in Um Nar, central eastern desert of Egypt, occur intercalated with schists of volcaniclastic and epiclastic origins within "ophiolitic-island arc rocks" of the Arabo-Nubian Shield. The BIF and its host rocks were affected by folding, thrusting, and regional metamorphism during the Pan-African Orogeny resulting in the development of north-verging overturned folds and E-W striking, S-dipping thrusts. Following the intrusion of granitoids, the entire sequence was refolded into south-plunging folds with NW-SE trending fold axes. Peak mineral assemblages of hornblende + plagioclase, and garnet + biotite + plagioclase + quartz in the host rocks, and andradite-rich garnet + epidote + hematite + magnetite + quartz in the BIF indicate metamorphism under epidote amphibolite facies conditions. Using the multiequilibrium approach of Thermocalc, and conventional thermobarometry, peak P-T conditions of metamorphism are estimated at 520 ± 30 °C, 5 ± 2 kbar. Fluids attending peak conditions in the oxide facies layers of the BIF were characterized by XCO2 ~ 0.03 and log fO2 ~ - 40. Textural and mineral chemical criteria suggest that, following peak conditions, the rocks underwent a stage of near-isobaric cooling or cooling and compression characteristic of a counter-clockwise P-T path.

El-Shazly, A. K.; Khalil, K. I.

2014-05-01

170

Rare earth elements content in geological samples from eastern desert, Egypt, determined by instrumental neutron activation analysis.  

PubMed

Twenty representative geological samples (tonalite, granodiorite, adamellite, syenogranite, rapakivi syenogranite, alkali feldspar granite and monzogranite) were collected from G. Kattar area in Eastern Desert, Egypt, for analysis by instrumental neutron activation as a sensitive nondestructive analytical tool for the determination of 14 rare earth elements (REEs) and to find out the following: (1) what information could be obtained about the REEs and distribution patterns of REEs in geological samples under investigation, (2) to estimate the accuracy, reproducibility and detection limit of the INAA method in case of the given samples. The samples were properly prepared together with standard reference material and simultaneously irradiated in a neutron flux of 7x10(11)n/cm(2)s in the TRIGA Mainz research reactor facilities. The gamma spectra were collected by an HPGe detector and the analysis was done by means of a computerized multichannel analyzer. The choice of the nuclear reaction, irradiation and decay times, and of the proper gamma radiation in counting are presented and discussed. The results are found to be in good agreement with certified values. PMID:20236830

El-Taher, A

2010-09-01

171

Nutritional parameters and chronic energy deficiency in older adults of desert areas of western Rajasthan, India.  

PubMed

Nutritional status was assessed in 212 older individuals (> or =60 years of age) in a cross - sectional study carried out in desert areas of western Rajasthan during 2003. Heights and weights were recorded and a family diet survey (one-day, 24-hour recall) was carried out in 200 households (HHs) from 20 villages. Body Mass Index (BMI) was used to classify nutritional status. The prevalence of Chronic Energy Deficiency (CED = BMI < 18.5) was > or = 40% in desert areas of India, indicating a "very high" public health problem. It was higher among older women (52%) compared with men (42.4%) and higher in those belonging to Scheduled Caste and Scheduled Tribes and in HHs of laborers, artisans, landless individuals, marginal farmers, and below poverty line families. CED did not differ (statistically) between the desert and plain areas of Rajasthan. CED prevalence among older adults in desert areas was actually lower (p < 0.001) than that found in their rural and tribal counterparts. Intervention programs initiated by the government may explain this finding. Our findings support the conclusion that regular nutritional monitoring of older adults in desert and drought prone areas is needed and can help appropriately target the need for intervention measures. PMID:19234995

Arlappa, N; Rao, K Mallikarjuna; Venkaiah, K; Brahmam, G N V; Vijayaraghavan, K

2009-01-01

172

Seismic hazard studies in Egypt  

NASA Astrophysics Data System (ADS)

The study of earthquake activity and seismic hazard assessment of Egypt is very important due to the great and rapid spreading of large investments in national projects, especially the nuclear power plant that will be held in the northern part of Egypt. Although Egypt is characterized by low seismicity, it has experienced occurring of damaging earthquake effect through its history. The seismotectonic sitting of Egypt suggests that large earthquakes are possible particularly along the Gulf of Aqaba-Dead Sea transform, the Subduction zone along the Hellenic and Cyprean Arcs, and the Northern Red Sea triple junction point. In addition some inland significant sources at Aswan, Dahshour, and Cairo-Suez District should be considered. The seismic hazard for Egypt is calculated utilizing a probabilistic approach (for a grid of 0.5° × 0.5°) within a logic-tree framework. Alternative seismogenic models and ground motion scaling relationships are selected to account for the epistemic uncertainty. Seismic hazard values on rock were calculated to create contour maps for four ground motion spectral periods and for different return periods. In addition, the uniform hazard spectra for rock sites for different 25 periods, and the probabilistic hazard curves for Cairo, and Alexandria cities are graphed. The peak ground acceleration (PGA) values were found close to the Gulf of Aqaba and it was about 220 gal for 475 year return period. While the lowest (PGA) values were detected in the western part of the western desert and it is less than 25 gal.

Mohamed, Abuo El-Ela A.; El-Hadidy, M.; Deif, A.; Abou Elenean, K.

2012-12-01

173

Heat production rate from radioactive elements in igneous and metamorphic rocks in Eastern Desert, Egypt.  

PubMed

Radioactive heat-production data of Igneous and Metamorphic outcrops in the Eastern Desert are presented. Samples were analysed using a low level gamma-ray spectrometer (HPGe) in the laboratory. A total of 205 rock samples were investigated, covering all major rock types of the area. The heat-production rate of igneous rocks ranges from 0.11 (basalt) to 9.53 microWm(-3) (granite). In metamorphic rocks it varies from 0.28 (serpentinite ) to 0.91 microWm(-3) (metagabbro). The contribution due to U is about 51%, as that from Th is 31% and 18% from K. The corresponding values in igneous rocks are 76%, 19% and 5%, respectively. The calculated values showed good agreement with global values except in some areas containing granites. PMID:16120480

Abbady, Adel G E; El-Arabi, A M; Abbady, A

2006-01-01

174

Diversity of bacteria nesting the plant cover of north Sinai deserts, Egypt  

PubMed Central

North Sinai deserts were surveyed for the predominant plant cover and for the culturable bacteria nesting their roots and shoots. Among 43 plant species reported, 13 are perennial (e.g. Fagonia spp., Pancratium spp.) and 30 annuals (e.g. Bromus spp., Erodium spp.). Eleven species possessed rhizo-sheath, e.g. Cyperus capitatus, Panicum turgidum and Trisetaria koelerioides. Microbiological analyses demonstrated: the great diversity and richness of associated culturable bacteria, in particular nitrogen-fixing bacteria (diazotrophs); the majority of bacterial residents were of true and/or putative diazotrophic nature; the bacterial populations followed an increasing density gradient towards the root surfaces; sizeable populations were able to reside inside the root (endorhizosphere) and shoot (endophyllosphere) tissues. Three hundred bacterial isolates were secured from studied spheres. The majority of nitrogen-fixing bacilli isolates belonged to Bacillus megaterium,Bacillus pumilus, Bacillus polymexa,Bacillus macerans,Bacillus circulans and Bacillus licheniformis. The family Enterobacteriaceae represented by Enterobacter agglomerans,Enterobacter sackazakii, Enterobacter cloacae, Serratia adorifera,Serratia liquefaciens and Klebsiella oxytoca. The non-Enterobacteriaceae population was rich in Pantoae spp., Agrobacterium rdiobacter, Pseudomonas vesicularis, Pseudomonas putida, Stenotrophomonas maltophilia, Ochrobactrum anthropi, Sphingomonas paucimobilis and Chrysemonas luteola.Gluconacetobacter diazotrophicus were reported inside root and shoot tissues of a number of tested plants. The dense bacterial populations reported speak well to the very possible significant role played by the endophytic bacterial populations in the survival, in respect of nutrition and health, of existing plants. Such groups of diazotrophs are good candidates, as bio-preparates, to support the growth of future field crops grown in deserts of north Sinai and irrigated by the water of El-Salam canal.

Hanna, Amira L.; Youssef, Hanan H.; Amer, Wafaa M.; Monib, Mohammed; Fayez, Mohammed; Hegazi, Nabil A.

2012-01-01

175

Late Carboniferous macrofauna from Wadi Araba, Eastern Desert, Egypt, and their paleoecological implications  

NASA Astrophysics Data System (ADS)

The Upper Carboniferous rocks at Wadi Araba are highly rich in macrofaunal content. The systematic description of these macrofauna reveals the identification of 34 species, 17 species of which are recorded for the first time from the Carboniferous rocks of Egypt, among them the trilobite Cummingella ( C.) carringtonensis carringtonensis (Etheridge). Moreover, the paleoeclogic study on some crinoid and brachiopod specimens shows predation and commensal relations with some endo and epibionts fauna. The study presents also crinoidal infestation by Oxytoma ( Palmoxytoma) cygnipes (Young and Bird) species, a relation which is recorded for the first time. Evidences of crushing or biting damages on some brachiopod shells that have been attributed to nautiloids or conchostracan arthropods are also reported. The microfacies study of the carbonate rocks in this area reveals the identification of five microfacies types indicating that the rocks were deposited in an environment ranging from restricted inner to outer shelf lagoonal environments with open circulation. The microfacies study indicates also the presence of two types of microorganisms, the filamentous microorganisms and the fossilized microbial carbonate communities, which played an important role in iron oxide precipitation and rock diagenesis.

El-Shazly, Soheir H.

2011-12-01

176

Construction of a hydrologic model for estimating Wadi runoff and ground water recharge in the Eastern Desert, Egypt.  

SciTech Connect

We constructed a hydrologic model to estimate the groundwater recharge rate for alluvial aquifers of the Eastern Desert from sporadic precipitation over the Red Sea hills. To estimate initial losses over sub-basins, transmission losses through channel routing, and downstream runoff, we developed an integrated model combining spatial rainfall distribution, an appropriate basin unit hydrograph, and appropriate infiltration parameters. Watersheds and stream networks identified from digital terrain elevation data were verified by comparison with co-registered Landsat thematic mapper scenes and geologic maps. Records of a November 1994 storm event acquired from rain gauges along the Nile River and the Red Sea shore were used to generate a spatial precipitation distribution for the study area. A 2 hour design hyetograph was adopted from rain gauge data for the 1994 flood event. The model was tested against records from the November 1994 flood event at the outlets of the Tarfa and Hammamat watersheds. Groundwater recharge rates were estimated for the alluvial aquifers within the major watersheds of the north Eastern Desert. We estimated that during the 1994 flood event, the ground water recharge through transmission losses ranged from 21 to 31% (Tarfa: 15.8 x 10{sup 6} m{sup 3}; Asyuti: 20 x 10{sup 6} m{sup 3}, Qena: 49 x 10{sup 6} m{sup 3}, Hammamat: 59 x10{sup 6} m{sup 3}) of the precipitated volume. The initial losses ranged from 65 to 77%. Only 3-7% of the precipitation reached the watershed outlets. Archival data show that rainfall events of the size of the November 1994 storm or larger occur every 40 months; thus, the annual recharge rates for the Tarfa, Asyuti, Qena, and Hammamat alluvial aquifers are estimated at 4.7 x 10{sup 6} m{sup 3}, 6 x 10{sup 6} m{sup 3}, 14.7 x 10{sup 6} m{sup 3}, and 17.7 x10{sup 6} m{sup 3}, respectively. Implications for the use of these renewable ground waters and similar water resources in other arid areas of Egypt and in neighboring countries are clear.

Gheith, H.; Sultan, M.; Environmental Research

2002-06-10

177

Structural and tectonic evolution of the Umm Gheig/El-Shush region, central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The rocks of the Wadi Umm Gheig/El-Shush area in the central Eastern Desert of Egypt form part of the Nubian Shield, a component of the Neoproterozoic Pan-African Orogeny. The rocks have been divided into three units: (i) low-grade metamorphosed rocks, which consist of metavolcanic rocks interleaved with slices of ophiolitic melange; (ii) high-grade metamorphic rocks, which consist of syn-tectonic granitoids; and (iii) post-tectonic granites, which intrude into both the low- and high-grade rocks. Three distinct tectonic and two magmatic events have been deduced from the structural analysis of the area. These are listed in chronological order: (i) the formation of the major D 1 sinistral strike-slip El-Shush Shear Zone, which occurs within the granitoid rocks (six individual granitoid bodies, all now intensely sheared, are thought to have been intruded into the active El-Shush Shear Zone); (ii) the emplacement of the metavolcanic rocks over the granitoid rocks by major D 2 thrusting along a low angle dip-slip shear zone; (iii) upright open folding of the rocks during D 3; and (iv) the intrusion of late stage granites, which are virtually undeformed. A model for the tectonic evolution of the study area is proposed. It is argued that the major strike-slip shear zone of the region is possibly related to island-arc accretion and that the various granitoid rocks were intruded along this active strike-slip zone. During the collision associated with island-arc accretion, ophiolite sheets were interleaved with the volcanic rocks and together were thrust over the granitoid basement. Field observations show that an important episode of folding occurred after thrusting and that the folds possess an axial planar fracture cleavage. They are, therefore, the result of a sub-horizontal tectonic compression rather than of diapirism as previously suggested. Thus, the domal structures of the Eastern Desert may be the result of folding rather than diapirism.

Ibrahim, S.; Cosgrove, J.

2001-08-01

178

The Neoproterozoic Kolet Um Kharit bimodal metavolcanic rocks, south Eastern Desert, Egypt: a case of enrichment from plume interaction?  

NASA Astrophysics Data System (ADS)

Neoproterozoic metavolcanic rocks of Kolet Um Kharit (KUKh) in the southern Eastern Desert of Egypt have been traditionally regarded as a bimodal island-arc sequence. However, geological and geochemical arguments presented here make this interpretation doubtful. Geochemically, these rocks are classified into mafic (tholeiitic basalts) and felsic (high-K rhyodacites to rhyolites) groups. Both the KUKh mafic and felsic metavolcanic rocks show similar geochemical characteristics, implying a genetic link. They have comparable trace element ratios, such as Zr/Nb (27 30 vs. 20 36), Y/Nb (5.44 6.25 vs. 5.05 5.9), K/Rb (577 1164 vs. 573 937), Ba/La (4.29 25 9 vs. 11.4 16.2), Nb/Yb (1.82 2.03 vs. 1.76 1.99). Similarly both groups have parallel LREE-enriched patterns (La/YbCN=2.37 2.81 vs. 2.55 3.17); and negative Nb and Ta anomalies (Nb/Lapm=0.51 0.58 vs. 0.45 0.52 and Ta/Lapm=0.51 0.62 vs. 0.49 0.55). The observed negative Nb and Ta anomalies in the KUKh metavolcanic rocks cannot be attributed to crustal contamination or fractional crystallization. These rocks could represent either a remnant of break-up LIP or were derived from an enriched mantle source containing subduction components beneath an intraoceanic back-arc basin. The recognition of the KUKh rocks as derived from an enriched mantle source revives interest in models that involve enrichment from “plume” interaction during the evolution of the Arabian-Nubian Shield.

Farahat, E. S.

2006-04-01

179

Remote sensing detection of gold related alteration zones in Um Rus area, Central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Phased Array L-band Synthetic Aperture Radar (PALSAR) images covering the Um Rus area in the Central Eastern Desert of Egypt were evaluated for mapping geologic structure, lithology, and gold-related alteration zones. The study area is covered by Pan-African basement rocks including gabbro and granodiorite intruded into a variable mixture of metavolcanics and metasediments. The first three principal component analyses (PCA1, PCA2, PCA3) in a Red-Green-Blue (RGB) of the visible through shortwave-infrared (VNIR + SWIR) ASTER bands enabled the discrimination between lithological units. The results show that ASTER band ratios ((2 + 4)/3, (5 + 7)/6, (7 + 9)/8) in RGB identifies the lithological units and discriminates the granodiorite very well from the adjacent rock units.The granodiorites are dissected by gold-bearing quartz veins surrounded by alteration zones. The microscopic examination of samples collected from the alteration zones shows sericitic and argillic alteration zones. The Spectral Angle Mapper (SAM) and Spectral Information Divergence (SID) supervised classification methods were applied using the reference spectra of the USGS spectral library. The results show that these classification methods are capable of mapping the alteration zones as indicated by field verification work. The PALSAR image was enhanced for fracture mapping using the second moment co-occurrence filter. Overlying extracted faults and alteration zone classification images show that the N30E and N-S fractures represent potential zones for gold exploration. It is concluded that the proposed methods can be used as a powerful tool for ore deposit exploration.

Amer, Reda; Kusky, Timothy; El Mezayen, Ahmed

2012-01-01

180

Preliminary results of a first record of gold and uranium in marble from Central Eastern Desert, Egypt: a witness for (syn- and post-?) metamorphic mineralization in metasediments  

Microsoft Academic Search

This paper records, for the first time, the mineralization of gold (0.98–2.76 ppm) and uranium (133–640 ppm) in marbles from\\u000a the Arabian-Nubian Shield of the Eastern Desert of Egypt. These auriferous and uraniferous marbles are hosted by sheared and\\u000a altered ophiolitic serpentinized ultramafic rocks of Gebel El-Rukham (ER), Wadi Daghbag (DG), and Wadi Al Barramiyah (BM).\\u000a They occur as massive or banded

M. M. Hamdy; G. A. Aly

2011-01-01

181

Late Neoproterozoic Nuqara Dokhan Volcanics, Central Eastern Desert, Egypt: Geochemistery and petrogenesis  

NASA Astrophysics Data System (ADS)

The Nuqara volcanic is one of the northernmost outcrops of the Arabian-Nubian Shield Dokhan volcanics. The origin and tectonic setting of the late Neoproterozoic Dokhan volcanics (ca. 610-560 Ma) in the Egyptian Eastern Desert is highly debated. The debate concerns the tectonic setting where they formed during transition between convergent to extensional regime or after the East- and the West-Gondwana collision (~600Ma). In order to solve this problem, lavas from Nuqara area were studied geologically and geochemically. Nuqara Dokhan volcanics comprises two main rock suites: (a) an intermediate volcanic suite, consisting of basaltic andesite, andesite and their associated pyroclastics rocks; and (b) a felsic volcanic suite composed of dacite, rhyolite and ignimbrites. The two suites display well-defined major and trace element trends and continuum in composition with wide ranges in SiO2 (52-75.73%), CaO (9.19-0.22%), MgO (5.29-0.05%), Sr (1367-7.4 ppm), Zr (688.5-172.7 ppm), Cr (207-0.4 ppm), and Ni (94.3-0.2 ppm). The Nuqara Dokhan volcanics are characterized by strong enrichment in LILE relative to HFSE and affiliated to the calc-alkaline subducted - related magmatism. Geochemical Modeling displays that the evolution of these rocks was governed by fractional crystallization of plagioclase, amphiboles, pyroxene, magnetite and apatite in the intermediate varieties and plagioclase, amphibole, magnetite, apatite and zircon in the felsic varieties. The obtained mineral chemistry of these volcanics reveals: (a) Plagioclase range in composition from An55 to An40 in basaltic andesite and from An39 to An24 in andesite. (b) Alkali feldspars have sanidine composition. (c) Clinopyroxenes have augite composition. The low Al2O3 contents (1.94-5.588 wt %) indicate that clinopyroxene crystallized at low - pressure conditions. (d) Amphiboles have magnesio- hornblende composition.

Hassan, Tharwat; Asran, Asran; Amron, Taha; Natflos, Theo

2014-05-01

182

GEOL 105, Earth Lab: SAND! A journey from mountains to beaches and western deserts Spring Term 2013 Professor David Harbor  

E-print Network

GEOL 105, Earth Lab: SAND! A journey from mountains to beaches and western deserts Spring Term 2013 harbord@wlu.edu; 540.784.8138 cell Take a journey with sand - follow its path as it erodes from the high with sand grains through the air in western sand dunes and trace its ancient path from the Appalachians west

Harbor, David

183

Stratigraphy, sedimentology and tectonic evolution of the Upper Cretaceous/Paleogene succession in north Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The stratigraphy, sedimentology and syn-depositional tectonic events (SdTEs) of the Upper Cretaceous/Paleogene (K-P) succession at four localities in north Eastern Desert (NED) of Egypt have been studied. These localities are distributed from south-southwest to north-northeast at Gebel Millaha, at North Wadi Qena, at Wadi El Dakhal, and at Saint Paul Monastery. Lithostratigraphically, four rock units have been recorded: Sudr Formation (Campanian-Maastrichtian); Dakhla Formation (Danian-Selandian); Tarawan Formation (Selandian-Thanetian) and Esna Formation (Thanetian-Ypresian). These rock units are not completely represented all over the study area because some of them are absent at certain sites and others have variable thicknesses. Biostratigrapgically, 18 planktonic foraminiferal zones have been recorded. These are in stratigraphic order: Globotruncana ventricosa Zone (Campanian); Gansserina gansseri, Contusotruncana contusa, Recimguembelina fructicosa, Pseudohastigerina hariaensis, Pseudohastigerina palpebra and Plummerita hantkenenoides zones (Maastrichtian); Praemurica incostans, Praemurica uncinata, Morozovella angulata and Praemurica carinata/Igorina albeari zones (Danian); Igorina albeari, Globanomanlina pseudomenradii/Parasubbotina variospira, Acarinina subsphaerica, Acarinina soldadoensis/Globanomanlina pseudomenardii and Morozovella velascoensis zones (Selandian/Thantian); and Acarinina sibaiyaensis, Pseudohastigerina wilcoxensis/Morozovella velascoensis zones (earliest Ypresian). Sedimentologically, four sedimentary facies belts forming southwest gently-dipping slope to basin transect have been detected. They include tidal flats, outer shelf, slumped continental slope and open marine hemipelagic facies. This transect can be subdivided into a stable basin plain plus outer shelf in the extreme southwestern parts; and an unstable slope shelf platform in the northeastern parts. The unstable slope shelf platform is characterized by open marine hemipelagic, fine-grained limestones and fine siliciclastic shales (Sudr, Dakhla, Tarawan and Esna formations). The northeastern parts are marked by little contents of planktonic foraminifera and dolomitized, slumped carbonates, intercalated with basinal facies. Tectonically, four remarkable syn-depositional tectonic events (SdTEs) controlled the evolution of the studied succession. These events took place strongly within the Campanian-Ypresian time interval and were still active till Late Eocene. These events took place at: the Santonian/Campanian (S/C) boundary; the Campanian/Maastrichtian (C/M) boundary; the Cretaceous/Paleogene (K/P) boundary; and the Middle Paleocene-Early Eocene interval. These tectonic events are four pronounced phases in the tectonic history of the Syrian Arc System (SAS), the collision of the Afro-Arabian and Eurasian plates as well as the closure of the Tethys Sea.

El Ayyat, Abdalla M.; Obaidalla, Nageh A.

2013-05-01

184

Stratigraphy, facies architecture, and palaeoenvironment of Neoproterozoic volcanics and volcaniclastic deposits in Fatira area, Central Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

Fatira area in the Central Eastern Desert, Egypt, is a composite terrane consisting of Neoproterozoic volcanics and sediments laid down in submarine to subaerial environment, intruded by voluminous old to young granitic rocks. The various lithofacies of the study area can be grouped in three distinct lithostratigraphic sequences, which are described here in stratigraphic order, from base to top as the Fatira El Beida, Fatira El Zarqa and Gabal Fatira sequences. Each depositional sequence, is intimately related to volcanic activity separated by time intervals of volcanic inactivity, such as marked hiatuses, reworked volcaniclasts, and or turbidite sedimentation. Four submarine facies groups have been recognized within the oldest, folded eruption sequence of Fatira El Beida. The southern part of the study area is occupied by sheet lava (SL), pillow lavas (PL), pillow breccias (PB), and overlying Bouma turbiditic volcaniclastites (VC). The four facies groups of Fatira El Beida sequence occur in a predictable upward-deepening succession, essentially from base to top, an SL-PL-PB-VC stacking pattern. The coeval tholeiitic mafic and felsic volcaniclastic rocks of this sequence indicate an extensional back-arc tectonic setting. The El Beida depositional sequence appears to fit a submarine-fan and slope-apron environment in an intra-arc site. The Fatira El Zarqa sequence involves a large volume of subaerial calc-alkaline intermediate to felsic volcanics and an unconformably overlying siliciclastic succession comprising clast-supported conglomerates (Gm), massive sandstone sheet floods (Sm) and mudstones (FI), together with a lateritic argillite paleosol (P) top formed in an alluvial-fan system. The youngest rock of Gabal Fatira sequence comprises anorogenic trachydacites and rhyolites with locally emergent domes associated with autobrecciation and sill-dyke rock swarms that could be interpreted as feeders and subvolcanic intrusions. Unconformity and lithofacies assemblages define seven events and three unconformity-bounded tectonic stages that record uplift-subsidence cycles in the study area. A proximal-distal relationship has been established within the depositional products, based on the relative dominance of erosional and depositional features.

Khalaf, Ezz El Din Abdel Hakim

185

A comparative analysis of dyke lineaments mapped from Shuttle Imaging Radar and Large Format Camera photography in hyperarid areas of the Eastern Desert, Egypt, and Red Sea Hills, Sudan  

Microsoft Academic Search

The Red Sea Hills (Sudan) and Eastern Desert (Egypt) have been selected, as areas with hyperarid climate, for a comparative study of SIR-B radar imagery and Large Format Camera (LFC) spaceborne photography. Some areas with extensive sand sheets in which dykes and dyke swarms were partially outcropping were studied in detail and a dyke lineament analysis was made using the

B. N. KOOPMANS

1988-01-01

186

A re-evaluation of the origin and setting of the Late Precambrian Hammamat Group based on SHRIMP UPb dating of detrital zircons from Gebel Umm Tawat, North Eastern Desert, Egypt  

Microsoft Academic Search

A sample from near the base of the sedimentary Hammamat Group at Gebel Umm Tawat, North Eastern Desert, Egypt, contains detrital zircons with sensitive high-resolution ion microprobe (SHRIMP) U- Pb ages as young as 585 ? 13 Ma. This age is within error of recent SHRIMP dates from the adjacent Dokhan Volcanic Series and establishes that they contributed material to

SIMON A. W ILDE; K HALID YO USSEF

2002-01-01

187

100 Kyr Old Desert of Western India: Morhodynamics and Environmental Significance  

NASA Astrophysics Data System (ADS)

The Late Quaternary oscillations in sea levels and resultant changes in the coastal environment have remained a popular aspect of study amongst the earthscientists and archaeologists. The Saurashtra peninsula of the western India that lies on the southwestern side of the Thar Desert, has archived a fascinating record of such environmental changes since last interglacial (~120kyr) in the form of a fossil desert exhibiting various aeolian land forms constituted by the sand largely derived from the coastal areas due to an oscillatory sea level change. A variety of dunes viz., coastal transverse, parabolic, longitudinal, barchans, climbing and falling dunes along with valley fills and sand sheets have been mapped. Being biogenic calcium carbonate rich, the sands have been lithified under the influence of an increase in moisture and thus the dune and bed forms are preserved in its best shape. The intense aeolian activities are also evident in the form of desert varnish on rocky outcrops. The sequence comprises smaller climate perturbations in the form of stabilization, erosion and karstification of older dunes and deposition of fluvial sediments in between. The paper deals with the mode of occurrence, response of sediments to wind dynamics and palaeo topography, internal structures, later modifications of sediments and significance of the geochronologically constrained aeolianites in understanding of environmental changes since 100kyr in the region.

Bhatt, N.

2012-04-01

188

A gravity study of the Great Basin-Sonoran Desert transition zone, Basin and Range province, western United States  

E-print Network

/& ~~& A GRAVITY STUDY OF THE GREAT BASIN-SONORAN DESERT TRANSITION ZONE, BASIN AND RANGE PROVINCE, WESTERN UNITED STATES A Thesis by DEBRA ANN BROOKS Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 1989 Major Subject: Geophysics A GRAVITY STUDY OF THE GREAT BASIN-SONORAN DESERT TRANSITION ZONE, BASIN AND RANGE PROVINCE, WESTERN UNITED STATES A Thesis by DEBRA ANN BROOKS Approued as to style...

Brooks, Debra Ann

1989-01-01

189

Pan-African adakitic rocks of the north Arabian-Nubian Shield: petrological and geochemical constraints on the evolution of the Dokhan volcanics in the north Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

The Precambrian basement of Egypt is part of the Red Sea Mountains and represents the north-western part of the Arabian-Nubian Shield (ANS). Five volcanic sections are exposed in the Egyptian basement complex, namely El Kharaza, Monqul, Abu Had, Mellaha and Abu Marwa. They are located in the north Eastern Desert (ED) of Egypt and were selected for petrological and geochemical studies as they represent the Dokhan volcanics. The volcanics divide into two main pulses, and each pulse was frequently accompanied by deposition of immature molasse type sediments, which represent a thick sequence of the Hammamat group in the north ED. Compositionally, the rocks form a continuum from basaltic andesite, andesite, dacite (lower succession) to rhyodacite and rhyolite (upper succession), with no apparent compositional gaps. These high-K calc-alkaline rocks have strong affinities to subduction-related rocks with enriched LILEs (Rb, Ba, K, Th, Ce) relative to high field strength elements (Nb, Zr, P, Ti) and negative Nb anomalies relative to NMORB. The lower succession displays geochemical characteristics of adakitic rocks with SiO2 >53 wt%, Al2O3 >15 wt%, MgO >2.5 wt%, Mg# >49, Sr >650 ppm, Y <17 ppm, Yb <2 ppm, Ni >25 ppm, Cr >50 ppm and Sr/Y >42.4. They also have low Nb, Rb and Zr compared to the coexisting calc-alkaline rhyodacites and rhyolites. The highly fractionated rhyolitic rocks have strong negative Eu anomalies and possess the geochemical characteristics of A-type suites. Trace element geochemical signatures indicate a magma source consistent with post-collisional suites that retain destructive plate signatures associated with subduction zones. The adakitic rocks in the northern ANS are generated through partial melting of delaminated mafic lower crust interacting with overlying mantle-derived magma. The Dokhan volcanics were likely generated by a combination of processes, including partial melting, crystal fractionation and assimilation.

Obeid, Mohamed A.; Azer, Mokhles K.

2014-11-01

190

Application of LANDSAT satellite imagery for iron ore prospecting in the western desert of Egypt  

NASA Technical Reports Server (NTRS)

The author has identified the following significant results. The delineation of the geological units and geological structures through image interpretation, corroborated by field observations and structural analysis, led to the discovery of new iron ore deposits. A new locality for iron ore deposition, namely Gebel Qalamun, was discovered, as well as new occurrences within the already known iron ore region of Bahariya Oasis.

Elshazly, E. M.; Abdel-Hady, M. A.; Elghawaby, M. A.; Khawasik, S. M. (principal investigators)

1977-01-01

191

New age constraints on the Middle Stone Age occupations of Kharga Oasis, Western Desert, Egypt  

E-print Network

reserved. doi:10.1016/j.jhevol.2007.01.004 Journal of Human Evolution 52 (2007) 690e701 #12;methods labeled to enhance our understanding of the Pleistocene human dispersal out of Africa and the nature of the emergence of modern human behavior (McBrearty and Brooks, 2000). While the occupation of arid northern Africa during

Asmerom, Yemane

192

Human Impact On Landscape And The Revenue In Wadi El Rayan Western Desert Egypt  

NASA Astrophysics Data System (ADS)

Wadi El-Rayan depression occupy about 1800 Km2, it lies in 170 km southwest Cairo. Two lakes in El-Rayan depression initiated since 1973 in a big project when people inundate with excess agricultural sewage water. This article aim to estimate the landscape's response and it's revenue to human's intervention. Two new geomorphological maps, before and after the lakes prepared in the field to understand the landscape changes and its characteristics. Water fluctuation in El Rayan Lakes required multitemporal Landsat image. Geomorphological landforms disappeared and others initiated and neo-ecosystem had been generated. Active elongated sand dune fields covered by water and the dune pattern changed from straight-linear pattern to braided pattern and sand sheets delineating that linear dunes lost activity. Hence avoid and avert dune‘s hazards on the agriculture west of Nile Valley. Landforms and geologic heritage demonstrated that there is an old lake under El Rayan depression. The artificial lakes lead to rise the water table which may abut attempts to utilize from the underground water my stored and water from artificial lakes may infiltrate and contaminate this water. The water volume changed in the southern lake from 501,2 km³ at 1984 to 1097,4 km³ at 1999.

Asayed El Gammal, El

2010-05-01

193

Neoproterozoic arc-back-arc system in the Central Eastern Desert of Egypt: Evidence from supra-subduction zone ophiolites  

NASA Astrophysics Data System (ADS)

Ophiolites are widely distributed in the Central Eastern Desert (CED) of Egypt, occurring as clusters in the northern (NCEDO) and southern (SCEDO) segments. Mineralogical and geochemical data on the volcanic sections of Wizer (WZO) and Abu Meriewa (AMO) ophiolites as representatives of the NCEDO and SCEDO, respectively, are presented. The WZO volcanic sequence comprises massive metavolcanics of MORB-like compositions intruded by minor boninitic dykes and thrust over island-arc metavolcanic blocks in the mélange matrix. Such transitional MORB-IAT-boninitic magmatic affinities for the WZO metavolcanics suggest that they most likely formed in a protoarc-forearc setting. Chemical compositions of primary clinopyroxene and Cr-spinel relicts from the WZO volcanic section further confirm this interpretation. The compositional variability in the WZO volcanic sequence is comparable with the associated mantle rocks that vary from slightly depleted harzburgites to highly depleted harzburgites containing small dunite bodies, which are residues after MORB, IAT and boninite melt formation, respectively. Source characteristics of the different lava groups from the WZO indicate generation via partial melting of a MORB source which was progressively depleted by melt extraction and variably enriched by subduction zone fluids. MORB-like magma may have been derived from ~ 20% partial melting of an undepleted lherzolite source, leaving slightly depleted harzburgite as a residuum. The generation of island-arc magma can be accounted for by partial melting (~ 15%) of the latter harzburgitic mantle source, whereas boninites may have been derived from partial melting (~ 20%) of a more refractory mantle source previously depleted by melt extraction of MORB and IAT melts, leaving ultra-refractory dunite bodies as residuum. The AMO volcanic unit occurs as highly deformed pillowed metavolcanic rocks in a mélange matrix. They can be categorized geochemically into LREE-depleted (La/Yb CN = 0.41-0.50) and LREE-enriched (La/Yb CN = 4.7-4.9) lava types that show an island arc to MORB geochemical signature, respectively, signifying a back-arc basin setting. This is consistent, as well, with their mantle section. Source characteristics indicate depleted to slightly enriched mantle sources with overall slight subduction zone geochemical affinities as compared to the WZO. Generally, CED ophiolites show supra-subduction zone geochemical signature with prevalent island arc tholeiitic and minor boninitic affinities in the NCEDO and MORB/island-arc association in the SCEDO. Such differences in geochemical characteristics of the NCEDO and SCEDO, along with the abundance of mature island arc metavolcanics which are close in age (~ 750 Ma) to the ophiolitic rocks, general enrichment in HFSE of ophiolites from north to south, and lack of a crustal break and major shear zones, is best explained by a geotectonic model whereby the CED represents an arc-back-arc system above a southeast-dipping subduction zone.

Farahat, E. S.

2010-12-01

194

Bi-Static Deep Electromagnetic Soundings for Martian Subsurface Characterization: Experimental Validation in the Egyptian Western Desert  

NASA Astrophysics Data System (ADS)

A bi-static version of the HF GPR TAPIR developed for martian deep soundings has been operated in the Egyptian Western Desert. The study presented focuses on the retrieval of the direction of arrival of the observed echoes on both simulated and measured d

Ciarletti, V.; Le Gall, A.; Berthelier, J. J.; Corbel, Ch.; Dolon, F.; Ney, R.; Reineix, A.; Guiffaud, Ch.; Clifford, S.; Heggy, E.

