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Geochemistry of island arc assemblage in the Eastern Desert of Egypt and the role of Pan-African magmatism in crustal growth of the Arabian–Nubian Shield:A review
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作者 Abdel-Aal MAbdel-Karim Mohamed MHamdy Adel A.Surour 《Acta Geochimica》 EI CAS CSCD 2024年第3期588-622,共35页
Neoproterozoic island arc assemblage of the Arabian–Nubian Shield(ANS)in the Eastern Desert(ED)of Egypt comprises juvenile suites of metavolcanics(MV),large amounts of meta-sedimentary rocks(MS),and voluminous metaga... Neoproterozoic island arc assemblage of the Arabian–Nubian Shield(ANS)in the Eastern Desert(ED)of Egypt comprises juvenile suites of metavolcanics(MV),large amounts of meta-sedimentary rocks(MS),and voluminous metagabbros-diorites(MGD)and syn-tectonic intrusions of older granitoids(OG).We report here the updates of these four rock units in terms of classification,distribution,chemical characteristics,geodynamic evolution,metamorphism,and ages.In addition,we discuss these integrated data to elucidate a reasonable and reliable model for crustal evolution in the ANS.The main features of these rock units indicate their relation to each other and the geodynamic environment dominated by early immature oceanic island arcs to primitive continental arcs.Integrated information of the island arc metavolcanic and plutonic rocks(gabbros,diorites,tonalites,and granodiorites)furnish evidence of the genetic relationships.These include proximity and a coeval nature in the field;all protolith magmas are subalkaline in nature following calc-alkaline series with minor tholeiitic affinities;common geochemical signature of the arc rocks and subduction-related magmatism;their similar enrichment in LREEs;and similar major element compositions with mafic melts derived from metasomatized mantle wedge.The volcano-sedimentary and the OG rocks underwent multiphase deformation events whereas the MGD complexes deformed slightly.Based on the magmatic,sedimentological,and metamorphic evolutions constrained by geochronological data as well as the progressive evolutionary trend from extensional to compressional regimes,a possible gradual decrease in the subducted slab dip angle is the most infl uential in any geodynamic model for arc assemblage in the ED of Egypt. 展开更多
关键词 Island arc assemblage MAGMATISM Crustal growth NEOPROTEROZOIC Arabian–Nubian Shield Eastern Desert EGYPT
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Assessment of groundwater suitability for different activities in Toshka district,south Egypt
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作者 Marwa M Aly Shymaa AK Fayad Ahmed MI Abd Elhamid 《Journal of Groundwater Science and Engineering》 2024年第1期34-48,共15页
Globally,groundwater has globally emerged as a crucial freshwater source for domestic,irrigation,and industrial needs.The evaluation of groundwater quality in the Toshka region is imperative to ensure its suitability ... Globally,groundwater has globally emerged as a crucial freshwater source for domestic,irrigation,and industrial needs.The evaluation of groundwater quality in the Toshka region is imperative to ensure its suitability for the extensive agricultural and industrial activities underway in this promising,groundwater-dependent development area.This is particularly significant as Egypt increasingly relies on groundwater reserves to address freshwater deficits and to implement mega-development projects in barren lands.In this study,fifty-two samples were collected from the recently drilled wells tapping into the Nubian Sandstone Aquifer(NSA)in the Toshka region.Groundwater quality was assessed through hydrochemical analysis,Piper diagram,and various indicators such as Na%,SAR,RSC,KR,MH and PI.The hydrochemical analysis revealed improved groundwater quality characteristics,attributed to continuous recharge from Lake Nasser.The Piper diagram categorised most of the water samples as"secondary salinity"water type.Almost all wells proved suitable for irrigation with only two wells unsuitable based on MH values and six wells based on KR values.Considering Total Hardness(TH)values,all samples were classified as"Soft",indicating their suitability for domestic and industrial purposes.Water Quality Index(WQI)results concluded that all samples met WHO and FAO guidelines for drinking and irrigation,respectively.Spatial distribution maps,constructed using GIS,facilitate the interpretation of the results.Regular monitoring of quality parameters is essential to detect any deviation from permissible limits. 展开更多
