A new record and a new ichnospecies of Arachnostega from the Middle Miocene of Egypt     

Olev Vinn  Ahmed M. El-Sabbagh  Magdy M. El-Hedeny  Mohamed A. Rashwan  Saleh A. Al Farraj 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(6):790-796

The ichnogenus Arachnostega Bertling, 1992 is recorded for the first time from a bioeroded, coral-rich, Middle Miocene limestone bed in the middle Siwa Escarpment Member (Marmarica Formation) at Siwa Oasis, northern Western Desert of Egypt. These burrowing traces are preserved on the surface of a few internal moulds of bivalves and gastropods. Until now, the ichnogenus Arachnostega included a single ichnospecies, A. gastrochaenae Bertling, 1992. In the material studied herein, two ichnospecies are identified, described, illustrated and compared with other, similar traces. One of these is a new ichnospecies of Arachnostega; this is here named A. siwaensis ichnosp. nov. It is distinguished from A. gastrochaenae in the possession of tunnels that usually branch in a V-pattern; intervals of ramification are longest in the main branch and decrease in second- and third-order branches. Arachnostega traces were produced in a warm, low-energy, shallow-marine (<10?m water depth) environment. Polychaetes are the most likely producers of marine Arachnostega, which are commonly occurred in the same studied bed. This new occurrence is significant in extending the known stratigraphical and geographical ranges of Arachnostega into the Middle Miocene of Egypt.  相似文献   

Response of Mollusk Assemblages to Environmental Conditions: A Case Study from the Burullus Lagoon,Egypt     

Orabi H. Orabi  Abd El-Monsef A. El-Badry  Ikhlas Alhejoj 《Journal of the Geological Society of India》2018,91(5):583-588

The identified mollusks from the Burullus lagoon of Egypt (Eastern Mediterranean) are represented by four bivalve species and four gastropod species. Sources of heavy metals pollution in the Burullus lagoon include phosphate fertilizers, sewage and oil spills from fishing boats.The Cerastoderma glaucum species has a wide distribution in the central part of the studied area with satisfying criteria required for good bio-monitors of pollution. High concentrations of heavy metals are found in water, at the eastern side of the lagoon, while low concentrations were detected in the central and western sides of the lagoon. Pirenella conica constitutes the total gastropods assemblages, reflecting this species tolerance to the high concentration of heavy metals. Meanwhile, the total pelecypods in bottom lagoon sediments are completely absent in the eastern parts of the lagoon, which may be due to the sensitivity of pelecypods to the accumulation of heavy metals.  相似文献   

Developing models and envelope curves for extreme floods in the Saudi Arabia arid environment     

Hatem A. Ewea  Nassir S. Al-Amri  Mohamed A. Dawoud  Amro M. Elfeki 《Natural Hazards》2018,94(2):801-817

Forecasting and monitoring extreme floods in arid regions like Saudi Arabia (SA) are a big challenge for engineers and hydrologists. It is difficult to derive reliable flood estimates at any site without adequate flood measurements. Therefore, envelope curves were developed for reliable estimates of flood peaks. Relaying on recorded flood events in SA, Francou–Rodier approach is used to develop the Regional Maximum Flood (RMF) for some wadis and for SA as a whole. A total of 3121 flood events in 32 arid basins of sizes varying from 99 to more than 4500 km² are collected and analyzed. Results show that established regional coefficients (K) range between 2.76 and 5.5. The RMF formula for the Saudi regions is Q?=?251 A^0.45. The flood-frequency analysis showed that the Log-Pearson Type III is best. The extreme observed floods for the envelope curve for K?=?5.5 accommodate floods of recurrence interval ranging between 1000 and 100,000 years. The study results provide more realistic runoff peaks for a design of flood protection works for SA watersheds and for the similar environment. Consequently, it is recommended to use the developed envelope curves and models for efficient, safe and precise hydraulic structures design in SA.  相似文献   

Geospatial analysis of land use driving force in coal mining area: case study in Ningdong,China     

El-Hamid  Hazem T. Abd  Caiyong  Wei  Yongting  Zhang 《GeoJournal》2021,86(2):605-620