2007-03-01

195

Resilience to disturbance and resistance to alien grass invasions in the cold desert of western North America  

Technology Transfer Automated Retrieval System (TEKTRAN)

Alien grass invasions are resulting in ecosystem-level transformations of entire landscapes in arid and semi-arid ecosystems. The cold desert of western US is undergoing such a transformation, and is considered one of the most imperiled large ecosystems in the US. To address the rapid and complex ch...

196

Nest site characteristics and nesting success of the Western Burrowing Owl in the eastern Mojave Desert  

USGS Publications Warehouse

We evaluated nest site selection at two spatial scales (microsite, territory) and reproductive success of Western Burrowing Owls (Athene cunicularia hypugaea) at three spatial scales (microsite, territory, landscape) in the eastern Mojave Desert. We used binary logistic regression within an information-theoretic approach to assess factors influencing nest site choice and nesting success. Microsite-scale variables favored by owls included burrows excavated by desert tortoise (Gopherus agassizii), burrows with a large mound of excavated soil at the entrance, and a greater number of satellite burrows within 5 m of the nest burrow. At the territory scale, owls preferred patches with greater cover of creosote bush (Larrea tridentata) within 50 m of the nest burrow. An interaction between the presence or absence of a calcic soil horizon layer over the top of the burrow (microsite) and the number of burrows within 50 m (territory) influenced nest site choice. Nesting success was influenced by a greater number of burrows within 5 m of the nest burrow. Total cool season precipitation was a predictor of nesting success at the landscape scale. Conservation strategies can rely on management of habitat for favored and productive nesting sites for this declining species.

Longshore, Kathleen M.; Crowe, Dorothy E.

2013-01-01

197

Upper Oligocene evaporites in basin fill of Sevier Desert region, western Utah ( USA).  

USGS Publications Warehouse

The basin fill beneath the Sevier Desert of western Utah contains evaporites that were deposited in a broad closed basin. All of the basin fill penetrated by the Gulf Oil 1 Gronning contains abundant volcanic detritus and its alteration products of Cenozoic age. Fission-track dating of tuffaceous sandstone yields ages of 26-28 m.y. Fossil pollen from mudstone in the evaporite-bearing strata includes forms no older than late Oligocene, in good agreement with the fission-track ages. Thus the age of evaporites is late Oligocene and younger. Anhydrite is present throughout approximately 900m of volcaniclastic rocks in the lower part of the section cut by the Gulf hole. Fossil pollen are indicative of an arid to semiarid flora.-from Authors

Lindsey, D.A.; Glanzman, R.K.; Naeser, C.W.; Nicholas, D.J.

1981-01-01

198

Pre and post-dispersal seed loss and soil seed dynamics of the dominant Bulnesia retama (Zygophyllaceae) shrub in a sandy Monte desert of western Argentina  

Microsoft Academic Search

In deserts and semi-deserts dominant plants seldom rely on a persistent seed bank to ensure their recruitment from sexual reproduction, which is generally based on the seeds produced in the last reproductive event. We studied pre- and post-dispersal seed loss of Bulnesia retama, a dominant shrub of the sandy Monte deserts (western Argentina). We hypothesised that pre- and post-dispersal seed

Y. Ribas-Fernández; L. Quevedo-Robledo; E. Pucheta

2009-01-01

199

U–Pb ID-TIMS dating of igneous and metaigneous rocks from the El-Sibai area: time constraints on the tectonic evolution of the Central Eastern Desert, Egypt  

Microsoft Academic Search

This paper presents new ID-TIMS U–Pb zircon and titanite ages from the El-Sibai gneiss complex in the Eastern Desert of Egypt.\\u000a The zircon data support previous studies, indicating that the protoliths of the gneissic (oldest) units in the area were emplaced\\u000a during the East African orogeny, and do not represent an older pre-Neoproterozoic, reworked cratonic basement. The crystallization\\u000a ages of

Lars Eivind Augland; AuglandArild Andresen; Gamal Yehia Boghdady

200

Chihuahuan Deserts Ecoregion: Chapter 27 in Status and trends of land change in the Western United States--1973 to 2000  

USGS Publications Warehouse

The Chihuahuan Desert is the largest of the North American deserts, extending from southern New Mexico and Texas deep into Mexico, with approximately 90 percent of its area falling south of the United States–Mexico border (Lowe, 1964, p. 24). The Chihuahuan Deserts Ecoregion covers approximately 174,472 km2 (67,364 mi2) within the United States, including much of west Texas, southern New Mexico, and a small portion of southeastern Arizona (Omernik, 1987; U.S. Environmental Protection Agency, 1997). The ecoregion is generally oriented from northwest to southeast, with the Madrean Archipelago Ecoregion to the west; the Arizona/New Mexico Mountains, Arizona/New Mexico Plateau, Southwestern Tablelands, and Western High Plains Ecoregions to the north; and the Edwards Plateau and Southern Texas Plains Ecoregions to the east (fig. 1).

Ruhlman, Jana; Gass, Leila; Middleton, Barry

2012-01-01

201

[Antoine Barthélémy Clot-Bey, a physician from Marseille founder of Western medicine in Egypt].  

PubMed

Born in Grenoble in 1793 Clot was first a doctor in Marseilles with great success and honour. But for unclear reasons he had to resign, and then decided to be recruited in Egypt, where he was soon called "Clot-Bey" (Bey = officer)": he contributed greatly to modernizing Egyptian medical system: he founded the School of medicine, that of pharmacy, and that of obstetrics, and promoted hygiens and variolisation. After Mehmet Ali abdicated he lost most of his influence, and left Egypt for ever in 1858. PMID:21598579

Ruf, Henri

2011-01-01

202

Water as resource and disturbance for wadi vegetation in a hyperarid area (Wadi Sannur, Eastern Desert, Egypt)  

Microsoft Academic Search

The structure of vegetation in Wadi Sannur (31°28?E, 29°10?N; Egypt) was analysed on a district scale, along 4 km of a wadi course where flooding occurs approximate every 7 years. Two hundred observations by point-quadrat, located on 45 transects, were made. Four types of habitats were sampled: terraces, channels, banks and bars. Each sample included the list of perennial species

Jacques Fossati; Guy Pautou; Jean-Paul Peltier

1999-01-01

203

Construction of a hydrologic model for estimating Wadi runoff and groundwater recharge in the Eastern Desert, Egypt  

Microsoft Academic Search

We constructed a hydrologic model to estimate the groundwater recharge rate for alluvial aquifers of the Eastern Desert from sporadic precipitation over the Red Sea hills. To estimate initial losses over sub-basins, transmission losses through channel routing, and downstream runoff, we developed an integrated model combining spatial rainfall distribution, an appropriate basin unit hydrograph, and appropriate infiltration parameters. Watersheds and

Hazem Gheith; Mohamed Sultan

2002-01-01

204

Upper Oligocene evaporites in basin fill of Sevier Desert region, western Utah  

SciTech Connect

The basin fill beneath the Sevier Desert of western Utah contains evaporites of late Oligocene age that were deposited in a broad closed basin. All of the basin fill penetrated by the Gulf Oil 1 Gronning (2458 m TD), one of only three deep holes in the basin, contains abundant volcanic detritus and its alteration products of Cenozoic age, when volcanism was intense in western Utah. Fission-track dating of tuffaceous sandstone, interbedded with evaporite minerals and representative of sandstone in the lower formations penetrated, yields ages of 26 to 28 m.y.; concordance of ages indicates no thermal resetting. Fossil pollen from mudstone in the evaporite-bearing strata includes forms no older than late Oligocene, in good agreement with the fission-track ages. Thus the age of the evaporites, and of all the basin fill penetrated by drilling, is late Oligocene and younger; previous work had assigned them ages ranging from Triassic to Eocene. Evaporite-bearing rocks were deposited during late Oligocene time in a broad closed basin under arid or semiarid conditions much like those of the Great Basin today. Anhydrite is present throughout approximately 900 m of volcaniclastic rocks in the lower part of the section cut by the Gulf hole, and more than 1500 m of anhydrite and halite is present in possibly equivalent strata in the nearby Argonaut dry hole. Fossil pollen from anhydrite-bearing rocks in the Gulf hole are indicative of an arid to semiarid flora, including plants similar to Mormon tea and possibly saltbush or buffalo berry. Evaporite minerals formed in the basin during dry periods; tuff was erupted from nearby volcanic centers, reworked by water, and deposited in the basin.

Lindsey, D.A. (Geological Survey, Denver, CO); Glanzman, R.K.; Naeser, C.W.; Nichols, D.J.

1981-02-01

205

Geotectonic significance of Neoproterozoic amphibolites from the Central Eastern Desert of Egypt: A possible dismembered sub-ophiolitic metamorphic sole  

Microsoft Academic Search

Supra-subduction zone ophiolites in the Egyptian Central Eastern Desert (CED) occur as clusters in its northern (NCEDO) and southern (SCEDO) parts, displaying abundant island arc–boninitic and MORB\\/island-arc geochemical affinities, respectively. An amphibolite belt, including the investigated massive to slightly foliated Wadi Um Gheig (WUG) amphibolites, is exposed in the southeast most of the NCEDO thrusting over the El Sibai gneissic

E. S. Farahat

2011-01-01

206

Molecular cloning and characterization of thermostable esterase and lipase from Geobacillus thermoleovorans YN isolated from desert soil in Egypt  

Microsoft Academic Search

Genes encoding an esterase (EstA) and lipase (LipA) from Geobacillus thermoleovorans YN, a strain isolated from Egyptian desert soil, were cloned and the respective proteins were expressed in Escherichia coli and characterized. Whereas LipA was cloned directly by PCR amplification from genomic DNA, a genomic library composed of 3000 clones was screened on tributyrin agar plates to find EstA. An

Nadia A. Soliman; Michael Knoll; Yasser R. Abdel-Fattah; Rolf D. Schmid; Stefan Lange

2007-01-01

207

Stable-isotope stratigraphy of the Cenomanian-Turonian (Upper Cretaceous) boundary event (CTBE) in Wadi Qena, Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

A high-resolution ?13C isotope record from Cenomanian-Turonian boundary interval of shallow marine successions in Egypt is presented. The ?13C curves show the typical features of the globally documented Cenomanian-Turonian positive excursion, including three of the main positive isotope peaks defining the Cenomanian-Turonian Boundary Event (CTBE). Based on high-resolution ammonite biostratigraphy, the CTBE started in the study area above the Late Cenomanian Neolobites vibrayeanus Zone within the Galala Formation, directly above the global sequence boundary Cenomanian 5 (SB Ce 5). A stratigraphic gap at that level cuts out the lower a-peak of the CTBE. The Cenomanian-Turonian boundary is located within the upper part of the positive excursion between carbon excursion peaks c and d, coinciding with the boundary between the Late Cenomanian Vascoceras cauvini and the Early Turonian Vascoceratid zones. The CTBE ended up-section of peak d, at the base of the Choffaticeras spp. Zone. The amplitude of the positive ?13C excursion in Egypt is very high (reaching 6.5‰ vs. V-PDB) and largely matches curves of European standard sections and others localities from different basins. Furthermore, the Lower Turonian Holywell Isotope Event, an important marker within the lowermost Turonian, has tentatively been recognized. The positive carbon stable isotope curves presented herein represent the outreach of the oceanic anoxic event (OAE) 2 in shallow-water nearshore sequences.

Nagm, Emad; El-Qot, Gamal; Wilmsen, Markus

2014-12-01

208

Zr-Y-Nb-REE mineralization associated with microgranite and basic dykes at EL Sela shear zone, South Eastern Desert, Egypt.  

PubMed

El Sela shear zone occurs in the younger granite rock of Gabal El Sela area, south Eastern Desert, Egypt near the Sudan Frontier. It comprises lines-arranged intrusions trending ENE-WSW and extend for about 1.5 km in length and reach up to 40 meters in width. These lines-arranged intrusions include multi-phase quartz veins, altered microgranite and altered basic dykes. These dykes hosting or acting as a source for uranium, rare metals (Zr, Y, Nb and Ga) and light rare earths (La, Ce, Sm and Nd) mineralizations. They show highly alteration, uranium enrichment and a strong enrichment in some rare metals and light rare earths contents (Zr?=?644, Y?=?133, Nb?=?136, Ga =184, La?=?50.19, Ce?=?105.47, Sm?=?24.81, Nd?=?78.91 ppm and and ? LREEs?=?259.38.). The chondrite normalised rare earth elements trends indicate strongly fractionated rare earth elements pattern with significant enriched of LREE according to HREE in both altered microgranite and altered basic dykes. Field radiometric measurements of the studied altered microgranite dyke revealed that eU reach up to 359 ppm with an average 78 ppm, while in the altered basic dyke reach up to 1625 ppm with an average 144 ppm. PMID:25332873

Shahin, Hassan Abd El-Razek Aly

2014-01-01

209

Thermodynamic modelling of Sol Hamed serpentinite, South Eastern Desert of Egypt: implication for two serpentinization stages in the Arabian-Nubian Shield ophiolites  

NASA Astrophysics Data System (ADS)

The Arabian-Nubian Shield is the largest tract of juvenile continental crust of Neoproterozoic age on Earth. This crust was generated due to arc-arc collision associated with the closing of the Mozambique Ocean. Distribution of ophiolitic rocks marks fossils suture zones in the shield. Petrological, mineral chemistry, whole-rock chemistry and thermodynamic studies are carried out to examine the serpentinite component of Sol Hamed ophiolite in south Eastern Desert of Egypt. The protolith mantle was harzburgite and formed in subduction zone of forearc setting. Serpentinization occurred in two stages. The first by intrusion of high concentrated CO2 fluid released from carbonate-bearing sediments and altered basalt at the subduction zone. The serpentinization achieved during isobaric cooling path at pressure of 1 kbar and before the emplacement. The minimum temperature limit of the serpentinization is above the breakdown of lizardite to antigorite and brucite (170 °C). The fluid composition during the isobaric cooling path was buffered by the metamorphic reactions. The second stage of serpentinization took place through prograde path which led to formation of chrysotile after lizardite. The increasing in the pressure during this stage occurred as a result of extensive duplex array and thrusting of oceanic crust. The crust in the forearc basin was overloaded by 28 km of obducted and thrusted oceanic crust from both mid-oceanic and forearc basins, respectively.

Abu-Alam, T.; Hamdy, M.

2012-04-01

210

An assessment of the external radiological impact in granites and pegmatite in central Eastern Desert in Egypt with elevated natural radioactivity.  

PubMed

The contents of natural radionuclides ((226)Ra, (232)Th and (40)K) were measured in investigated samples (granite Gabal Ras Barud, Eastern Desert in Egypt) by using gamma spectrometry (NaI (Tl) 3?×3?). The activities of (226)Ra, (232)Th series and (40)K are between (3.8±0.5 and 172.8±1135.1±56.8 8.6), (2.3±0.3 and 103.8±5.2) and (53.1±2.7 and 1135.1±56.8) Bq kg(-1), respectively. With average total annual dose being only 67.2 ?Sv y(-1), this value is about 6.72 % of the 1.0 mSv y(-1) recommended by the International Commission on Radiological Protection (ICRP-60, 1990) as the maximum annual dose to members of the public. Geochemical studies revealed that Gabal Ras Barud is formed from a highly fractionated biotite granite, with SiO(2) >75 % and generally enriched in alkali with K/Na >8 %. PMID:21131664

Uosif, M A M; Abdel-Salam, L M

2011-11-01

211

Finite strain analysis of metavolcanics and metapyroclastics in gold-bearing shear zone of the Dungash area, Central Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Dungash gold mine area is situated in an EW-trending quartz vein along a shear zone in metavolcanic and metasedimentary host rocks in the Eastern Desert of Egypt. These rocks are associated with the major geologic structures, which are attributed to various deformational stages of the Neoproterozoic basement rocks. Field geology, finite strain and microstructural analyses were carried out and the relation-ships between the lithological contacts and major/minor structures have been studied. The R f/? and Fry methods were applied on the metavolcano-sedimentary and metapyroclastic samples from 5 quartz veins samples, 7 metavolcanics samples, 3 metasedimentary samples and 4 metapyroclastic samples in Dungash area. Finite-strain data show that a low to moderate range of deformation of the metavolcano-sedimentary samples and axial ratios in the XZ section range from 1.70 to 4.80 for the R f/? method and from 1.65 to 4.50 for the Fry method. We conclude that finite strain in the deformed rocks is of the same order of magnitude for all units of metavolcano-sedimentary rocks. Furthermore, the contact between principal rock units is sheared in the Dungash area under brittle to semi-ductile deformation conditions. In this case, the accumulated finite strain is associated with the deformation during thrusting to assemble nappe structure. It indicates that the sheared contacts have been formed during the accumulation of finite strain.

Kassem, Osama M. K.; Abd El Rahim, Said H.

2014-11-01

212

Egypt and Red Sea  

NASA Technical Reports Server (NTRS)

A panaramic view of eastern Egypt, The Red Sea and Saudi Arabia beyond (24.0N, 33.0E). In this desert country, where water is life, the high Aswan Dam and the impounded waters of the Nile River in the foreground assure water availability into the next century. The Red Sea beyond, part of the Suez Canal seaway, serves as a commercial link to the world and separates Egypt from Saudi Arabia.

1982-01-01

213

Effects of protective fencing on birds, lizards, and black-tailed hares in the Western Mojave Desert  

USGS Publications Warehouse

Effects of protective fencing on birds, lizards, black-tailed hares (Lepus californicus), perennial plant cover, and structural diversity of perennial plants were evaluated from spring 1994 through winter 1995 at the Desert Tortoise Research Natural Area (DTNA), in the Mojave Desert, California. Abundance and species richness of birds were higher inside than outside the DTNA, and effects were larger during breeding than wintering seasons and during a high than a low rainfall year. Ash-throated flycatchers (Myiarchus cinerascens), cactus wrens (Campylorhynchus brunneicapillus), LeConte's thrashers (Toxostoma lecontei), loggerhead shrikes (Lanius ludovicianus), sage sparrows (Amphispiza belli), and verdins (Auriparus flaviceps) were more abundant inside than outside the DTNA. Nesting activity was also more frequent inside. Total abundance and species richness of lizards and individual abundances of western whiptail lizards (Cnemidophorous tigris) and desert spiny lizards (Sceloporus magister) were higher inside than outside. In contrast, abundance of black-tailed hares was lower inside. Structural diversity of the perennial plant community did not differ due to protection, but cover was 50% higher in protected areas. Black-tailed hares generally prefer areas of low perennial plant cover, which may explain why they were more abundant outside than inside the DTNA. Habitat structure may not affect bird and lizard communities as much as availability of food at this desert site, and the greater abundance and species richness of vertebrates inside than outside the DTNA may correlate with abundances of seeds and invertebrate prey.

Brooks, M.

1999-01-01

214

Geothermal resources of the western arm of the Black Rock Desert, northwestern Nevada. Part I. Geology and geophysics  

SciTech Connect

Studies of the geothermal potential of the western arm of the Black Rock Desert in northwestern Nevada included a compilation of existing geologic data on a detailed map, a temperature survey at 1-meter depth, a thermal-scanner survey, and gravity and seismic surveys to determine basin geometry. The temperature survey showed the effects of heating at shallow depths due to rising geothermal fluids near the known hot spring areas. Lower temperatures were noted in areas of probable near-surface ground-water movement. The thermal-scanner survey verified the known geothermal areas and showed relatively high-temperature areas of standing water and ground-water discharge. The upland areas of the desert were found to be distinctly warmer than the playa area, probably due to the low thermal diffusivity of upland areas caused by low moisture content. Surface geophysical surveys indicated that the maximum thickness of valley-fill deposits in the desert is about 3200 meters. Gravity data further showed that changes in the trend of the desert axis occurred near thermal areas. 53 refs., 8 figs., 3 tabs.

Schaefer, D.H.; Welch, A.H.; Maurer, D.K.

1983-01-01

215

Bistatic GPR Measurements in the Egyptian Western Desert - Measured and Simulated data  

NASA Astrophysics Data System (ADS)

The TAPIR (Terrestrial And Planetary Investigation Radar) instrument has been designed at CETP (Centre d'etude des Environnements Terrestre et Planetaires) to explore the deep Martian subsurface (down to a few kilometers) and to detect liquid water reservoirs. TAPIR is an impulse ground penetrating radar operating at central frequencies ranging from 2 to 4 MHz operating from the surface. In November 2005, an updated version of the instrument working either in monostatic or in bi-static mode was tested in the Egyptian Western Desert. The work presented here focuses on the bi-static measurements performed on the Abou Saied plateau which shows a horizontally layered sub-surface. The electromagnetic signal was transmitted using one of the two orthogonal 70 m loaded electrical dipole antennas of the transmitting GPR. A second GPR, 50 or 100 meters apart, was dedicated to the signal reception. The received waves were characterized by a set of 5 measurements performed on the receiving GPR : the two horizontal components of the electric field and the three composants of the magnetic field. They were used to compute the direction of arrival of the incoming waves and to retrieve more accurately their propagation path and especially to discriminate between waves due to some sub-surface reflecting structure and those due to interaction with the surface clutter. A very efficient synchronization between the two radars enabled us to perform coherent additions up to 2^{31} which improves dramatically the obtained signal to noise ratio. Complementary electromagnetic measurements were conducted on the same site by the LPI (Lunar and Planetary Institute) and the SwRI (Southwest Research Institute). They provided independent information which helped the interpretation of the TAPIR data. Accurate simulations obtained by FDTD taking into account the information available are presented and used for both the interpretation of the measured data and the validation of the instrument.

Ciarletti, V.; Le Gall, A.; Berthelier, J.; Ney, R.; Corbel, C.; Dolon, F.

2006-12-01

216

Effects of Protective Fencing on Birds, Lizards, and Black-Tailed Hares in the Western Mojave Desert.  

PubMed

/ Effects of protective fencing on birds, lizards, black-tailed hares (Lepus californicus), perennial plant cover, and structural diversity of perennial plants were evaluated from spring 1994 through winter 1995 at the Desert Tortoise Research Natural Area (DTNA), in the Mojave Desert, California. Abundance and species richness of birds were higher inside than outside the DTNA, and effects were larger during breeding than wintering seasons and during a high than a low rainfall year. Ash-throated flycatchers (Myiarchus cinerascens), cactus wrens (Campylorhynchus brunneicapillus), LeConte's thrashers (Toxostoma lecontei), loggerhead shrikes (Lanius ludovicianus), sage sparrows (Amphispiza belli), and verdins (Auriparus flaviceps) were more abundant inside than outside the DTNA. Nesting activity was also more frequent inside. Total abundance and species richness of lizards and individual abundances of western whiptail lizards (Cnemidophorous tigris) and desert spiny lizards (Sceloporus magister) were higher inside than outside. In contrast, abundance of black-tailed hares was lower inside. Structural diversity of the perennial plant community did not differ due to protection, but cover was 50% higher in protected areas. Black-tailed hares generally prefer areas of low perennial plant cover, which may explain why they were more abundant outside than inside the DTNA. Habitat structure may not affect bird and lizard communities as much as availability of food at this desert site, and the greater abundance and species richness of vertebrates inside than outside the DTNA may correlate with abundances of seeds and invertebrate prey. KEY WORDS: Birds; Fenced protection; Lepus californicus, Lizards; Mojave Desert; Off-highway vehicles; Protected area management; Sheep grazing PMID:9950700

BROOKS

1999-04-01

217

Mesozoic evolution of northeast African shelf margin, Libya and Egypt  

SciTech Connect

The present tectonic features of the northeast African shelf margin between the Nile delta and the Gulf of Sirte are products of (1) precursory late Paleozoic basement arches, (2) early Mesozoic rifting and plate separation, and (3) Late Cretaceous structural inversion. The 250 km-wide and highly differentiated Mesozoic passive margin in the Western Desert region of Egypt is developed above a broad northwest-trending Late Carboniferous basement arch. In northeastern Libya, in contrast, the passive margin is restricted to just the northernmost Cyrenaica platform, where subsidence was extremely rapid in the Jurassic and Early Cretaceous. The boundary between the Western Desert basin and the Cyrenaica platform is controlled by the western flank of the basement arch. In the middle Cretaceous (100-90 Ma), subsidence accelerated over large areas of the Western desert, further enhancing a pattern of east-west-trending subbasins. This phase of rapid subsidence was abruptly ended about 80 Ma by the onset of structural inversion that uplifted the northern Cyrenaica shelf margin and further differentiated the Western Desert subbasin along a northeasterly trend.

Aadland, R.K.; Schamel, S.

1989-03-01

218

Characterization of the thermally metamorphosed mantle-crust transition zone of the Neoproterozoic ophiolite at Gebel Mudarjaj, south Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

A suite of mantle-crust transition zone (Moho transition zone = MTZ) rocks are exceptionally well exposed in Gebel Mudarjaj area, southeastern desert of Egypt. The MTZ rocks were thermally metamorphosed by younger granitic intrusion, forming mafic-ultramafic hornfels with characteristic metamorphic mineral assemblages. The MTZ rocks are remarkably thin (30-50 m thick) and are composed mainly of dunites, troctolites, gabbroic rocks and pyroxenite masses overlying a basal serpentinized mantle harzburgite section. The Cr# of spinels of the basal serpentinized harzburgites and the MTZ dunites are on average 0.76 and 0.74, respectively, which is consistent with the range for arc peridotite spinels. The melt in equilibrium with these MTZ rocks is compositionally similar to boninitic magmas produced by high degrees of partial melting. The basal harzburgites and MTZ dunites have been produced by 19-23% mantle melting, and are compositionally similar to supra-subduction zone (SSZ) peridotites. The mantle melt in equilibrium with pyroxenites was formed after 16-17% partial melting, which subsequently reacted with the lower crustal gabbroic rocks to produce pyroxenites. The occurrence of pyroxenite masses at the crust-mantle boundary suggests a medium- to high-pressure accumulation of pyroxenes in mid- to lower crustal magma chambers. The original MTZ rocks were partially or fully hydrated, prior to the granitic intrusion, during the regional metamorphism, tectonic disruption and emplacement as various fragments of a dismembered ophiolite, to form antigorite-bearing serpentinized mafic-ultramafic rocks. Progressive metamorphic assemblages then overprinted the primary features due to the contact metamorphism of the MTZ rocks. The resultant metamorphic mineral assemblages are: (1) olivine + anthophyllite + tremolite ± chlorite ± talc (in the basal serpentinites), (2) olivine + enstatite ± chlorite (in the MTZ dunites), and (3) olivine + aluminous spinel (pleonaste) + chlorite + magnetite ± enstatite (in the troctolites). The peak of thermal metamorphism was about 650°-700 °C and < 7 kb, equivalant to the upper amphibolite facies.

Ahmed, Ahmed Hassan; Gharib, Moustafa E.; Arai, Shoji

2012-06-01

219

Origin of wehrlite cumulates in the Moho transition zone of the Neoproterozoic Ras Salatit ophiolite, Central Eastern Desert, Egypt: crustal wehrlites with typical mantle characteristics  

NASA Astrophysics Data System (ADS)

Ultramafic cumulates, mainly crustal true wehrlites, were discovered and described in the mantle-crust transition zone (MTZ) and the extremely lower layered gabbro sequence of the Ras Salatit ophiolite, Central Eastern Desert, Egypt. They form either boudinaged lensoidal tabular bodies or interdigitated layers often concordant with the planolinear fabrics of the Ras Salatit ophiolite rocks. The contact between wehrlites and the host MTZ dunite or layered gabbro is razor sharp, lobate and/or sinuous, without chilled margins or any visible deformations. The Ras Salatit wehrlites are orthopyroxene-free and composed mainly of olivine and clinopyroxene. They are texturally equilibrated and show a characteristic poikilitic texture. Crystallization order of the Ras Salatit wehrlites is olivine/spinel followed by clinopyroxene with the absence of plagioclase. Olivine and clinopyroxene of the Ras Salatit wehrlites are compositionally uniform and conspicuously high in Mg#, mostly around 0.93 and 0.92, respectively. Moreover, the clinopyroxene shows low Ti and Al contents coupled with marked depletion in LILE. The calculated melt in equilibrium with clinopyroxene from the Ras Salatit wehrlites is largely similar to lavas from the Izu-Bonin forearc. Given the above characteristics, the Ras Salatit wehrlites were produced by crystal accumulation from a hydrous depleted basaltic/tholeiitic melt corresponding to temperatures between 1,000 and 1,100°C at the oceanic crustal pressure (~2 kbar). The involved hydrous tholeiitic melt has been probably formed by fluid-assisted partial melting of a refractory mantle source (similar to the underlying harzburgites) in a somewhat shallow sub-arc environment.

Gahlan, Hisham A.; Arai, Shoji; Abu El-Ela, Fawzy F.; Tamura, Akihiro

2012-02-01

220

Variations in eruptive style and depositional processes of Neoproterozoic terrestrial volcano-sedimentary successions in the Hamid area, North Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

Two contrasting Neoproterozoic volcano-sedimentary successions of ca. 600 m thickness were recognized in the Hamid area, Northeastern Desert, Egypt. A lower Hamid succession consists of alluvial sediments, coherent lava flows, pyroclastic fall and flow deposits. An upper Hamid succession includes deposits from pyroclastic density currents, sills, and dykes. Sedimentological studies at different scales in the Hamid area show a very complex interaction of fluvial, eruptive, and gravitational processes in time and space and thus provided meaningful insights into the evolution of the rift sedimentary environments and the identification of different stages of effusive activity, explosive activity, and relative quiescence, determining syn-eruptive and inter-eruptive rock units. The volcano-sedimentary deposits of the study area can be ascribed to 14 facies and 7 facies associations: (1) basin-border alluvial fan, (2) mixed sandy fluvial braid plain, (3) bed-load-dominated ephemeral lake, (4) lava flows and volcaniclastics, (5) pyroclastic fall deposits, (6) phreatomagmatic volcanic deposits, and (7) pyroclastic density current deposits. These systems are in part coeval and in part succeed each other, forming five phases of basin evolution: (i) an opening phase including alluvial fan and valley flooding together with a lacustrine period, (ii) a phase of effusive and explosive volcanism (pulsatory phase), (iii) a phase of predominant explosive and deposition from base surges (collapsing phase), and (iv) a phase of caldera eruption and ignimbrite-forming processes (climactic phase). The facies architectures record a change in volcanic activity from mainly phreatomagmatic eruptions, producing large volumes of lava flows and pyroclastics (pulsatory and collapsing phase), to highly explosive, pumice-rich plinian-type pyroclastic density current deposits (climactic phase). Hamid area is a small-volume volcano, however, its magma compositions, eruption styles, and inter-eruptive breaks suggest, that it closely resembles a volcanic architecture commonly associated with large, composite volcanoes.

Khalaf, Ezz El Din Abdel Hakim

2013-07-01

221

Slip distribution model of two small-sized inland earthquakes and its tectonic implication in north-eastern desert of Egypt  

NASA Astrophysics Data System (ADS)

Two slip distribution models of the 1999 and 2006 Beni-Suef earthquakes ( Mw 4.5 and Mw 4.2, respectively) were revealed using waveform inversion with an empirical Green's function method. Waveform data used were recorded by the Egyptian Seismic Network's short-period stations. To identify the active fault plane associated with each event and to estimate the best fitting rupture velocity, a set of slip distribution models was recovered on both nodal planes of the focal mechanism with a range of fixed rupture velocities. The result for the 1999 event shows that the northwest trending plane consistently provided better fitting solutions than the southwest trending plane. This implies that the slip was left-lateral on a northwest trending plane dipping toward the southwest. The 2006 event caused a slip movement on a dip-slip fault dipping towards the north. The rupture velocities were founded to be 3.5 km/s and 3.0 km/s which gave a comparatively small residual for the 1999 and 2006 earthquakes, respectively. The corresponding slip distribution models for the 1999 and 2006 events provide their seismic moments of 7.6E + 15 N m and 2.5E + 15 N m and moment magnitudes of 4.5 and 4.2, respectively. From the viewpoint of tectonics in the region, the present results imply an extensional tectonic process along the pre-existing WNW-ESE/NW-SE faults that may be transferred from the Gulf of Suez-Red Sea rift towards the northeastern desert in Egypt. This finding implies the diving of the northeastern of African plate beneath the Eurasian plate.

Abdel-Fattah, A. K.; Kim, K. Y.; Fnais, M. S.

2011-11-01

222

Multi-stage emerald formation during Pan-African regional metamorphism: The Zabara, Sikait, Umm Kabo deposits, South Eastern desert of Egypt  

NASA Astrophysics Data System (ADS)

The genesis of gem-quality deep green emeralds of Zabara, Sikait and Umm Kabo (South Eastern Desert, Egypt) is to date a controversial topic. The emerald-bearing biotite schists and quartz lenses are interpreted alternatively as a product of (i) thrust-fault-shear zone - controlled large scale alkali-metasomatism driven by post-magmatic fluid flow or of (ii) a large scale interaction between syntectonic pegmatitic magma or hydrothermal fluids with pre-existing basic to ultrabasic rocks, or of (iii) a syn- to post-tectonic regional metamorphism and small scale blackwall metasomatism. Detailed microstructural and chemical analyses of the Egyptian emeralds and their host rocks show that three generations of beryl can be distinguished: a colourless pegmatitic beryl; a pale green Cr-poor beryl crystallized from pegmatite-related hydrothermal fluids; and a deep green Cr- and Mg-rich emerald. The crystallization of the Cr- and Mg-rich emerald was controlled by the very local availability of Cr, Mg and Be-rich metamorphic fluids during the Pan-African tectono-thermal event. Emerald-rich quartz lenses demonstrate that those fluids locally did mobilize quartz, too. The pale green emeralds found within the pegmatites in association with colourless beryl are the product of a mobilization of colourless pegmatitic beryl and/or phenakite by late pegmatitic fluids slightly enriched in Cr by an interaction with the Cr-rich country rocks. The late pegmatitic fluids are typically Na-rich as is demonstrated by the pervasive albitization of the pegmatites. The complex interplay of magmatic and regional metamorphic events during the genesis of the Egyptian emeralds/beryls makes it impossible through stable oxygen isotope data to relate their genesis to the one or the other event.

Grundmann, G.; Morteani, G.

2008-02-01

223

Processing and interpretation of ASTER TIR data for mapping of rare-metal-enriched albite granitoids in the Central Eastern Desert of Egypt  

NASA Astrophysics Data System (ADS)

ASTER level 1B (radiance at the sensor) TIR-bands and level 2B04 (surface emissivity) data were analyzed to detect four of 14 rare-metal-enriched albite granite, which are classified as I-type magnetite-series (G3 type) granites in the Central Eastern Desert of Egypt. Analysis of the shapes of laboratory emissivity spectrum of albite granite samples measured by portable emission spectrometer and albite mineral spectra from ASTER spectral library at the website of JPL of NASA showed that, albite granite samples has a higher emissivity in bands 12, 13 and 14 than in bands 10 and 11. To identify and map this type of granite, Quartz Index, as well as band ratios, band ratio combination and band combinations were used, based on the shapes of the analyzed emissivity spectrum of albite granite samples and albite mineral. The Quartz Index (QI) was high for quartz-rich/feldspar poor rocks and was low for K-feldspar or gypsum-rich rocks. Albite rich granites were detected as dark pixels in the QI image. The proposed band ratio b12/b11 clearly identified the albite granite bodies as dark regions. False color images of band combination of 14:12:10 and 12:13:11 in R:G:B clearly mapped the albite granite bodies as light brownish yellow and light greenish regions respectively. A new ASTER colored composite band ratio combination b12/b13:b11/b12:b14/b13 as R:G:B is applied successfully for mapping albite granite in the study area. This new combination clearly separated albite granite as pinkish magenta color. An ASTER scene covering the study area acquired on a different date was used to determine the effect of atmospheric and surface temperature conditions on the ratio and the mathematical band operation. The results indicated no significance differences.