关键词 Nubian Sandstone Aquifer Water Quality Assessment Hydro-chemical Analysis Irrigation Quality Indicators Domestic Use Water Quality Index
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The Current Conservation Efforts and Future Prospects for the Endangered Nubian Ibex (Capra nubiana ibex) in Sudan
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作者 Lubna Mohammed Abdallah Hassan Mutasim Essa Abdallah Adam +1 位作者 Latifa Altigani Adam Abakar Nasir Yousif Gaboush Brema 《Journal of Environmental Protection》 2024年第1期39-62,共24页
A comprehensive action plan for the conservation of the endangered species, the Nubian ibex in Sudan, can be developed by gaining a thorough understanding of their current status, conservation strategy, and relevant l... A comprehensive action plan for the conservation of the endangered species, the Nubian ibex in Sudan, can be developed by gaining a thorough understanding of their current status, conservation strategy, and relevant laws and regulations, as well as raising awareness about the importance of protecting endangered species. The Nubian ibex is listed as an endangered species on The International Union for Conservation of Nature (IUCN) Red List, highlighting the need for further research on population conservation efforts due to insufficient population data. To address this knowledge gap, a questionnaire was conducted with various stakeholders, including police officers, researchers, and lecturers, representing a diverse range of organizations and universities. The findings revealed that hunting is the primary factor contributing to endangerment. Mammals account for 80% of endangered species, while reptiles comprise less than one-tenth. Research centers are recognized as the main governing body, and 85% of participants are concerned about the declining population. Hunting accounted for less than half of the threats to the ibex population in Sudan, while habitat loss made up a quarter. Mining, climate change, human activity, and agriculture were also identified as risks. However, there were no plans, strategies, procedures, or measures in place to conserve the Nubian ibex. There were also no initiatives to preserve its biodiversity, and awareness about endangered species was lacking. Although participants believed that laws were effective in protecting the ibex, no licenses were issued for its conservation, and annual surveys were not conducted. Additionally, there were no recorded instances of Mukhalfat related to the Nubian ibex. In light of these findings, we propose various conservation measures to address these challenges. These measures include the implementation of laws and regulations, conducting annual surveys to monitor population trends, protecting habitats, establishing breeding and releasing programs, launching awareness campaigns, undertaking rehabilitation efforts, enhancing research efforts, and developing comprehensive conservation strategies. Additionally, it is crucial to foster cooperation among wildlife institutes to ensure the effective implementation of these conservation measures. 展开更多
关键词 Nubian Ibex SUDAN Endangered Species Conservation Status Law REGULATIONS AWARENESS
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Genomic analysis of indigenous goats in Southwest Asia reveals evidence of ancient adaptive introgression related to desert climate
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作者 Hojjat Asadollahpour Nanaei Yudong Cai +8 位作者 Akil Alshawi Jiayue Wen Tanveer Hussain Wei-Wei Fu Nai-Yi Xu Abdulameer Essa Johannes ALenstra Xihong Wang Yu Jiang 《Zoological Research》 SCIE CAS CSCD 2023年第1期20-29,共10页
