3D Crustal and Lithospheric Structures in the Southeastern Mediterranean and Northeastern Egypt

Crustal and lithospheric thicknesses of the southeastern Mediterranean Basin region were determined using 3D Bouguer and elevation data analysis. The model is based on the assumption of local isostatic equilibrium. The calculated regional and residual Bouguer anomaly maps were employed for highlighting both deep and shallow structures. Generally, the regional field in the area under study is considered to be mainly influenced by the density contrast between the crust and upper mantle. Use of the gravity and topographic data with earthquake focal depths has improved both the geometry and the density distribution in the 3-D calculated profiles. The oceanic-continental boundary, the basement relief, Moho depth and lithosphere-asthenosphere boundary maps were estimated. The results point to the occurrence of thick continental crust areas with a thickness of approximately 32 km in northern Egypt. Below the coastal regions, the thickness of crust decreases abruptly (transition zone). An inverse correlation between sediment and crustal thicknesses shows up from the study. Furthermore, our density model reveals the existence of a continental crustal zone below the Eratosthenes Seamount block. Nevertheless, the crustal type beneath the Levantine basin is typically oceanic; this is covered by sedimentary sequences more than 14 km thick. The modeled Moho map shows a depth of 28–30 km below Cyprus and a depth of 26–28 km beneath the south Florence Rise in the northern west. However, the Moho lies at a constant shallow depth of 22–24 km below the Levantine Basin, which indicates thinning of the crust beneath this region. The Moho map reveals also a maximum depth of about 33–35 km beneath both the northern Egypt and northern Sinai, both of which are of the continental crust. The resulting mantle density anomalies suggest important variations of the lithosphere-asthenosphere boundary (LAB) topography, indicating prominent lithospheric mantle thinning beneath south Cyprus (LAB ~90 km depth), followed by thickening beneath the Eratosthenes seamount, Florence Rise, Levantine Basin and reaching to maximum thickness below Cyprian Arc (LAB ~115–120 km depth), and further followed by thinning in the north African margin plate and north Sinai subplate (LAB ~90–95 km depth). According to our density model profiles, we find that almost all earthquakes in the study area occurred along the western and central segments of the Cyprian arc while they almost disappear along the eastern segment. The active subduction zone in the Cyprian Arc is associated with large negative anomalies due to its low velocity upper mantle zone, which might be an indication of a serpentinized mantle. This means that collision between Cyprus and the Eratosthenes Seamount block is marked by seismic activity. Additionally, this block is in the process of dynamically subsiding, breaking-up and being underthrusted beneath Cyprus to the north and thrusted onto the Levantine Basin to the south.     

Epi- and endobiont faunal communities on an Egyptian Mediterranean rocky shore: species composition and their competition for space

The exposed calcareous rocky area of the Abu Qir Headland,east of Alexandria,Egypt which range from coarse grains,through pebbles,cobbles,and boulders to rocky platforms,was signifi cantly colonized by sclerobionts(epibionts and endobionts).The epibiont species diversity was comparatively higher than that of endobionts.Epibiont communities included bryozoans(the anascan-grade cheilostome Bifl ustra savartii),serpulid(Hydroides elegans,Spirobranchus cf.tetraceros,Vermiliopsis striaticeps and Protula or Apomatus)and spirorbid(Spirorbis)wormtubes,and balanoid barnacles(Amphibalanus amphitrite,Balanus trigonus,and Perforatus perforatus).The cheilostome bryozoan colonies,which developed extensive sheets,proliferated on the study rocky shore either encrusting the bioeroded basement directly,or encrusting other epilithic taxa,particularly balanoid barnacles and serpulid worms.Encrusters displayed a remarkable marginal competitive interaction(overgrowth and stand-off)for space on the study rocky shore.On the other hand,endobionts were not well represented on the studied rocky shore exposure.It was possible to identify three ichnotaxa:Gastrochaenolites,Maeandropolydora,and Finichnus.The fi ndings documented represent a signifi cant contribution to our knowledge of sclerobionts composition,sequence of their colonization and/or bioerosion,and their mutual relationships on the intertidal rocky shore of the Abu Qir Headland.     

Geology and rare-earth element geochemistry of highly evolved, molybdenite-bearing granitic plutons, Southeastern Desert, Egypt

The field relations, mineralogy, and major and trace elements (including REE analyses of whole-rock samples and minerals) of granites and their associated molybdenite uranium mineralized aplites in Southeastern Desert, Egypt, have been studied. The granites are leucocratic and mostly peraluminous in nature with muscovite increasing at the expense of biotite. The chemical and mineralogical characteristics of the granitic rocks indicate that their melts originated from the LILE-enriched mantle wedge by partial melting and are contaminated by crustal melts, followed by thermogravitational processes. Leucogranites with higher Na2O/K2O ratios from Um Dargag and Um Maiat crystallized under H2O-saturated equilibrium conditions in which the exsolved vapor continuously migrated away. The REE patterns of the granites studied are characterized by LREE enrichments and negative Eu anomalies. In comparison, the potassic aplites and the more sodic leucogranites are depleted in LREE, enriched in HREE and show more remarkable negative Eu anomalies. Allanite and monazite are the most important REE carriers in the granites. These minerals are strongly enriched in LREE, whereas fluorite and xenotime, which are more abundant in the aplites, are enriched in HREE. The average Lu/Ce ratio represents the fractionation trend with respect to HREE. It is 0.71 for radioactive fluorite, and it increases to 1.22 for non-radioactive fluorite. The high REE contents of molybdenite represent re-deposition of the mobilized Mo and REE. Due to the strong control of accessory minerals, the REEs are of limited use in petrogenetic modelling of highly evolved granitic systems.     

CFD-Based Model for Estimating the River Bed Morphological Characteristics near Cylindrical Bridge Piers Due to Debris Accumulation

Water Resources - The scour and flow field patterns with accumulation of debris around bridge piers are completely different due to the reduction of flow area and the increase in depth average...     

Air pollution forecasting from sky images with shallow and deep classifiers

Air pollution is one of the most important problems in the new era. Detecting the level of air pollution from an image taken by a camera can be informative for the people who are not aware of exact air pollution level be declared daily by some organizations like municipalities. In this paper, we propose a method to predict the level of the air pollution of a location by taking an image by a camera of a smart phone then processing it. We collected an image dataset from city of Tehran. Afterward, we proposed two methods for estimation of level of air pollution. In the first method, the images are preprocessed and then Gabor transform is used to extract features from the images. At the end, two shallow classification methods are employed to model and predict the level of air pollution. In the second proposed method, a Convolutional Neural Network(CNN) is designed to receive a sky image as an input and result a level of air pollution. Some experiments have been done to evaluate the proposed method. The results show that the proposed 9 method has an acceptable accuracy in detection of the air pollution level. Our deep classifier achieved accuracy about 59.38% which is 10 about 6% higher than traditional combination of feature extraction and classification methods.     

浙江花岗岩中斜长石钾交代产生的条纹长石

对研究区内花岗岩类的60个薄片进行了岩相学研究.研究的目的是确定区内岩石中普遍存在的矿物组成及结构类型.     

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

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.