Aboelkhair, Hatem; Ninomiya, Yoshiki; Watanabe, Yasushi; Sato, Isao

2010-08-01

224

Bionomics of malaria vectors in two physiographically different areas of the epidemic-prone Thar Desert, north-western Rajasthan (India)  

Microsoft Academic Search

Entomological and parasitological investigations were carried out on malaria vectors and disease prevalence in two sets of villages, the highly irrigated Indira Gandhi Nahar Pariyojana (IGNP) command-area villages (Madassar and Awai), and the truly desertic non-command (unirrigated) area villages (Kanasar and Khetusar), located in different ecological conditions in the Thar Desert, north-western Rajasthan (India). Malaria prevalence, as determined through sustained

B. K Tyagi; S. P Yadav

2001-01-01

225

Holocene freshwater carbonate structures in the hyper-arid Gebel Uweinat region of the Sahara Desert (Southwestern Egypt)  

NASA Astrophysics Data System (ADS)

The eastern part of the Sahara is at present the driest region of the desert. Yet the extensive animal rock art in the area, presumed to depict real activities in the lives of the painters, suggests that environmental conditions were significantly different when the rock art was produced. Here we report on exploration of the area, which led to the discovery of morphologically-distinct carbonate structures that line the walls of two valleys in Gebel Uweinat, and were likely formed in standing water. The carbonate structures comprise what appear to be shoreline carbonate formations, and date back to 8100 and 9400 years BP. The chemical and morphological similarity of these formations to carbonate structures from modern lakes suggests that these lakes contained fresh, standing water suitable for human and animal use. However, the significant quartz content suggests that windblown sand was pervasive, and thus the vegetation cover may have been sparse. This discovery supports the possibility of grasslands in the area, which may have been able to support human habitation, and adds to the evidence for a wetter climate in the area in the early Holocene.

Marinova, Margarita M.; Meckler, A. Nele; McKay, Christopher P.

2014-01-01

226

Occurrence of hexavalent chromium in ground water in the western Mojave Desert, California  

USGS Publications Warehouse

About 200 samples from selected public supply, domestic, and observation wells completed in alluvial aquifers underlying the western Mojave Desert were analyzed for total dissolved Cr and Cr(VI). Because Cr(VI) is difficult to preserve, samples were analyzed by 3 methods. Chromium(VI) was determined in the field using both a direct colorimetric method and EPA method 218.6, and samples were speciated in the field for later analysis in the laboratory using a cation-exchange method developed for the study described in this paper. Comparison of the direct colorimetric method and EPA method 218.6 with the new cation-exchange method yielded r2 values of 0.9991 and 0.9992, respectively. Total dissolved Cr concentrations ranged from less than the 0.1 ??g/l detection limit to 60 ??g/l, and almost all the Cr present was Cr(VI). Near recharge areas along the mountain front pH values were near neutral, dissolved O2 concentrations were near saturation, and Cr(VI) concentrations were less than the 0.1 ??g/l detection limit. Chromium(VI) concentrations and pH values increased downgradient as long as dissolved O 2 was present. However, low Cr(VI) concentrations were associated with low dissolved O2 concentrations near ground-water discharge areas along dry lakes. Chromium(VI) concentrations as high as 60 ??g/l occurred in ground water from the Sheep Creek fan alluvial deposits weathered from mafic rock derived from the San Gabriel Mountains, and Cr(VI) concentrations as high as about 36 ??g/l were present in ground water from alluvial deposits weathered from less mafic granitic, metamorphic, and volcanic rocks. Chromium(III) was the predominant form of Cr only in areas where dissolved O2 concentrations were less than 1 mg/l and was detected at a median concentration of 0.1 ??g/l, owing to its low solubility in water of near-neutral pH. Depending on local hydrogeologic conditions and the distribution of dissolved O2, Cr(VI) concentrations may vary considerably with depth. Samples collected under pumping conditions from different depths within wells show that Cr(VI) concentrations can range from less than the 0.1 ??g/l detection limit to 36 ??g/l in a single well and that dissolved O2 concentrations likely control the concentration and redox speciation of Cr in ground water.

Ball, J.W.; Izbicki, J.A.

2004-01-01

227

Chromium, chromium isotopes and selected trace elements, western Mojave Desert, USA  

USGS Publications Warehouse

Chromium(VI) concentrations in excess of the California Maximum Contaminant Level (MCL) of 50 ??g/L occur naturally in alkaline, oxic ground-water in alluvial aquifers in the western Mojave Desert, southern California. The highest concentrations were measured in aquifers eroded from mafic rock, but Cr(VI) as high as 27 ??g/L was measured in aquifers eroded from granitic rock. Chromium(VI) concentrations did not exceed 5 ??g/L at pH < 7.5 regardless of geology. ??53Cr values in native ground-water ranged from 0.7 to 5.1??? and values were fractionated relative to the average ??53Cr composition of 0??? in the earth's crust. Positive ??53Cr values of 1.2 and 2.3??? were measured in ground-water recharge areas having low Cr concentrations, consistent with the addition of Cr(VI) that was fractionated on mineral surfaces prior to entering solution. ??53Cr values, although variable, did not consistently increase or decrease with increasing Cr concentrations as ground-water flowed down gradient through more oxic portions of the aquifer. However, increasing ??53Cr values were observed as dissolved O2 concentrations decreased, and Cr(VI) was reduced to Cr(III), and subsequently removed from solution. As a result, the highest ??53Cr values were measured in water from deep wells, and wells in discharge areas near dry lakes at the downgradient end of long flow paths through alluvial aquifers. ??53Cr values at an industrial site overlying mafic alluvium having high natural background Cr(VI) concentrations ranged from -0.1 to 3.2???. Near zero ??53Cr values at the site were the result of anthropogenic Cr. However, mixing with native ground-water and fractionation of Cr within the plume increased ??53Cr values at the site. Although ??53Cr was not necessarily diagnostic of anthropogenic Cr, it was possible to identify the extent of anthropogenic Cr at the site on the basis of the ??53Cr values in conjunction with major-ion data, and the ??18O and ??D composition of water from wells.

Izbicki, J.A.; Ball, J.W.; Bullen, T.D.; Sutley, S.J.

2008-01-01

228

Geotectonic significance of Neoproterozoic amphibolites from the Central Eastern Desert of Egypt: A possible dismembered sub-ophiolitic metamorphic sole  

NASA Astrophysics Data System (ADS)

Supra-subduction zone ophiolites in the Egyptian Central Eastern Desert (CED) occur as clusters in its northern (NCEDO) and southern (SCEDO) parts, displaying abundant island arc-boninitic and MORB/island-arc geochemical affinities, respectively. An amphibolite belt, including the investigated massive to slightly foliated Wadi Um Gheig (WUG) amphibolites, is exposed in the southeast most of the NCEDO thrusting over the El Sibai gneissic association and intruded by late- to post-orogenic granitoids and gabbros. The WUG rocks are metamorphosed under epidote amphibolite to common amphibolite facies. The amphiboles are calcic and represented by actinolitic hornblende to magnesio-hornblende in the epidote amphibolites and magnesio- to ferro-hornblende in the amphibolites. Plagioclase composition varies from pure albite (An3-8) in the epidote amphibolites to andesine and labradorite (An36-65) in the amphibolites. The estimated P-T conditions are in favor of their metamorphism under epidote amphibolite (c. 550-600 °C and 2-3 ± 1.5 kbar) and amphibolite (c. 618-720 °C and 3-6 ± 1.5 kbar) facies. The peak metamorphic conditions point to a burial depth of c.15-20 km. Geochemically, the WUG amphibolites show basaltic to andesitic compositions of tholeiitic affinity. They display LILE-enriched MORB-normalized patterns with negative Nb anomalies characteristic of the subduction-related rocks. However, their chondrite-normalized rare-earth element (REE) patterns vary from LREE-depleted (LaN/YbN = 0.29 to 0.49) to LREE-enriched (LaN/YbN = 2.97 to 3.74). Few samples show major and trace element contents typical of boninitic rocks, including U-shaped REE pattern. On the standard tectonic discrimination diagrams the WUG amphibolites plot mostly in the island-arc fields with some samples of MORB and boninitic affinities. Greenschist facies metamorphosed NCEDO obviously share these geochemical characteristics, implying formation in the same tectonic environment, i.e. forearc basin. This argues that the WUG amphibolites likely represent remnants of a dismembered metamorphic sole beneath the NCEDO. Their formation possibly involves intra-forearc basin thrusting followed by emplacement of ophiolite as imbricated stack of dismembered thrust slices in an accretionary wedge setting. This revives interests in geotectonic model in which the CED represents a forearc-arc-back-arc system above a southeast-dipping subduction zone.

Farahat, E. S.

2011-07-01

229

The hydrochemical evolution of brackish groundwater in central and northern Sinai (Egypt) and in the western Negev (Israel)  

NASA Astrophysics Data System (ADS)

SummaryCretaceous trans-boundary aquifers in the central and northern parts of Sinai (Egypt) and the Negev (Israel), are geographically and geologically both contiguous and continuous. Hydrogeological and hydrochemical studies of these aquifers, with disregard to political boundaries, are scarce. The Lower Cretaceous Kurnub Group aquifer in Sinai and the Negev hosts paleowater mostly replenished during the Pleistocene. The objectives of this study are to elucidate the relationship between regional structural elements and the salinization of groundwater in the Kurnub Group in Sinai and further downstream in the Negev. The stable plateaus in southern Sinai and the fold structures in the north continuing into the Negev are separated by the W-E striking Minshara-Ramon shear zone. With the exception of higher salinities in the north, the chemical composition of Kurnub Group groundwater north and south of the shear zone is similar. Similarly, groundwater in the overlying Upper Cretaceous aquifer differs from Kurnub groundwater only within and north of the shear zone and is characterized by higher Cl concentrations, lower Mg/rCa ratios (due to high Ca in the calcareous aquifer) and by a "heavier" isotopic signature. Inverse hydrogeochemical modeling using PHREEQC indicates that the increase in salinity of Kurnub groundwater within the shear zone and in adjacent areas could be due to two different sources: First, the salinization process could be the result of mixing with sulfate-rich brackish groundwater occurring in Jurassic formations, which are in fault-controlled lateral contact with the Kurnub Group aquifer. Second, the salinity differences could be from unflushed seawater in the subsurface of the northern Sinai and western Negev, i.e. possible remnants of the post-Messinian (Lower Pliocene) transgression, which penetrated into northern Sinai, the western Negev and the Coastal Plain of Israel both through erosional channels, which were incised during the Neogene, and by flooding over outcrops of permeable formations.

Rosenthal, E.; Zilberbrand, M.; Livshitz, Y.

2007-04-01

230

Utilization of airborne gamma ray spectrometric data for geological mapping, radioactive mineral exploration and environmental monitoring of southeastern Aswan city, South Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The present work utilizes airborne gamma ray spectrometric data in a trial to refine surface geology of igneous, metamorphic and sedimentary rocks, detect any radioactive mineralization and monitor environment at southeastern Aswan city, South Eastern Desert, Egypt. This area is mainly covered with igneous rocks (younger granites, older granites, metasediments, metavolcanics, metagabbro, Tertiary basalt and ring complex), metamorphic rocks as well as sedimentary rocks (Um Barmil Formation, Timsah Formation, Abu Aggag Formation and wadi sediments). Airborne gamma ray spectrometry can be very helpful in mapping surface geology. This provides estimates of the apparent surface concentrations of the most common naturally occurring radioactive elements, such as potassium (K), equivalent uranium (eU) and equivalent thorium (eTh). This is based on the assumption that, the absolute and relative concentrations of these radioelements vary measurably and significantly with lithology. The composite image technique is used to display simultaneously three parameters of the three radioelement concentrations and their three binary ratios on one image. The technique offers much in terms of lithological discrimination, based on colour differences and showed efficiency in defining areas, where different lithofacies occur within areas mapped as one continuous lithology. The integration between surface geological information and geophysical data led to detailing the surface geology and the contacts between different rock units. Significant locations or favourable areas for uranium exploration are defined, where the measurements exceed (X + 2S), taking X as the arithmetic mean of eU, eU/eTh and eU/K measurements and S as the standard deviation corresponding to each variables. The study area shows the presence of four relatively high uraniferous zones. These zones cannot be ignored and need further ground follow-up. In addition, the trend analysis based on the three radioelement maps and the published geological map shows that, most of the well-developed structural lineaments have NW, NE and ENE trends. Moreover, the average radiation dose rates in the study area, which range from 0.57 to 1.3 mSv yr-1 average, are calculated from the exposure rate for each rock unit. The dose rate levels still remain in the safe side to individuals and less than the maximum permissible from the natural gamma radiation sources, except younger granites and ring complex.

Youssef, Mohamed A. S.; Elkhodary, Shadia T.

2013-12-01

231

Petrogenesis of carbonated meta-ultramafic lenses from the Neoproterozoic Heiani ophiolite, South Eastern Desert, Egypt: A natural analogue to CO2 sequestration  

NASA Astrophysics Data System (ADS)

Among a set of peculiar meta-ultramafics, carbonate-orthopyroxenites are observed for the first time in the Heiani ophiolite belt, South Eastern Desert, Egypt. They form massive lensoidal masses up to 50 m long and 20 m wide. The lenses show a marked structural concordance with their neighboring country rocks. The typical country rocks are represented by the following high-grade metamorphic rocks: kyanite-muscovite schists, amphibolites, kyanite-bearing biotite gneisses, migmatites, granite gneisses and mobilizates. The studied carbonate-orthopyroxenites consist mainly of metamorphic orthopyroxene + magnesite, among other metamorphic, relict primary and retrograde secondary minerals. According to primary chromian spinel (Cr#, 0.7-0.84) chemistry and morphology, absence of clinopyroxene and presence of primary mantle olivine (Fo89-91) as relicts in the metamorphic orthopyroxene, the Heiani carbonate-orthopyroxenites seem to have formed from a highly depleted mantle peridotite precursor. At a late collisional stage during the Pan-Africa terrane accretion and the E-W crustal shortening (ca. 650-620 Ma), high-grade (upper amphibolite facies) low-P/high-T regional metamorphism (ca. 660 Ma) accompanied by CO2-metasomatism resulted in formation of the Heiani carbonate-orthopyroxenites. Mostly the carbonate-bearing shelf sediments beneath and/or in juxtaposition with the Heiani ophiolite are considered to be the proven source of the CO2-rich fluids. Although, a mixed sedimentary-mantle C source is not unlikely. A mineral paragenetic correlation with experimental data for the system MgO-SiO2-H2O-CO2 suggests metamorphic conditions consistent with those of the high-grade country rocks; i.e. 630-650 °C, 6-7 kbar (20-23 km depth) and high-XCO2 (0.6-0.7). The CO2-bearing fluids discharging along faults gave rise to regionally widespread carbonate-bearing assemblages. Accordingly, the Heiani carbonate-orthopyroxenites are considered the by-products of natural carbon sequestration by an ultramafic rock.

Gahlan, Hisham A.; Arai, Shoji; Almadani, Sattam A.

2015-02-01

232

Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers  

Microsoft Academic Search

BACKGROUND: Fairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers

WN Brostoff; JG Holmquist; J Schmidt-Gengenbach; PV Zimba

2010-01-01

233

Preliminary crustal deformation model deduced from GPS and earthquakes’ data at Abu-Dabbab area, Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

A local geodetic network consisting of eleven benchmarks has been established to study the recent crustal deformation in the Abu-Dabbab area. Seven campaigns of GPS measurements have been collected started from October 2008 and ended in March 2012. The collected data were processed using Bernese version 5.0, and the result values were adjusted to get the more accurate positions of the GPS stations. The magnitudes of horizontal displacements are variable from one epoch to another and in the range of 1-3 (±0.2) mm/yr. Due to the differences in rates of the horizontal displacement; the area is divided into two main blocks. The first one, moves to the east direction of about 3 mm/yr, while the second block, moves to the SW direction of about 6 mm/yr. According to the strain fields that were calculated for the different epochs of measurement, the main force is compression force and is taken the NW-SE to NWW-SEE direction. This force could be because of local and regional tectonic processes affecting on the study area. The maximum values of compression stress are found in the southern central and western part of study area. Estimated accumulation of this strain energy may be considered as an indicator of the possibility of earthquake occurrence. From the seismic tomography study, the 3D Vp and Vp/Vs crustal models indicate high Vp/Vs values forms an elongated anomaly, in the central part of the study area, that extends from a depth of 12 km to about 1-2 km of depth is obtained. By using this crustal model in relocations all seismicity informed that most of the seismicity strongly tend to occur in a cluster manner exactly above the southern part of the study area. Based on the conducted source mechanism study, it is noticed that shallow earthquakes are associated by a high CLVD ratio (up to 40%). Furthermore, initiation of a high level seismic activity, without a large seismic main shock is observed in the Abu-Dabbab area. The distribution of micro-earthquakes tends to align in an ENE-WSW direction marking a zone of activity verse the Red Sea. The nucleation of the seismic activity beneath the southern part of the Abu-Dabbab crust is more consistent with the obtained crustal deformation result by increasing the crustal movement in the south part than the northern part. Then, based on the obtained results of the above mentioned studies; seismic tomography; source mechanisms, and crustal deformation we conclude that these seismic activities that are associated by crustal deformation are owing to some magma activity beneath the crust of the Abu-Dabbab area.

Mohamed, Abdel-Monem S.; Hosny, A.; Abou-Aly, N.; Saleh, M.; Rayan, A.

2013-06-01

234

Morphologic-anthropological investigations in tomb K93.12 at Dra' Abu el-Naga (Western Thebes, Egypt).  

PubMed

In this study we present the analysis of the human remains from tomb K93.12 in the Ancient Egyptian necropolis of Dra' Abu el-Naga, located opposite the modern city of Luxor in Upper Egypt on the western bank of the Nile. Archaeological findings indicate that the rock tomb was originally built in the early 18th dynasty. Remains of two tomb-temples of the 20th dynasty and the looted burial of the High Priest of Amun Amenhotep have been identified. After the New Kingdom the tomb was reused as a burial place until the 26th dynasty. The skeletal and mummified material of the different tomb areas underwent a detailed anthropological and paleopathological analysis. The human remains were mostly damaged and scattered due to extensive grave robberies. In total, 79 individuals could be partly reconstructed and investigated. The age and sex distribution revealed a male predominance and a high percentage of young children (< 6 years) and adults in the range of 20 to 40 years. The paleopathological analysis showed a high prevalence of stress markers such as cribra orbitalia in the younger individuals, and other pathological conditions such as dental diseases, degenerative diseases and a possible case of ankylosing spondylitis. Additionally, 13 mummies of an intrusive waste pit could be attributed to three different groups belonging to earlier time periods based on their style of mummification and materials used. The study revealed important information on the age and sex distribution and diseases of the individuals buried in tomb K93.12. PMID:24818442

Lösch, Sandra; Moghaddam, Negahnaz; Paladin, Alice; Rummel, Ute; Hower-Tilmann, Estelle; Zink, Albert

2014-01-01

235

Aerosol transport over the western Mediterranean basin: Evidence of the contribution of fine particles to desert dust plumes over Alborán Island  

NASA Astrophysics Data System (ADS)

months (June 2011 to January 2012) of aerosol property data were obtained at the remote site of Alborán Island (35.95°N, 3.03°W) in the western Mediterranean basin. The aim of this work is to assess the aerosol properties according to air mass origin and transport over this remote station with a special focus on air mass transport from North Africa. For air masses coming from North Africa, different aerosol properties showed strong contributions from mineral dust lifted from desert areas. Nevertheless, during these desert dust intrusions, some atmospheric aerosol properties are clearly different from pure mineral dust particles. Thus, Angström exponent ?(440-870) presents larger values than those reported for pure desert dust measured close to dust source regions. These results combine with ?(440, 670) - ?(670, 870) ? 0.1 and low single scattering albedo (?(?)) values, especially at the largest wavelengths. Most of the desert dust intrusions over Alborán can be described as a mixture of dust and anthropogenic particles. The analyses support that our results apply to North Africa desert dust air masses transported from different source areas. Therefore, our results indicate a significant contribution of fine absorbing particles during desert dust intrusions over Alborán arriving from different source regions. The aerosol optical depth data retrieved from Sun photometer measurements have been used to check Moderate Resolution Imaging Spectroradiometer retrievals, and they show reasonable agreement, especially for North African air masses.

Valenzuela, A.; Olmo, F. J.; Lyamani, H.; Granados-Muñoz, M. J.; Antón, M.; Guerrero-Rascado, J. L.; Quirantes, A.; Toledano, C.; Perez-Ramírez, D.; Alados-Arboledas, L.

2014-12-01

236

Multiprocess evolution of landforms in the Kharga Region, Egypt: Applications to Mars  

NASA Technical Reports Server (NTRS)

In order to understand better the polygenetic evolution of landforms on the martian surface, field studies were conducted in and around the Kharga Depression, Egypt. The Kharga region, on the eastern edge of Egypt's Western Desert, was subject to erosion under mostly hyperarid climatic conditions, punctuated by brief pluvial episodes of lesser aridity, since early Pleistocene time. The region contains numerous landforms analogous to features on the martian surface: yardangs carved in layered surficial deposits and in bedrock, invasive dune trains, wind-modified channels and interfluves, and depressions bounded by steep scarps. Like many of the topographic depresions on Mars, the Kharga Depression was invaded by crescentic dunes. In Egypt, stratigraphic relations between dunes, yardangs, mass-wasting debris, and wind-eroded flash-flood deposits record shifts in the relative effectiveness of wind, water, and mass-wasting processes as a function of climate change.

Breed, C. S.; Mccauley, J. F.; Grolier, M. J.

1984-01-01

237

Microseismic monitoring of the hydraulic-fracture growth and geometry in the Upper Bahariya member, Khalda concession, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

Three-component, downhole geophones are installed in production wells at the Khalda and Kahraman sites to monitor hydraulic fracturing treatment in a nearby well. Locatable microseismic events were distributed in space around the treatment well using the hypocenter-velocity inversion method. The E-W oriented microseismic pattern aligns with the proposed specifications of fracture model design at both the Khalda and Kahraman sites. Due to the small magnitude and long separation distance between the treatment well and the recording string, microseismicity was dominantly observed during the main fracturing operation at both the Khalda and Kahraman sites, with calculated magnitudes less than -0.3?Mw. In addition, the calculated confidence for locatable events was generally average or low. The seismic zone through the mainfrac treatment was estimated to spread over 58?m height and 320?m length at the Khalda site, while the zone of the Kahraman site was enclosed within 25?m height and 250?m length. The stimulated reservoir volume (SRV) at the Khalda site was estimated to be 433?200?m3, with asymmetrical wings around the stimulation well, but at the Kahraman site the stimulation imaging was marginally successful and the stimulated SRV was only 247?000?m3. In general, the two microseismic experiments at Khalda and Kahraman were relatively successful in locating the microseismic events and calculating the SRV within the producing horizon, elucidating the importance of the microseismic technique in monitoring reservoir stimulation.

Abdulaziz, Abdulaziz M.

2014-08-01

238

Subduction-related cryptic metasomatism in fore-arc to nascent fore-arc Neoproterozoic mantle peridotites beneath the Eastern Desert of Egypt: mineral chemical and geochemical evidences  

NASA Astrophysics Data System (ADS)

Mantle spinel peridotites beneath the Arabian Nubian Shield (ANS) in the Eastern Desert (ED) of Egypt were formed in arc stage in different tectonic setting. Thus they might subject to exchange with the crustal material derived from recycling subducting oceanic lithosphere. This caused metasomatism enriching the rocks in incompatible elements and forming non-residual minerals. Herein, we present mineral chemical and geochemical data of four ophiolitic mantle slice serpentinized peridotites (W. Mubarak, G. El-Maiyit, W. Um El Saneyat and W. Atalla) widely distributed in the ED. These rocks are highly serpentinized, except some samples from W. Mubarak and Um El-Saneyat, which contain primary olivine (Fo# = 90-92 mol %) and orthopyroxene (En# = 86-92 mol %) relics. They have harzburgite composition. Based on the Cr# and Mg# of the unaltered spinel cores, all rocks formed in oceanic mantle wedge in the fore-arc setting, except those from W. Atalla formed in nascent fore-arc. This implies that the polarity of the subduction during the arc stage was from the west to the east. These rocks are restites formed after partial melting between 16.58 in W. Atalla to 24 % in G-El Maiyit. Melt extraction occurred under oxidizing conditions in peridotites from W. Mubarak and W. Atalla and under reducing conditions in peridotites from G. El-Maiyit and Um El-Saneyat. Cryptic metasomatism in the studied mantle slice peridotites is evident. This includes enrichment in incompatible elements in minerals and whole rocks if compared with the primitive mantle (PM) composition and the trend of the depletion in melt. In opx the Mg# doesn't correlate with TiO2, CaO, MnO, NiO and Cr2O3concentrations. In addition, in serpentinites from W. Mubarak and W. Atalla, the TiO2spinel is positively correlated with the TiO2 whole-rock, proposing enrichment by the infiltration of Ti-rich melts, while in G. El- Maiyit and Um El-Saneyat serpentinites they are negatively correlated pointing to the reaction with the Ti-rich melts. All rocks are enriched LREE, FMEs and HFSEs. This took place mostly by different agents. As the H2O-rich liquid, which seems to have been produced from the subducting oceanic slab percolating peridotites, gradually loses trace elements, the HFSEs are fractionated from LILEs and REEs. This could explain the high ratios of (Nb/La)N and (Nb/Ba)N of some of the studied rocks. All the studied serpentinized mantle slices have subchonddritic to near chondritic ratios of Nb/Ta (< 13.8) and Zr/ Hf (< 36.09). It is suggested that Nb did not fractionate from Ta and Zr from Hf. There are might be silicate melts enriched the peridotites in Ta rather than Nb causing a much great decrease in the Nb/Ta especially serpentinites from W. Mubarak. This melt/fluid might have been derived from recycled subducted oceanic crust or from hot asthenosphere. Concentrations of U in all the studied samples (except for W. Mubarak serpentinites) are positively correlated with LILEs, Pb and Mo, indicating that the studied serpentinites were enriched in these elements from the same fluids, most probably derived from subducted oceanic lithosphere. Positive anomalies of Li (in W. Mubarak and G. El-Maiyit serpentinites), U (except for W. Mubarak serpentinites), Mo and Pb are characteristics of hydrothermally altered ocean-floor peridotites. High Sr/Nd ratios may be typical of the hydrous metasomatism caused by hydrous melt/fluid.

Hamdy, Mohamed; Salam Abu El-Ela, Abdel; Hassan, Adel; Kill, Youngwoo; Gamal El Dien, Hamed

2013-04-01

239

Westward prograding metamorphism in mantle peridotites from the Eastern Desert of Egypt: clues to the subduction polarity of the Arabian Nubian Shield intra-oceanic arc ophiolite  

NASA Astrophysics Data System (ADS)

Neoproterozoic arc mantle beneath the Arabian Nubian Shield (ANS) in the Eastern Desert (ED) of Egypt exhumed due to intra-oceanic upthrusting are represented mainly by exposed ophiolitic peridotites serpentinized to different degree. Metamorphism is related to the Pan-African collision and the subduction of oceanic lithosphere. However, polarity of the Pan-African intra-oceanic subduction is still questionable. We here trace the variation of the degree of serpentinization and regional metamorphism of six serpentinite masses, widely distributed in the ED (from the east to the west: W (Wadi). Alam, W. Igla, W. Mubarak, G. El-Maiyit, W. Um El Saneyat and W. Atalla). This is based on their mineralogy, textures and mineral chemistry. The studied rocks have harzburgite composition and they all formed in oceanic mantle wedge in the fore-arc setting, except those from W. Atalla that formed in MOR-arc transition setting. Much difference in the degree of serpentinization is obvious among these rocks. They are mainly partly serpentinized containing primary olivine and orthopyroxene at W. Alam and W. Igla, while they are completely serpentinized in the other localities. With the increased degree of metamorphism, textures were transformed from the pseudomorphic to the non-pseudomorphic. The most common retrograde assemblage is composed of lizardite ± chrysotile± brucite± magnetite. The serpentine prograde textures can be viewed as a continuum from retrograde lizardite pseudomorphic textures, to very fine-grained transitional texture of lizardite and chrysotile, to chrysotile-antigorite interlocking texture and finally to antigorite interpenetrating texture. These textures appear to represent successive stages in a recrystallization event. In late subduction-related metamorphism and early collisional emplacement stage, mylonitic-antigorite serpentinites formed and antigorite became the major phase in G. El-Maiyit, Um El-Saneyat and W. Atalla. The polygonal units of the hourglass texture and the penetrative fabric of the serrate veins in all serpentinized peridotites indicate that fracturing of these rocks was developed in a dynamic regime. The late emplacement of veins of brucite, carbonates and oxides were most probably formed during the final stage of exhumation and under a stress regime in the brittle-ductile transition. As the grade of metamorphism increases Fe released from olivine and orthopyroxene and Cr released from chromite are accommodating in antigorite-rich serpentinites. Serpentine in veins also tends to have less substitutions, which is consistent with the fact that Al, Cr and Ni are relatively immobile during alteration and therefore remain in their original microstructural site. Compositional zoning in spinel grains in all serpentinites reflect variation in the degree of alteration. The biggest variation of spinel compositions are among serpentinites from Um El-Saneyat and W. Atalla. With increasing the degree of alteration, size of the aluminian chromite core decreases while width of the intermediate Fe3+-rich aluminian chromite to ferrian-chromite zone and the outer Cr-magnetite to magnetite zones increase. The alteration zones were formed in a temperature < 400 ° C to 550 ° C corresponding to the low green-schist to the lower amphibolite facies. We propose that this is concordant with a westward polarity of the subducting oceanic lithosphere, associating the intra-oceanic arc ophiolite during the closure of the Mozambique ocean.

Salam Abu El-Ela, Abdel; Hamdy, Mohamed; Abu-Alam, Tamer; Hassan, Adel; Gamal El Dien, Hamed

2013-04-01

240

Multi-element association analysis of stream sediment geochemistry data for predicting gold deposits in Barramiya gold mine, Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The use of traditional statistical methods can provide suitable indicators of geochemical element dispersion, and aids in targeting potential areas for mineral exploration. Analyzes of stream sediments from an ophiolite suite of ophiolitic mélange matrix and metasediments belt are used for regional geochemical prospecting of gold in the Barramiya mining district, Eastern Desert, Egypt. The principal rocks exposed in the study area are Late-Proterozoic volcano-sedimentary sequences intruded by serpentinite, small bodies of Older and Younger Granitoids, all injected by dykes of various compositions. Gold production derived mainly from shear zone with Au-bearing quartz veins hosted by ultramafic schists and serpentinites at fault intersections or along the basal décollement of the major thrusts, especially where granitoid massifs and stocks are common. Orebodies are mainly sulfide-bearing quartz and quartz-carbonate lodes associated with graphite-schist, listvenite and marble exposures, showing signs of structural control expressed in preferable orientation and consistent meso- and microfabrics. The area has two known gold deposits where several chromite mines are present. Auriferous veins are confined along E and ENE fracture systems and zones in a passive tectonic contact between the serpentinites and the metasediments. Results of 425 stream sediment samples from an area of ˜73 km2 analyzed for 13 trace elements are presented using simple statistical and R-mode factor methods. The overall sample density achieved by the survey is ˜6 samples/km2. Significant variations in background metal contents are recorded near the known mineralized sites. Preliminary visual interpretation of individual spatial distribution patterns of Ag, As, Au, Cu, Mo, Pb, and W show clear-cut relationships with known gold mineralization in the study area. Geochemical patterns of these elements delineate drainage basins with anomalous concentration of elements genetically related to gold mineralization. Gold in analyzed samples ranges from <0.02 to 3.51 ppm with average 0.21 ppm. Most of the high element concentrations in stream sediments are found in the graphite-schist and serpentinized marble rocks. Application of R-mode factor analysis indicates significant components of the sample composition. These reflect lithological, environmental and mineralization controls. Preparation of factor score map for the association Ag-Au-As-Cu-Zn-Pb-Mo-W enables a more precise delineation of zones of known gold mineralization as well as areas that may contain (on geological grounds) primary gold mineralization. The exploration significance of some anomalies has not been established, but a number of these anomalies may be related to undiscovered mineralization while others may be of no economic significance. Groundwater pH influences the hydromorphic dispersion patterns of Ag, As, and Au in different ways and this requires consideration during data interpretation.

Harraz, Hassan Z.; Hamdy, Mohamed M.; El-Mamoney, Mohamed H.

2012-06-01

241

Zonation of primary haloes of Atud auriferous quartz vein deposit, Central Eastern Desert of Egypt: A potential exploration model targeting for hidden mesothermal gold deposits  

NASA Astrophysics Data System (ADS)

The Atud gold mine located in the Neoproterozoic diorite and metagabbro of the Central Eastern Desert of Egypt has been initially excavated during Pharaonic times. Between 1953 and 1969, the Egyptian Geological Survey and Mining Authority performed underground prospection in the auriferous quartz vein and metasomatic alteration zones in the main Atud area, estimating a principal gold lode of 19,000 tones (16.28 g/ton), and 1600 tons of damp (1.24 g/ton). Yet the potentiality of the deposit has not been exhausted. However, for exploration of hidden ore, quantitative characterization using trace elements zoning of mineralization haloes with 280 samples from surface and three underground mining levels is applied. This was through multivariate statistical analysis (Factor analysis) of 11 selected trace elements. Axial (vertical) extents of primary haloes above and beneath gently dipping orebody are also visualized to interpret the level of erosion, determine the direction of mineralizing solutions as well as to examine whether the hidden orebody is promising at the Atud mine. Axial zones of primary dispersion aureoles of trace elements are: Ag, As, S and U around the auriferous quartz veins; Cu, and Pb in the surface horizons; and Zn, Ni, Co, and U along the lower margin of mineralization zone. Gold contents in bedrock and quartz vein samples from level-42M are the highest (5.7 and 40.3 ppm, respectively). In the transverse (lateral) direction, the maximum relative accumulation of Au and Zn occurs at the Northern Shaft; Pb, Cu, As, and U at the Main Shaft; and Ag, S, Co, and Ni at the Southern Shaft. The estimated axial zonation sequence of indicator elements using the variability index is Pb ? Cu ? Ag ? Au ? As ? S ? Ni ? Co ? U ? Zn. According to this zonation, an index such as (Pb × Cu)D/(U × Zn)D can be a significant for predicting the Au potentiality at a particular depth. In addition, the Pb/U zonality index is an appropriate indicator for the degree of erosion at the Atud gold mine. The degree of surficial zonality of the mineralization as deduced from geochemical maps and the level of erosion of the geochemical anomalies as well as the decreasing of gold content with depth recorded throughout the different underground mine workings make it necessary for the prospection model to evaluate the drainage patterns dissecting the mineralized zone. The application of R-mode factor analysis estimated seven statistical factors, and factor score maps are portrayed. Factors 1 (Ag, Au, As, Co, S, U and Zn) and 2 (Zn, U, Co and S) significantly reflect the Au-mineralization (ore-controlled), and their score maps enable a more precise delineation of auriferous quartz veins and the area which may contain primary gold mineralization. The other factors reveal the distribution of Cu- and Pb-bearing minerals (supergene alteration factors), and Ba and Ni in the host diorite (lithologically-controlled). These are consistent with the calculated maximum relative accumulation of trace elements, proposing a potential model of exploration based on integrating underground geochemical data from old gold mine workings with spatial information from R-mode factor score maps.

Harraz, Hassan Z.; Hamdy, Mohamed M.