Understanding how evolutionary pressures related to climate change have shaped the current genetic background of domestic animals is a fundamental pursuit of biology. Here, we generated wholegenome sequencing data fro... Understanding how evolutionary pressures related to climate change have shaped the current genetic background of domestic animals is a fundamental pursuit of biology. Here, we generated wholegenome sequencing data from native goat populations in Iraq and Pakistan. Combined with previously published data on modern, ancient(Late Neolithic to Medieval periods), and wild Capra species worldwide, we explored the genetic population structure, ancestry components, and signatures of natural positive selection in native goat populations in Southwest Asia(SWA). Results revealed that the genetic structure of SWA goats was deeply influenced by gene flow from the eastern Mediterranean during the Chalcolithic period, which may reflect adaptation to gradual warming and aridity in the region. Furthermore, comparative genomic analysis revealed adaptive introgression of the KITLG locus from the Nubian ibex(C. nubiana) into African and SWA goats. The frequency of the selected allele at this locus was significantly higher among goat populations located near northeastern Africa. These results provide new insights into the genetic composition and history of goat populations in the SWA region. 展开更多
关键词 GOAT Adaptation KITLG Southwest Asia Nubian ibex
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Evaluation of the Effect of Gurusa, a Ugandan Cereal-Based Fermented Food on Serum Lipid Profile and Body Weight of Wistar Albino Rats
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作者 Atamgba Agbor Asuk Abbas Kisambira +1 位作者 Muhammad Lubowa Denis Ssenabulya 《Food and Nutrition Sciences》 2016年第4期284-293,共10页
The effect of Gurusa, a fermented traditional food on lipid profile and body weight was investigated. Thirty male albino rats weighing between 75 - 115 g assigned into five study groups designated A to E (n = 6) were ... The effect of Gurusa, a fermented traditional food on lipid profile and body weight was investigated. Thirty male albino rats weighing between 75 - 115 g assigned into five study groups designated A to E (n = 6) were fed 20 g of prepared pellets and tap water given ad libitum. The animals were served graded doses of Gurusa. Group A was served 100% rat chow pellets (made of maize bran);groups B, C and D were given pellets of 75% rat chow and 25% Gurusa, 50% rat chow and 50% Gurusa, 25% rat chow and 75% Gurusa respectively while group E was served 100% Gurusa. The lipid profile showed a dose dependent effect of Gurusa administration as one moves down the groups. Group D had a reverse action of group B and showed significant (P < 0.05) increase in TC, TG and HDL compared to groups A and B but a significant (P < 0.05) decrease in LDL compared to group B. Weight changes in group B produced a significant (P < 0.05) increase in MWI and GR compared to the other groups. There was no significant (P ≥ 0.05) difference in MWI and GR of group D when compared with group A. However group C showed significant (P < 0.05) increase in MWI and GR when compared with group A. Gurusa consumption alters both lipid profile and body weight and its combination with maize bran or other foods rich in dietary fibre, have potential to serve therapeutic purposes in the prevention of atherosclerosis and obesity depending on the intended objective. 展开更多
关键词 Traditional Diet ATHEROSCLEROSIS OBESITY Proximate Composition nubians
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Late Neoproterozoic adakitic magmatism of the eastern Arabian Nubian Shield 被引量:2
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作者 Grant M.Cox John Foden Alan S.Collins 《Geoscience Frontiers》 SCIE CAS CSCD 2019年第6期1981-1992,共12页
Late Neoproterozoic adakitic magmatism within the Eastern Arabian Nubian Shield has been dated at633.2±9.0 Ma(2σ).These magnas intrude the forearc Ad Dawadimi Basin,which is composed of metapelitic schists and g... Late Neoproterozoic adakitic magmatism within the Eastern Arabian Nubian Shield has been dated at633.2±9.0 Ma(2σ).These magnas intrude the forearc Ad Dawadimi Basin,which is composed of metapelitic schists and greywacke along with ophiolitic melanges of boninitic affinity which underwent inversion and deformation by^620 Ma.This adakitic magmatism,while intruding parts of the Ad Dawadimi Basin,predates this deformation,but is possibly coincident with basin closure.As adakitic magmatism requires melting of an amphibolite or eclogitic source,empirical and experimental constraints require anomalously hot supra-subduction zone mantle.Considering that this magmatism immediately predates basin inversion,these magmas possibly pinpoint the timing of the slab breaking,marking the terminal stages of arc magmatism,terrane accretion and the influx of hot oceanic asthenospheric mantle.This influx of hot asthenospheric mantle may also be responsible for postcolltsional A-type magmatism. 展开更多
关键词 Arabian Nubian SHIELD ADAKITES A-TYPE MAGMATISM
