A sensitivity study on the numerical model of displacement and deformation of embedded brittle rock bodies in extension environment during salt tectonics     

Shiyuan Li 《Arabian Journal of Geosciences》2016,9(16):680

Many salt bodies contain large rock inclusions (called stringers) such as carbonate or anhydrite bodies. Mostly, large rock inclusions embedded in salt bodies have different ways of movement and deformation, including displacement, folding and fracturing. A finite element model with adaptive remeshing has been built for downbuilding simulation. The standard model set-up is constrained by observations from the South Oman Salt Basin. Based on the generic model in the previous research which shows the fracture, overtrusting or folding deformation during downbuilding process, a sensitivity study has been conducted on the numerical model of the deformation and displacement of brittle rock bodies, including the parameters such as the initial depth and the distance between them. The results of simulation are analyzed based on the data from SOSB and Zechstein salt basin. The study shows that the frequency of the break and the size of stringer fragments are strongly affected by the initial depth and thickness of stringers and the basement configuration.  相似文献   

Sedimentology of the Baluti Formation in the Galley Derash,Amadiya, North Iraq: insight on carbonate turbidite facies and their depositional environmental     

Sa’ad Zeki Abdul-Kader Al-Mashaikie  Suhad Kalaf Abdul-Razzak  Madhat Eliwie Naser 《Arabian Journal of Geosciences》2016,9(19):723

The Baluti Formation is exposed succession of the Rhaetian age (Upper Triassic). These strata are interpreted herein for the first time to redeposit in a deep marine setting (distally steepened carbonate ramp/medial to distal slope) on the northwestern margin of the Neo-Tethys. The Galley Derash section is apparently continuous with no evidence for either subaerial exposure or submarine erosion. The absence of erosional scours in the study area confirms emplacement of these strata below both fair-weather and storm wave base. Event beds, particularly those resulting from sediment gravity flows, dominate the Rhaetian interval. The Upper Rhaetian strata are primarily assigned to the Galley Derash Valley. It records an upward transition from moderate-scale, olistolith-bearing debris flow deposits (debrite) to medium-/thin-bedded turbidites remobilized as sediment slumps/slides. The succession is dominated by medium- to thin-bedded calcareous turbidites and hemipelagic suspension deposits. Very low fossil assemblages, particularly stromatolite fragments, and planktonic bivalves occur within some intervals in the section. Rapid and relatively continuous sedimentation is attested to by the thickness of the section, the abundance of calcareous turbidites, and the thin nature of the intercalated hemipelagic beds. Low content of badly preserved fossils and evidence of continuous and rapid sedimentation refer to alteration by tectonic disturbances or diagenesis. This makes the Baluti Beds as a supplementary section for the Rhaetian successions in Iraq.  相似文献   

Textural evidences for dissolution of silica-rich rocks of the Ypresian phosphatic series,Gafsa-Metlaoui basin,southwestern Tunisia: implication of biogenic silica supply on genesis of fibrous clays     

Mongi Felhi  Raja Saidi  Nabil Fattah  Ali Tlili 《Arabian Journal of Geosciences》2016,9(17):695

The present work aimed to determine the mineralogical composition of Ypresian series and to clarify the influence of the dissolution of siliceous frustules on the genesis of fibrous clay minerals. The specimens sampled from CPG trench are mainly constituted of silica-rich rocks at Mides area located at the western part of Gafsa-Metlaoui basin. The samples were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM) in order to determine texture of constituents. The data obtained indicate that the bulk rock samples are mainly made up of opal CT and clay minerals. The latter consists of palygorskite-sepiolite minerals associated with smectite and few amount of illite. The trend of mineralogical composition indicates that fibrous clay minerals are more concentrated at the upper part. SEM observations indicated that palygorskite mineral appears as thread-like facies, which surround foliated texture of smectite in the lower part of the Mides section, although with the low Mg activity confirmed by the absence of dolomite. But, at the upper part of the Mides section, SEM observations revealed the occurrence of siliceous frustules, which have numerous dissolved areas and replacement of carbonate tests by silica. The dissolution saturated the depositional environment with silica which is required for the formation of palygorskite and sepiolite minerals, in addition to high Mg activity confirmed by the presence of dolomite in the bulk rock, which is required basically for the formation of sepiolite. Although the genesis mode of palygorskite and sepiolite is similar with very little difference, the genesis of sepiolite needs a high alkalinity than the formation of palygorskite.  相似文献   

Geohazards induced by anthropic activities of geoconstruction: a review of recent failure cases     

Khalid Elbaz  Jack S. Shen  Arul Arulrajah  Suksun Horpibulsuk 《Arabian Journal of Geosciences》2016,9(18):708