2015-01-01

242

Structural controls, temperature-pressure conditions and fluid evolution of orogenic gold mineralisation at the Betam mine, south Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Betam gold deposit, located in the southern Eastern Desert of Egypt, is related to a series of milky quartz veins along a NNW-trending shear zone, cutting through pelitic metasedimentary rocks and small masses of pink granite. This shear zone, along with a system of discrete shear and fault zones, was developed late in the deformation history of the area. Although slightly sheared and boudinaged within the shear zone, the auriferous quartz veins are characterised by irregular walls with a steeply plunging ridge-in-groove lineation. Shear geometry of rootless intra-folial folds and asymmetrical strain shadows around the quartz lenses suggests that vein emplacement took place under a brittle-ductile shear regime, clearly post-dating the amphibolite-facies regional metamorphism. Hydrothermal alteration is pervasive in the wallrock metapelites and granite including sericitisation, silicification, sulphidisation and minor carbonatisation. Ore mineralogy includes pyrite, arsenopyrite and subordinate galena, chalcopyrite, pyrrhotite and gold. Gold occurs in the quartz veins and adjacent wallrocks as inclusions in pyrite and arsenopyrite, blebs and globules associated with galena, fracture fillings in deformed arsenopyrite or as thin, wire-like rims within or around rhythmic goethite. Presence of refractory gold in arsenopyrite and pyrite is inferred from microprobe analyses. Clustered and intra-granular trail-bound aqueous-carbonic (LCO2 + Laq ± VCO2) inclusions are common in cores of the less deformed quartz crystals, whereas carbonic (LCO2 ± VCO2) and aqueous H2O-NaCl (L + V) inclusions occur along inter-granular and trans-granular trails. Clathrate melting temperatures indicate low salinities of the fluid (3-8 wt.% NaCl eq.). Homogenisation temperatures of the aqueous-carbonic inclusions range between 297 and 323°C, slightly higher than those of the intra-granular and inter-granular aqueous inclusions (263-304°C), which are likely formed during grain boundary migration. Homogenisation temperatures of the trans-granular H2O-NaCl inclusions are much lower (130-221°C), implying different fluids late in the shear zone formation. Fluid densities calculated from aqueous-carbonic inclusions along a single trail are between 0.88 and 0.98 g/cm3, and the resulting isochores suggest trapping pressures of 2-2.6 kbar. Based on the arsenopyrite-pyrite-pyrrhotite cotectic, arsenopyrite (30.4-30.7 wt.% As) associated with gold inclusions indicates a temperature range of 325-344°C. This ore paragenesis constrains f S2 to the range of 10-10 to 10-8.5 bar. Under such conditions, gold was likely transported mainly as bisulphide complexes by low salinity aqueous-carbonic fluids and precipitated because of variations in pH and f O2 through pressure fluctuation and CO2 effervescence as the ore fluids infiltrated the shear zone, along with precipitation of carbonate and sericite. Wallrock sulphidation also likely contributed to destabilising the gold-bisulphide complexes and precipitating gold in the hydrothermal alteration zone adjacent to the mineralised quartz veins.

Zoheir, Basem A.

2008-01-01

243

Evidence for population fragmentation within a subterranean aquatic habitat in the Western Australian desert  

Microsoft Academic Search

The evolution of subterranean animals following multiple colonisation events from the surface has been well documented, but few studies have investigated the potential for species diversification within cavernicolous habitats. Isolated calcrete (carbonate) aquifers in central Western Australia have been shown to contain diverse assemblages of aquatic subterranean invertebrate species (stygofauna) and to offer a unique model system for exploring the

M T Guzik; S J B Cooper; W F Humphreys; S Ong; T Kawakami; A D Austin

2011-01-01

244

Geomicrobiological Changes in Two Ephemeral Desert Playa Lakes in the Western United States  

Microsoft Academic Search

The geochemistry and microbiology of two ephemeral playa lakes in the Western United States, Surprise Valley Alkali Lake (SVAL) and Eldorado Playa (EP), were examined over one wetting cycle, revealing dramatic temporal changes in suspended mineralogy, aqueous chemistry, and bacterial populations. In SVAL the predominant suspended mineral changed from smectite to vermiculite and clinoptilolite, which led to a depletion of

Kyle C. Costa; Joy Hallmark; Jason B. Navarro; Brian P. Hedlund; Duane P. Moser; Stephanie Labahn; Debbie Soukup

2008-01-01

245

Isolation and characterization of osmotolerant bacteria from thar desert of western Rajasthan (India).  

PubMed

The Thar Desert harsher environment harbors a limited diversity of life forms due to extreme conditions like low moisture of sandy soils and high soil temperature. In the present study, osmotolerant bacteria from the Thar soils were isolated and characterized. Bacteria were isolated from 20 soil samples (100 g), collected from sand dunes, suspended in water and absolute alcohol. A total of 11 biochemical and morphological tests were carried out for generic identification of bacteria. Osmotic tolerance capacity of isolates was examined on glycerol, NaCI and alcohol; and sequencing of 16S rRNA gene was also performed for bacterial identification. 16S to 23S rRNA internal transcribed spacer analysis (RISA) was done for phylogenetic analysis of isolates. The soil suspended in water contained 2.5 x 10(6) bacteria/g of soil while alcohol suspended soil had 4.4 x 10(4) bacteria/g. The 24 bacterial isolates were found tolerant to 26% glycerol, 14% NaCI and 10% of alcohol, and 22 out of 24 isolates were found Gram positive. The results showed that 45.83% and 41.67% bacteria belong to Bacillus spp. and Corynebacterium spp., respectively, while Acinetobacter spp., Aeromonas spp. and Staphylococcus spp. were in equal proportion (4.16% each). Six isolates were selected for 16S rRNA gene sequencing and five were found 95% similar with Bacillus licheniformis whereas one isolate was identified as B. subtilis. All the isolates showed good growth up to 50 degrees C with gradual reduction on subsequent increment of temperature. Out of 24 isolates, six could survive at 65 degrees C while one isolate could grow at 63 degrees C. Growth kinetic studies revealed that the reduction in generation time in solute(s) and temperature stress was more as compared to generation time in plain medium. This study suggests that virgin sand dunes may be a rich source of bacteria, tolerant to osmotrophic solutes, and can be examined for plant growth promotion activity in agriculture. Moreover, study might help to resolve the tactic adopted by microbes to defeat desiccation induced by various types of solutes. PMID:24432519

Sharma, Ramavtar; Manda, Rajni; Gupta, Shikha; Kumar, Sushil; Kumar, Vinod

2013-12-01

246

The meaning of desert color in earth orbital photographs  

NASA Technical Reports Server (NTRS)

The color of desert surfaces as seen in earth orbital photographs is indicative of soil composition. Apollo-Soyuz photographs of the Sturt and Simpson Deserts of Australia confirm that sand grains become redder as the distance from the source increases. Reddening is caused by a thin iron-oxide coating on individual sand grains and can be used, in some cases, to map relative-age zones. Photographs of the Western (Libyan) Desert of Egypt indicate three distinct and nearly parallel color zones that have been correlated in the field with: (1) arable soil composed of quartz, clay, and calcium carbonate particles; (2) relatively active sand with or without sparse vegetation; and (3) relatively inactive sand mixed with dark (desert-varnished) pebbles. The youngest sands are in the form of longitudinal dunes, which are migrating to the south-southeast along the prevailing wind direction. Some of the young dune fields are encroaching on the western boundary of the fertile Nile Valley.

El-Baz, F.

1978-01-01

247

Effects of Protective Fencing on Birds, Lizards, and Black-Tailed Hares in the Western Mojave Desert  

Microsoft Academic Search

Effects of protective fencing on birds, lizards, black-tailed hares (Lepus californicus), perennial plant cover, and structural diversity of perennial plants were evalu- ated from spring 1994 through winter 1995 at the Desert Tor- toise Research Natural Area (DTNA), in the Mojave Desert, California. Abundance and species richness of birds were higher inside than outside the DTNA, and effects were larger

MATTHEW BROOKS

1999-01-01

248

Evidence for population fragmentation within a subterranean aquatic habitat in the Western Australian desert  

PubMed Central

The evolution of subterranean animals following multiple colonisation events from the surface has been well documented, but few studies have investigated the potential for species diversification within cavernicolous habitats. Isolated calcrete (carbonate) aquifers in central Western Australia have been shown to contain diverse assemblages of aquatic subterranean invertebrate species (stygofauna) and to offer a unique model system for exploring the mechanisms of speciation in subterranean ecosystems. In this paper, we investigated the hypothesis that microallopatric speciation processes (fragmentation and isolation by distance (IBD)) occur within calcretes using a comparative phylogeographic study of three stygobiontic diving beetle species, one amphipod species and a lineage of isopods. Specimens were sequenced for the mitochondrial cytochrome c oxidase 1 gene from three main sites: Quandong Well, Shady Well (SW) and Mt. Windarra (MW), spanning a 15?km region of the Laverton Downs Calcrete. Phylogenetic and haplotype network analyses revealed that each species possessed a single divergent clade of haplotypes that were present only at the southern MW site, despite the existence of other haplotypes at MW that were shared with SW. IBD between MW and SW was evident, but the common phylogeographic pattern most likely resulted from fragmentation, possibly by a salt lake adjacent to MW. These findings suggest that microallopatric speciation within calcretes may be a significant diversifying force, although the proportion of stygofauna species that may have resulted from in situ speciation in this system remains to be determined. PMID:21343944

Guzik, M T; Cooper, S J B; Humphreys, W F; Ong, S; Kawakami, T; Austin, A D

2011-01-01

249

Combining molecular-marker and chemical analysis of Capparis decidua (Capparaceae) in the Thar Desert of Western Rajasthan (india).  

PubMed

The Thar Desert, a very inhospitable place, accommodates only plant species that survive acute drought, unpredictable precipitation, and those can grow in the limited moisture of sandy soils. Capparis decidua is among one of the few plants able to grow well under these conditions. This species is highly exploited and has been naturally taken, as local people use it for various purposes like food, timber and fuel, although, no management or conservation efforts have been established. The present study was conducted in this arid area of Western Rajasthan (India) with the aim to obtain preliminary molecular information about this group of plants. We evaluated diversity among 46 samples of C. decidua using chemical parameters and random amplified polymorphic DNA (RAPD) markers. Fourteen chemical parameters and eight minerals (total 22 variables) of this species fruits were estimated. A total of 14 RAPD primers produced 235 band positions, of which 81.27% were polymorphic. Jaccard's similarity coefficients for RAPD primers ranged from 0.34 to 0.86 with a mean genetic similarity of 0.50. As per observed coefficient of variation, NDF (Neutral Detergent Fiber) content was found to be the most variable trait followed by starch and soluble carbohydrate. The Manhattan dissimilarity coefficient values for chemical parameters ranged between 0.02-0.31 with an average of 0.092. The present study revealed a very low correlation (0.01) between chemical parameters and RAPD-based matrices. The low correlation between chemical- and RAPD-based matrices indicated that the two methods were different and highly variable. The chemical-based diversity will assist in selection of nutritionally rich samples for medicinal purpose, while genetic diversity to face natural challenges and find sustainable ways to promote conservation for future use. PMID:23894984

Kumar, Sushil; Sharma, Ramavtar; Kumar, Vinod; Vyas, Govind K; Rathore, Abhishek

2013-03-01

250

Methanogens at the top of the world: occurrence and potential activity of methanogens in newly deglaciated soils in high-altitude cold deserts in the Western Himalayas.  

PubMed

Methanogens typically occur in reduced anoxic environments. However, in recent studies it has been shown that many aerated upland soils, including desert soils also host active methanogens. Here we show that soil samples from high-altitude cold deserts in the western Himalayas (Ladakh, India) produce CH4 after incubation as slurry under anoxic conditions at rates comparable to those of hot desert soils. Samples of matured soil from three different vegetation belts (arid, steppe, and subnival) were compared with younger soils originating from frontal and lateral moraines of receding glaciers. While methanogenic rates were higher in the samples from matured soils, CH4 was also produced in the samples from the recently deglaciated moraines. In both young and matured soils, those covered by a biological soil crust (biocrust) were more active than their bare counterparts. Isotopic analysis showed that in both cases CH4 was initially produced from H2/CO2 but later mostly from acetate. Analysis of the archaeal community in the in situ soil samples revealed a clear dominance of sequences related to Thaumarchaeota, while the methanogenic community comprised only a minor fraction of the archaeal community. Similar to other aerated soils, the methanogenic community was comprised almost solely of the genera Methanosarcina and Methanocella, and possibly also Methanobacterium in some cases. Nevertheless, ~10(3) gdw(-1) soil methanogens were already present in the young moraine soil together with cyanobacteria. Our results demonstrate that Methanosarcina and Methanocella not only tolerate atmospheric oxygen but are also able to survive in these harsh cold environments. Their occurrence in newly deglaciated soils shows that they are early colonizers of desert soils, similar to cyanobacteria, and may play a role in the development of desert biocrusts. PMID:24348469

Aschenbach, Katrin; Conrad, Ralf; Reháková, Klára; Doležal, Ji?í; Janatková, Kate?ina; Angel, Roey

2013-01-01

251

U-Pb ID-TIMS dating of igneous and metaigneous rocks from the El-Sibai area: time constraints on the tectonic evolution of the Central Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

This paper presents new ID-TIMS U-Pb zircon and titanite ages from the El-Sibai gneiss complex in the Eastern Desert of Egypt. The zircon data support previous studies, indicating that the protoliths of the gneissic (oldest) units in the area were emplaced during the East African orogeny, and do not represent an older pre-Neoproterozoic, reworked cratonic basement. The crystallization ages of three compositionally distinct orthogneiss protoliths are c. 685, 682 and 679 Ma, respectively. A U-Pb titanite age from one orthogneiss overlaps with the protolith age, indicating that the gneisses did not undergo post-magmatic high-temperature metamorphism. The gneissic textures of the rocks are therefore interpreted to reflect syn-emplacement deformation. This, and evidence for static amphibolite facies metamorphism in country-rock metavolcanics, lead us to conclude that the gneisses of El-Sibai do not represent an exhumed middle crustal gneiss dome, but are part of the island arc affined allochthon into which they were emplaced synchronously with NW-ward nappe translation. We also report ages from rocks cross-cutting the gneisses and the surrounding island arc affined assemblages that yield the hitherto youngest robust pre-Cretaceous intrusive ages in the Eastern Desert. The dated rocks are an anorthosite and a cross-cutting syenogranite giving ages of c. 541 and 540 Ma, respectively. We consider this late magmatic pulse to be anorogenic, most likely reflecting a separate extensional event involving asthenospheric upwelling and decompression melting of the mantle.

Augland, Lars Eivind; Andresen, Arild; Boghdady, Gamal Yehia

2012-01-01

252

The significance of gneissic rocks and synmagmatic extensional ductile shear zones of the Barud area for the tectonics of the North Eastern Desert, Egypt  

Microsoft Academic Search

The mainly tonalitic gneissic rocks, amphibolites, schists and rarer migmatites of the Barud area, at the southern margin of the Egyptian North Eastern Desert (NED) have previously been viewed as products of ultrametamorphism or granitization of pre-PanAfrican basement. The Qena–Safaga Line of approximately NW-striking steeply dipping faults was also regarded as marking the boundary between these NED rocks and the

Abdel-Rahman Fowler; Khaled G. Ali; Sayed M. Omar; Hassan A. Eliwa

2006-01-01

253

Effects of Protective Fencing on Birds, Lizards, and Black-Tailed Hares in the Western Mojave Desert  

Microsoft Academic Search

Lepus californicus  ), perennial plant cover, and structural diversity of perennial plants were evaluated from spring 1994 through winter 1995\\u000a at the Desert Tortoise Research Natural Area (DTNA), in the Mojave Desert, California. Abundance and species richness of birds\\u000a were higher inside than outside the DTNA, and effects were larger during breeding than wintering seasons and during a high\\u000a than a

MATTHEW BROOKS

1999-01-01

254

Active synchronous counterclockwise rotation and northwards translation of Africa toward Eurasia during the Late Cretaceous: A paleomagnetic study on the Alkaline volcanic field of Wadi Natash (ca. 100-86Ma), South Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

In order to shed light on the paleo-tectonic movement of Africa during the Late Cretaceous, the two end members of the alkaline volcanic field of Wadi Natash (ca. 100-86Ma) in the South Eastern Desert of Egypt were studied paleomagnetically. The Wadi Natash volcanic field (24.5°N-34.25°E) is made up of a succession of differentiated flows grading from alkali olivine basalt [AOB] to trachyte-phonolite [Tr/Ph]. The oldest flows of the AOB (104±7 Ma) and the youngest Tr/Ph plugs and ring dykes (86Ma) as well as the interflows sandstones [ previously know as Nubian sandstone were sampled allover the field > 400km2. The isothermal remanent magnetization [IRM] study revealed that the remanence in Wadi Natash volcanics reside mainly in magnetite with some subsidiary goethite/hematite sites. On the other hand, goethite/hematite are the sole remanence carriers in the Nubian-type interflow sandstone. After the progressive stepwise thermal demagnetization of all samples, the visual isolation and subsequent calculation of the best-fit line of the characteristic remanence [ChRM] direction of each sample, followed by the calculation of the site and rock-unit means revealed that: 1- In the tilt-corrected coordinates, the mean ChRM of the oldest AOB flows [N=12 sites

Lotfy, H.

2009-04-01

255

Desert Ecosystems  

NSDL National Science Digital Library

The Desert Ecosystems site describes the geology and climate, plants and animals, and cultural history of the main U.S. desert regions including: the Mojave Desert, the Great Basin, and the Colorado/Sonoran desert. There are also descriptions and photos of water in the desert, coyotes, the desert tortoise, and the creosote bush.

256

Scale insects and mealy bugs (Homoptera: Coccoidea) attacking deciduous fruit trees in the western north coast of Alexandria, Egypt.  

PubMed

This investigation covered a survey of scale insects and mealy bugs infesting ten growing species of deciduous fruit trees in three localities in Alexandria govemorate. These localities were Merghem, Burg El-Arab, and El-Nahda about 50 Km. West of Alexandria under both rain-fed and irrigation system conditions. The common inspected fruit trees were fig, white mulberry, pomegranate, apple, pear, apricot, European plum, peach, almond, and persimmon. It was shown that a group of twenty scale insects and meaty bug species pertaining to fifteen genera belonging to six families of the super family: Coccoidea were collected and identified during the elapsing period from January to December, 2004. Among these species, Diaspidiotus perniciosus (Comstock) was recorded for the first time in Egypt. In the present study, many insect and non-insect parasitoids and predators were also found associated with these scale insects and mealy bugs on deciduous fruit trees in the three concerned localities throughout this investigation. These natural enemies were identified and recorded. PMID:19226793

Mourad, A K; Moursi Khadiga, S; Mesbah, H A; Abdel-Razak Soad, I

2008-01-01

257

Composition, age, and origin of the ~620 Ma Humr Akarim and Humrat Mukbid A-type granites: no evidence for pre-Neoproterozoic basement in the Eastern Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Humr Akarim and Humrat Mukbid plutons, in the central Eastern Desert of Egypt, are late Neoproterozoic post-collisional alkaline A-type granites. Humr Akarim and Humrat Mukbid plutonic rocks consist of subsolvus alkali granites and a subordinate roof facies of albite granite, which hosts greisen and Sn-Mo-mineralized quartz veins; textural and field evidence strongly suggest the presence of late magmatic F-rich fluids. The granites are Si-alkali rich, Mg-Ca-Ti poor with high Rb/Sr (20-123), and low K/Rb (27-65). They are enriched in high field strength elements (e.g., Nb, Ta, Zr, Y, U, Th) and heavy rare earth elements (La n /Yb n = 0.27-0.95) and exhibit significant tetrad effects in REE patterns. These geochemical attributes indicate that granite trace element distribution was controlled by crystal fractionation as well as interaction with fluorine-rich magmatic fluids. U-Pb SHRIMP zircon dating indicates an age of ~630-620 Ma but with abundant evidence that zircons were affected by late corrosive fluids (e.g., discordance, high common Pb). ?Nd at 620 Ma ranges from +3.4 to +6.8 (mean = +5.0) for Humr Akarim granitic rocks and from +4.8 to +7.5 (mean = +5.8) for Humrat Mukbid granitic rocks. Some slightly older zircons (~740 Ma, 703 Ma) may have been inherited from older granites in the region. Our U-Pb zircon data and Nd isotope results indicate a juvenile magma source of Neoproterozoic age like that responsible for forming most other ANS crust and refute previous conclusions that pre-Neoproterozoic continental crust was involved in the generation of the studied granites.

Ali, Kamal A.; Moghazi, Abdel-Kader M.; Maurice, Ayman E.; Omar, Sayed A.; Wang, Qiang; Wilde, Simon A.; Moussa, Ewais M.; Manton, William I.; Stern, Robert J.

2012-10-01

258

Effect of the temperature variation between Mediterranean Sea and Syrian deserts on the dust storm occurrence in the western half of Iran  

NASA Astrophysics Data System (ADS)

Recent dust storms have caused crises in western Iran, which necessitate the prediction of these storms a few days before their occurrence. This is the first study of its type that analyzes the effect of temperature differences between the Mediterranean Sea surface and Syrian deserts (creation zone of the dusts storms) on the formation of dust storms in the west of Iran. The study also seeks to identify any changes in the atmospheric temperature created by the extreme dust storm of July 5, 2009 in west of Iran (Sanandaj City). In this study, the MODIS images from 2000 to 2008, and particulate matter data of the Sanandaj station from 2008 to 2012 were utilized to identify the dust storm days. The Mediterranean Sea surface temperature data were extracted from NOAA satellites for dust storm days up to four days preceding them. The web site of world weather was used to obtain the temperature of Damascus, Syria station as the selected land station. According to the results, significant differences were acquired between surface temperatures of Damascus station and the Mediterranean Sea in the dust storm days and up to three days before them. As the dust storm days approached, a rising trend was observed in changes of the temperature difference between land and sea. Thermal map analysis of the atmosphere of the Syrian deserts on July 5, 2009 showed significant decrease in the levels of 1000 hPa and 500 hPa but for the days preceding it no significant changes were observed. It can be concluded that the temperature difference between the Mediterranean Sea surface and the Syrian deserts four days before the dust storm occurrences is the important factor in predicting this event.

Amanollahi, Jamil; Kaboodvandpour, Shahram; Qhavami, Samira; Mohammadi, Bakhtiyar

2015-03-01

259

Late Neoproterozoic volcanics and associated granitoids at Wadi Ranga, south Eastern Desert, Egypt: A transition from subduction related to intra-arc magmatism  

NASA Astrophysics Data System (ADS)

The late Neoproterozoic of Wadi Ranga area, south Eastern Desert was characterized by extensive magmatism consisting predominantly of calc-alkaline older granitoids, Ranga volcanics and granite porphyry intrusions forming a belt of volcanic-intrusive complexes. Geological studies of the Ranga volcanics revealed two sequences of volcanic suites: the older mafic sequence composed essentially of basalt/basaltic andesite lava flows and the associated pyroclastics, while the younger felsic one represented by pitchstone porphyry. Geochemically, the older granitoids are exhibit low K-calc-alkaline characters and most likely formed in a convergent margin (arc) tectonic environment. Basalt/basaltic andesites are compositionally uniform with tholeiitic affinity. They have trace element characteristics of arc related volcanics with low Nb (0.2-0.9 ppm), Zr/Nb ratios of 40-81 with an average 54 compared to 32 in average N-MORB, signify a convergent margin setting with a depleted mantle wedge. Low Mg# (45 to 60 with an average 51), Co and Ni contents may be indicative of a non-plume-influenced mantle wedge. Compositionally, these mafic volcanics are commensurate with modern intra-arc basalts. REE modeling indicates that the magma from which these mafic volcanics were formed was generated by about 17-30% partial melting of a depleted mantle that composed mainly of spinel lherzolite in an extensional marginal basin. Geochemical characters of major, trace and REE patterns of the granite and pitchstone porphyries proved their formation from the same magma source which is originally different from the magma producing the mafic volcanics. The relative enrichment in K2O and LREE of the pitchstone porphyry along with the depletion in CaO and MgO relative to granite porphyry probably resulted from crustal contamination processes.

Gharib, Moustafa Esmail; Ahmed, Ahmed Hassan

2012-12-01

260

Geology and organic geochemistry of Dakla Shale, Egypt  

SciTech Connect

The Dakla Formation is late Campanian to Paleocene in age and, in eastern Egypt, is overlain by the Nubian Sandstone and underlain by the phosphate-bearing Duwi Formation. Lithologically, samples of the Dakla shale member collected in the Red Sea area consist of marls to marly clays, range from brown to black in color, and are bounded at the top and bottom by phosphate-bearing strata. Organic carbon and extractable C/sub 15+/ hydrocarbon concentrations for samples from Quseir, Hamrawein, and Safaga ranged from 3.8 to 5.9% C/sub org/ and 550 to 2400 ppM HC, and may be petroleum source rocks in areas where burial and thermal conditions are adequate. Shale samples from the Quseir region yielded Fischer assay results of 40 gal/ton, and thus have considerable potential as oil shales. Samples from the Sibaiya region in the Nile Valley are light to dark gray shale and average 0.2% C/sub org/. In this area, the phosphate deposits associated with the Dakla Formation are presently being exploited. The Dakla shale samples from the Abu Tartur region, in the Western Desert, contain organic carbon concentrations in excess of 4.0%. Such values are considered suitable for potential petroleum source rocks where other conditions are satisfied. Recent exploration activity in the Western Desert region may make petroleum source rock studies of the Dakla shales increasingly important.

Robison, V.D.; Troeeger, U.

1983-03-01

261

Late Holocene Paleoclimatic Reconstruction from Playa Lake Sediments, Thar Desert, India: Comparison between Eastern and Western Margins  

NASA Astrophysics Data System (ADS)

Located in the downstream of south-west monsoonal winds, the Thar Desert of India is a region of sharp climatic gradient (rainfall change of ~1mm/km). Low annual rainfall (500-100 mm/yr) and high evapo- transpiration (2000-1500 mm/yr) lead to a negative water balance in the region. Across this region of negative water balance, numerous shallow, endorheic saline playa lakes are present and fed by rainfall events. This contribution reconstructs the late Holocene paleo-hydrological conditions by a multi-proxy study comprising lithostratigraphy, mineralogy, elemental and isotope geochemistry along with optical dating of sediments from two lakes, viz. Phulera (eastern margin of the desert with rainfall of 500 mm/yr) and Pokharan (arid core with rainfall of 200 mm/ yr). Geochemical proxies on closely sampled cores along with mineralogical abundance enabled identification of four zones of comparable chemical weathering, aeolian activity and salinity that are manifestations of changes in precipitation and aridity. Zone IV dated to ~7 - 4.3 ka suggested high energy storm surge events. Between 4.3 - 2.8 ka (zone III), geochemical evidences indicated fluctuating brackish and fresh water regime. During 2.8 - 1.4 ka (zone II), the lakes experienced hypersaline condition and finally the lakes desiccated at ~1.4 ka. During this event, the dominance of gypsum (CaSO4.2H2O) in the Pokharan playa and abundance of proto- dolomite (Ca(Mg,Fe)(CO3)2) in the Phulera playa suggest that the magnitude of evaporation was higher in the west compared to east. The sub recent zone I (1.4 - 0 ka) indicates overall improved south-west monsoon condition in the region. In this presentation a synthesis of the overall records from the playa lakes of the region and its import on the climatic gradients through time will be presented.

Roy, P.; Nagar, Y.; Singhvi, A.; Smykatz-Kloss, W.

2006-05-01

262

Late Cretaceous multicolored shales and phosphatic sedimentary rocks in Egypt  

SciTech Connect

Upper Cretaceous transitional fluvial to marine variegated shale (upper Nubia Formation) and the fully marine Duwi (phosphate) Formation occur as thin, widespread, shallow-marine deposits in an east-west-trending belt spanning the lower-middle latitudes of Egypt. On a larger scale, the phosphoritic rocks in Egypt represent but a small portion of a laterally extensive Middle Eastern-North African phosphogenic province of Upper Cretaceous-Lower Tertiary age that accounts for accumulation of minable marine phosphate in excess of 70 billion tons. Phosphorites, porcelanites/cherts, organic carbon-rich shales, glauconitic sandstones, and bioclastic and fine-grained carbonate rocks variously reflect major hemipelagic and shallow-water carbonate sedimentation. Biosiliceous hemipelagic deposits, now diagenetically altered to procelanite and chert, reflect low energy depositional conditions that were periodically interrupted by high energy, possibly storm-induced currents and/or down-slope redeposition. Both dark shales and porcelanites locally contain abundant organic matter and are commonly finely laminated. Porcelanites and black shales are phosphatic, containing phosphatic grains identical, morphologically and chemically, to those found in associated phosphorites, and are probably the source from which the phosphorites were derived. The organic carbon-rich shales of the Duwi Formation appear to be quite laterally extensive and may, depending on thermal maturity, represent potential hydrocarbon source rocks in other portions of the region (e.g., Western Desert, Gulf of Suez), where they are more deeply buried.

Glenn, C.R.; Garrison, R.E.; Arthur, M.A.

1983-03-01

263

Solar Energy for Rural Egypt  

NASA Astrophysics Data System (ADS)

Egypt is currently experiencing the symptoms of an energy crisis, such as electricity outage and high deficit, due to increasing rates of fossil fuels consumption. Conversely, Egypt has a high solar availability of more than 18.5 MJ daily. Additionally, Egypt has large uninhabited deserts on both sides of the Nile valley and Sinai Peninsula, which both represent more than 96.5 % of the nation's total land area. Therefore, solar energy is one of the promising solutions for the energy shortage in Egypt. Furthermore, these vast lands are advantageous for commissioning large-scaled solar power projects, not only in terms of space availability, but also of availability of high quality silicon (sand) required for manufacturing silicon wafers used in photovoltaic (PV) modules. Also, rural Egypt is considered market a gap for investors, due to low local competition, and numerous remote areas that are not connected to the national electricity grid. Nevertheless, there are some obstacles that hinder the progress of solar energy in Egypt; for instance, the lack of local manufacturing capabilities, security, and turbulent market in addition to other challenges. This paper exhibits an experience of the authors designing and installing decentralized PV solar systems, with a total rated power of about 11 kW, installed at two rural villages in at the suburbs of Fayoum city, in addition to a conceptual design of a utility scale, 2 MW, PV power plant to be installed in Kuraymat. The outcomes of this experience asserted that solar PV systems can be a more technically and economically feasible solution for the energy problem in rural villages.

Abdelsalam, Tarek I.; Darwish, Ziad; Hatem, Tarek M.

264

The Formation of the Patterns of Desert Shrub Communities on the Western Ordos Plateau, China: The Roles of Seed Dispersal and Sand Burial  

PubMed Central

The western Ordos Plateau is a key area of shrub diversity and a National Nature Reserve of endangered shrub species in north-west China. Desert expansion is becoming the most important threat to these endangered species. However, little is known about the effects of sand burial on the dynamics of the shrub community. This study aims to investigate how the shrubs as a community and as different individual shrubs respond to the disturbances caused by the desert expansion. The approach used by this study is to separate the seed-dispersal strategy from the sand-burial forces that are involved in structuring the shrub communities at different disturbance stages. Four communities for different disturbance stages were surveyed by using 50×50 m plots. The individual shrubs were classified into coloniser and successor groups at the seed-dispersal stage and strong and weak sand-burial tolerance groups at the sand-expansion stage. We employed spatial point pattern analysis with null models for each community to examine the seed-dispersal strategy and sand-burial forces affecting community distribution patterns. At the seed-dispersal stage, the interactions between the colonisers and the successors showed significant positive correlation at a scale of 0–1 m and significant negative correlation at a scale of 2 m; significant negative correlations between the groups with strong and weak sand-burial tolerance in the early stage of sand expansion at scales of 3–6 m, and significant positive correlation in the later stage of sand expansion at a scale of 13 m, were found. Seed-dispersal strategy is a reasonable mechanism to explain the shrub community pattern formation in the earlier stages, whereas sand burial is the primary reason for the disappearance of shrubs with weak sand-burial tolerance, this irreversible disturbance causes homogenisation of the community structure and produces aging populations of shrub species. This has an important influence on the succession direction of desert shrub communities. PMID:23922877

Wang, Yange; Yang, Xiaohui; Shi, Zhongjie

2013-01-01

265

Desert Features  

NSDL National Science Digital Library

Sand covers only about 20 percent of the Earth's deserts. Nearly 50 percent of desert surfaces are gravel plains where removal of fine-grained material by the wind has exposed loose gravel and occasional cobbles. This web page, produced by the U.S. Geological Survey, features text and photographs that describe desert landforms, soils, plants, and the role of water in the formation of desert landscapes.

266

Resilience to stress and disturbance, and resistance to Bromus tectorum l. invasion in cold desert shrublands of western North America  

USGS Publications Warehouse

Alien grass invasions in arid and semi-arid ecosystems are resulting in grass–fire cycles and ecosystem-level transformations that severely diminish ecosystem services. Our capacity to address the rapid and complex changes occurring in these ecosystems can be enhanced by developing an understanding of the environmental factors and ecosystem attributes that determine resilience of native ecosystems to stress and disturbance, and resistance to invasion. Cold desert shrublands occur over strong environmental gradients and exhibit significant differences in resilience and resistance. They provide an excellent opportunity to increase our understanding of these concepts. Herein, we examine a series of linked questions about (a) ecosystem attributes that determine resilience and resistance along environmental gradients, (b) effects of disturbances like livestock grazing and altered fire regimes and of stressors like rapid climate change, rising CO2, and N deposition on resilience and resistance, and (c) interacting effects of resilience and resistance on ecosystems with different environmental conditions. We conclude by providing strategies for the use of resilience and resistance concepts in a management context. At ecological site scales, state and transition models are used to illustrate how differences in resilience and resistance influence potential alternative vegetation states, transitions among states, and thresholds. At landscape scales management strategies based on resilience and resistance—protection, prevention, restoration, and monitoring and adaptive management—are used to determine priority management areas and appropriate actions.

Chambers, Jeanne C.; Bradley, Bethany A.; Brown, Cynthia S.; D'Antonio, Carla; Germino, Matthew J.; Grace, James B.; Hardegree, Stuart P.; Miller, Richard F.; Pyke, David A.

2013-01-01

267

The surface pollen and relative pollen production of the desert vegetation of the Alashan Plateau, western Inner Mongolia  

Microsoft Academic Search

This preliminary investigation focuses on the comparison of the recent pollen precipitation and its related vegetation of\\u000a eight different plant communities in the Alashan Region, the most western part of the Inner Mongolia Autonomous Region. Most\\u000a zonal and azonal communities can be well identified by their pollen spectra. Relative pollen production factors of various\\u000a plant taxa have been calculated and

U. Herzschuh; H. Kürschner; Yuzhen Ma

2003-01-01

268

Movement of water through the thick unsaturated zone underlying Oro Grande and Sheep Creek Washes in the western Mojave Desert, USA  

USGS Publications Warehouse

Previous studies indicate that a small quantity of recharge occurs from infiltration of streamflow in intermittent streams in the upper Mojave River basin, in the western Mojave Desert, near Victorville, California. Chloride, tritium, and stable isotope data collected in the unsaturated zone between 1994 and 1998 from boreholes drilled in Oro Grande and Sheep Creek Washes indicate that infiltration of streamflow occurs to depths below the root zone, and presumably to the water table, along much of Oro Grande Wash and near the mountain front along Sheep Creek Wash. Differences in infiltration at sites along each wash are the result of hydrologic variables such as proximity to the mountain front, quantity of streamflow, and texture of the subsurface deposits. Differences in infiltration between the washes are the result of large-scale geomorphic processes. For example, Oro Grande wash is incised into the Victorville fan and infiltration has occurred at approximately the same location over recent geologic time. In contrast, Sheep Creek Wash overlies an active alluvial fan and the stream channel can move across the fan surface through time. Infiltration does not occur to depths below the root zone at control sites outside of the washes.

Izbicki, J.A.; Radyk, J.; Michel, R.L.

2002-01-01

269

Integrated biostratigraphy, stage boundaries and Paleoclimatology of the Upper Cretaceous-Lower Eocene successions in Kharga and Dakhala Oases, Western Desert, Egypt  

NASA Astrophysics Data System (ADS)

The Upper Cretaceous-Lower Eocene succession in the studied sections is divided into four rock units that arranged from base to top: the Dakhla, Tarawan, Esna and the Thebes formations. Detailed study of the foraminifera and calcareous nannofossils has led to the recognition of 58 and 82 species, respectively. Based on planktonic foraminifera and calcareous nannofossils 8 planktonic foraminiferal biozones (CF4, P2, P3, P4, E1, E2, E3 and E4) have been recognized as well as 8 calcareous nannofossil biozones (CC25b, NP3, NP4, NP5, NP6, NP7/8, NP9, and NP10). At Gabal Teir/Tarawan section, Kharga Oasis, the Paleocene can be divided into three stages; Danian, Selandian and Thanetian. The Danian/Selandian boundary is placed at P3a/P3b zonal boundary (LO of Igorina albeari) which corresponds to the level of LO of Lithoptychius ulii, Fasciculithus pileatus, Fasciculithus involutus and Lithoptychius janii (upper part of Zone NP4). The Selandian/Thanetian boundary, on the other hand, can be traced within the foraminiferal Zone P4 (Globanomalina pseudomenardii Zone) and between the nannofossil zones NP6 and NP7/8 (LO of Discoaster mohleri). At Gabal Ghanima section, the Paleocene/Eocene boundary is located within the lower part of the Esna Formation. It can be traced at the base of planktonic foraminiferal Zone E1 (LOs of Acarinina africana, A sibaiyaensis and Morozovella allinsoensis), and at the NP9a/NP9b subzonal boundary (LO of Rhomboaster spp). However, the lower Eocene succession seems to be condensed and punctuated by minor hiatus (absence of Subzone NP10a). The dominance of cool water nannofossil species in the late Maastrichtian and early Danian interval suggests a gradual decrease in the surface water paleotemperature. However, a slight warming condition prevailed around the Danian/Selandian transition as evidenced by the warm water nannofossil species. At the P/E boundary interval, the high abundance of warm-water taxa (e.g. Discoaster, Sphenolithus, Rhomboaster, Tribrachiatus and Pontosphaera species) indicates a warm-water paleotemperatures.