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Slaughtering Performance and Meat Quality of Hainan Black Goat and Its Hybrid Offsprings with Nubian Black Goat 被引量:3
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作者 Wei Limin Sun Ruiping +6 位作者 Liu Yan Liu Ruina Liu Quanwei Zheng Xinli Wang Feng Huang Lili Xing Manping 《Animal Husbandry and Feed Science》 CAS 2019年第2期49-52,共4页
In order to compare the slaughter performance and meat quality of Hainan black goats and hybrid offsprings of Nubian Black Goat and Hainan Black Goat, six 7-month-old Hainan black goats and six hybrid offsprings were ... In order to compare the slaughter performance and meat quality of Hainan black goats and hybrid offsprings of Nubian Black Goat and Hainan Black Goat, six 7-month-old Hainan black goats and six hybrid offsprings were selected to determine slaughter performance and muscle quality. The results showed that hybridization of Nubian black goat and Hainan black goat significantly improved the production performance and slaughter performance of hybrid offsprings (P>0.05). The meat quality of F1 hybrid black goat had no significant difference with that of Hainan black goat except for the hardness and elasticity (P<0.05). Therefore, the crossbred progenies of Nubian black goat and Hainan black goat have advantages in meat yield and meat performance, and the main meat quality indexes are not significantly different, which meets the market requirements for high-yield and high-quality hybrid combinations, and can be used for cross promotion. 展开更多
关键词 HAINAN BLACK Goats Nubian BLACK Goats HYBRID OFFSPRING SLAUGHTER PERFORMANCE Meat quality
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Neoproterozoic Tectonic Events of Egypt 被引量:1
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作者 Mohamed ABD EL-WAHED Zakaria HAMIMI 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2021年第4期1366-1405,共40页
The Egyptian Nubian Shield(ENS)represents the northwestern part of the Arabian-Nubian Shield and the northern extension of the East African Orogen.The ENS is regarded as being formed due to northward-directed escape t... The Egyptian Nubian Shield(ENS)represents the northwestern part of the Arabian-Nubian Shield and the northern extension of the East African Orogen.The ENS is regarded as being formed due to northward-directed escape tectonics.It is characterized by mild accretion and suture zones dominated by major strike-slip zones with a commonly sinistral sense of movement;some shear zones display a dextral sense of shear.It is dominated by gneisses and migmatites in the south,arc volcaniclastic metasediments and highly dismembered ophiolites in the central parts,whereas its northern part is dominated by late-to post-tectonic granitoids.In southern Sinai,the Neoproterozoic rocks are grouped into four complexes,namely Feiran–Solaf,Sa’al–Zaghra,Kid and Taba.The ENS ophiolites were formed between 730–750 Ma,mainly in a supra-subduction zone setting.The ENS has undergone a Neoproterozoic deformation history involving three successive phases:(1)Early N–S shortening phase(D1),(2)Syn-accretionary phase(D2)and(3)Post-accretionary phase(D3).The initial island-arc stage(780–730 Ma)is a N–S shortening phase initiated by collision between the Eastern Desert tectonic terrane to the north with both the Gebeit and Gabgaba terranes to the south(830–720 Ma).During the arc-splitting and back-arc spreading stage(730–620),voluminous syn-tectonic granitoids intruded into the ENS(750–610 Ma).The E–W-directed compressional/transpressional phase(620–450 Ma)led to the overall uplift of the central part of the ENS and consequently the development and exhumation of the core complexes in oblique convergent zones.The E–W intense shortening deformation resulted also in the formation of NW-and NE-striking sinistral and dextral strike-slip shear zones,respectively.The latest periods of the E–W-directed compressional/transpressional regime were characterized by deposition of the molasse-type Hammamat Sediments unconformably over the Dokhan Volcanics,or interbedded with them.The combined thrusting,folding and sinistral-reverse shearing structures have been interpreted to resulted from the E–Wdirected compressional/transpressional phase in response to the oblique shortening of the Arabian-Nubian Shield between East and West Gondwana. 展开更多
关键词 Neoproterozoic deformation N–S shortening syn-accretionary phase post-accretionary phase Egyptian Nubian Shield