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Textural characteristics of sediments along the southern Red Sea coastal areas,Saudi Arabia     

Omar A. Alharbi  Allan T. Williams  Michael R. Phillips  Tony Thomas 《Arabian Journal of Geosciences》2016,9(19):735

A lack of understanding exists of the origin and textural characteristics of Saudi Arabian Red Sea coastal sediments. This paper concerns the southern coastline of Jizan on the Saudi Red Sea. It is some 160 km long characterised by either narrow rocky headlands with intermittent pocket beaches or wide low-lying beaches dissected by wadis. Granulometric testing of samples from 135 locations showed that beach sand size was mainly very fine to medium grained (M _z = 3.93 Ø), sorting ranged from 1.65 to 0.41 and skewness values from ?051 to 0.39, being mainly negative; dune sands were medium to fine grained (M _z = 1.13 Ø; average sorting 2.8), while skewness variations within dune samples indicated symmetrical to fine skewed values (б _Ι = 0.55 to 0.89). Most foreshore samples were derived from wadis. Wadi mud levels can be high, e.g. Baysh (84%), and wadi Samrah (90%) with mean grain size ranging from very fine to medium sand (M _z = 3.9 Ø), sorting being well to poor (0.45 to 1.52) due to sediment influxes. Sabkha had a wide range of sand/mud and significantly higher carbonate percentages than other environments. Sediment source differences and littoral reworking contributed to grain size variation. The carbonate content varied between 1.5 and 31.5% due to hinterland contributions, and spatial analysis showed increasing quantities of carbonate minerals towards the south. On the wider geographical front, findings from Jizan are similar to those of the Northern United Arab Emirates (UAE), including sabkhas, being composed of sand, skeletal carbonate, fine fluvial material and wind-blown silt and clay components of wadi origin. Further work on the northeastern Red Sea edge can hopefully confirm these findings.  相似文献   

Time and frequency domains response analyses of April 2015 Greece’s earthquake in the Nile Delta based on GNSS-PPP     

Mosbeh R. Kaloop  Mostafa Rabah 《Arabian Journal of Geosciences》2016,9(4):316

Earthquake response characteristic and sensitivity of 1-Hz Global Navigation Satellite System - precise point positioning (GNSS-PPP) for a seismic response in time and frequency domains are the main objectives of this study. The Delta and Cairo areas, Egypt, experiencing the shock of the Greece earthquake occurring on April 16, 2015 (18:50 hours), is presented in this study. The results of this study reveal that the seismic wave effect is very small and can be neglected inside the Delta region and the strong motion occurred in an upward direction for the whole monitoring area. Furthermore, the time-frequency analysis illustrates the ability of the time and frequency domains to use and analyze the surface motion based on a 1-Hz sampling frequency and to detect the small- and high-strength motions of seismic waves.  相似文献   

Assessment of pollution sources in the southeastern of the Riyadh and its impact on the population/Saudi Arabia     

Abeer Salman  Manahil Al-Tayib  Sulafa Hag-Elsafi  Nada Al-Duwarij 《Arabian Journal of Geosciences》2016,9(4):328

The rapid growth of Riyadh—capital of Saudi Arabia—is pushing the area to more pollution and incentive for reorganization. The aim of this research is to assess air pollutants in southeast of Riyadh and detect opinion of the population about their environment. The assessment was done by analyzing 405 questionnaires, evaluating thermal band of Landsat 8, and spatial analyzing of particular matter and chemicals in 19 air samples by geostatistical tool in the ArcMap. Most of the inhabitants stated that they are suffering from bad odor, sewage leakage, and dust mainly from a cement factory. The thermal band of Landsat clarified the location of the pollution sources mainly the 1st industrial city, Yammama Cement Factory, and power plant in Farouq area. The ordinary kriging maps showed that the highest concentration of PM₁₀ (>403 μg/m³) lied to the northern and western side of the study area and caused a health issue to most inhabitants.  相似文献   

Did satellite imagery supersede aerial imagery? A perspective from 3D geopositioning accuracy     

Altan Yilmaz  Mustafa Erdogan  Hadi Hakan Maras  Bahadir Aktug  Suleyman Sirri Maras 《Arabian Journal of Geosciences》2016,9(4):324