GeoJournal - Geospatial techniques such as remote sensing and Geographic Information System are very important for studying the dynamic process of land use. To analyze the land use change and...  相似文献   

Adsorption of Congo red and crystal violet dyes onto cellulose extracted from Egyptian water hyacinth     

Salahuddin  Nehal  Abdelwahab  Mohamed A.  Akelah  Ahmed  Elnagar  Marlen 《Natural Hazards》2021,105(2):1375-1394

Natural Hazards - The present investigation has highlighted the utility of floating aquatic Egyptian hyacinth, which is considered as a significant reason for environmental problems in Nile River,...  相似文献   

Contribution of remote sensing and GIS to analysis of the risk of flooding in the Zat basin (High Atlas-Morocco)     

Bouaida  Jihad  Witam  Omar  Ibnoussina  Mounsif  Delmaki  Abd El Fettah  Benkirane  Myriam 《Natural Hazards》2021,105(2):1835-1859

Natural Hazards - Despite the controversy regarding their use, school buildings are often assigned as emergency evacuation shelters, temporary accommodation and aid distribution hubs following...  相似文献   

Cretaceous fossils of South-Central Africa: An illustrated guide,Michael R. Cooper,CRC Press,London (2018), 168p. ISBN: 978-1-138-33650-6 (Hbk). ISBN: 978-0-429-44297-1 (eBook). Hardback: price £ 31.95     

Martin Munt  Mohamed Abioui 《Proceedings of the Geologists' Association. Geologists' Association》2021,132(1):144

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Modeling and Simulating Ground Motion from Potential Seismic Sources to Kuwait: Local and Regional Scenarios     

Abd el-aal  A. K.  Parol  J.  Al-Jeri  F.  Al-Enezi  A. 《Geotectonics》2021,55(3):423-438

Geotectonics - The urban development in Kuwait is growing rapidly in the past few years. Recently, a large number of new bridges, tall buildings and other infrastructures are constructed in Kuwait....  相似文献   

Seepage Through Earth Dams with Internal Cut Off     

Attia  Michael  Abdel Razek  Mohamed  Salam  Adel Abdel 《Geotechnical and Geological Engineering》2021,39(8):5767-5774

Geotechnical and Geological Engineering - Failure in earth dams mainly occurs due to seepage to the unprotected downstream face of the dam. Therefore, many precautions are taken into consideration...  相似文献   

Geology and Mineral Chemistry of Uranium- and Thorium-bearing Minerals in Rare-Metal (NYF) Pegmatites of Um Solimate,South Eastern Desert,Egypt     

Mohamed A. ALI  Ahmed E. ABDEL GAWAD  Mohamed M. GHONEIM 《《地质学报》英文版》2021,95(5):1568-1582

The garnet muscovite granitic pegmatite of Um Solimate, in southern Egypt, represents a promising asset for strategic and economic metals, especially Bi–Ni–Ag–Nb–Ta as well as U and Th. The ore bodies occur as large masses, pockets and/or veins of very coarse-grained pegmatites, which consist mainly of K-feldspar, quartz and albite with subordinate muscovite, garnet, and biotite. Radiometric data revealed that eU- and eTh-contents of the pegmatites reach up to 39 ppm and 82 ppm, respectively. The studied pegmatites are enriched in primary U and Th minerals (uraninite, coffinite, thorianite and uranothorite) as well as Hf-rich zircon and monazite, which give rise to anomalous radioactive zones. Niobium-tantalium-bearing minerals (i.e. ferrocolumbite, microlite and uranopyrochlore), xenotime, barite, galena, fluorite, and apatite are ubiquitous, and, consequently, the studied pegmatites belong tothe Niobium–Yttrium–Fluorine-type (NYF) family. The noble metal mineralization includes argentite (Ag2S), native Ni and Bi as well as bismite and bismoclite. In addition, beryl and tourmaline are observed in pegmatites near the contact with metasediments and ultramafic bodies. The observed compositional variations of Ta/(Ta+Nb) and Mn/(Mn+Fe) ratios in columbite (0.08–0.45 and 0.11–0.57, respectively) and Hf contents in zircon (3.54–6.46 wt%) may reflectan extreme degree of magmatic fractionation leading to formation of the pegmatite orebody.  相似文献