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Lactation Performance of Primiparous Nubian Ewes and Yunling Black Ewes 被引量:1
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作者 LENG Jing CHU Ke ZHU Ren-jun YANG Shu-li MAO Hua-ming 《Animal Husbandry and Feed Science》 CAS 2009年第11期6-9,共4页
[ Objective] To evaluate lactation performance of primiparous Nubian ewes and Yunling Black ewes. [ Method] Healthy primiparous Nubian ewes (20 ewes lambing twins and 19 ewes lambing single) and Yunling Black ewes ... [ Objective] To evaluate lactation performance of primiparous Nubian ewes and Yunling Black ewes. [ Method] Healthy primiparous Nubian ewes (20 ewes lambing twins and 19 ewes lambing single) and Yunling Black ewes (4 ewes lambing twins and 15 ewes lambing single) were used to study the effects of breeds and litter size on lactation performance. [Result] The total milk yield of the Nubian ewes lambing twins was 14.81% higher than that of the Nubian ewes lambing single ( P 〈 0.05) and 22.93% higher than that of the Yunling Black ewes lambing twins ( P 〈 0.05). The total milk yield of the Yunling Black ewes lambing twins was 32.80% higher than that of the Yunling Black ewes lambing single ( P〈 0.05 ), but the total milk yield of the Nubian ewes lambing single was 42.20% higher than that of the Yunling Black ewes lambing single ( P 〈 0.05). The Nubian goats and the Yunling Black goats had similar lactation curves. The milk yield gradually increased during the early lactation period (5 - 15 d post partum), and the lactation peak lasted for 20 d (15 -35 d post partum). Then the milk yield gradually decreased. The predicted values showed the milk yield of the ewes may rapidly decrease during 80 -120 d post partum. Until Day 70 post partum, the Nubian ewes lambing twins had lost 3.06% more body weight than those lambing single had (P〈0.05); the Yunling Black ewes lambing twins had lost 0.89% more body weight than those lambing single had (P〈0.05). The Nubian ewes lambing lost 3.22% -5.39% more body weight than those with the same litter size did ( P 〈 0.05). [ Conclusion] The regular pattern of primiparous lactation is similar between the Nubian ewes and the Yunling Black ewes, and their lactation performance is closely related to breeds and litter size. 展开更多
关键词 Nubian ewes Yunling Black ewes PRIMIPARITY Lactation performance
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Tonian–Ediacaran Tectonometamorphic History of the Sa'al Complex,Sinai(Egypt):Implications for the Tectonostratigraphic Framework of the Northern Arabian–Nubian Shield
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作者 Mohamed W.ALI-BIK Suranjan GHOSH +2 位作者 NPRABHAKAR Said HAbd El RAHIM Hilmy EMOUSSA 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2022年第5期1545-1565,共21页
The Sa'al Metamorphic Complex(SMC;southern Sinai)encompasses the oldest arc rocks in the Arabian–Nubian Shield,comprising two non-consanguineous metavolcanic successions(the Agramiya Group and the Post-Ra'aya... The Sa'al Metamorphic Complex(SMC;southern Sinai)encompasses the oldest arc rocks in the Arabian–Nubian Shield,comprising two non-consanguineous metavolcanic successions(the Agramiya Group and the Post-Ra'ayan Formation)separated by the metasediments of the Ra'ayan Formation.It experienced three distinct deformational events(D_(1)–D_(3))and two low-medium grade regional metamorphic events(M_1–M_(2)).The Agramiya Group and the Ra'ayan Formation experienced all tectonometamorphic events(D_1–D_(3)and M_(1)–M_(2)),whereas the Post-Ra'ayan volcanic rocks were only affected by the D_(3)and M_(2)events.D_(1)is an extensional event and is connected to the late Rodinia break-up(~Tonian;900–870 Ma).The M_(1)metamorphism variably affected the older Agramiya Group,the rhyolitic tuffs experiencing lower to upper greenschist facies conditions and the basic and intermediate volcanic rocks undergoing amphibolite facies metamorphism.The Ra'ayan Formation metasediments experienced upper greenschist to amphibolite facies metamorphism.The upper greenschist facies M_(2)affected the youngest Post-Ra'ayan volcanic rocks and other stratigraphic successions.The compressive D_(2)and D_(3)events were coeval with the accretion of dismembered terranes in the assembly of Gondwana.D_(2)can be linked to the Tonian–Cryogenian arc-arc assembly(~880–760 Ma;in Elat and Sinai),whereas D_(3)and the accompanying M_(2)is constrained to 622–600 Ma(Ediacaran). 展开更多