In this study, the geometric accuracy comparison of aerial photos and WorldView-2 satellite stereo image data is evaluated with the different number and the distribution of the ground control points (GCPs) on the basis of large scale map production. Also, the current situation of rivalry between airborne and satelliteborne imagery was mentioned. The geometric accuracy of Microsoft UltraCam X 45 cm ground sampling distance (GSD) aerial imagery and WorldView-2 data both with and without GCPs are also separately analyzed. The aerial photos without any GCP by only using global navigation satellite system (GNSS) and inertial measurement unit (IMU) data with tie points give an accuracy of ±1.17 m in planimetry and ±0.71 m in vertical that means nearly two times better accuracy than the rational polynomial coefficient (RPC) of stereo WorldView-2. Using one GCP affects the accuracies of aerial photos and WorldView-2 in different ways. While this situation distorts the aerial photo block, it corrects the shift effect of RPC in WorldView-2 and increases the accuracy. By using four or more GCPs, ½?pixel (～0.23 m) accuracy in aerial photos and 1 pixel (～0.50 m) accuracy in WorldView-2 can be achieved in horizontal. In vertical, aerial photos have 1 pixel (～0.55 m) and WorldView-2 has 1.5 pixels (～0.85 m) accuracy. These results show that Worldview-2 imagery can be used in the production of class I 1:5000 scale maps according to the ASPRS Accuracy Standards for Digital Geospatial Data in terms of geometric accuracy. It is concluded that the rivalry between aerial and satellite imagery will continue for some time in the future.  相似文献   

Pb-Zn (Ba) deposits of the oriental Saharan Atlas (north-east of Algeria): distribution,control and implications for mining exploration     

Haddouche Omar  Boutaleb Abdelhak  Chamam Madjid  Ysbaa Saadia  Hammouche Hanafi  Boubaya Djamel 《Arabian Journal of Geosciences》2016,9(5):422

Analysis and integration of geological/metallogenic data and digitally processed gravimetric/aeromagnetic data to the oriental Saharan Atlas domain were carried out to understand the spatial distribution and structural control on Pb-Zn (Ba) deposits of the oriental Saharan Atlas. The use of this combined technique suggests that most of mineral deposits appear to be regionally controlled by structural trends (subparallel NE-SW-trending) along margins of subsiding sedimentary basins. Mineralization occurs along or near major NE-SW-trending faults, locally intersected by NW-SE-trending faults. In addition, mineral deposits are usually either inside anticlinal hinge zones (example, Merouana, Ichmoul and Ain Mimoum ore deposits) or on the flanks of anticlinal structures (example, Ain Bougda ore deposit). In “diapiric zone”, mineral deposits are generally located on diapiric structures borders (peridiapiric concentrations), related to NE-SW/NE-SW and E-W-trending faults. Other mineral concentrations occurs along the margins of tectonic troughs zones (example, Morsott trough) resulting probably by NW-SE-trending deep faults movement. In summary, our research suggested that regional parameters, such as NE-SW/NW-SE-trending lineaments, intersections of these lineament zones and margins of subsiding sedimentary basins/diapiric structures, serve as significant indicators and provides a valuable framework for guiding the early stages of Pb-Zn (Ba) mineral exploration; other considerations must then be applied in this region, like integration of surficial geochemical anomalies that allows better delineation of targets for further mineral exploration.  相似文献   

Carbon and nitrogen dynamics of the intertidal seagrass, <Emphasis Type="Italic">Zostera japonica</Emphasis>, on the southern coast of the Korean peninsula     

Jong-Hyeob Kim  Seung Hyeon Kim  Young Kyun Kim  Kun-Seop Lee 《Ocean Science Journal》2016,51(4):635-645

Seagrasses require a large amount of nutrient assimilation to support high levels of production, and thus nutrient limitation for growth often occurs in seagrass habitats. Seagrasses can take up nutrients from both the water column and sediments. However, since seagrasses inhabiting in the intertidal zones are exposed to the air during low tide, the intertidal species may exhibit significantly different carbon (C) and nitrogen (N) dynamics compared to the subtidal species. To examine C and N dynamics of the intertidal seagrass, Zostera japonica, C and N content and stable isotope ratios of above- and below-ground tissues were measured monthly at the three intertidal zones in Koje Bay on the southern coast of Korea. The C and N content and stable isotope (δ¹³C and δ¹⁵N) ratios of seagrass tissues exhibited significant seasonal variations. Both leaf and rhizome C content were not significantly correlated with productivity. Leaf δ¹³C values usually exhibited negative correlations with leaf productivity. These results of tissue C content and δ¹³C values suggest that photosynthesis of Z. japonica in the study site was not limited by inorganic C supply, and sufficient inorganic C was provided from the atmosphere. The tissue N content usually exhibited negative correlations with leaf productivity except at the upper intertidal zone, suggesting that Z. japonica growth was probably limited by N availability during high growing season. In the upper intertidal zone, no correlations between leaf productivity and tissue elemental content and stable isotope ratios were observed due to the severely suppressed growth caused by strong desiccation stress.  相似文献