Khalil, H.; Al Sawy, S.

2014-08-01

270

Image and statistical analyses of early sorghum remains (8000 B.P.) from the Nabta Playa archaeological site in the Western Desert, southern Egypt  

Microsoft Academic Search

Carbonized grains of sorghum, with consistent radiocarbon dates of ca. 8000 B.P., have been excavated at an early Holocene archaeological site (E-75-6) in Nabta Playa near the Egyptian-Sudanese border. The objective of the investigations reported here was to classify these early sorghum grains within the known wild or domesticated races or working groups of sorghum through the use of image-analysis

J. A. Dahlberg; K. Wasylikowa

1996-01-01

271

High-stress paleoenvironment during the late Maastrichtian to early Paleocene in Central Egypt  

E-print Network

-stress conditions prevailed in central Egypt as elsewhere in the marginal eastern Tethys. Ã? 2002 Elsevier Science B). In the Eastern Desert, the Sinai and Negev, sediment deposition occurred in a deeper middlHigh-stress paleoenvironment during the late Maastrichtian to early Paleocene in Central Egypt

Keller, Gerta

272

Eternal Egypt  

NSDL National Science Digital Library

Available in English, French, and Arabic, Eternal Egypt is a website with a wealth of information on "the artifacts, characters, and places that together comprise the wonder that is Eternal Egypt." The website is organized so visitors can choose between a guided tour, begin with one of the cultural highlights (such as The Temple of Luxor or Part of a Wall of a Tomb), or simply explore and discover. A key feature of the website is the context provided in relation to various topics, so that a visitor can learn about the artifacts, but also how they connect to other people, places and artifacts, and where they fit in terms of an overall timeline and on a multimedia map of Egypt. Topics include: Arts and Crafts (Libraries, Architecture, Paintings and Relief, Sculpture, Humanities, Crafts), Science (Archaeology, Mathematics, Astronomy, Medicine, Social Science, Engineering), Agriculture (Irrigation, Herding, Farming, Crops), Commerce and Trade (Transportation), Government (Leaders, Seats of Power, Theocracy, Military), and Society and Culture (Family, Food and Drinks, Clothing, Sports and Entertainment, Religion and Spirituality).

273

The 40Ar/39Ar thermochronology of the eastern Mojave Desert, California, and adjacent western Arizona with implications for the evolution of metamorphic core complexes  

NASA Astrophysics Data System (ADS)

Mesozoic thickening and Cenozoic extension resulted in the juxtaposition of upper and middle crustal rocks in the eastern Mojave Desert, southeastern California and western Arizona. The application of 40Ar/39Ar thermochronology to rocks in this region provides information about the timing and nature of thrusting, plutonism, metamorphism, denudation, and detachment faulting. The 40Ar/39Ar ages of 175 to 125 Ma from the Clipper, Piute, Turtle, Mohave, Bill Williams, and Hualapai Mountains are interpreted to be the result of a middle Mesozoic thermal event(s) caused by crustal thickening. The 40Ar/39Ar data from the Clipper and Piute Mountains suggest that this thermal event was followed by a period of cooling at rates of 1°-5°C/m.y. Orogenesis culminated during the Late Cretaceous when rocks exposed in the Old Woman-Piute, Chemehuevi, and Sacramento Mountains attained temperatures >500°C which reset the K-Ar systems of minerals from Proterozoic rocks. High-grade metamorphism in the Old Woman Mountains area was caused by the intrusion of the Old Woman-Piute batholith at 73±1 Ma. Cooling rates following batholith emplacement in the Old Woman Mountains were ˜100°C/m.y. between 73 and 70 Ma and 5°-10°C/m.y. from 70 to ˜30 Ma. Between 65 and 25 Ma the entire eastern Mojave Desert underwent a period of cooling at a rate of 2°-10°C/m.y. By 30 Ma, rocks exposed in the Old Woman-Piute, Marble, Ship, Clipper, and Turtle Mountains were below ˜100°C. The 40Ar/39Ar ages from the Sacramento Mountains suggest that mylonitization caused by the onset of regional extension occurred at 23±1 Ma. When extension started in the Chemehuevi Mountains, rocks exposed in the southwestern and northeastern portions of footwall to the Chemehuevi detachment fault were at ˜180°C and ˜350°C, respectively. This suggests that the exposed part of the Chemehuevi detachment fault initiated at a dip of 5°-30° or as a series of higher-angle faults that cut to a depth of 10-12 km and were later rotated to their present dip. Unroofing of the footwalls to detachment faults in the Sacramento and Chemehuevi Mountains resulted in average cooling rates of 10°-50°C/m.y. between 22 and 15 Ma.

Foster, David A.; Harrison, T. Mark; Miller, Calvin F.; Howard, Keith A.

1990-11-01

274

DESERT SYMPOSIUM 2013 DESERT STUDIES CENTER, Zzyzx  

E-print Network

DESERT SYMPOSIUM 2013 DESERT STUDIES CENTER, Zzyzx April 19-22, 2013 Persistent drought lowers estimated survival in adult Agassiz's desert tortoises-water input in on a disturbed Mojave Desert alluvial fan Schweich, Tom Day 1

de Lijser, Peter

275

Configuration of the limestone aquifers in the central part of Egypt using electrical measurements  

NASA Astrophysics Data System (ADS)

The Western Desert of Egypt is an area of natural expansion for agricultural, industrial, and civil activities. This expansion has led to a great demand for groundwater. In the central part of Egypt, on the western limestone plateau, vertical electrical sounding and borehole geophysical logging were conducted to delineate aquifer boundaries. The measurements were interpreted using the lithological information from the drilled wells as a constraining factor. Fractured chalky limestone sediments represent the main aquifer, which is covered by sand and gravel deposits and which rests directly on partially saturated and highly resistive massive limestone. Discontinuous clay layers, which overlie the aquifer unit, were detected in the southern part of the study area as well as a relatively thin marly limestone layer in the northern part. The integrated analyses carried out represent a significant and cost-effective method for delineating the main aquifer in this area. In turn, future well locations can be placed with more confidence than before, in accordance with the evaluation of the potentiality of the groundwater aquifers in the area. Although the groundwater is normally brackish, it can serve the acute demands for water, especially for agricultural purposes.

Abou Heleika, M. M.; Niesner, E.

2009-03-01

276

Fairy, tadpole, and clam shrimps (Branchiopoda) in seasonally inundated clay pans in the western Mojave Desert and effect on primary producers  

PubMed Central

Background Fairy shrimps (Anostraca), tadpole shrimps (Notostraca), clam shrimps (Spinicaudata), algae (primarily filamentous blue-green algae [cyanobacteria]), and suspended organic particulates are dominant food web components of the seasonally inundated pans and playas of the western Mojave Desert in California. We examined the extent to which these branchiopods controlled algal abundance and species composition in clay pans between Rosamond and Rogers Dry Lakes. We surveyed branchiopods during the wet season to estimate abundances and then conducted a laboratory microcosm experiment, in which dried sediment containing cysts and the overlying algal crust were inundated and cultured. Microcosm trials were run with and without shrimps; each type of trial was run for two lengths of time: 30 and 60 days. We estimated the effect of shrimps on algae by measuring chlorophyll content and the relative abundance of algal species. Results We found two species of fairy shrimps (Branchinecta mackini and B. gigas), one tadpole shrimp (Lepidurus lemmoni), and a clam shrimp (Cyzicus setosa) in our wet-season field survey. We collected Branchinecta lindahli in a pilot study, but not subsequently. The dominant taxa were C. setosa and B. mackini, but abundances and species composition varied greatly among playas. The same species found in field surveys also occurred in the microcosm experiment. There were no significant differences as a function of experimental treatments for either chlorophyll content or algal species composition (Microcoleus vaginatus dominated all treatments). Conclusions The results suggest that there was no direct effect of shrimps on algae. Although the pans harbored an apparently high abundance of branchiopods, these animals had little role in regulating primary producers in this environment. PMID:21143855

2010-01-01

277

Ancient Egypt  

NSDL National Science Digital Library

Drawing on its superb collection of materials from archaeological excavations, the British Museum presents this extensive learning resource on Ancient Egypt. The site features texts, images, and interactive elements detailing Egyptian daily life, mythology, timekeeping, geography, architecture, governance, business, writing, and rituals of death. The material is clearly and simply written so that the site would be useful for primary school students, but it is informative and substantial enough to be of interest to college students and curious adults as well. Thoroughly hyperlinked and replete with images that can be enlarged for detailed perusal, the site goes beyond the typical teaser Websites so often posted by lesser museums.

278

Desert Sojourn.  

ERIC Educational Resources Information Center

Focuses on an activity in which the students in a beginning drawing class used middle-value brown paper and earthen shades of conte to draw pictures of bones in a desert environment. Discusses how the assignment teaches appreciation of the colors, sounds, and shapes of the desert. (CMK)

Greenman, Geri

1999-01-01

279

Precambrian Research 124 (2003) 87104 Structural evolution of the Neoproterozoic Western  

E-print Network

; Suture 1. Introduction The Neoproterozoic rocks of the Eastern Desert of Egypt form a belt of rugged­Heiani suture, southeastern Egypt Mohamed G. Abdelsalama,, Mamdouh M. Abdeenb, Hamid M. Dowaidarc, Robert J, TX 75083, USA b The National Authority for Remote Sensing and Space Sciences, Cairo, Egypt c Ain

Stern, Robert J.

280

Global observations and spectral characteristics of desert dust and  

E-print Network

Global observations and spectral characteristics of desert dust and biomass burning aerosols Martin characteristics of desert dust and biomass burning scenes · Conclusions and Outlook #12;where Rayleigh R340 Saudi-Arabian lowlands Kara-Bogaz Gol Lybian Desert SaharaWestern Sahara Bodèle Prospero et al, 2002

Graaf, Martin de

281

Higher education in Egypt  

Microsoft Academic Search

Egypt's policy on higher education, the author argues, must take account of the realities of declining government budgets and employment and increasing reliance on the private sector, which must become more competitive internationally. Education in Egypt must increase Egyptians'ability to cope with economic disequilibria: to respond quickly and effectively to changing technological and market opportunities. The Government of Egypt's strategy

Alan Richards

1992-01-01

282

WESTERN  

E-print Network

utilized as native hay, especially when harvested in overflow or run in sites that collect additional moisture. Erosion control/reclamation: Western wheatgrass is well suited for stabilization of disturbed soils because of its strong spreading rhizomes. It should not be planted with aggressive introduced grasses, but is very compatible with slower developing natives such as bluebunch wheatgrass (Pseudoroegneria spicata), thickspike wheatgrass (Elymus lanceolatus ssp. lanceolatus), streambank wheatgrass (Elymus lanceolatus ssp. psammophilus), and needlegrass species (Achnatherum spp., Hesperostipa spp., Nassella spp., Stipa spp., and Ptilagrostis spp.). Its relatively good drought tolerance combined with strong rhizomatous root systems and adaptation to a variety of soils makes this species ideal for reclamation in areas receiving 12 to 20 inches annual precipitation. Its low growth form, vigorous sod, and low maintenance requirements make it ideal for ground cover purposes. This grass can be used in urban areas where irrigation water is limited to provide ground cover and to stabilize ditch banks, dikes, and roadsides.

Pascopyrum Smithii (rydb; A. Löve

283

Fracture types detected in eastern Mediterranean reservoirs (Turkey and Egypt)  

SciTech Connect

Most of Turkey's reservoirs are in the fractured Cretaceous Mardin Formation; however, new possibilities in fractured Paleozoic sandstones are being sought. The dominant fractures are fold related and are found on the northern flanks of the asymmetrical anticlines. The strike of these fractures is perpendicular to bedding planes and parallel to dip. There are fewer tear-fault-related and crestal-position fractures, but these may have a greater vertical extent. Fractures are present in all the producing areas of Egypt except the Nile delta. Basement fractures associated with shear zones in the southern Gulf of Suez have become an important exploration target. Fracture orientations are related to the major shear orientations except where later folding and faulting have caused structural rotation. The development of Zeit Bay field has shown that fractured basement rock can constitute a significant reservoir. The fracture reservoirs in northern Sinai and the Western Desert are in Cretaceous and Jurassic limestones and/or dolomitic limestones. The major shear fractures are parallel to the northwest-north-northwest compressive stresses that formed the reservoir structures; however, local fold- and fault-related fractures are also present.

Nurmi, R.; Taha, M. (Schlumberger, Dubai (United Arab Emirates )

1988-08-01

284

Geochemical modeling of evaporation process in Lake Qarun, Egypt  

NASA Astrophysics Data System (ADS)

Lake Qarun is an inland closed saline lake. It lies within the Fayoum Depression in the Western Desert of Egypt. Evaporation modeling has been carried out using PHREEQC to simulate the geochemical evolution of surface drainage waters inflow towards lake water. In the case of Lake Qarun, it is the first attempt to carry out such kind of modeling. Performance of this model helped to address the different sources of dissolved major ions to Lake Qarun and to identify the mechanisms control the lake's water chemistry. The model demonstrated that evaporation-crystallization process is the main mechanism controlling the evolution of lake water chemistry where major ions Na+, Mg2+, Cl- and SO42- have been built up in the lake by evaporation while Ca2+ and HCO3- are depleted by calcite precipitation. Moreover, the simulated model reproduced the real data observed in Lake Qarun except in the case of SO42- which is in real more enriched in the lake than the model output. The additional source of SO42- is reported to be from groundwater. The models result agreed well with the modified evolutionary Hardie and Eugster's scheme (1970) in which the final major composition of Lake Qarun water is Na-Mg-SO4-Cl type. In future, the monitoring of Lake Qarun chemistry with detection of any other sources of elements and/or local reactions inside the lake can be detected by performing the simulated evaporation model reported by the present study.

Abdel Wahed, Mahmoud S. M.; Mohamed, Essam A.; El-Sayed, Mohamed I.; M'nif, Adel; Sillanpää, Mika

2014-09-01

285

Thar Desert  

NASA Technical Reports Server (NTRS)

This ASTER sub-scene covers an area of 12 x 15 km in NW India in the Thar Desert. The sand dunes of the Thar Desert constantly shift and take on new shapes. Located in northwestern India and eastern Pakistan, the desert is bounded on the south by a salt marsh known as the Rann of Kutch, and on the west by the Indus River plain. About 800 kilometers long and about 490 kilometers wide, the desert's terrain is mainly rolling sandhills with scattered growths of shrub and rock outcroppings. Only about 12 to 25 centimeters of rain fall on the desert each year, and temperatures rise as high as 52 degrees Celsius. Much of the population is pastoral, raising sheep for their wool. The image is located at 24.4 degrees north latitude and 69.3 degrees east longitude.

The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

2001-01-01

286

Megaliths and Neolithic astronomy in southern Egypt  

NASA Astrophysics Data System (ADS)

The Sahara west of the Nile in southern Egypt was hyperarid and unoccupied during most of the Late Pleistocene epoch. About 11,000 years ago the summer monsoons of central Africa moved into Egypt, and temporary lakes or playas were formed. The Nabta Playa depression, which is one of the largest in southern Egypt, is a kidney-shaped basin of roughly 10km by 7km in area. We report the discovery of megalithic alignments and stone circles next to locations of Middle and Late Neolithic communities at Nabta, which suggest the early development of a complex society. The southward shift of the monsoons in the Late Neolithic age rendered the area once again hyperarid and uninhabitable some 4,800 radiocarbon years before the present (years BP). This well-determined date establishes that the ceremonial complex of Nabta, which has alignments to cardinal and solstitial directions, was a very early megalithic expression of ideology and astronomy. Five megalithic alignments within the playa deposits radiate outwards from megalithic structures, which may have been funerary structures. The organization of the megaliths suggests a symbolic geometry that integrated death, water, and the Sun. An exodus from the Nubian Desert at ~4,800 years BP may have stimulated social differentiation and cultural complexity in predynastic Upper Egypt.

Malville, J. Mckim; Wendorf, Fred; Mazar, Ali A.; Schild, Romauld

1998-04-01

287

Studies on the nutritional status of children aged 0–5 years in a drought-affected desert area of western Rajasthan, India  

Microsoft Academic Search

Objective: The present study was undertaken to assess the impact of drought on the nutritional status of pre-school children aged 0-5 years from a rural population in a desert area facing drought conditions very frequently. Design: The sampling design for assessment was the three-stage sampling technique. Setting: The study was carried out in 24 villages belonging to six tehsils (sub-units

Madhu B Singh; Ranjana Fotedar; J Lakshminarayana; PK Anand

2006-01-01

288

Desert Graphics  

NSDL National Science Digital Library

In this lesson plan students will learn about how climates differ, in particular, how desert climates compare to climates in other areas. They will also learn how meteorologists collect all kinds of weather data, including daily high and low temperatures and average monthly rainfall, from all over the world. Students will use similar weather data to create a graph comparing three climates.

289

Food Deserts  

Microsoft Academic Search

Food deserts and accessibility represent a new frontier in the assault of life-threatening, dietrelated diseases, including diabetes, obesity, hypertension, and atherosclerosis. Scholars represent the research literature from diverse disciplines, such as anthropology, agriculture, sociology, economics, marketing, public policy, sociology, and social epidemiology. Applied sociology has not contributed to this important conversation. Applied sociology's integration and use of theory, methods, and

Anthony Troy Adams; Monika J. Ulrich; Amanda Coleman

2010-01-01

290

Desert Survivors!  

ERIC Educational Resources Information Center

This article describes a special third-grade classroom unit based on the reality show "Survivor." The goal of this engaging and interactive unit was to teach students about physical and behavioral adaptations that help animals survive in various desert biomes. The activity combines research, argument, and puppet play over one week of…

Horton, Jessica; Friedenstab, Steve

2013-01-01

291

Geography of Ancient Egypt  

NSDL National Science Digital Library

This activity focuses on the importance of geographic features and the abundance of natural resources that helped ancient Egypt become the world's first superpower. Students will learn about the geography and resources available to the ancient Egyptians. Read each question below carefully. Using the following maps: modern political map geographical features map natural resources map archaeological sites map And the following features on the Egypt's Golden Empire website: natural resources farming Answer each question below using as much detail as possible. What countries border modern-day Egypt? (modern political map) Name the major bodies of water that surround an are a part of Egypt. (modern political map) What ...

Mr. Myers

2010-09-30

292

Life in Egypt!  

NSDL National Science Digital Library

What is the difference between life in the United States and life in Egypt? Use this fact chart to record your findings! Where is Egypt? Sightseeing in Egypt Use this time to record your findings in the "places" section of your fact chart and complete any other section you can with the information you have learned! Facts about Egypt Language (with audio) A Day in the Life Use this time to record your findings in the "people" section of your fact chart and complete ...

Pendleton, Ms.

2011-04-07

293

Types of Deserts  

NSDL National Science Digital Library

Deserts are classified by their location and dominant weather pattern into several types: trade wind, midlatitude, rain shadow, coastal, monsoon, or polar deserts. Former desert areas presently in nonarid environments are paleodeserts, and extraterrestrial deserts exist on other planets. This site, produced by the U.S. Geological Survey, describes each type of desert using text and photographs.

294

Nile behaviour and Upper Palaeolithic humans in Upper Egypt  

NASA Astrophysics Data System (ADS)

There is evidence of a decreasing human occupation of the Upper Egyptian Nile valley during the MIS 5 to MIS 3 period. Whereas very large extraction sites of the Middle Stone Age have been recorded, only very few sites of the Upper Palaeolithic have been found. The best explanation of this fact is that during the Late Middle Stone Age and the Upper Palaeolithc there was nearly no need for raw materials because there was only a very restricted population present in Upper Egypt. From about 22 ka BP an important population increase is registered by the presence of numerous Late Palaeolithic sites. During the whole LGM there is abundant presence of humans along the Nile Valley in Upper Egypt. This population was mainly living from fishing. There seems to be an abrupt end of the Palaeolithic occupation after 12.8 ka BP. Until now, no sites were found in the Valley until some rare Epipaleolithic sites occur about 8.0 ka BP. It will be suggested that these population changes are influenced by the river Nile behaviour. The best interpretation of the observations in the Upper Egyptian Nile Valley is the hypothesis that at the same time that Nile flow was reduced because of the dryness in its source area, the impact of aeolian activity was increased over Northeast Africa. The increased aeolian activity by northern winds in the Fayum and Wadi Ryan during the LGM resulted in the accumulation of aeolian sand in the valley. That aeolian sand was transported along the western Nile valley cliffs until it was accumulated when the Nile Valley change it S-N direction, such as at Nag'Hammadi. At other places sand was invading the Nile valley, directly from the Western Desert, creating a damming of the Nile at several places such as Armant and Aswan. As Nile flow was quite reduced, the Nile was unable to erode all the incoming sand and the Nile water with its important clay content was dammed. At several places large lakes were created in the Nile Valley. Those lakes were an ideal place for the settlement of the Late Palaeolithic fishers. There came an abrupt end to this situation when the Nile returned to its meandering regime at the end of the LGM. This situation created an catastrophic food crisis for the

Vermeersch, Pierre M.

2014-05-01

295

Desert USA: Desert Animals and Wildlife  

NSDL National Science Digital Library

This great educational website about Desert Animals and Wildlife was created by DesertUSA, a publication designed to explore and educate about "the beauty, life, and culture of North American deserts." The Desert Animals and Wildlife homepage contains extensive lists of links to sites for different Mammals, Birds and Fish, Reptiles and Amphibians, and Insects and Spiders. The animal link selections include the Mexican Gray Wolf, Desert Pupfish, Desert Iguana, and Finback Whale just to name a few. The specific animal pages include photos and information categorized in areas such as Distribution, Habitat, Description, and Life Cycle. There is a feature link to a webpage on Desert Animal Survival, a list of links to relevant DesertUSA Articles and Information, and links to websites dedicated to other DesertUSA subjects such as Plants / Wildflowers, and Peoples and Cultures.

296

Desert Dwellers  

NSDL National Science Digital Library

This lesson plan is part of the discoveryschool.com lesson plan library for grades 9-12. This lesson focuses on desert ecology, geography, and development, with an emphasis on desertification and what can be done to prevent it. It includes objectives, materials, procedures, discussion questions, evaluation ideas, performing extensions, suggested readings, and vocabulary. There are videos available to order which complement this lesson, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.

297

Desert USA: Desert Plants and Wildflowers  

NSDL National Science Digital Library

Desert plants have adapted to the extremes of heat and aridity by using both physical and behavioral mechanisms, much like desert animals. The ingenuity and variety of these many adaptations are explored in a set of links to wildflowers, cacti and succulents, trees, shrubs, and grasses. Links to related topics such as desert plant survival, wildflower articles, and others are also included.

2000-01-01

298

The Cretaceous glauconitic sandstones of Abu Tartur, Egypt  

NASA Astrophysics Data System (ADS)

The Abu Tartur mine is located in the Western Desert of Egypt, 50 km west of El Kharga City. Geologically, the Abu Tartur plateau is built by a sequence of Upper Cretaceous (Campanian - Maastrichtian) phosphorites, black shales and glauconitic sandstones. The phosphate deposits are of great economic importance and have been mined since their discovery in 1967. Outcrop sections were measured, sampled, sedimentologically characterized and described. One specific glaucony layer was investigated mineralogically and chemically in detail and compared to a subsurface sample from the mine. Two depositional regimes can be interpreted based on sedimentary architecture and structures: 1) a deeper-water hemipelagic environment, where phosphorites and organic carbon-rich shales were deposited and 2) a shallower, prograding higher energy shelf environment with glauconies. From a sequence stratigraphic perspective 1) was deposited during the transgressive systems tract and the early highstand while 2) was deposited during the remaining highstand and a lowstand prograding wedge (Glenn & Arthur, 1990). Petrographic and SEM investigations show that the glaucony grains are of authochtonous origin. XRF, EMPA and thin-section analyses show that the glaucony grains from the outcrop differ significantly in their chemical composition, morphology and color from the grains of the mine sample. The fresh glauconies are enriched in Fe2O3 and K2O compared to the surface samples. XRD analyses of the clay fraction of the six outcrop samples and the mine sample show that the grains consist of illite(glauconite)/smectite mixed-layers, with more illite layers (80 %) in the mine sample. The charge distribution diagram muscovite-pyrophyllite-celadonite shows a clear trend from smectitic glaucony to illitic glaucony, the mine sample plots exactly in the field for glauconites. All these features indicate that the surface samples are strongly altered by weathering and that glauconite progressively transforms into iron-rich illte/smectite mixed layers and then into smectites. For any chemical and mineralogical characterization of glauconites at surface, these weathering effects have to be taken into consideration. GLENN, C. R. & ARTHUR, M. A. (1990): Anatomy and origin of a Cretaceous phosphorites-greensand giant, Egypt. Sedimentology, 37, 123-154.

Pestitschek, Brigitte; Gier, Susanne; Essa, Mahmoud; Kurzweil, Johannes

2010-05-01

299

Childbirth in ancient Egypt.  

PubMed

Medicine in ancient Egypt was much more advanced than the rest of the Biblical world, especially in trauma surgery. Care at the time of childbirth was however virtually non-existent. There were no trained obstetricians or midwives but a galaxy of gods were at hand. This article traces what we can piece together about pregnancy of childbirth from the evidence we have in tombs and papyri of Egypt. PMID:15602999

Chamberlain, Geoffrey

2004-11-01

300

Geochemical signatures of Late Holocene paleo-hydrological changes from Phulera and Pokharan saline playas near the eastern and western margins of the Thar Desert, India  

NASA Astrophysics Data System (ADS)

Stratigraphical, mineralogical, geochemical and optical dating methods were used to reconstruct paleo-hydrological changes in two playas (Phulera, 500 mm/a and Pokharan, 200 mm/a) in near extremum climatic regions of the Thar Desert. Sediment successions in shallow profiles from Phulera and Pokharan contain three and four stratigraphic units, respectively, each with characteristic geochemical properties. These units reflect changes in chemical weathering, detrital input, salinity and provide a measure of the changes in precipitation (i.e. monsoon) through time. Sediments from Pokharan suggest short rainfall events during ca. 6.6-4 ka, relatively stable fresh water (higher and persistent rainfall) regime during 4-2.3 ka, and a hyper saline (low rainfall) condition during 2.3-1.1 ka. Sediments at Phulera, record hyper saline (low rainfall) lacustrine conditions during <2.3 ka to >1.4 ka. Higher abundance of gypsum in Pokharan (2.3-1.1 ka) and proto-dolomite in Phulera (2.3-1.4 ka) are nearly synchronous and reflect enhancement of salinity. Selenite crystals in Pokharan and large desiccation cracks in buried horizons at Phulera reflect desiccation of playas at ca. 2 ka. Both playas progressively became less saline after 1.4 ka. Given the regional nature of this record, these changes are attributed to fluctuation of the monsoon over the Indian sub continent.

Roy, P. D.; Nagar, Y. C.; Juyal, N.; Smykatz-Kloss, W.; Singhvi, A. K.

2009-03-01

301

Desert Dust Air Mass Mapping in the Western Sahara, using Particle Properties Derived from Space-based Multi-angle Imaging  

NASA Technical Reports Server (NTRS)

Coincident observations made over the Moroccan desert during the SAhara Mineral dUst experiMent (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from Multi-angle Imaging SpectroRadiometer (MISR) observations, and to place the sub-orbital aerosol measurements into the satellite's larger regional context. On three moderately dusty days for which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05 to 0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR's ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape, and single-scattering albedo. For the three study days, the satellite observations (a) highlight regional gradients in the mix of dust and background spherical particles, (b) identify a dust plume most likely part of a density flow, and (c) show an air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometers away.

Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Fiebig, Marcus; Schladitz, Alexander; von Hoyningen-Huene, Wolfgang

2008-01-01

302

Carbon uptake and change in net primary productivity of oasis-desert ecosystem in arid western China with remote sensing technique  

Microsoft Academic Search

Arid and semi-arid ecosystems exhibit a spatially complex biogeophysical structure. According to arid western special climate-vegetation\\u000a characters, the fractional cover of photosynthetic vegetation (PV), non-photosynthetic vegetation (NPV), bare soil and water\\u000a are unmixed, using the remote sensing spectral mixture analysis. We try the method to unmix the canopy funation structure\\u000a of arid land cover in order to avoid the differentiation

Jie Zhang; Xiaoling Pan; Zhiqiang Gao; Qingdong Shi; Guanghui Lv

2006-01-01

303

3-rd Year Lab course: Mineral Desert Dust Comparison between the Tel-Aviv University dust forecasts and PM10 data  

E-print Network

the Eastern Sahara, through Egypt, into Israel brings both coarse and fine fractions. A long-distance dust3-rd Year Lab course: Mineral Desert Dust Comparison between the Tel-Aviv University dust forecasts and PM10 data 1. Introduction Airborne mineral dust from the world's deserts makes a major contribution

Harnik, Nili

304

Safsaf Oasis, Egypt  

NASA Technical Reports Server (NTRS)

These images show two views of a region of south-central Egypt, each taken by a different type of spaceborne sensor. On the left is an optical image from the Landsat Thematic Mapper, and on the right is a radar image from the Spaceborne Imaging Radar-C/X-band Synthetic Aperture Radar (SIR-C/X-SAR). This comparison shows that the visible and infrared wavelengths of Landsat are only sensitive to the materials on the surface, while the radar wavelengths of SIR-C/X-SAR can penetrate the thin sand cover in this arid region to reveal details hidden below the surface. Field studies in this area indicate that the L-band radar can penetrate as much as 2 meters (6.5 feet) of very dry sand to image buried rock structures. Ancient drainage channels, shown at the bottom of this image, are filled with sand more than 2 meters (6.5 feet) thick and therefore appear dark because the radar waves cannot penetrate them. Only the most recently active channels are visible in the Landsat scene. Some geologic structures at the surface are visible in both images. However, many buried features, such as rock fractures and the blue circular granite bodies in the upper center of the image on the right, are visible only to the radar. The Safsaf Oasis is located near the bright yellow feature in the lower left center of the Landsat image. Scientists are using the penetrating capabilities of radar imaging in desert areas to study structural geology, mineral exploration, ancient climates, water resources and archaeology. Each image is 30.8 kilometers by 25.6 kilometers (19.1 miles by 15.9 miles) and is centered at 22.7 degrees north latitude, 29.3 degrees east longitude. North is toward the upper right. In the Landsat image, the colors are assigned as follows: red is Band 7 (mid-infrared); green is Band 4 (near infrared); and blue is Band 1 (visible blue light). The colors assigned to the radar frequencies and polarizations are as follows: red is L-band, horizontally transmitted and received; green is C-band, horizontally transmitted and received; and blue is X-band, vertically transmitted and received. The radar image was acquired by the Spaceborne Imaging Radar-C/ X-band Synthetic Aperture Radar (SIR-C/X-SAR) on April 16, 1994, on board the space shuttle Endeavour. SIR-C/X-SAR, a joint mission of the German, Italian and United States space agencies, is part of NASA's Earth Science Enterprise. The Landsat Program is managed jointly by NASA, the National Oceanic and Atmospheric Administration and the United States Geological Survey.

Spaceborne Imaging Radar-C and X-Band Synthetic Aperture Radar (SIR-C/X-SAR) is part of NASA's Mission to Planet Earth. The radars illuminate Earth with microwaves allowing detailed observations at any time, regardless of weather or sunlight conditions. SIR-C/X-SAR uses three microwave wavelengths: L-band (24 cm), C-band (6 cm) and X-band (3 cm). The multi-frequency data will be used by the international scientific community to better understand the global environment and how it is changing. The SIR-C/X-SAR data, complemented by aircraft and ground studies, will give scientists clearer insights into those environmental changes which are caused by nature and those changes which are induced by human activity. SIR-C was developed by NASA's Jet Propulsion Laboratory. X-SAR was developed by the Dornier and Alenia Spazio companies for the German space agency, Deutsche Agentur fuer Raumfahrtangelegenheiten (DARA), and the Italian space agency, Agenzia Spaziale Italiana (ASI), with the Deutsche Forschungsanstalt fuer Luft und Raumfahrt e.v.(DLR), the major partner in science, operations, and data processing of X-SAR.

1998-01-01

305

Desert Voices: Southwestern Children's Literature.  

ERIC Educational Resources Information Center

Examines three books with different ways of writing about the desert. Discusses: "Here Is the Southwestern Desert" by Madeline Dunphy, "The Desert Is My Mother" by Pat Mora, and "The Desert Mermaid" by Alberto Blanco. (PA)

Polette, Keith

1997-01-01

306

76 FR 28767 - Desert Southwest Customer Service Region-Rate Order No. WAPA-152  

Federal Register 2010, 2011, 2012, 2013

...Intertie) and Ancillary Services Rates for Western Area...existing NITS and Ancillary Services formula rates expire...FURTHER INFORMATION CONTACT: Mr. Darrick Moe...Manager, Desert Southwest Customer Service Region, Western...

2011-05-18

307

Desert USA: Desert Animals And Wildlife  

NSDL National Science Digital Library

It is a miracle that life can survive in the extreme conditions of the desert. Users can learn about mammals (including wolves), insects and spiders, fish and birds(including hawks), and reptiles and amphibians (including rattlesnakes) that have adapted and, in fact, thrive in the harsh desert ecosystems. Links to related topics such as animal survival in the desert and animal rescues are included.

2000-01-01

308

Animal brucellosis in Egypt.  

PubMed

Brucellosis is a highly contagious zoonosis that affects the public health and economic performance of endemic as well as non-endemic countries. In developing nations, brucellosis is often a very common but neglected disease. The purpose of this review is to provide insight about brucellosis in animal populations in Egypt and help to understand the situation from 1986 to 2013. A total of 67 national and international scientific publications on serological investigations, isolation, and biotyping studies from 1986 to 2013 were reviewed to verify the current status of brucellosis in animal populations in Egypt. Serological investigations within the national surveillance program give indirect proof for the presence of brucellosis in cattle, buffaloes, sheep, goats, and camels in Egypt. Serologic testing for brucellosis is a well-established procedure in Egypt, but most of the corresponding studies do not follow the scientific standards. B. melitensis biovar (bv) 3, B. abortus bv 1, and B. suis bv 1 have been isolated from farm animals and Nile catfish. Brucellosis is prevalent nationwide in many farm animal species. There is an obvious discrepancy between official seroprevalence data and data from scientific publications. The need for a nationwide survey to genotype circulating Brucellae is obvious. The epidemiologic situation of brucellosis in Egypt is unresolved and needs clarification. PMID:25390047

Wareth, Gamal; Hikal, Ahmed; Refai, Mohamed; Melzer, Falk; Roesler, Uwe; Neubauer, Heinrich

2014-11-01

309

Where Deserts Form  

NSDL National Science Digital Library

Most of Earth's deserts can be found in dry areas created by global circulation patterns. The deserts of our world are not restricted by latitude, longitude, or elevation. This site, produced by the U.S. Geological Survey, uses text and pictures to describe how atmospheric circulation patterns influence the locations of deserts on Earth and possibly on other terrestrial planets as well.

310

SHUTTLE IMAGING RADAR PROVIDES FRAMEWORK FOR SUBSURFACE GEOLOGIC EXPLORATION IN EGYPT AND SUDAN.  