关键词 deformation microstructure METAMORPHISM Sa'al Metamorphic Complex Arabian–Nubian Shield
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Meat Quality Characteristics of Hainan Black Goat and Its Hybrid with Nubian Black Goat
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作者 Zheng Xinli Sun Ruiping +6 位作者 Wei Limin Wang Feng Chao Zhe Liu Hailong Liu Quanwei Huang Lili Xing Manping 《Animal Husbandry and Feed Science》 CAS 2017年第5期271-274,共4页
[Objective] The paper was to understand the meat quality characteristics of Hainan black goat and its hybrid with Nubian black goat. [Method]Four 6-month-old Hainan black goats and Hainan black goat × Nubian blac... [Objective] The paper was to understand the meat quality characteristics of Hainan black goat and its hybrid with Nubian black goat. [Method]Four 6-month-old Hainan black goats and Hainan black goat × Nubian black goat F1 were slaughtered respectively,and the contents of crude protein,total fat,moisture,amino acids,mineral elements( Se,Zn and Mn) and fatty acid were determined. [Result]There was no significant difference in total fat,crude fat and moisture content in muscle of Hainan black goat × Nubian black goat F1 and Hainan black goat( P > 0. 05). The Fe content in the muscle of Hainan black goat × Nubian black goat F1 was significantly higher than that in Hainan black goat( P < 0. 05). There was no significant difference in EAA,NEAA,TAA and FAA between Hainan black goat × Nubian black goat F1 and Hainan black goat( P > 0. 05). The C17∶ 0 methyl heptadecanoate content in the muscle of Hainan black goat × Nubian black goat F1 was extremely lower than that in Hainan black goat( P < 0. 01),but the saturated fatty acid content and total unsaturated fatty acid content in the muscle of Hainan black goat × Nubian black goat F1 was lower than that in Hainan black goat( P > 0. 05). [Conclusion]The meat quality characteristics of Hainan black goat × Nubian black goat F1 had little difference with its female parent,and the goal of breeding had been basically achieved. 展开更多
关键词 HAINAN BLACK GOAT Nubian BLACK GOAT HYBRID MEAT QUALITY
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Cultivation Features Using Meteorological and Satellite Data from 2001 to 2010 in Dakhla Oasis, Egypt
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作者 Reiji Kimura Hiroshi Kato Erina Iwasaki 《Journal of Water Resource and Protection》 2015年第3期209-218,共10页
The differences between the oasis region and the regions of the Nile delta and Nile valley in Egypt are due mainly to the regions’ access to water. The oasis region depends on underground water, while the other regio... The differences between the oasis region and the regions of the Nile delta and Nile valley in Egypt are due mainly to the regions’ access to water. The oasis region depends on underground water, while the other regions rely on the Nile River. Numerous studies on cultivation in the Nile delta have been accumulated. However, few studies have addressed cultivation in the oasis region. This study examines cultivation throughout the government and local well districts using meteorological and satellite data from 2001 to 2010, and the interview in Rashda Village, Dakhla Oasis. Since the reference evapotranspiration (ET0) is lower in winter than in summer, cultivation in winter makes sense from the viewpoint of saving irrigation water. Evapotranspiration is highest in the order of date palm, rice paddy, winter wheat, and clover hay under sufficient wet conditions in Rashda Village. Cultivation features and water requirements were examined using the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Water Index (NDWI). Results indicated a distinct difference in cultivation systems between the summer and winter seasons in the government well district. Water requirements for date palm in the local well district were 2.6 times those for winter plants in the government well district, using the accumulated NDWI value. 展开更多
关键词 Ground WATER EVAPOTRANSPIRATION Normalized DIFFERENCE Vegetation INDEX Normalized DIFFERENCE WATER INDEX Nubian AQUIFER
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Relationships between Hydraulic Parameters of the Nubian Aquifer and Wells in El Shab Area, South Western Desert, Egypt (A Case Study)
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作者 Maged El Osta 《International Journal of Geosciences》 2012年第5期1107-1119,共13页