USGS Publications Warehouse

Shuttle Imaging Radar provides a pictorial framework to guide exploration for mineral resources (potential placers), groundwater sources, and prehistoric archaeological sites in the Western Desert of Egypt and Sudan. Documented penetration by the SIR-A signal of dry surficial sediment to depths of a meter or more revealed bedrock geologic features and networks of former stream valleys otherwise concealed beneath windblown sand, alluvium, and colluvial deposits. 'Radar units' mapped on SIR-A images according to relative brightness and degree of mottling correspond to subsurface geologic and topographic features identified in more than 50 test pits. Petrologic examination of pit samples confirms that a variety of depositional environments existed in this now hyper-arid region before it was mantled by windblown sand sheets and dunes. Wet sand was discovered in two buried valleys shown on the radar images and located in the field with the aid of co-registered maps and Landsat images, and a satellite navigation device. Buried valleys whose streams once traversed mineralized zones are potential sites of placers (gold, tin).

Breed, Carol S.; McCauley, John F.; Schaber, Gerald G.

1984-01-01

311

Recent environmental change and prehistoric human activity in Egypt and Northern Sudan  

NASA Astrophysics Data System (ADS)

This paper reviews the various Late Quaternary records that are available from western Egypt and northern Sudan, which includes more than 500 published radiocarbon dates and various sedimentary archives from local landscape components, including palaeolakes, soils, drainages (wadis), and archaeological sites. This palaeoenvironmental compilation frames the spatial and temporal context of local cultural activities when the region was most hospitable ˜9000-6000 BP; at this time, monsoonal weather influenced the portion of the African continental interior, creating enough convective rainfall for occasional surface water storage. In this part of the modern Sahara, rapid hydroclimatic changes play a key role in geomorphic evolution and resource availability. As 'watering holes' formed and dried up in the Early to Middle Holocene, Neolithic people developed various subsistence strategies, including opportunistic hunting of small animals (e.g. gazelle and hare), and food-related (e.g. wild sorghum, millet, and legumes) activities: gathering, plant cultivation and livestock-rearing. During its wettest phases during the 'monsoonal maximum,' the area was drought-prone, sustaining a meager steppe-shrub desert flora. Further desertification and aeolian deflation during the Middle and Late Holocene fostered technological innovation, migration and settlement, as well as the further development of agrarian communities and complex culture.

Nicoll, Kathleen

2004-03-01

312

Desert Fishes Council  

NSDL National Science Digital Library

Desert fish biologists have a one-stop information resource in this comprehensive Web site from the Desert Fishes Council (DFC), an organization established to "preserve the biological integrity of desert aquatic ecosystems and their associated life forms, to hold symposia to report related research and management endeavors, and to effect rapid dissemination of information concerning activities of the Council and its members." Any interested user may freely access field-related news and conference proceedings; ten desert fish videos; the Desert Fishes Council Listserv; and a number of databases offering taxonomic information, distribution maps, photos, and more.

313

249BERRY ET AL. --Defining the Desert Tortoise(s) Chelonian Conservation and Biology, 2002, 4(2):249262  

E-print Network

pavementswithcreosotebushandocotillobrokenbymicro- phyll woodland washes typical of the western Sonoran Desert (Fig. 2; U.S. Fish and Wildlife verde­saguaro cactuscommunitiesoftheSonoranDesertuplandsaswellas ecotonal desert grasslands (Martin, 1995; Averill-Murray et al., 2002a; Van Devender, 2002b). In Mexico, habitats include Sonoran Desert

Murphy, Bob

314

Geoarchaeology: An International Journal, Vol. 16, No. 1, 35 (2001) 2001 John Wiley & Sons, Inc.  

E-print Network

that initial expedition, he joined Fred Wendorf and Romuald Schild in the Western Desert of Egypt, where he that Egypt was not always as desolate as described by early desert ex- plorers and researchers on a variety of geomorphic settings extending from the Libyan Plateau, west into the Western Desert of Egypt

Nicoll, Kathleen

315

Female desert bighorn sheep in the Sonora desert  

NSDL National Science Digital Library

Desert bighorn sheep use a lot of energy to regulate their internal temperature in the desert. During the summer the sheep eat plants and drink water every few days. In the winter, desert plants contain enough water for sheep survival.

Katie Hale (California State University, Fullerton;Student, Biological Sciences)

2007-01-13

316

[Medical education in Egypt].  

PubMed

Modern medical training in Egypt was started by Antoine Clot Bey in 1837 and became part of the university programme in 1919. At present, it comprises six years of university education, followed by one year of internships and one year of compulsory employment with a state-owned hospital. There are now 13 medical faculties in Egypt, using three different curricula: traditional, Islamic and innovative. Their implementation is hampered by the large number of students (15,500 men and 7500 women), the low salaries and motivation of the instructors, the teaching in English rather than Arabic and the lack of recent study materials. It is therefore rather difficult to compare the effectiveness of the Egyptian system with that in the Netherlands. Due partly to the differences in language and culture, Dutch authorities are reluctant to recognise Egyptian medical diplomas. PMID:12092309

Barnard, H

2002-06-15

317

New paleocene sepiid coleoids (cephalopoda) from Egypt: evolutionary significance and origin of the sepiid 'rostrum'.  

PubMed

New coleoid cephalopods, assignable to the order Sepiida, are recorded from the Selandian/Thanetian boundary interval (Middle to Upper Paleocene transition, c. 59.2 Ma) along the southeastern margin (Toshka Lakes) of the Western Desert in Egypt. The two genera recognised, Aegyptosaepia n. gen. and ?Anomalosaepia Weaver and Ciampaglio, are placed in the families Belosaepiidae and ?Anomalosaepiidae, respectively. They constitute the oldest record to date of sepiids with a 'rostrum-like' prong. In addition, a third, generically and specifically indeterminate coleoid is represented by a single rostrum-like find. The taxonomic assignment of the material is based on apical parts (as preserved), i.e., guard, apical prong (or 'rostrum-like' structure), phragmocone and (remains of) protoconch, plus shell mineralogy. We here confirm the shell of early sepiids to have been bimineralic, i.e., composed of both calcite and aragonite. Aegyptosaepia lugeri n. gen., n. sp. reveals some similarities to later species of Belosaepia, in particular the possession of a distinct prong. General features of the phragmocone and protoconch of the new form are similar to both Belocurta (Middle Danian [Lower Paleocene]) and Belosaepia (Eocene). However, breviconic coiling and the presence of a longer ventral conotheca indicate closer ties with late Maastrichtian-Middle Danian Ceratisepia. In this respect, Aegyptosaepia n. gen. constitutes a link between Ceratisepia and the Eocene Belosaepia. The occurrence of the new genus near the Selandian/Thanetian boundary suggests an earlier origin of belosaepiids, during the early to Middle Paleocene. These earliest known belosaepiids may have originated in the Tethyan Realm. From northeast Africa, they subsequently spread to western India, the Arabian Plate and, probably via the Mediterranean region, to Europe and North America. PMID:24348918

Koš?ák, Martin; Jagt, John W M; Speijer, Robert P; Stassen, Peter; Steurbaut, Etienne

2013-01-01

318

What's It Like Where You Live? Desert  

NSDL National Science Digital Library

This site provides excellent background information on deserts. Large print and superb pictures make this site very appealing to younger students. Topics include: What is a Desert Like?, Types of Deserts, What causes Deserts?, Deserts of the World, Desert Plants, Desert Animals, and links to other desert sites.

2002-01-01

319

Climate Change and the Fate of Desert Springs  

NASA Astrophysics Data System (ADS)

Springs are integral components of the unique web of life in desert ecosystems of the western United States. Many desert springs would not exist without local mountains to intercept and store water from rainfall and snowmelt, and many desert aquatic ecosystems would not exist without the springs, illustrating the connectivity between landscape processes (the realm of geoscientists) and ecosystem functioning (the realm of ecologists). On a human scale, early exploration, inhabitation, and survival in the arid and semiarid western United States would not have been feasible without springs. People living there today continue to value springs as dependable sources of water for irrigation, livestock, drinking, and recreational and economic uses (e.g., hot springs). Unfortunately, some desert springs may be less resistant to the effects of climate change than others. How can this resistance be quantified?

Frisbee, Marty D.; Wilson, John L.; Sada, Donald W.

2013-04-01

320

Mental health in Egypt.  

PubMed

The concepts and management of mental health in Egypt are presented from the Pharaonic era through the Islamic Renaissance until today. Papyri from the Pharaonic period show that Soma and Psyche were not differentiated and mental disorders were described as symptoms of the heart and uterus. Although theories of causation were of a mystical nature, mental disorders were treated on a somatic basis. In the Islamic era, mental patients were neither maltreated nor tortured as a consequence of the belief that they may be possessed by a good Moslem genie. In the 14th century mental disorders was one of the four departments in Cairo's Kalawoon Hospital, a precursor of the place of psychiatry in general hospitals that was accepted in Europe six centuries later. The mental health services in Egypt today are described, and transcultural studies carried out in Egypt of the prevalence and phenomenology of anxiety, schizophrenia, depression, suicide, conversion and obsessive compulsive disorders are reviewed. The psychiatric services for children are in their infancy. Since 1983 the common and semi-accepted use of hashish has been joined by abuse by heroin and other substances. PMID:16342608

Okasha, Ahmed

2005-01-01

321

Desert Water Keepers  

NSDL National Science Digital Library

In this outdoor, sunny day activity, learners experiment with paper leaf models to discover how some desert plants conserve water. Learners explore adaptations of various desert plants such as waxy coatings, thick stems, and spines and fine hairs to see which characteristics best help a plant hold water. Learners compare their model leaves to real desert leaves if they are available. Even in a nondesert region, the activity can be done at a local botanical garden that may include a desert plant collection or in any hot, dry area.

Science, Lawrence H.

1980-01-01

322

Reclaiming freshwater sustainability in the Cadillac Desert  

USGS Publications Warehouse

Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%.

Sabo, John L.; Sinha, Tushar; Bowling, Laura C.; Schoups, Gerrit H.W.; Wallender, Wesley W.; Campana, Michael E.; Cherkauer, Keith A.; Fuller, Pam L.; Graf, William L.; Hopmans, Jan W.; Kominoski, John S.; Taylor, Carissa; Trimble, Stanley W.; Webb, Robert H.; Wohl, Ellen E.

2010-01-01

323

Reclaiming freshwater sustainability in the Cadillac Desert  

PubMed Central

Increasing human appropriation of freshwater resources presents a tangible limit to the sustainability of cities, agriculture, and ecosystems in the western United States. Marc Reisner tackles this theme in his 1986 classic Cadillac Desert: The American West and Its Disappearing Water. Reisner's analysis paints a portrait of region-wide hydrologic dysfunction in the western United States, suggesting that the storage capacity of reservoirs will be impaired by sediment infilling, croplands will be rendered infertile by salt, and water scarcity will pit growing desert cities against agribusiness in the face of dwindling water resources. Here we evaluate these claims using the best available data and scientific tools. Our analysis provides strong scientific support for many of Reisner's claims, except the notion that reservoir storage is imminently threatened by sediment. More broadly, we estimate that the equivalent of nearly 76% of streamflow in the Cadillac Desert region is currently appropriated by humans, and this figure could rise to nearly 86% under a doubling of the region's population. Thus, Reisner's incisive journalism led him to the same conclusions as those rendered by copious data, modern scientific tools, and the application of a more genuine scientific method. We close with a prospectus for reclaiming freshwater sustainability in the Cadillac Desert, including a suite of recommendations for reducing region-wide human appropriation of streamflow to a target level of 60%. PMID:21149727

Sabo, John L.; Sinha, Tushar; Bowling, Laura C.; Schoups, Gerrit H. W.; Wallender, Wesley W.; Campana, Michael E.; Cherkauer, Keith A.; Fuller, Pam L.; Graf, William L.; Hopmans, Jan W.; Kominoski, John S.; Taylor, Carissa; Trimble, Stanley W.; Webb, Robert H.; Wohl, Ellen E.

2010-01-01

324

STONE PAVEMENTS IN DESERTS  

Microsoft Academic Search

Stone pavements are armored surfaces comprising intricate mosaics of coarse particles, usually only one or two stones thick, set on or in fine material. They occur widely in many unvegetated areas, and preeminently in hot deserts. Pavement studies in several deserts, and especially in Chile and California, suggest that: 1) deflation may be a relatively unimportant process of pavement formation;

RONALD U. COOKE

1970-01-01

325

Desert Perchlorate Field Work  

USGS Multimedia Gallery

USGS scientists dig soil pits in Nevada's Amargosa Desert to study the distribution of natural perchlorate and to determine the atmospheric-soil-plant interactions that affected perchlorate's cycling in a terrestrial ecosystem. Amargosa Desert, Nevada ~17 km south of Beatty; ~20 km east of D...

326

The effect of drought on four plant communities in the northern Mojave Desert  

SciTech Connect

Desert plant communities contain many perennial plant species that are well adapted to arid environments; therefore, one would intuitively believe that perennial desert species readily survive drought conditions. Abundant research on plant-soil-water relationships in North American deserts has shown that many species can maintain water uptake and growth when the soil-water potential is low. Little research, however, has focused on how prolonged drought conditions affect plant species in vegetation associations in desert ecosystems. A prolonged and widespread drought occurred in much of the western United States, including the Northern Mojave Desert, from 1987 through 1991. During this drought period vegetation characterization studies, initiated in 1990, by the US Department of Energy (DOE) at Yucca Mountain, Nevada, allowed EG and G Energy Measurements to collect data that could be used to infer how both desert vegetation associations and desert plant species reacted to a prolonged drought. This paper presents the preliminary results.

Schultz, B.W. [Desert Research Inst., Reno, NV (United States); Ostler, W.K. [EG and G Energy Measurements, Inc., Las Vegas, NV (United States)

1993-12-31

327

Calcareous benthonic foraminifera across the Cretaceous/Paleocene transition of Gebel Um El-Ghanayem, Kharga Oasis, Egypt  

NASA Astrophysics Data System (ADS)

The studies of benthic calcareous foraminifera of the Maastrichtian-early Paleocene Dakhla Formation in Gebel Um El-Ghanayem (Western Desert, Egypt), improve reconstruction of depositional environments of these successions. In total, 68 taxa of benthic foraminifera were identified in the studied succession. The late Maastrichtian assemblages (Zone CF3) are dominated by calcareous foraminifera with tapered tests, this tapered taxon Loxostomum applinae, Lox. tegulatum various dentalinid taxa, and Buliminella cushmani dominate in CF3 Biozone. We thus interpret these faunas as being dominated by infaunal morphogroups, suggesting a moderately eutrophic environment. Danian assemblages are characterized by abundant epifaunal trochospiral species, such as Cibicidoides abudurbensis, Cibicidoides farafraensis, and Gyroidinoides girardanus. The infaunal morphogroups make up 25-47% of fauna in the Danian, in contrast to 62-76% in the Upper Maastrichtian. This dominance of the Danian benthic foraminiferal assemblages by epifaunal or mixed epifaunal/infaunal morphogroups suggests that the food supply to the benthos was less abundant than in the latest Cretaceous. The Cretaceous/Paleocene boundary (K/Pg) is within the upper unit of the Lower Kharga Member and marked by a hiatus in at least the top of CF3 Zone of the Upper Maastrichtian to the Lower Paleocene (base Plc Zone).

Orabi, Orabi H.; Khalil, Hamza M.

2014-08-01

328

Gastroenterology in ancient Egypt.  

PubMed

Physicians in ancient Egypt devoted their care to disorders of individual organs. Notable among the specialties was gastroenterology, a subject matter that occupied a major portion of the surviving medical papyri. Although they did not name diseases as we know them, Pharaonic physicians described a host of gastroenterological symptoms for which an extensive array of therapeutics was prescribed. Their clinical accounts indicated an impressive knowledge of gastric and anorectal conditions. In their thinking on disease mechanism, the circulating materia peccans absorbed from feces represented a major cause of medical symptoms and disorders. This served as the rationale for the popular practice of self-purgation with enemas. PMID:2033225

Chen, T S; Chen, P S

1991-04-01

329

Schistosomiasis and Cancer in Egypt: Review  

PubMed Central

Schistosomiasis is not known to be associated with any malignant disease other than bladder cancer. Bladder cancer is still the most common malignant tumor among males in Egypt and some African and Middle East countries. However, the frequency rate of bladder cancer has declined significantly during the last 25 years. This drop is mainly related to the control of Schistosomiasis. Many studies have elucidated the pathogenic events of Schistosomal-related bladder cancer with a suggested theory of pathogenesis. Furthermore, the disease presents with a distinct clinicopathologic profile that is quite different from bladder cancer elsewhere with younger age at presentation, more male predominance, more invasive stages, and occurrence of squamous cell carcinoma pathologic subtype. However, recent data suggest that this profile has been dramatically changed over the past 25 years leading to minimization of the differences between its features in Egypt and that in Western countries. Management of muscle-invasive localized disease is mainly surgery with 5-year survival rates of 30–50%. Although still a debatable issue, adjuvant and neoadjuvant chemotherapy and radiotherapy have improved treatment outcomes including survival and bladder preservation rates in most studies. This controversy emphasizes the need of individualized treatment options based on a prognostic index or other factors that can define the higher risk groups where more aggressive therapy is needed. The treatment for locally advanced and/or metastatic disease has passed through a series of clinical trials since 1970s. These phase II and III trials have included the use of single agent and combination of chemotherapy and radiotherapy regimens. The current standard of systemic chemotherapy of generally fit patients is now the gemcitabine–cisplatin combination. In conclusion, a changing pattern of bladder cancer in Egypt is clearly observed. This is mainly due to the success in the control of Schistosomiasis. It may also be due to increased exposure to other etiologic factors that include smoking, pesticides, and/or other causative agents. This change will ultimately affect disease management.

Khaled, Hussein

2013-01-01

330

Deserts : geology and resources  

USGS Publications Warehouse

Approximately one-third of the Earth's land surface is desert, arid land with meager rainfall that supports only sparse vegetation and a limited population of people and animals. Deserts stark, sometimes mysterious worlds have been portrayed as fascinating environments of adventure and exploration from narratives such as that of Lawrence of Arabia to movies such as "Dune." These arid regions are called deserts because they are dry. They may be hot, they may be cold. They may be regions of sand or vast areas of rocks and gravel peppered with occasional plants. But deserts are always dry. Deserts are natural laboratories in which to study the interactions of wind and sometimes water on the arid surfaces of planets. They contain valuable mineral deposits that were formed in the arid environment or that were exposed by erosion. Because deserts are dry, they are ideal places for human artifacts and fossils to be preserved. Deserts are also fragile environments. The misuse of these lands is a serious and growing problem in parts of our world.

Walker, Alta Sharon

1996-01-01

331

What Is A Desert?  

NSDL National Science Digital Library

Approximately one-third of the Earth's land surface is desert, arid land with meager rainfall that supports only sparse vegetation and a limited population of people and animals. Deserts are also fragile environments. The misuse of these lands is a serious and growing problem in parts of our world. This web page, produced by the U.S. Geological Survey, describes how deserts are defined and classified. It features text, photographs, and a map showing the distribution of non-polar arid land.

332

DISTRIBUTIONAL CHANGES AND POPULATION STATUS FOR AMPHIBIANS IN THE EASTERN MOJAVE DESERT  

EPA Science Inventory

A number of amphibian species historically inhabited sparsely distributed wetlands in the Mojave Desert of western North America, habitats that have been dramatically altered or eliminated as a result of human activities. The population status and distributional changes for amphi...

333

88 2012 desert symposium Earliest delivery of sediment from the  

E-print Network

88 2012 desert symposium Earliest delivery of sediment from the Colorado River to the Salton Trough et al., 2008, 2011). Despite recent advances, age constraints from two locations challenge our California and northwestern Mexico, and location of Split Mountain Gorge (SMG, star) in the western Salton

Dorsey, Becky

334

Understanding attacks on tourists in Egypt  

Microsoft Academic Search

This article analyses the relationship between tourism and the terrorist attacks carried out by Muslim groups during the past two years in Egypt. The paper examines the relationship between Islam, hospitality and the notion of tourism — and finds that Islam does not reject tourism per se. However, the nature of tourism development in Egypt, and especially in Upper Egypt,

Heba Aziz

1995-01-01

335

Empire and Muslim conversion: historical reflections on Christian missions in Egypt  

Microsoft Academic Search

This article considers Christian evangelization among Muslims in the late nineteenth and twentieth centuries and traces its relationship to the global and local dynamics of Western imperialism. Focusing on Egypt, where Anglo-American Protestant missionaries were active, the article examines why missionaries encountered fierce resistance from Muslim audiences despite the small number of Muslim conversions and how they inadvertently galvanized Egyptian

Heather J. Sharkey

2005-01-01

336

PALM DESERT ENERGY INDEPENDENCE PROGRAM  

E-print Network

PALM DESERT ENERGY INDEPENDENCE PROGRAM SUMMARY OF LOAN PROCESS Proiect Scopina The first step by the property owner. Applications and instructions are available online at the Palm Desert web site that the applicant is the property owner through a City of Palm Desert contract with a nationally-recognized title

Kammen, Daniel M.

337

BIODIVERSITY Sonoran Desert Ecosystem transformation  

E-print Network

BIODIVERSITY RESEARCH Sonoran Desert Ecosystem transformation by a C4 grass without the grass Sonoran Desert Arizona Upland of the Santa Catalina Mountains, Arizona, USA. Methods We measured species was significantly lower in plots with dominant P. ciliare cover. Main conclusions Rich desert scrub (15­25 species

338

Impact of highway geometry and posted speed on operating speed at multi-lane highways in Egypt  

PubMed Central

The paper presents an analysis of roadway factors and posted speed limits that affect the operating speed at multi-lane highways in Egypt. Field data on multi-lane highways in Egypt are used in this investigation. The analysis considers two categories of highways. The first consists of two desert roads (Cairo–Alexandria and Cairo–Ismailia desert roads) and the second consists of two agricultural roads (Cairo–Alexandria and Tanta–Damietta agricultural roads). The paper includes three separate relevant analyses. The first analysis uses the regression models to investigate the relationships between operating speed (V85) as dependent variable, and roadway factors and posted speed as independent variables. The road factors are lane width, shoulder width, pavement width, median width, number of lanes in each direction, and existence of side access along each section. The second analysis uses the Artificial Neural Network (ANN) to explore the previous relationships while the third one examines the suitability of the posted speed limits on the roads under study. It is found that the ANN modeling gives the best model for predicting the operating speed and the most influential variables on V85 are the pavement width, followed by the median width and the existence of side access along section. It is also found that the posted speed limit has a very small effect on the operating speed due to the bad behavior of drivers in Egypt. These results are so important for controlling V85 on multi-lane rural highways in Egypt.

Semeida, Ahmed M.

2012-01-01

339

Infectious diseases in ancient Egypt.  

PubMed

Techniques for studying infectious disease in the ancient world are discussed. A brief survey of infectious diseases, such as schistosomiasis and malaria, in ancient Egypt is presented, and the physical traces of these diseases are examined. A discussion of the ancient Egyptian physician's response to infectious disease is included. There are two substantial sources of evidence for infectious diseases-physical remains and descriptions in Egyptian medical papyri. This preliminary survey suggests that ancient Egypt was far from the idyllic paradise on the Nile that some historians would like to imagine. PMID:15081501

Brier, Bob

2004-03-01

340

The application of petrophysics to resolve fluid flow units and reservoir quality in the Upper Cretaceous Formations: Abu Sennan oil field, Egypt  

NASA Astrophysics Data System (ADS)

Petrophysical flow unit concept can be used to resolve some of the key challenges faced in the characterization of hydrocarbon reservoirs. The present study deals with petrophysical evaluation of some physical properties of the Upper Cretaceous rock samples obtained from the Abu-Roash and the Bahariya Formations at southwest of Sennan oil field in the Western Desert of Egypt. The aim of this study was achieved through carrying out some petrophysical measurements of porosity, bulk density, permeability, mean hydraulic radius (Rh), irreducible water saturation, and radius of pore throat at mercury saturation of 35% in order to determine reservoir characteristics. In this study, the relationships obtained between the measured petrophysical properties such as porosity, permeability and pore throat flow unit types were established for 53 sandstone core samples obtained from two different stratigraphic units. Flow zone indicator (FZI) has been calculated to quantify the flow character of the Abu-Roash and Bahariya reservoir rocks based on empirically derived equations of robust correlation coefficients. The correlations among porosity, permeability, bulk density, mean hydraulic radius and pore throat flow properties reflect the most important reservoir behavior characteristics. The calculated multiple regression models indicate close correlation among petrophysical properties and Rh and R35%. The obtained models are able to predict Rh and R35% by using porosity and permeability, to map reservoir performance and predict the location of stratigraphic traps.

Lala, Amir Maher Sayed; El-sayed, Nahla Abd El-Aziz

2015-02-01

341

Modified Grey Model and its application to groundwater flow analysis with limited hydrogeological data: a case study of the Nubian Sandstone, Kharga Oasis, Egypt.  

PubMed

Groundwater flow at Kharga Oasis, located in the western desert of Egypt, was previously analyzed using numerical models; however, the lack of basic data often limits the implementation of these models, as well as introducing a problem for model calibration and validation. The Grey Model (GM) was used to overcome these difficulties of data limitation and uncertainty of hydrogeological conditions. However, no clear theories exist for selecting the number of input model trends and the most suitable values of input parameters. Therefore, in the current study, a modification of the GM is newly proposed and called the Modified Grey Model (MGM) in an attempt to determine a process for selecting the best input models' trends with the appropriate values of input parameters to achieve acceptable fitting to observations. The sensitivity analysis results showed that the MGM produced more stable results than the GM using a wide range of values for input parameters. Moreover, the MGM reduced the calculation time required for fitting the measured piezometric level trends by 99.8%. Three development scenarios of groundwater withdrawal were proposed that involved either expanding the present extraction rate or redistributing the groundwater withdrawal over the recent working production wells (RWPWs). The results concluded that the groundwater table in the northern part of the oasis could be temporally recovered to an economical piezometric level; however, the table in the southern part is severely decreased. Therefore, new production wells are recommended to be constructed in the southern part far enough from the RWPWs. PMID:24092253

Mahmod, Wael Elham; Watanabe, Kunio

2014-02-01

342

Analysis of groundwater flow in arid areas with limited hydrogeological data using the Grey Model: a case study of the Nubian Sandstone, Kharga Oasis, Egypt  

NASA Astrophysics Data System (ADS)

Management of groundwater resources can be enhanced by using numerical models to improve development strategies. However, the lack of basic data often limits the implementation of these models. The Kharga Oasis in the western desert of Egypt is an arid area that mainly depends on groundwater from the Nubian Sandstone Aquifer System (NSAS), for which the hydrogeological data needed for groundwater simulation are lacking, thereby introducing a problem for model calibration and validation. The Grey Model (GM) was adopted to analyze groundwater flow. This model combines a finite element method (FEM) with a linear regression model to try to obtain the best-fit piezometric-level trends compared to observations. The GM simulation results clearly show that the future water table in the northeastern part of the study area will face a severe drawdown compared with that in the southwestern part and that the hydraulic head difference between these parts will reach 140 m by 2060. Given the uncertainty and limitation of available data, the GM produced more realistic results compared with those obtained from a FEM alone. The GM could be applied to other cases with similar data limitations.

Mahmod, Wael Elham; Watanabe, Kunio; Zahr-Eldeen, Ashraf A.

2013-08-01

343

Eyewitness introduction to Egypt: "The gift of the Nile".  

PubMed

Northeastern corner of Africa, lying at the crossroads between the two continents of Europe and Asia (in the Sinai Peninsula), while bordering Libya, Sudan, Israel and the Red Sea. Egypt is the most ancient tourist country in the world. Several health fact-finding missions in the last few years were made to this small country that is frequently defined by the Valley of the Nile. With the spreading deserts on either side, or a very rich heritage of ancient relics, these scenic vistas are without equal elsewhere in the world. Although there are significant cultural differences among the population, Egypt has a long history of ethnic and religious compassion. Among the many rarities, main tourist attractions include the three great Pyramids of Giza and the Sphinx, amazing ancient wonders of the world. These fact-finding missions included how health and medical care are defined, how people and culture are intertwined with its physical features, land use, and the economy and its resources. PMID:19927898

Brown, Geraldine

2009-01-01

344

Desert Adaptations: Water  

NSDL National Science Digital Library

In this activity, students experiment with methods of water conservation by desert plants and animals. They will learn to observe a model situation and make inferences about real organisms, use a balance and record data, and describe and communicate observations relating to specialized organisms and interaction with a dry environment.

1998-01-01

345

Geospatial Revolution: Food Deserts  

NSDL National Science Digital Library

Food deserts refer to a lack of easy access to nutritious food. They exist all over America as an outcome of poverty. This video from Penn State Public Broadcasting’s Geospatial Revolution shows how geospatial technology can help change this reality.

Wpsu

2010-11-11

346

Egypt's falling IMR.  

PubMed

In Egypt, the infant mortality rate (IMR) has been reduced from 120/1000 live births in 1979 to 55/1000 births in 1988. This is one of the fastest declines of a country's IMR on record. A government commitment to increase per capita GNP and to meet the health and welfare needs of the people contributed to decline in the IMR. In the 1950s and 1960s, the Egyptian government executed a land reform program while it also assisted farmers with advice and extension services. These events greatly increased crop production which in turn led to an improvement in the people's quality of life. Other factors that helped the IMR to decrease were not planned. For example, employment opportunities expanded throughout the Middle East. Egyptians who took these jobs sent money back to their villages, therefore adding to the village's resources. As a result of this departure of manpower, real agricultural wages for the landless increased substantially. In addition, the highly motivated farmers increased production which caused an increase in jobs and demand for work. The US also played a significant role in the fall of the IMR. US aid concentrated on programs that would reduce the incidence of many infectious diseases that mostly strike infants and children 5 years old. Examples include immunization programs, village sanitation and safe water and drainage projects, and an oral rehydration project. The aforementioned examples of the Egyptian government and people's total commitment to the development of their economy and the improvement in the standard of living all contributed to the rapid decline of the IMR. PMID:12282155

1988-08-31

347

A study of Desert Dermatoses in the Thar Desert Region  

PubMed Central

Introduction: Desert dermatology describes the cutaneous changes and the diseases affecting those living in the desert. Diurnal variation in temperature is high and is characteristic of the deserts. The lack of water affects daily activities and impacts dermatological conditions. Adaptation to the desert is therefore important to survival. This original article focuses on dermatoses occurring in a population in the Thar desert of India, predominantly located in Rajasthan. Materials and Methods: This is a descriptive study involving various dermatoses seen in patients residing in the Thar desert region over a duration of 3 years. Results: Infections were the most common condition seen among this population and among them fungal infections were the most common. The high incidence of these infections would be accounted for by the poor hygienic conditions due to lack of bathing facilities due to scarcity of water and the consequent sweat retention and overgrowth of cutaneous infective organisms. Pigmentary disorders, photodermatoses, leishmaniasis and skin tumors were found to be more prevalent in this region. Desert sweat dermatitis was another specific condition found to have an increased incidence. Conclusion: The environment of the desert provides for a wide variety of dermatoses that can result in these regions with few of these dermatoses found in much higher incidence than in other regions. The concept of desert dermatology needs to be understood in more details to provide better care to those suffering from desert dermatoses and this article is a step forward in this regard. PMID:25657392

Chatterjee, Manas; Vasudevan, Biju

2015-01-01

348

ASTER View of Sharm El Sheik, Egypt  

NASA Technical Reports Server (NTRS)

The Red Sea golf resort in Sharm El Sheik, Egypt, where President Clinton met with Israeli Prime Minister Ehud Barak and Palestinian Authority President Yasser Arafat, stands out against the desert landscape in this image acquired on August 25, 2000.

This image of the southern tip of the Sinai Peninsula shows an area about 30 by 40 kilometers (19 by 25 miles) in the visible and near infrared wavelength region. Vegetation appears in red. The blue areas in the water at the top and bottom of the image are coral reefs. The airport is visible just to the north of the golf resort.

Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is one of five Earth-observing instruments launched December 18, 1999, on NASA's Terra satellite. The instrument was built by Japan's Ministry of International Trade and Industry. A joint U.S./Japan science team is responsible for validation and calibration of the instrument and the data products. Dr. Anne Kahle at NASA's Jet Propulsion Laboratory, Pasadena, Calif., is the U.S. Science team leader; Moshe Pniel of JPL is the project manager. ASTER is the only high resolution imaging sensor on Terra. The primary goal of the ASTER mission is to obtain high-resolution image data in 14 channels over the entire land surface, as well as black and white stereo images. With revisit time of between 4 and 16 days, ASTER will provide the capability for repeat coverage of changing areas on Earth's surface.

The broad spectral coverage and high spectral resolution of ASTER will provide scientists in numerous disciplines with critical information for surface mapping, and monitoring dynamic conditions and temporal change. Example applications are: monitoring glacial advances and retreats, monitoring potentially active volcanoes, identifying crop stress, determining cloud morphology and physical properties, wetlands Evaluation, thermal pollution monitoring, coral reef degradation, surface temperature mapping of soils and geology, and measuring surface heat balance.

2000-01-01

349

Egypt: The Anatomy of Succession  

Microsoft Academic Search

This article examines how the procedural aspects of Egypt's first presidential elections permitted the ruling regime to persist without a serious challenge. By taking stock of how the procedural rules of the game were manipulated to favour the incumbent, and the creation of an administrative body with extra- judicial powers guaranteeing the known result, this article will argue that the

Joshua Stacher

2008-01-01

350

Muslim Brotherhood in Egypt & Sudan  

Microsoft Academic Search

This article compares the evidence from two related movements: the contemporary Muslim Brotherhood in Egypt, and the cluster of organisations that have been closely associated with Hasan al-Turabi in Sudan, in order to query the extent to which Islamism is compatible with liberal democratic politics. The answers suggested are, in the Egyptian case, hopeful, but for Sudan decidedly pessimistic. However,

Mohammed Zahid; Michael Medley

2006-01-01

351

Tectonic framework of northeast Egypt and its bearing on hydrocarbon exploration  

SciTech Connect

Detailed structural study of northern and central Sinai, the northern Eastern Desert, and the northern Gulf of Suez clarified the tectonic framework of northeast Egypt. This framework is related to the movements between the African Plate and the Eurasian and Arabian Plates. Late Cretaceous folding and thrusting in response to oblique convergence between the African and Eurasian Plates formed NE-ENE oriented, doubly plunging, en echelon folds of the northern Egypt fold belt. This fold belt is well exposed in northern Sinai and a few other places but is concealed under younger sediments in the other parts of northern Egypt. Younger folding of local importance is related to dextral slip on the Themed Fault (Central Sinai) in post Middle Eocene-pre Miocene time. Early Miocene rifting of the Afro-Arabian Plate led to the opening of the Suez rift and deposition of significant syn-rift facies. Half grabens and tilted fault blocks dominate the rift. Slightly tilted fault blocks characterize the competent Middle Eocene limestones of the Eastern Desert south of the Cairo-Suez road but north of this road, Middle Eocene rocks are locally dragged on nearby E-W and NW-SE oriented faults forming fault-drag folds. Ductile Upper Eocene and Miocene rocks are also folded about gentle NW-SE oriented doubly plunging folds. The different stages of tectonic activity in northern Egypt contributed to the development of different types of structural traps as well as different source, reservoir, and cap rocks. The sedimentary history of the region indicates well developed marine sediments of Jurassic, Cretaceous, Eocene, and Miocene ages. Basin development in structurally low areas provided good sites for hydrocarbon generation and maturation.

Khalil, M. [Gulf of Suez Petroleum Company, Cairo (Egypt); Moustafa, A.R.