For proper water management in the new reclaimed areas, hydraulic parameters of both aquifer and wells related to transmissivity, specific capacity, well loss, formation loss, and water entrance velocity, as well as t... For proper water management in the new reclaimed areas, hydraulic parameters of both aquifer and wells related to transmissivity, specific capacity, well loss, formation loss, and water entrance velocity, as well as the relationship between these parameters are the main target after construction of production wells. In El Shab area, the Nubian Sandstone aquifer has a large range of transmissivity (from 483.12 to 1489.24 m2/day) and, also, specific capacity (from 203 to 486.32 m2/day). Relationship of specific capacity and transmissivity is constructed and the established empirical equations can be used to predict the transmissivity of the Nubian aquifer in all new proposed sites for well drilling at which the specific capacity measured without performing pumping tests. On the other hand, the drilled wells in El Shab area exhibit relatively high well losses (25%). The causes for high well losses (entrance velocity (Vn) through water well screen and the distance from the point of water entrance in the well to the point of intake in the pump) are discussed and the relationships are constructed, which seem a positive linear correlation. Relationships between well losses constant for 30 wells with transmissivity and specific capacity, are constructed. These relationships are useful for estimating hydraulic characteristics that are needed for the designs of wells and well fields and for preliminary water-resources management. 展开更多
关键词 Nubian SANDSTONE AQUIFER TRANSMISSIVITY Specific Capacity WELL Loss ENTRANCE Velocity WELL Efficiency
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Microspherules-Bearing White Sandstone: Implication of Cosmic Impact Event near Jurassic-Cretaceous Boundary in West Central Sinai, Egypt
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作者 Hanan S. Badawy Ahmed M. Zayed Mohamed G. Shahien 《Journal of Geoscience and Environment Protection》 2016年第7期53-65,共14页
The presence of glass microspherules enclosing relict grains, shattered quartz and silicon carbide in white sandstone beds near the Jurassic-Cretaceous boundary in west central Sinai indicates a cosmic impact event. C... The presence of glass microspherules enclosing relict grains, shattered quartz and silicon carbide in white sandstone beds near the Jurassic-Cretaceous boundary in west central Sinai indicates a cosmic impact event. Characterization of the impact microspherules and proposing a reasonable scenario for their origin are the aims of this work. Field observations, optical, binocular, scanning electron and high-resolution transmitted electron microscopy investigations and chemical analyses were carried out. The study revealed that glass microspherules have high Al<sub>2</sub>O<sub>3</sub> and FeO contents and low CaO and MgO contents. The high content of Al<sub>2</sub>O<sub>3</sub> indicates that the source of microtektite-like microspherules is attributed to the melting of a clay-rich sandstone and carbonaceous matter, while the high content of FeO indicates admixing with projectile matter. The reaction between silica and carbon was carried out under conditions of high temperature (T > 1000&#176C) and carbon (C/Si > 1) which resulted in the production of silicon carbide with microdiamond intergrowth. Consequently, this intergrowth is in accordance with the impact origin via rapid condensation and growth within a vapor phase. In spite of the fact that no source crater has been recognized to date in the study area, the authors propose at least a single cosmic impact event scenario for the recorded glass microspherules in west central Sinai. The impact excavated the Paleozoic siliciclastic sedimentary rocks and then the glass microspherules showered the area of study. The deposition of microtektite-like glass particles within the white sandstone beds of the Malha Formation took place in the fluvial plain terrestrial environment. This setting precluded severe post-depositional reworking, yielding preservation of the glass particles in a primary layer. Eventually, lateral migration of the braided channels led to the reworking of the microspherules layer and the spatial dispersal of the shattered quartz. 展开更多
关键词 Impact Glass MICROTEKTITES EJECTA Nubian Sandstone SiC
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