1995-08-01

352

Desert Studies May 29 -July 23, 2014  

E-print Network

Desert Studies Institute 2014 9 May 29 - July 23, 2014 EXTENDED STUDIES BoiseStateUniversity DesertStudiesInstitute ExtendedStudiesOffice 220E.ParkcenterBlvd. Boise,Idaho83706-3940 9 The Desert Studies Institute workshops desert environments. 9 Faculty The faculty of the Desert Studies Institute is selected annually

Barrash, Warren

353

Desert Dreams RSVP: sustainabilityevents@asu.edu  

E-print Network

Desert Dreams RSVP: sustainabilityevents@asu.edu Parking and directions: sustainability screening of an award-winning film, Desert Dreams. Desert Dreams showcases five seasons of life in the Sonoran Desert and dispels the notion that deserts are barren places. Through a score of natural sounds

Zhang, Junshan

354

Palynology and Stratigraphy of the Nubian Sandstone in Libya and Comparison with Egypt  

NASA Astrophysics Data System (ADS)

The so-called "Nubian Sandstone" outcrops along a wide area from Algeria to the Red Sea, forming two regressive phases. The lower phase is represented in Egypt by the Basal Clastic Unit, the Desert Rose Unit, the Abu Ballas Formation and the Matruh Shale. In Libya it is represented by the Mesak Sandstone, Sarir Sandstone, Cabao Sandstone and Kiklah Formation. In both countries, these successions are covered by a carbonate sequence, resulting from the Tethyan transgression during the Cenomanian. In Egypt however, the upper regressive phase is represented by the Taref Sandstone which was deposited during a brief period of active progradation, following the Tethyan incursion. This is not observed in Libya. Comparison of palynological studies in Libya with those documented by several authors in Egypt reveals that the "Nubian" facies in Libya were deposited before equivalent facies in Egypt. The Basal Clastic Unit, dated as Hautrauvian-Barremian, may be equivalent, at least to a part of the Neocomian Cabao Sandstone in NW Libya. Jarmah Member of the Mesak Formation in Libya was dated as Berriasian on the basis of Pilosisporites and Trilobosporites. This makes it older than any "Nubian" unit in Egypt. The Matruh Shale was assigned to the Aptian on the basis of Tricolpites, and the Abu Balls Formation 34 as Aptian-Albian on the basis of Tricolpites and Rousisporites radiatus. Whereas, there is no equivalent to the Aptian in NW Libya, the Aptian-Albian of Egypt is similar to Zone 1 of the Kiklah Formation and As Sarir Sandstone, which were dated as early Albian on the basis of Afropollis spp., and Perotriletes pannuceus, an Albian element not recorded in Egypt. The Plant Beds in southwestern Egypt were dated as Cenomanian on the basis of advanced angiosperm pollen. In Libya, equivalent bodies were considered Vraconian, representing the uppermost Albian, because it lacks Cenomanian pollen (e.g. Tricolpites mutabilis). Comparison of local sea-level changes with global sea-level curves is used to reconstruct paleogeography. Integration of palynology with geological data and tectonic implications indicates that, despite similarity in paleogeographic processes of the Nubian Sandstone, geological and structural settings remain different. The "Nubian Sandstone" provides a typical succession that can be studied in the light of sequence stratigraphy.

Tekbali, Ali; Hlal, Osama

2013-04-01

355

Unchanging Desert Sand Dunes  

NASA Astrophysics Data System (ADS)

Deserts are one of the major landforms on earth. They occupy nearly 20% of the total land area but are relatively less studied. With the rise in human population, desert regions are being gradually occupied for settlement posing a management challenge to the concerned authorities. Unrestrained erosion is generally a feature of bare dunes. Stabilized dunes, on the other hand, do not undergo major changes in textures, and can thus facilitate the growth of vegetation. Keeping in view of the above factors, better mapping and monitoring of deserts and particularly of sand dunes is needed. Mapping dunes using field instruments is very arduous and they generate relatively sparse data. In this communication, we present a method of clustering and monitoring sand dunes through imagery captured by remote sensing sensors. Initially Radon spectrum of an area is obtained by decomposition of the image into various projections sampled at finer angular directions. Statistical features such as mode, entropy and standard deviation of Radon spectrum are used in delineation and clustering of regions with different dune orientations. These clustered boundaries are used to detect if there are any changes occurring in the dune regions. In the experiment's, remote sensing data covering various dune regions of the world are observed for possible changes in dune orientations. In all the cases, it is seen that there are no major changes in desert dune orientations. While these findings have implications for understanding of dune geomorphology and changes occurring in dune directions, they also highlight the importance of a wider study of dunes and their evolution both at regional and global scales. Results for Dataset 1 & Dataset 2 Results for Dataset 3

Gadhiraju, S.; Banerjee, B.; Buddhiraju, K.; Shah, V.

2013-12-01

356

Arizona-Sonora Desert Museum  

NSDL National Science Digital Library

The Arizona-Sonora Desert Museum is a zoo, natural history museum and botanical garden, whose mission is to inspire people to live in harmony with the natural world by fostering love, appreciation, and understanding of the Sonoran Desert. The Center for Sonoran Desert Studies conducts the educational and scientific functions of the Museum and is a hub for research, education and conservation of the Sonoran Desert Region. The Center's activities range from on-grounds and outreach education programs for school children and adults, to conducting ecological research in the Sonoran Desert region and advising museum staff, other conservation organizations, and the public on scientific and educational matters. The website has extensive information about desert ecology, environments, animals, and plants, with some content presented in Spanish. There are numerous programs and classes presented, hiking clubs, tours, and activities for Scouts.

357

Desert Farming Benefits from Microbial Potential in Arid Soils and Promotes Diversity and Plant Health  

PubMed Central

Background To convert deserts into arable, green landscapes is a global vision, and desert farming is a strong growing area of agriculture world-wide. However, its effect on diversity of soil microbial communities, which are responsible for important ecosystem services like plant health, is still not known. Methodology/Principal Findings We studied the impact of long-term agriculture on desert soil in one of the most prominent examples for organic desert farming in Sekem (Egypt). Using a polyphasic methodological approach to analyse microbial communities in soil as well as associated with cultivated plants, drastic effects caused by 30 years of agriculture were detected. Analysing bacterial fingerprints, we found statistically significant differences between agricultural and native desert soil of about 60%. A pyrosequencing-based analysis of the 16S rRNA gene regions showed higher diversity in agricultural than in desert soil (Shannon diversity indices: 11.21/7.90), and displayed structural differences. The proportion of Firmicutes in field soil was significantly higher (37%) than in the desert (11%). Bacillus and Paenibacillus play the key role: they represented 96% of the antagonists towards phytopathogens, and identical 16S rRNA sequences in the amplicon library and for isolates were detected. The proportion of antagonistic strains was doubled in field in comparison to desert soil (21.6%/12.4%); disease-suppressive bacteria were especially enriched in plant roots. On the opposite, several extremophilic bacterial groups, e.g., Acidimicrobium, Rubellimicrobium and Deinococcus-Thermus, disappeared from soil after agricultural use. The N-fixing Herbaspirillum group only occurred in desert soil. Soil bacterial communities were strongly driven by the a-biotic factors water supply and pH. Conclusions/Significance After long-term farming, a drastic shift in the bacterial communities in desert soil was observed. Bacterial communities in agricultural soil showed a higher diversity and a better ecosystem function for plant health but a loss of extremophilic bacteria. Interestingly, we detected that indigenous desert microorganisms promoted plant health in desert agro-ecosystems. PMID:21912695

Köberl, Martina; Müller, Henry; Ramadan, Elshahat M.; Berg, Gabriele

2011-01-01

358

Jeeps Penetrating a Hostile Desert  

ERIC Educational Resources Information Center

Several jeeps are poised at base camp on the edge of a desert aiming to escort one of them as far as possible into the desert, while the others return to camp. They all have full tanks of gas and share their fuel to maximize penetration. In a friendly desert it is best to leave caches of fuel along the way to help returning jeeps. We solve the…

Bailey, Herb

2009-01-01

359

Geochronologic and isotopic evidence for involvement of pre-Pan-African crust in the Nubian shield, Egypt  

SciTech Connect

Two Late Proterozoic granitic bodies from the Eastern Desert of Egypt, the ca. 578 Ma Nakhil and the ca. 595 Ma Aswan granites, provide insights into processes of crust formation in the Arabian-Nubian shield. Evidence for involvement of an older crustal component in the formation of the Nakhil granite includes (1) U/Pb zircon data that establish a crystallization age of 578 {plus minus} 15 Ma and indicate the presence of inherited zircons possibly as old as 1.6 Ga; (2) an elevated model initial {sup 87}Sr/{sup 86}Sr (0.7136); and (3) an elevated initial {sup 207}Pb/{sup 204}Pb (15.561) relative to model mantle compositions at 578 Ma. Evidence for involvement of an older crustal component in the Aswan granite comes from the elevated initial {sup 207}Pb/{sup 204}Pb (15.611). In contrast, extensive crustal contamination is not reflected in the high initial {epsilon}{sub Nd} (+5.7) for the Nakhil and the low initial {sup 87}Sr/{sup 86}Sr (0.7029) for the Aswan granite. The contrasting inferences from the different isotopic systems can be explained by the high whole-rock Nd and Sr concentration for the the Nakhil (87 ppm Nd) and the Aswan (173 ppm Sr) granites, respectively, that suggest that the Nd and Sr isotopic composition of the older component has been overshadowed by the more primitive material. Similar contrasts in Pb, Sr, and Nd isotopic data from the eastern and western shield margins can be interpreted in the same manner and might suggest widespread involvement of older crustal components in the formation of the Late Proterozoic Arabian-Nubian shield.

Sultan, M.; Chamberlain, K.R.; Bowring, S.A.; Arvidson, R.E. (Washington Univ., St. Louis, MO (USA)); Abuzied, H. (Cairo Univ. (Egypt)); El Kaliouby, B. (Ain Shams Univ., Abassia, Cairo (Egypt))

1990-08-01

360

Metal and fluid sources in a potential world-class gold deposit: El-Sid mine, Egypt  

NASA Astrophysics Data System (ADS)

Lode gold mineralization at the El-Sid mine area is associated with the ca. 600 Ma Fawakhir granite intrusion, which cuts the ~737 Ma ophiolite nappes in the Central Eastern Desert of Egypt. The mineralized quartz veins are hosted by ~E- and NE-trending fault/fracture sets cutting the western boundary of the intrusion and sheared ophiolites. The results of electron microprobe analyses of gold-associated hydrothermal sulfide and silicate minerals suggest that Au was mobilized alongside Ni, Co, Cr and As from the adjacent ophiolitic serpentinite. After granite emplacement, hydrothermal fluids interacted with the sheared serpentinite, leaching metals and re-depositing them in the faults/fractures and adjacent wall rock in a cyclic process. Low-salinity aqueous-carbonic fluids with significant quantities of volatile species (CO2, CH4, and N2 ± H2S) leached and transported Au from deep to shallow crustal levels. Carbon dioxide had a buffering effect on the Au-bearing hydrothermal solution, maintaining its pH within a narrow near-neutral range, where elevated gold concentration was transported by complexation with reduced magmatic sulfur in a reducing environment. Gold deposition along fault/fracture conduits in the Fawakhir granite and adjacent serpentinite resulted from interplay of pressure drop, fluctuations in oxygen and sulfur fugacities, and exsolution of the volatile phases. Infiltration of meteoric water may have contributed to the formation of the late stage gold-sulfide mineralization that formed at shallower levels during terrane uplift. Sulfidation of the Fe-rich magmatic minerals was, on the other hand, the overriding process in the wall rock as evidenced by abundant disseminated sulfides with gold inclusions. Considering the structural control by regional shear zones (fluid conduits) and the voluminous granitic and ophiolitic rocks (metal sources), a high tonnage gold deposit amenable to open pit mining at the El-Sid mine area is very likely.

Helmy, Hassan; Zoheir, Basem

2014-11-01

361

BEST MANAGEMENT PRACTICES & GUIDANCE MANUAL: DESERT  

E-print Network

CALIFORNIA ENERGY COMMISSION BEST MANAGEMENT PRACTICES & GUIDANCE MANUAL: DESERT RENEWABLE ENERGY Manual: Desert Renewable Energy Projects was prepared by the staffs of the California Energy Commission............................................................................................................................5 The Desert Region

362

Aspects of Mycorrhizae in Desert Plants  

Microsoft Academic Search

\\u000a Mycorrhizal symbioses are critical to desert plants since they face the challenges of scarce, sporadic precipitation, nutrient\\u000a deficiencies, intense solar radiation, and the high temperatures found in hot deserts. Deserts are covering increasingly more\\u000a of the Earth's surface area as desertification increases globally. Mycorrhizal desert plants have a greater chance of survival\\u000a in the harsh desert environment. Desert plants form

Martha E. Apple

363

Namaqualand, South Africa – an overview of a unique winter-rainfall desert ecosystem  

Microsoft Academic Search

Namaqualand is a winter-rainfall desert of some 50?000 km2, located in north-western South Africa. For a desert ecosystem, the region is characterized by a unique selective regime, namely highly predictable annual rainfall and a moderate temperature regime throughout the year. This selective regime is responsible for the unique plant ecological features of Namaqualand. These include: the dominance of communities by dwarf

R. M. Cowling; K. J. Esler; P. W. Rundel

1999-01-01

364

Geochemical, UPb zircon, and Nd isotope investigations of the Neoproterozoic Ghawjah Metavolcanic rocks, Northwestern Saudi Arabia  

E-print Network

to the "Younger Volcanic" rocks from the Central Eastern Desert (CED) of Egypt, in terms of stratigraphic from Egypt south to Sudan, Eritrea, and Ethiopia on the western flank of the Red Sea and on the eastern

Stern, Robert J.

365

Regional geothermal exploration in Egypt  

NASA Technical Reports Server (NTRS)

A study is presented of the evaluation of the potential geothermal resources of Egypt using a thermal gradient/heat flow technique and a groundwater temperature/chemistry technique. Existing oil well bottom-hole temperature data, as well as subsurface temperature measurements in existing boreholes, were employed for the thermal gradient/heat flow investigation before special thermal gradient holes were drilled. The geographic range of the direct subsurface thermal measurements was extended by employing groundwater temperature and chemistry data. Results show the presence of a regional thermal high along the eastern margin of Egypt with a local thermal anomaly in this zone. It is suggested that the sandstones of the Nubian Formation may be a suitable reservoir for geothermal fluids. These findings indicate that temperatures of 150 C or higher may be found in this reservoir in the Gulf of Suez and Red Sea coastal zones where it lies at a depth of 4 km and deeper.

Morgan, P.; Boulos, F. K.; Swanberg, C. A.

1983-01-01

366

Egypt: Social Responsibility Disclosure Practices  

Microsoft Academic Search

This paper offers updated evidence on social disclosure trends in Egypt. It examines whether Egyptian companies care about\\u000a the community as an important stakeholder in their Internet social reporting. In doing so, the paper employs content analysis\\u000a to measure and explore the social responsibility self-disclosure practices of major Egyptian companies in their online annual\\u000a reports and\\/or Websites. The analysis shows

Aly Salama

367

Orthopedic surgery in ancient Egypt  

PubMed Central

Background — Ancient Egypt might be considered the cradle of medicine. The modern literature is, however, sometimes rather too enthusiastic regarding the procedures that are attributed an Egyptian origin. I briefly present and analyze the claims regarding orthopedic surgery in Egypt, what was actually done by the Egyptians, and what may have been incorrectly ascribed to them. Methods — I reviewed the original sources and also the modern literature regarding surgery in ancient Egypt, concentrating especially on orthopedic surgery. Results — As is well known, both literary sources and the archaeological/osteological material bear witness to treatment of various fractures. The Egyptian painting, often claimed to depict the reduction of a dislocated shoulder according to Kocher’s method, is, however, open to interpretation. Therapeutic amputations are never depicted or mentioned in the literary sources, while the specimens suggested to demonstrate such amputations are not convincing. Interpretation — The ancient Egyptians certainly treated fractures of various kinds, and with varying degrees of success. Concerning the reductions of dislocated joints and therapeutic amputations, there is no clear evidence for the existence of such procedures. It would, however, be surprising if dislocations were not treated, even though they have not left traces in the surviving sources. Concerning amputations, the general level of Egyptian surgery makes it unlikely that limb amputations were done, even if they may possibly have been performed under extraordinary circumstances. PMID:25140982

Blomstedt, Patric

2014-01-01

368

Desert Research Institute: Research  

NSDL National Science Digital Library

Operating as the nonprofit research campus of the University and Community College System of Nevada, the Desert Research Institute (DRI) conducts more than $27 million in environmental research each year with the help of its approximately 400 research faculty and support staff. The informational research page of the main Web site offers descriptions; publications; links; and other relevant facts from the various arms of the institute, which include the Division of Atmospheric Sciences, Division of Earth and Ecosystem, Division of Hydrologic Sciences, Center for Arid Lands Environmental Management, Center for Watersheds and Environmental Sustainability, and several others.

1969-12-31

369

Lost in the Desert!  

NSDL National Science Digital Library

Students learn about the interconnectedness of the body, with a particular focus on the skin as one of the most important homeostatic organ systems, in this case study in which the protagonist sets out on a three-hour drive across the Arizona desert to meet his fiancee in California, and never shows up. The case was designed to be used with students in a lower-level anatomy and physiology class who are interested in pursuing careers in nursing, occupational therapy, and other health related fields.

David L. Evans

2002-01-01

370

The Geometry of Desert  

E-print Network

, therefore, that according to fault forfeits first the more culpable and vicious deserve to go "behind" those who are less culpable or vicious. 3 We will probably want to expand our understanding of fault forfeits first in a second way as well. Suppose... then be multiplied by .8 to deter­ mine their weight from the standpoint of desert.) Similarly, a significantly vicious individual may have a multiplier of.3 (corresponding, of course, to a discount rate of70%), while a completely blameless individual will have a...

Kagan, Shelly

2005-01-01

371

Desert-Tropicals.com  

NSDL National Science Digital Library

Created by plant enthusiast Philippe Faucon, Desert-Tropicals.com is a well-designed website with information about, and pictures of, over 3,500 plants. Plant lists are organized by scientific and common name, succulents, xeriscape plants, palm trees, herbs, and trees. The plant lists are quite extensive, and each species receives its own description page with a nice close-up photo as well as brief information about family, frost and heat tolerance, sun exposure, origin, propagation, and more. The site also connects to articles, a Bulletin Board, Bookstore, and relevant links.

Faucon, Philippe

372

The Hellenistic Royal Court. Court Culture, Ceremonial and Ideology in Greece, Egypt and the Near East, 336-30 BCE  

Microsoft Academic Search

In the Hellenistic empires of Alexander the Great and his successors in Greece, Egypt and the Near East, new forms of court culture and political ideology developed during the last three centuries BCE. Appropriated by Parthian kings and Roman emperors alike, the culture of these Macedonian courts eventually influenced the evolution of royal ideology and court culture in both western

R. Strootman

2007-01-01

373

Land suitability assessment for perennial crops using remote sensing and Geographic Information Systems: A case study in northwestern Egypt  

Microsoft Academic Search

The main objective of this study was to develop a Geographic Information Systems-based model for land suitability assessment for guava, olive and date palm in the North-western coast of Egypt. Soil, climatic and landscape database as well as satellite image have been integrated through Geographic Information Systems (GIS). A Landsat ETM+ image dated 2001, was classified using maximum likelihood classifier

A. Shalaby; Y. O. Ouma; R. Tateishi

2006-01-01

374

Sphinx and Great Pyramid of Giza, Egypt  

USGS Multimedia Gallery

The Spinx and the Great Pyramid of Giza, Egypt are pictured here. USGS and University of Pennsylvania research shows that ancient pollen and charcoal preserved in deeply buried sediments in Egypt's Nile Delta document the region’s ancient droughts and fires, including a huge drought 4,200...

375

Music in ancient Mesopotamia and Egypt  

Microsoft Academic Search

Almost all categories of instruments were represented in Mesopotamia and Egypt, from clappers and scrapers to rattles, sistra, flutes, clarinets, oboes, trumpets, harps, lyres, lutes, etc. As early as 2600 B.C. harps and lyres are attested at Ur. In the New Kingdom, Egypt borrowed several instruments from Mesopotamia: the angular vertical harp, square drum, etc. The organ, invented in Ptolemaic

1981-01-01

376

Consuming Bodies: Cultural Fantasies of Ancient Egypt  

Microsoft Academic Search

This article explores the legacy of ancient Egypt in popular culture, from the 19th century onwards - through the theme of consumption. A range of media is covered including literature, film and performance. I argue that Egypt has been a constant mirror for contemporary culture in terms of the body, sexuality and the Orient. In the West, Egyptian bodies have

LYNN MESKELL

1998-01-01

377

Desert landscape irrigation  

SciTech Connect

Industrialization can take place in an arid environment if a long term, overall water management program is developed. The general rule to follow is that recharge must equal or exceed use. The main problem encountered in landscape projects is that everyone wants a lush jungle setting, tall shade trees, ferns, with a variety of floral arrangements mixed in. What we want, what we can afford, and what we get are not always the same. Vegetation that requires large quantities of water are not native to any desert. Surprisingly; there are various types of fruit trees, and vegetables that will thrive in the desert. Peaches, plums, nut trees, do well with drip irrigation as well as tomatoes. Shaded berry plans will also do well, the strawberry being one. In summary; if we match our landscape to our area, we can then design our irrigation system to maintain our landscape and grow a variety of vegetation in any arid or semiarid environment. The application of science and economics to landscaping has now come of age.

Quinones, R.

1995-06-01

378

Supersymmetry without the Desert  

E-print Network

Naturalness of electroweak symmetry breaking in weak scale supersymmetric theories may suggest the absence of the conventional supersymmetric desert. We present a simple, realistic framework for supersymmetry in which (most of) the virtues of the supersymmetric desert are naturally reproduced without having a large energy interval above the weak scale. The successful supersymmetric prediction for the low-energy gauge couplings is reproduced due to a gauged R symmetry present in the effective theory at the weak scale. The observable sector superpotential naturally takes the form of the next-to-minimal supersymmetric standard model, but without being subject to the Landau pole constraints up to the conventional unification scale. Supersymmetry breaking masses are generated by the F-term and D-term VEVs of singlet and U(1)_R gauge fields, as well as by anomaly mediation, at a scale not far above the weak scale. We study the resulting patten of supersymmetry breaking masses in detail, and find that it can be quite distinct. We construct classes of explicit models within this framework, based on higher dimensional unified theories with TeV-sized extra dimensions. A similar model based on a non-R symmetry is also presented. These models have a rich phenomenology at the TeV scale, and allow for detailed analyses of, e.g., electroweak symmetry breaking.

Yasunori Nomura; David Poland

2006-09-26

379

Supersymmetry without the Desert  

SciTech Connect

Naturalness of electroweak symmetry breaking in weak scale supersymmetric theories may suggest the absence of the conventional supersymmetric desert. We present a simple, realistic framework for supersymmetry in which (most of) the virtues of the supersymmetric desert are naturally reproduced without having a large energy interval above the weak scale. The successful supersymmetric prediction for the low-energy gauge couplings is reproduced due to a gauged R symmetry present in the effective theory at the weak scale. The observable sector superpotential naturally takes the form of the next-to-minimal supersymmetric standard model, but without being subject to the Landau pole constraints up to the conventional unification scale. Supersymmetry breaking masses are generated by the F-term and D-term VEVs of singlet and U(1){sub R} gauge fields, as well as by anomaly mediation, at a scale not far above the weak scale. We study the resulting pattern of supersymmetry breaking masses in detail, and find that it can be quite distinct. We construct classes of explicit models within this framework, based on higher dimensional unified theories with TeV-sized extra dimensions. A similar model based on a non-R symmetry is also presented. These models have a rich phenomenology at the TeV scale, and allow for detailed analyses of, e.g., electroweak symmetry breaking.

Nomura, Yasunori; Poland, David

2006-09-26

380

Published: 23 June 2011 Another Revolution Afoot in Egypt  

E-print Network

1 Published: 23 June 2011 Another Revolution Afoot in Egypt: Top-Notch Science Egypt has launched way to cure fanaticism. Op-Ed by Ahmed H. Zewail Cairo -- Nearly 100 days after the revolution, Egypt journalist Emad Ahmed wrote in a recent essay on "Egypt's Bridges" to the future, the post-revolution

Zewail, Ahmed

381

Amebiasis in schistosomiasis endemic and non-endemic areas in Egypt.  

PubMed

Stool and blood specimens were collected from each of 404 and 576 individuals at Sindbis village (Qualiubia Governorate) in the Nile Delta where schistosomiasis is endemic and El-Rashda village (New Valley Governorate) in the Western Desert of Egypt where there is no schistosomiasis; respectively. Based on the microscopical examination of stool specimens, the prevalence of infection with Entamoeba (E. histolytica and/or E. dispar which are morphologically indistinguishable) was higher at Sindbis than at El Rashda village (29.3% and 20%, respectively). At Sindbis, the prevalence of Entamoeba (both species) was 35.2% (50/142) in S. mansoni infected individuals versus 26.3% (69/262) in S. mansoni negative individuals. Serum antibodies develop only against E. histolytica but not against E. dispar infection. When serological results were considered, the prevalence of E. histolytica was 4.7% in Sindbis and 3.4% at El Rashda based on those who were positive microscopically and serologically in the two villages, respectively. In other words, only 16-17% of those who were positive microscopically can be considered infected with E. histolytica as determined serologically. However, the prevalence of E. histolytica (present or past) based on those who were positive serologically whether positive or negative microscopically was 13.4% and 12.7% at the two villages, respectively. At Sindbis, the prevalence of E. histolytica infection was lower in S. mansoni negative (8.5%) than in S. mansoni positive (16.0%) individuals. These epidemiologic data suggest that: (1) S. mansoni infection may suppress the immune response of the host and therefore, the prevalence of E. histolytica based on serological testing is probably underestimated in the S. mansoni infected people and it may be higher than in the S. mansoni negative people. (2) Serological examinations can be used in determining the true prevalence of E. histolytica (present or past infections) until a routine test for detecting E. histolytica specific antigen in stool becomes available to differentiate E. histolytica from E. dispar infections. PMID:9425808

Mansour, N S; Youssef, F G; Mikhail, E M; Mohareb, E W

1997-12-01

382

Longevity and growth strategies of the desert tortoise ( Gopherus agassizii) in two American deserts  

Microsoft Academic Search

The desert tortoise occurs in two strikingly different desert regimes in the southwestern United States. In the Mojave Desert, rainfall is more irregular and resources are more limited than in the Sonoran Desert. We examined the age structure of tortoise populations from these two deserts to determine whether the difference in resource availability has driven an evolutionary divergence in life

A. J. Curtin; G. R. Zug; J. R. Spotila

2009-01-01

383

Livestock grazing and the desert tortoise in the Mojave Desert  

USGS Publications Warehouse

A large part of the Mojave Desert is not in pristine condition, and some current conditions can be related to past grazing-management practices. No information could be found on densities of the desert tortoise (Gopherus agassizii) or on vegetative conditions of areas that had not been grazed to allow managers a comparison of range conditions with data on tortoises. Experimental information to assess the effect of livestock grazing on tortoises is lacking, and researchers have not yet examined whether the forage that remains after grazing is sufficient to meet the nutritional needs of desert tortoises.

Oldemeyer, John L.

1994-01-01

384

Late Quaternary history of the Atacama Desert  

E-print Network

#12;#12;#12;#12;#12;73 Late Quaternary history of the Atacama Desert Claudio Latorre, Julio L and Kate Rylander Of the major subtropical deserts found in the Southern Hemisphere, the Atacama Desert is the driest. Throughout the Quaternary, the most pervasive climatic influence on the desert has been

Vuille, Mathias

385

Desert Rock Coatings Ronald I. Dorn  

E-print Network

Chapter 7 Desert Rock Coatings Ronald I. Dorn Introduction Desert landforms are characterized by an abundance of `bare' rock and mineral surfaces. Mountains host widespread exposures of bedrock. Gravel desert, that the supposed funda- mental bare-rock nature of desert landforms stretches the truth. In reality, rock coatings

Dorn, Ron

386

Gujarat, Western India  

NASA Technical Reports Server (NTRS)

Extremely high sediment loads are delivered to the Arabian Sea along the coast of Pakistan (upper left) and western India. In the case of the Indus River (far upper left) this sedimentation, containing large quantities of desert sand, combines with wave action to create a large sand-bar like delta. In the arid environment, the delta lacks much vegetation, but contains numerous mangrove-lined channels. This true-color image from May 2001 shows the transition from India's arid northwest to the wetter regions farther south along the coast. The increase in vegetation along the coast is brought about by the moisture trapping effect of the Western Ghats Mountain Range that runs north-south along the coast. Heavy sediment is visible in the Gulf of Kachchh (north) and the Gulf of Khambhat(south), which surround the Gujarat Peninsula.

2002-01-01

387

The Kamil Crater in Egypt.  

PubMed

We report on the detection in southern Egypt of an impact crater 45 meters in diameter with a pristine rayed structure. Such pristine structures are typically observed on atmosphereless rocky or icy planetary bodies in the solar system. This feature and the association with an iron meteorite impactor and shock metamorphism provides a unique picture of small-scale hypervelocity impacts on Earth's crust. Contrary to current geophysical models, ground data indicate that iron meteorites with masses of the order of tens of tons can penetrate the atmosphere without substantial fragmentation. PMID:20651117

Folco, Luigi; Di Martino, Mario; El Barkooky, Ahmed; D'Orazio, Massimo; Lethy, Ahmed; Urbini, Stefano; Nicolosi, Iacopo; Hafez, Mahfooz; Cordier, Carole; van Ginneken, Matthias; Zeoli, Antonio; Radwan, Ali M; El Khrepy, Sami; El Gabry, Mohamed; Gomaa, Mahomoud; Barakat, Aly A; Serra, Romano; El Sharkawi, Mohamed

2010-08-13

388

[Urinary schistosomiasis in ancient Egypt].  

PubMed

First described by Theodor Bilharz in 1851, Schistosoma haematobium, the worm responsible for urinary schistosomiasis, was a major health problem along the Nile Valley until the present days. Haematuria, the main symptom of this parasitic disease, was known and treated in Egyptian medical papyri since 1550 B.C. A relationship between haematuria and the god Seth was envisaged. Sir Marc Armand Ruffer, pioneer of paleopathology, found (1910) calcified Schistosoma eggs in Egyptian mummies of the xxth dynasty, establishing that bilharzia plagued ancient Egypt people. The ELISA method demonstrated the Schistosoma circulating anodic antigen in 45% of mummies studied. PMID:19617021

Ziskind, Bernard

2009-12-01

389

Mojave Desert Ecosystem Project  

NSDL National Science Digital Library

A Department of Defense (DOD) program, the Mojave Ecosystem Database Program (MEDP) represents the DOD's "first attempt to meld together a shared scientific database that can be used to affect dynamic sustainable land management decisions." Although the mission statement of MEDP reflects a somewhat oxymoronic goal, e.g., maintaining "critical DOD installations within the Mojave Desert Ecosystem ... while protecting the environment," the site nevertheless represents an opportunity for researchers to access environmental models and potentially influence land management within the Mojave Ecoregion. The searchable site offers information about and/or access to Geospatial Data, Metadata, Geomorphic Landform Data, and a Spatial Bibliography, among other regional resources. An excellent selection of links points users to a wealth of additional and variously detailed (governmental) information.

390

Applications of remote sensing, GIS, and groundwater flow modeling in evaluating groundwater resources: Two case studies; East Nile Delta, Egypt and Gold Valley, California, USA  

NASA Astrophysics Data System (ADS)

Quaternary aquifer, East Nile Delta, Egypt. Due to the progressive increase in the development of desert land in Egypt, the demand for efficient water resources management and accurate land cover change information is increasing. In this study, we introduce a methodology to map and monitor land cover change patterns related to agricultural development and urban expansion in the desert fringes of the Eastern Nile Delta region. Using a hybrid classification approach, we employ multitemporal Landsat TM/ETM+ images from 1984, 1990, and 2003 to produce three land cover/land use maps. Post-classification comparison of these maps was used to obtain "from-to" statistics and change detection maps. The change detection results show that agricultural development increased 14% through the study period. Land reclamation during 1990-2003 exceeded that during 1984-1990 by a factor of two, reflecting a systematic national plan for desert reclamation that went into effect. We find that the increase in urbanization (by ˜21,300 hectares) during 1990-2003 was predominantly due to encroachment into traditionally cultivated land at the fringes of urban centers. Our results accurately quantify the land cover changes and delineate their spatial patterns, demonstrating the utility of Landsat data in analyzing landscape dynamics over time. Such information is critical for making efficient and sustainable policies for resource management. A three dimensional GIS-based groundwater flow model was developed to delineate a safe future framework for groundwater development in the Quaternary aquifer north Ismaelia Canal, East Nile Delta where a progressive rise in head associated with agricultural development is reported. The calibrated transient model was used to predict the future head distribution after 20 years assuming the same landuse. Results of this run showed that the groundwater head continued to increase with maximum increase up to 2.0 m in the unconfined part of the aquifer which jeopardizes a considerable area of the agricultural land with soil salinity and water logging. Therefore, three strategies, each with three scenarios, extending between 2004 and 2024 were designed to involve different pumping stress and infiltration rates from irrigation return to control the rising water level and estimate the production potential of the aquifer during drought. Gold Valley, Death Valley, California, USA. This study evaluates the hydrogeology of Gold Valley as a typical example of intermountain basins of Death Valley area and develops a GIS-based model that reasonably estimates the precipitation infiltration rates from altitude and slope data of the catchment area. Water balance calculations of the hydrological parameters in Gold Valley, provided by Inyo County, California, indicated that the majority of recharge takes place at high altitude (>1100 m) during winter with a negligible effect of evaporation on the stable isotopic composition of groundwater. Furthermore, water balance calculations in Gold Valley were utilized in identifying the coefficients of a GIS-based model that subsequently was refined to the best fit with the calculations of the water budget. A resistivity survey conducted in Gold Valley showed that groundwater is collected in upstream compartmentalized reservoirs and suggests that groundwater flow mostly takes place through the fracture zone of the bedrock. This pattern explains the relationship between precipitational infiltration in the Gold Valley catchment area and the attachment spring flow in Willow Creek. The estimated water budget in Gold Valley and the geoelectric profiles provided from this study can be investigated into the Death Valley Regional Groundwater Flow model (DVRGWF). In addition, the GIS-based model can be efficiently applied in other intermountain basins in Death Valley or other areas of arid environment of the Western U.S. to estimate the local precipitational infiltration. Accurate estimates of flux, well defined flow systems, and locations of recharge/discharge in mountain ranges provide e

Abdelaziz Ali Ismael, Abdulaziz Mohamed

391

Dental surgery in ancient Egypt.  

PubMed

Many different surgical procedures have over the years been attributed to the ancient Egyptians. This is also true regarding the field of dental surgery. The existence of dentists in ancient Egypt is documented and several recipes exist concerning dental conditions. However, no indications of dental surgery are found in the medical papyri or in the visual arts. Regarding the osteological material/mummies, the possible indications of dental surgery are few and weak. There is not a single example of a clear tooth extraction, nor of a filling or of an artificial tooth. The suggested examples of evacuation of apical abscesses can be more readily explained as outflow sinuses. Regarding the suggested bridges, these are constituted of one find likely dating to the Old Kingdom, and one possibly, but perhaps more likely, dating to the Ptolemaic era. Both seem to be too weak to have served any possible practical purpose in a living patient, and the most likely explanation would be to consider them as a restoration performed during the mummification process. Thus, while a form of dentistry did certainly exist in ancient Egypt, there is today no evidence of dental surgery. PMID:24665522

Blomstedt, Patric

2013-01-01

392

From (b)edouin to (a)borigine: the myth of the desert noble savage.  

PubMed

This article examines the myth of the supposed superiority of the desert noble savage over civilized man. With the Bedouin of Arabia and the Aborigines of Australia as its two prime examples, the article argues that two versions of this myth can be traced: one in which the desert noble savage is valorized due to his valour, physical prowess and martial skill (Bedouin); and another, later version, where the desert noble savage is valorized as a pacifist, an ecologist and a mythmaker/storyteller (Aborigines). The article concludes by examining the way in which this turn from one type of desert noble savage to another reflects the manner in which western modernity has shifted its values from Cartesian dualities and Enlightenment rationalism to that of networks, potentialities, ecology and myth. PMID:19886291

Graulund, Rune

2009-01-01

393

Desert Life in the American Southwest  

NSDL National Science Digital Library

DesertUSA.com (DUSA) provides this interesting site, offering a plethora of general information on the deserts of the United States. Designed as an educational tool for discovering "the beauty, life and culture of North American deserts," the site contains illustrated text, factual summaries, virtual reality tours, movie/audio clips, and stories. All materials focus on desert-related topics, including plants, animals, geology, cultural and natural history, and parks, among others. The site has much to offer -- from the basics of the desert environment, to a photo-illustrated guide of desert flora and fauna, to details on specific arid and semi-arid deserts of the American Southwest. A glossary of desert terms and brief descriptions of features of the Chihuahuan, Great Basin, Mojave and Sonoran Deserts round out the site.

394

Mate desertion in the snail kite  

USGS Publications Warehouse

Mate desertion during the breeding cycle was documented at 28 of 36 (78%) snail kite, Rostrhamus sociabilis nests in Florida between 1979 and 1983. Offspring mortality occurred at only one deserted nest, however. Parents that were deserted by their mates continued to care for their young until independence (3?5 additional weeks) and provided snails at a rate similar to that of both parents combined before desertion. Males and females deserted with nearly equal frequency, except in 1982 when more females deserted. No desertion occurred during drought years, whereas desertion occurred at nearly every nest during favourable conditions. The occurrence of mate desertion was generally related to indirect measures of snail abundance: foraging range, snail delivery rates to the young and growth rates. Small broods were deserted more frequently by females than by males and tended to be deserted earlier than large ones. After desertion, deserters had the opportunity to re-mate and nest again since breeding seasons were commonly lengthy, but whether they did so was impossible to determine conclusively in most cases. The deserted bird sometimes incurred increased energetic costs and lost breeding opportunities during periods of monoparental care.

Beissinger, S.R.; Snyder, N.F.R.

1988-01-01

395

First Report of Leishmania tropica from a Classical Focus of L. major in North-Sinai, Egypt  

E-print Network

cycle is anthroponotic, control efforts targeting a non-human reservoir would have little effect, but reducing household level exposure to sand flies (e.g., insecticide-treated bed- nets) would be appropriate. Regardless, it is apparent that El Barth... Desert of Egypt. Am J Trop Med Hyg 49: 598–607. 10. Schlein Y, Warburg A, Schnur LF, Le Blancq SM, Gunders AE, 1984. Leishmaniasis in Israel: reservoir hosts, sandfly vectors and Leishmania l strains in the Negev, Central Arava and along the Dead...

Shehata, Magdi G.; Samy, Abdallah Mohammed; Doha, Said A.; Fahmy, Adel R.; Kaldas, Rania M.; Furman, Barry D.; Villinski, Jeffrey T.

2009-08-01

396

Genome Sequences of SAT 2 Foot-and-Mouth Disease Viruses from Egypt and Palestinian Autonomous Territories (Gaza Strip)  

PubMed Central

Two foot-and-mouth disease virus (FMDV) genome sequences have been determined for isolates collected from recent field outbreaks in North Africa (Egypt) and the Middle East (Palestinian Autonomous Territories). These data represent the first examples of complete genomic sequences for the FMDV SAT 2 topotype VII, which is thought to be endemic in countries immediately to the south of the Sahara desert. Further studies are now urgently required to provide insights into the epidemiological links between these outbreaks and to define the pathogenicity of this emerging lineage. PMID:22843860

Valdazo-González, Begoña; Knowles, Nick J.; Hammond, Jef

2012-01-01

397

USGS Scientists in Wadi Degla, Northern Egypt  

USGS Multimedia Gallery

USGS scientists looking at Eocene sandstones and limestones in Wadi Degla, northern Egypt. This area was studied to understand the Levant Basin Province, as both regions have similar rock formations....

2010-04-07

398

Ancient Egypt, Sacred Science, and Transatlantic Romanticism  

E-print Network

science and theology, describing a natural process and atNatural and Spiritual Mysteries, By Way of Representations and Correspondences (the link to Egypt is evident from the title), presents a visionary theology

Redd, Marques Jerard

2011-01-01

399

Desert and desertification in Iran  

NASA Astrophysics Data System (ADS)

One of the greatest environmental concerns in Iran as in other arid and semiarid countries is the transformation of once productive, or marginally productive, land to deteriorated land and soil unable to support plants and animals. Because the land becomes barren and dry, the process is described as desertification, which occurs as a sequence of events. The area of deserts in Iran is about 340,000 Km2 (less than one fifth of its total area), of which 100,000 Km2 is being used for some cultivation, 120,000 Km2 is subjected to moving sands about 40 % of which is active sand dunes. Most of features and processes usual in world famous deserts are also observed in Iran: low precipitation, high evaporation, poor or lack of vegetation, saline and alkaline soils, low population and small and sparse oases. The deserts of Iran are generally classified in the subtropical, warm, arid and semiarid group, but the effect and presence of some geographical and geoclimatical factors such as height, vicinity to Indian Ocean and so on do some changes in climatic conditions and geographical features causing some local and regional differences in them. Geographically, two groups of deserts have been known in Iran: (1) Coastal deserts which, like a ribbon with variable width, stretch from extreme southeast to extreme southwest, at the north parts of Oman Sea and Persian Gulf. One important feature of these deserts is relatively high humidity which differentiates them from other deserts. This causes an increase in vegetation coverage and hence a decrease in eolian erosion and also a dominance of chemical weathering to that of physical. (2) internal deserts, which rest in central, eastern and southeastern plateau of the country and in independent and semi dependent depressions. This situation, which is due to the surrounding high mountains, blocks humidity entry and causes the aridity of these deserts. Wind as a dominant process in the area causes deflated features such as Reg (desert pavement), Kalut (Yardang), Hoodoo and wind deposited features such as different kinds of sand dunes (Seif, Nebka, Rebdous, Barkhan, Ghourd, Erg) and Loess, most of which exhibit beautiful landscapes suitable for ecotourism and scientific tours. Salt deserts (Kavir or Playas), which rest in the lowest parts of internal depressions, are the most current features in Iran deserts. The most extensive and specific salt deserts are in the course of floods or at the end of them, which consist of fine grained sediments in the lowest parts of the depressions. Many factors have been participated in the formation of salt deserts in Iran, the most important of which, are morphotectonical (such as folding and faulting due to the last epirogenic and orogenic movements), climatical and hydrological (occurred in Quaternary), geological and pedological (such as the presence of Neogene evaporitic formations).

Bahrami, M.

2009-04-01

400

Analysis of utilization of desert habitats with dynamic simulation  

USGS Publications Warehouse

The effects of climate and herbivores on cool desert shrubs in north-western Utah were investigated with a dynamic simulation model. Cool desert shrublands are extensively managed as grazing lands, and are defoliated annually by domestic livestock. A primary production model was used to simulate harvest yields and shrub responses under a variety of climatic regimes and defoliation patterns. The model consists of six plant components, and it is based on equations of growth analysis. Plant responses were simulated under various combinations of 20 annual weather patterns and 14 defoliation strategies. Results of the simulations exhibit some unexpected linearities in model behavior, and emphasize the importance of both the pattern of climate and the level of plant vigor in determining optimal harvest strategies. Model behaviors are interpreted in terms of shrub morphology, physiology and ecology.

Williams, B.K.

1986-01-01

401

Native Perennial Grass Communities of the Carson Desert of Northwestern Nevada  

Microsoft Academic Search

Ahstract-A generalized distribution of the perennial grasses in the western Great Basin reveals an inter-mixing of species of the two grass Tribes Hordeae and Agrostideae (following the nomencla­ ture of Hitchcock 1950). The dominant genera are Agropyron and Achnatherum -Hesperostipa. In the Lahontan trough of the Carson Desert, a third Tribe of grasses, Zoysieae, is represented by Hilaria jamesii. The

James A. Young; Charlie D. Clements

1999-01-01

402

Cation content of leaves of desert shrubs and its relationship to taxonomic and ecological classification  

SciTech Connect

This study combines cation content of leaves with seasonal soil water availability to improve the ecological classification of desert shrub taxa in the intermountain region of the western United States. Three classifications are suggested: xerophytes, xerohalophytes and osmophytes. Taxa in the Chenopodiaceae are assigned in all three classifications.

Rickard, W.H.

1982-01-01

403

Mammal and Flea Relationships in the Great Basin Desert: From H. J. Egoscue's Collections  

Microsoft Academic Search

Host-parasite association among 58 flea species parasitizing 40 mammal species in the Great Basin Desert of the western United States was investigated. Increased flea species richness was correlated with larger geographic ranges and stable locomotion of hosts. Hosts from habitats of moderately low productivity (sage and grass) and of Peromyscus maniculatus size, 10-33 g, had the highest flea species richness.

Robert L. Bossard

2006-01-01

404

Water relations and photosynthesis of a barrel cactus, Ferocactus acanthodes , in the Colorado desert  

Microsoft Academic Search

The structural characteristics, water relations, and photosynthesis of Ferocactus acanthodes (Lemaire) Britton and Rose, a barrel cactus exhibiting Crassulacean acid metabolism (CAM), were examined in its native habitat in the western Colorado desert. Water storage in its succulent stem permitted nighttime stomatal opening ot continue for about 40 days after the soil water potential became less than that of the

Park S. Nobel

1977-01-01

405

A new strategy for analyzing the chronometry of constructed rock features in deserts  

Microsoft Academic Search

The western Great Basin contains thousands of constructed rock features, including rock rings, cairns, and alignments. Unlike subtractive geoglyphs, such as the Nasca Lines of Peru, that remove desert pavement, these surface features alter the location and positioning of cobble- to boulder- sized rocks. The chronology of surface rock features has remained unconstrained by numerical ages because no prior chronometric

Niccole Villa Cerveny; Russell Kaldenberg; Judyth Reed; David S. Whitley; Joseph Simon; Ronald I. Dorn

2006-01-01

406

Effects of Off-Road Vehicles on Vertebrates in the California Desert  

Microsoft Academic Search

Off-road vehicle (ORV) use provides a fann of outdoor recreation that is increasingly popular. The purpose of this study was to examine the impact of these machines on creosote shrub habitat and associated wildlife in the western California Desert. Comparisons at eight paired sites (Control and ORV use) demonstrate that ORV-use areas have significantly fewer species ofveriebrates, greatly reduced abundance

R. Bruce Bury; Roger A. Luckenbach; Stephen D. Busack

407

Structure of desert seed banks: comparisons across four North American desert sites  

Microsoft Academic Search

The similarities and differences in seed bank structure across four locations in the North American deserts (Curlew Valley, Utah in the Great Basin; Rock Valley, Nevada in the Mojave Desert; Silverbell, Arizona in the Sonoran Desert; and Jornada, New Mexico in the Chihuahuan Desert) were compared using published data. Species composition at Curlew Valley was most distinctive among the four

Qinfeng Guo; Philip W Rundel; David W Goodall

1999-01-01

408

Urban Desert Agriculture Transport Mixed Urban Desert AgricultureTransport Mixed  

E-print Network

Urban Desert Agriculture Transport Mixed 0 10 20 30 40 Landuse Genera Urban Desert Agriculture dependent variables: plant diversity and soil NO3-N content. In the desert variation in both plant diversity was significantly higher than in the desert and was best modeled by human population density and impervious surface

Hall, Sharon J.

409

Diversity and adaptations in the Mojave desert  

NSDL National Science Digital Library

Deserts are characterized by low humidity, little rainfall, extreme temperatures, and a small amount of vegetation. However, deserts are not "dead zones" and host a variety of organisms adapted to these conditions.

Katie Hale (California State University, Fullerton; Student, Biological Sciences)

2007-01-13

410

Pinacate beetle from the Mojave desert  

NSDL National Science Digital Library

The beetle's outer covering helps it survive in the harsh desert environment. These beetles also give off an unpleasant smell to deter predators. Beetles and other insects are eaten in the desert for their water and nutrient content.

Katie Hale (California State University, Fullerton;Student, Biological Sciences)

2007-01-13

411

On expressive punishment and holisitic desert  

E-print Network

are cleared up and made consistent through employing a holistic notion of punitive desert. Holism is the view that accurate desert judgments must reference an actually obtaining just distribution of punishment. In my view, the expressive function is feasible...

Greenblum, Jake

2009-05-15

412

Egypt's population policies and family planning program: a critical examination  

E-print Network

in rural Egypt are using a birth control method calls into question the "success" of Egypt's population program as a national endeavor and reveals a distinct disparity between contraceptive prevalence in rural areas as opposed to urban areas. This thesis...

Carr, Aline B.

1996-01-01

413

Phytoremediation for Oily Desert Soils  

NASA Astrophysics Data System (ADS)

This chapter deals with strategies for cleaning oily desert soils through rhizosphere technology. Bioremediation involves two major approaches; seeding with suitable microorganisms and fertilization with microbial growth enhancing materials. Raising suitable crops in oil-polluted desert soils fulfills both objectives. The rhizosphere of many legume and non-legume plants is richer in oil-utilizing micro-organisms than non-vegetated soils. Furthermore, these rhizospheres also harbour symbiotic and asymbiotic nitrogen-fixing bacteria, and are rich in simple organic compounds exuded by plant roots. Those exudates are excellent nutrients for oil-utilizing microorganisms. Since many rhizospheric bacteria have the combined activities of hydrocarbon-utilization and nitrogen fixation, phytoremediation provides a feasible and environmentally friendly biotechnology for cleaning oil-polluted soils, especially nitrogen-poor desert soils.

Radwan, Samir

414

6, 17491792, 2006 Desert dust regional  

E-print Network

ACPD 6, 1749­1792, 2006 Desert dust regional modelling A. S. Zakey et al. Title Page Abstract Discussions Development and testing of a desert dust module in a regional climate model A. S. Zakey1 , F 6, 1749­1792, 2006 Desert dust regional modelling A. S. Zakey et al. Title Page Abstract

Paris-Sud XI, Université de

415

Desert-Adapted Crocs Found in Africa  

NSDL National Science Digital Library

This National Geographic site details the discovery of several small communities of crocodiles living on the southern edge of Africa's Sahara in desert conditions. The desert crocodiles have apparently adapted to the changing environment in northern Africa; 8,000 to 10,000 years ago, what is now desert was probably lush savannah and grasslands.

Mayell, Hillary; News, National G.

416

Center for Desert Archaeology Archaeology Southwest  

E-print Network

Center for Desert Archaeology Archaeology Southwest Center for Desert Archaeology Archaeology Southwest Issue Editors: Jesse A. M. Ballenger and Vance T. Holliday Archaeology Southwest is a Quarterly Publication of the Center for Desert Archaeology Volume 23, Number 3 Summer 2009 TM Paleoindians

Holliday, Vance T.

417

Tertiary Normal Faulting in the Canyon Range, Eastern Sevier Desert.  

PubMed

The contact between pre-Mesozoic and Tertiary rocks in the western Canyon Range, west-central Utah, has been interpreted as a large, low-angle normal fault that marks the breakaway zone of the hypothesized, basin-forming Sevier Desert detachment. Recent fieldwork suggests that the contact may in fact be depositional along much or all of its length. Deformational fabric in the supposed footwall likely traces to the Mesozoic Sevier orogeny rather than to Tertiary detachment faulting. Kinematic indicators at the range front are not generally consistent with low-angle normal-fault motion; instead, well-exposed high-angle faults are the dominant range-bounding structures. The Tertiary conglomerates of the western Canyon Range foothills, previously viewed as an evolving syntectonic deposit related to detachment faulting, are here reinterpreted as three distinct units that reflect different periods and tectonic settings. The pattern in these conglomerates, and in fault-offset gravity-slide deposits that mantle the western foothills, is consistent with block faulting and rotation along several generations of high-angle structures. Local seismic-reflection data lend qualitative support to this interpretation, and underscore the need to consider alternative working hypotheses for evolution of the Sevier Desert basin. PMID:10517882

Wills; Anders

1999-11-01

418

Prickly pear desert cactus flower in the Mojave desert  

NSDL National Science Digital Library

The prickly pear cactus is a desirable meal for many desert organisms because of its water storing capability. Cacti have no leaves which reduces water loss. However, it has many spines and thorns for shade and to keep predators from eating it.

Katie Hale (California State University, Fullerton;Student, Biological Sciences)

2007-01-13

419

Gains from Improved Irrigation Water Use Efficiency in Egypt  

Microsoft Academic Search

Egypt's fortunes hinge on the Nile. However, little research to date has evaluated economic efficiency improvements that could be achieved by altering Egypt's agricultural water use patterns. This study develops an integrated catchment scale framework to identify potential economic benefits that can be supported by Egypt's irrigation water use. An optimization framework is developed to identify improvements in national farm

Abdelaziz A Gohar; Frank A Ward

2011-01-01

420

THE EGYPT LABOR MARKET PANEL SURVEY: INTRODUCING THE 2012 ROUND  

E-print Network

of the 1998 and 2006 rounds of the ELMPS have been the workhorse of labor market research in Egypt. The public Market Panel Survey, carried out by the Economic Research Forum (ERF) in cooperation with Egypt's Central market and human resource development research in Egypt, being the first and most comprehensive source

Levinson, David M.

421

Opportunities for woody crop production using treated wastewater in Egypt  

Technology Transfer Automated Retrieval System (TEKTRAN)

The Nile River provides nearly 97% of Egypt's freshwater supply. Egypt's share of Nile waters is allocated according to international treaty obligations and is fixed at 55.5 billion cubic meters annually. As a result, Egypt will not be able to meet increasing water demand using freshwater from the N...

422

Alternate Energy from the Desert  

Microsoft Academic Search

Due to rapid growth of the world's population and more demands for energy, and due to limited amount of fossil fuels (which provide 95 % of the world's energy needs), harnessing of alternate energy sources such as solar and wind power should be considered. In addition to the mountain passes with usually high wind, vast and flat desert areas could

E. Malek

2003-01-01

423

Factors determining desert dune type  

Microsoft Academic Search

While most observers recognize four elemental types of desert dunes (longitudinal, transverse, barchan and star1-3) there is little agreement about which factors determine these types. The angular relationships between the resultant of sand shifting winds and both the crest and principal slipfaces of the elemental types have been discussed qualitatively for many decades. These relationships have been quantified but the

R. J. Wasson; R. Hyde

1983-01-01

424

Mosses in the Desert: Fascinating  

E-print Network

of transcription and translation: ­ (i) upon rewetting, transcripts converted into proteins that repair proteins to the transcript level (half-way to a protein). ­ review of making proteins: ­ DNA transcription mRNA ­ translation proteins #12;· B. In desert mosses, the key to their survival is the separation

Ahmad, Sajjad

425

On a Crowded Desert Island.  

ERIC Educational Resources Information Center

Suggests reference sources most appropriate for a desert island. In addition to "Robinson Crusoe" (Daniel Defoe) and a reference guide to the literature of travel, the list includes basic books on reference work, guides to reference sources, journals, an almanac, encyclopedias, a guide to English usage, and a book of quotations. (14 references)…

Rothstein, Samuel

1989-01-01

426

The Sonoran Desert, Arizona Upland  

NSDL National Science Digital Library

This tutorial explains the ecosystem of the Arizona Upland region of the Sonoran Desert and describes the plants and animals that live there. Students will discover the interactions of the living and non-living parts of the ecosystem. There is an interactive glossary within the text.

427

Comparison of health care financing in Egypt and Cuba: lessons for health reform in Egypt.  

PubMed

Egypt and Cuba are both lower-middle income countries with a history of socialist rule, which have embarked on economic liberalization since the 1990s. Cuba has achieved exemplary health status whereas health status in Egypt is lower than could be expected for its level of income. In this article, health care financing mechanisms in both countries are analysed on their effectiveness, efficiency, and equity, with the objective of identifying the determinants of success in the Cuban health system from which valuable lessons for current health reforms in Egypt may be derived. PMID:16761679

Gericke, C A

2005-01-01

428

Space science education for postgraduate students in Minoufiyia University, Egypt  

NASA Astrophysics Data System (ADS)

In 1986 the author with his colleagues in the Physics Department, Faculty of Science, Minoufiyia University, Minoufiyia, Egypt created a new branch in the physics department, to award the M.Sc. and Ph.D. degree in Atmospheric physics. Courses in solar, solar-terrestrial, and atmospheric physics were necessary for M.Sc. and Ph.D. students, because they not studded it before in the undergraduate level. Till now, seven students obtained on M.Sc. degree, and two students obtained on Ph.D. from the Physics Department of Minoufiya University in Solar, Solar-Terrestrial, and Space Physics, and there are one Ph.D and two M.Sc. under the awarding. This current extend to other six Egyptian Universities (Cairo, Ain Shams, Helwan, Alexandria, Mansoura, and Minua), where five students obtained on Ph.D degree, and thirteen students obtained on M.Sc. in Solar, Solar-terrestrial, and Space Physics from the six universities under the supervision of the author. In April 2002 the author succeeded to obtain on the agreement of the Minoufiyia University Council by construction Space Research Center, as a first center for space research in the Egyptian Universities (20 Universities), as a part from the Desert Environment Research Institute for temporal time, then after the growth, it will be independent center. Beside the research work in space science and technology, the center have the validity to award Diploma, M.Sc and Ph.D. in space science for postgraduate students. There are different courses in space science and technology for each level of the three degrees. According to the program of the European Mediterranean Countries (TEMPS III) for developing the higher education level, the center constructed a project for developing space science and technology education in the center in collaboration with European Universities and Space Research Centers. This paper explain in detail the experience in Space Science Education in Minoufiya University, and how expand it to the other universities in Egypt.

Mosalam Shaltout, M. A.

429

Monitoring Wadi El Raiyan lakes of the egyptian desert for inorganic pollutants by ion-selective electrodes, ion chromatography, and inductively coupled plasma spectroscopy.  

PubMed

Wadi El Raiyan is a great depression located southwest of Cairo in the western desert of Egypt, one of the most arid regions of the world. In 1973, Wadi El Raiyan was connected with the agricultural wastewater drainage system of the El Faiyum province to provide a reservoir for the wastewater that exceeded the capacity of Lake Qarun north of the province. Pollutants from agricultural waste including pesticides and fertilizers as well as other effluents of industrial activities and runoffs certainly will pass into the biotic elements of the ecosystem. This report presents the status of inorganic pollutants including anions, cations, and trace metals in the two lakes and the surrounding springs of Wadi El Raiyan using ion chromatography, ion-selective electrodes, and inductively coupled plasma emission spectroscopy. The report also includes the levels of selected metals in the vegetation community of the area. The result of this investigation revealed a great improvement in water quality of the Wadi El Raiyan lakes compared to 1988 report by Saleh et al. Mercury was not detected in any of the samples and the level of lead was significantly reduced. Cadmium levels were much higher than those seen earlier. The higher level of cadmium might be used as an indicator to track the contamination of water by human waste. Concentrations of common anions were not significantly different from those reported earlier. However, an increase in the level of cyanide was observed. Levels of heavy metals in vegetation around the lakes were also found to be lower than previously reported. PMID:10702352

Saleh, M A; Ewane, E; Jones, J; Wilson, B L

2000-03-01

430

The boatbuilding industry of New Kingdom Egypt  

E-print Network

restricted to Crete. In later, Mycenaean times it spread as an effective tool throughout the Mycenaean world" and undoubtedly came into contact with NK Egypt via the well-established trade patterns woven amongst the centers of the Eastern Mediterranean...THE BOATBUiLDING INDUSTRY OF NEW KIN DOM EGYPT A Thesis by CHRISTOPHER MOUNTFORT MONROE Submitted to the Office of Graduate Studies of Texas A@M University in partial fulfillment of the requirements for the degree of MASTER OF ARTS August...

Monroe, Christopher Mountfort

2012-06-07

431

A review of the emergence of Plasmodium falciparum-dominated malaria in irrigated areas of the Thar Desert, India.  

PubMed

Recently, there has been a resurgence of malaria in several parts of India, and the Thar Desert in north-western India, is currently suffering from the impact of repeated annual epidemics. Nearly all malaria epidemics in the Thar Desert have come about with the progression of canal-irrigation work, particularly the massive Indira Gandhi Nahar Pariyojana (IGNP). Therefore, the Thar Desert provides an excellent model for understanding the underlying factors responsible for the exacerbation of malaria, pathways of evolution of the epidemics, succession in anopheline fauna, changes in the vector breeding and feeding preferences and, most importantly, the possible repercussions of mismanagement of irrigation systems. Before the initiation of canalised irrigation only Anopheles stephensi, breeding exclusively in household and community-based underground water reservoirs, and transmitting malaria at a low level, was prevalent in the interior of the Thar Desert. Since the 1980s, extensive irrigation with water from three different canal systems has altered the desert physiography, vector preponderance, distribution and vectorial capacity, whilst triggering the emergence of Plasmodium falciparum-dominated malaria in the virgin levees of the Thar Desert. The major objective of bringing the Himalayan waters to the xeric environment of the Thar was to transform it into verdure through growing irrigation-intensive crops like paddy, groundnut, cotton, mustard, wheat and sugarcane, besides providing drinking water to the desert dwellers. The change in crop pattern, retention of high surface moisture, and excessive canalisation rife with mismanagement of irrigation water have attracted several anophelines, including Anopheles culicifacies, which were earlier unknown in the desert. Thus, A. culicifacies has penetrated into the interior of the Thar Desert, along with irrigation and is now established in vast areas covered by the IGNP project. The distribution of P. falciparum-dominated malaria in the Thar Desert is more or less synchronous with the spread of IGNP-related irrigated agriculture and of A. culicifacies. PMID:14732244

Tyagi, B K

2004-01-01

432

Distribution of desert varnish in Arizona  

NASA Technical Reports Server (NTRS)

Desert varnish is the dark coat of clay and ferromanganese oxides developed on exposed rock surfaces in arid regions. It forms from the accretion of material from windblown dust. The distribution of desert varnish was mapped in Arizona. It was discovered that desert varnish could be mapped on a regional scale. Well developed desert varnish is common on stable rock surfaces in areas having alkaline soils and less than about 25 cm of annual precipitation. Rock surfaces in areas having more than 40 cm of annual precipitation are generally devoid of desert varnish. An experiment was conducted with varnished desert pavement stone. The stones were broken in half and half was set on a roof in central Illinois from April until October. Removed from the alkaline desert environment, it only took seven months for the varnish to develop an eroded appearance. This experiment graphically illustrates the dependency of desert varnish on alkalinity. In this context, the zones of eroded desert varnish in Arizona indicate that the area of active desert varnish formation has fluctuated, expanding in drier times and contracting/eroding in wetter times.

Elvidge, Christopher D.

1989-01-01

433

Geological and geophysical investigation of Kamil crater, Egypt  

NASA Astrophysics Data System (ADS)

We detail the Kamil crater (Egypt) structure and refine the impact scenario, based on the geological and geophysical data collected during our first expedition in February 2010. Kamil Crater is a model for terrestrial small-scale hypervelocity impact craters. It is an exceptionally well-preserved, simple crater with a diameter of 45 m, depth of 10 m, and rayed pattern of bright ejecta. It occurs in a simple geological context: flat, rocky desert surface, and target rocks comprising subhorizontally layered sandstones. The high depth-to-diameter ratio of the transient crater, its concave, yet asymmetric, bottom, and the fact that Kamil Crater is not part of a crater field confirm that it formed by the impact of a single iron mass (or a tight cluster of fragments) that fragmented upon hypervelocity impact with the ground. The circular crater shape and asymmetries in ejecta and shrapnel distributions coherently indicate a direction of incidence from the NW and an impact angle of approximately 30 to 45°. Newly identified asymmetries, including the off-center bottom of the transient crater floor downrange, maximum overturning of target rocks along the impact direction, and lower crater rim elevation downrange, may be diagnostic of oblique impacts in well-preserved craters. Geomagnetic data reveal no buried individual impactor masses >100 kg and suggest that the total mass of the buried shrapnel >100 g is approximately 1050-1700 kg. Based on this mass value plus that of shrapnel >10 g identified earlier on the surface during systematic search, the new estimate of the minimum projectile mass is approximately 5 t.

Urbini, Stefano; Nicolosi, Iacopo; Zeoli, Antonio; El Khrepy, Sami; Lethy, Ahmed; Hafez, Mahfooz; El Gabry, Mohamed; El Barkooky, Ahmed; Barakat, Aly; Gomaa, Mahomoud; Radwan, Ali M.; El Sharkawi, Mohamed; D'Orazio, Massimo; Folco, Luigi

2012-11-01

434

Thermal Performance of Exposed Composed Roofs in Very Hot Dry Desert Region in Egypt (Toshky)  

E-print Network

that the thermal transmittance (UValue) has a major role in chosen the constructed materials. Also the thermal insulation considered the suitable manner for damping the thermal stresses through day time and makes the interior environment of the building near...

Khalil, M. H.; Sheble, S.; Morsey, M. S.; Fakhry, S.

2010-01-01

435

SHRIMP zircon dating and Sm\\/Nd isotopic investigations of Neoproterozoic granitoids, Eastern Desert, Egypt  

Microsoft Academic Search

There is an increasing evidence for the involvement of pre-Neoproterozoic zircons in the Arabian–Nubian Shield, a Neoproterozoic crustal tract that is generally regarded to be juvenile. The source and significance of these xenocrystic zircons are not clear. In an effort to better understand this problem, older and younger granitoids from the Egyptian basement complex were analyzed for chemical composition, SHRIMP

Ewais M. M. Moussa; Robert J. Stern; William I. Manton; Kamal A. Ali

2008-01-01

436

Prehistoric occupation of the eastern desert, Egypt: a key to landform analysis  

SciTech Connect

Surface scatters of lithic artifacts on Quaternary faulted relict surfaces and terrace flights represent the first Prehistoric sites reported from the west bank, Gulf of Suez. These aid in analyzing the geomorphifc history of the Gulf, a Neogene rift valley. Diagnostic artifacts include Lower Palaeolithic choppers and Acheulean hand axes; Middle Palaeolithic Levallois flakes and points, denticulate scrapers, and a discoidal core; Late Palaeolithic blade and scrapers and blades; and a Neolithic tanged point, side scraper, and chipped axe. Tectonic and climatic changes are indicated by vertical distribution of Prehistoric sites. Similar artifact assemblages at different relative elevations on bedrock horsts imply laterally varying tectonic uplift rates. Large elevation differences between Middle and Late Palaeolithic-bearing alluvial terraces indicate rapid erosional landscape change. This allows tentative correlation of widely separated terrace flights and indicates the latest possible age of drainage abandonment. Considerable climatic amelioration would have been required for Prehistoric occupation of this arid region. Sites were probably situated above then-active drainages. Additionally, today's limited rainfall cannot account for the amount of erosion since Prehistoric occupation. Therefore, at least three pluvials, corresponding to the Lower, Middle, and Late Palaeolithic, are postulated; these apparently controlled both landscape development and human occupation of this marginal ecosystem. Archaeological analysis can thus be useful as a tool for semiquantitative evaluation of erosion cycles and uplift rates.

Gawarecki, S.L.; Hoffman, M.A.; Perry, S.K.

1985-01-01

437

Paleoclimatic and Tectonic History of the Eastern Desert, Egypt and Surroundings  

NASA Technical Reports Server (NTRS)

This report covers work for the Planetary Geology and Geophysics Program, which has focused on three areas: analysis of the tectonics and paleoclimatic conditions in north eastern Africa, analysis of surficial geology and damage associated with the 1993 Missouri River floods and rates of lava flow degradation at Lunar Crater volcanic field in Nevada. Work has resulted in several dozen abstracts, several dissertations and a number of papers.

Arvidson, Raymond E.

1997-01-01

438

Diagenetic and metamorphic history of the Umm Nar BIF, Eastern Desert, Egypt  

Microsoft Academic Search

The Umm Nar BIF was formed in a sedimentary environment. It is confined to an upper stratigraphic zone of pre-Pan-African metamorphosed shelf deposits. During the Pan-African deformational history, the BIF and the host metasediments were tectonically' overlain by ophiolitic melange succession. The metasediments and the mélange were subjected to a major folding phase and then thrust over the ``Shaitian'' sheared

M. M. El Aref; A. El Dougdoug; M. Abdel Wahed; A. W. El Manawi

1993-01-01

439

Diagenetic and metamorphic history of the Umm Nar BIF, Eastern Desert, Egypt  

Microsoft Academic Search

The Umm Nar BIF was formed in a sedimentary environment. It is confined to an upper stratigraphic zone of pre-Pan-African\\u000a metamorphosed shelf deposits. During the Pan-African deformational history, the BIF and the host metasediments were tectonically'\\u000a overlain by ophiolitic melange succession. The metasediments and the mélange were subjected to a major folding phase and then\\u000a thrust over the “Shaitian” sheared

M. M. El Aref; A. El Dougdoug; M. Abdel Wahed; A. W. El Manawi

1993-01-01

440

Spectral reflectance of biogenic crust developed on desert dune sand along the Israel-Egypt border  

Microsoft Academic Search

The effect of biogenic crust on imagery acquired by spaceborne sensors is demonstrated. The crust consists mostly of microphytes such as cyanobacteria. The macrophytes (higher vegetation) on the sand dunes are sparse and have a relatively low spectra! reflectance response. However, since a considerable ponton of the ground is covered by this biogenic crust, (which has a different spectral reflectance

A. Karnieli; H. Tsoar

1995-01-01

441

Unusual dominance by desert pupfish (Cyprinodon macularius) in experimental ponds within the Salton Sea Basin  

USGS Publications Warehouse

In October 2006, months after shallow experimental ponds in the Salton Sea Basin were filled with water from the Alamo River and Salton Sea, fish were observed in several ponds, although inlets had been screened to exclude fish. During October 2007November 2009, nine surveys were conducted using baited minnow traps to document species and relative abundance of fish. Surveys yielded 3,620 fish representing five species. Desert pupfish (Cyprinodon macularius), the only native species encountered, was the most numerous and comprised >93% of the catch. Nonnative species included western mosquitofish (Gambusia affinis, 4.1%), sailfin molly (Poecilia latipinna, 2.8%), and tilapia (a mixture of hybrid Mozambique tilapia Oreochromis mossambicus ?? O. urolepis and redbelly tilapia Tilapia zillii, <0.1%). Dominance by desert pupfish, which persisted over our 2 years of study, was unusual because surveys conducted in nearby agricultural drains yielded relatively few desert pupfish.

Saiki, Michael K.; Martin, Barbara A.; Anderson, Thomas W.

2011-01-01

442

Women's "Justification" of Domestic Violence in Egypt  

ERIC Educational Resources Information Center

We explored the influences of women's social learning, marital resources and constraints, and exposure to norms about women's family roles on their views about wife hitting or beating among 5,450 participants in the 2005 Egypt Demographic and Health Survey. One half justified wife hitting or beating for some reason. Women from rural areas who were…

Yount, Kathryn M.; Li, Li

2009-01-01

443

Review of Parasitic Zoonoses in Egypt  

PubMed Central

This review presents a comprehensive picture of the zoonotic parasitic diseases in Egypt, with particular reference to their relative prevalence among humans, animal reservoirs of infection, and sources of human infection. A review of the available literature indicates that many parasitic zoonoses are endemic in Egypt. Intestinal infections of parasitic zoonoses are widespread and are the leading cause of diarrhea, particularly among children and residents of rural areas. Some parasitic zoonoses are confined to specific geographic areas in Egypt, such as cutaneous leishmaniasis and zoonotic babesiosis in the Sinai. Other areas have a past history of a certain parasitic zoonoses, such as visceral leishmaniasis in the El-Agamy area in Alexandria. As a result of the implementation of control programs, a marked decrease in the prevalence of other zoonoses, such as schistosomiasis and fascioliasis has been observed. Animal reservoirs of parasitic zoonoses have been identified in Egypt, especially in rodents, stray dogs and cats, as well as vectors, typically mosquitoes and ticks, which constitute potential risks for disease transmission. Prevention and control programs against sources and reservoirs of zoonoses should be planned by public health and veterinary officers based on reliable information from systematic surveillance. PMID:24808742

Youssef, Ahmed I.; Uga, Shoji

2014-01-01

444

Evidence for early cat taming in Egypt  

Microsoft Academic Search

The remains are described of a young small felid found in a Predynastic burial at Hierakonpolis, Upper Egypt. Osteometric and zoogeographical arguments indicate that the specimen, dated to around 3700 B.C. on the basis of the associated pottery, belongs to Felis silvestris. In the same cemetery several other animal species, both wild and domestic, have been found. The left humerus

Veerle Linseele; Wim Van Neer; Stan Hendrickx

2007-01-01

445