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11.
Abdullah O. Bamousa 《Arabian Journal of Geosciences》2018,11(18):562
Intra-continental depressions occurred in Central Arabia, within the evaporite-bearing Sulaiy Formation, and extends for over 550 km along N-S arcuate belt, passing through eastern Ar Riyadh, Saudi Arabia. They mark Jurassic/Cretaceous contact within the Interior Homocline of Central Arabia, accommodating Neogene and Quaternary deposits. Two en echelon major depressional areas were discovered, the northern major depressional area and the southern major depressional area. The first depressional area occurs between Al Artawiyah and Ad Dilam towns, following the arcuate Jurassic/Cretaceous contact. It contains five depressions: N-S Al Artwaiyah depression; NW-SE Ath Thumamah depression, northeast of Riyadh; NW-SE Jinadriyah depression, east of Riyadh; E-W Al Kharj depression; and N-S Ad Dilam depression. All five depressions seems to be formed by tectonic and subsequent geomorphic events, except for Al Artawiyah and Jinadriyah depression, which developed mainly by tectonic events. Southern major depressional area steps over to southwest of Ad Dilam, and occurs from Hawtat bani tamim to Layla towns. This Hawtah-Layla major depression trends N-S, and Cretaceous units strike NNE, which is a slightly oblique relationship, suggesting expression of deep-seated structures. Tectonic features were part of the Alpine-Himalayan orogeny, developing during Eocene. They followed by a geomorphic event (karsts and subsequent collapse) that took place during Mid Pleistocene. Ad Dilam depression is a surface expression of three oil and gas fields, while the southern major depression between Hawtat Bani Tamim and Layla towns is a surface expression of four oil and gas fields. Yet, other several depressional areas are also accommodating Quaternary desert sediments, and they contain economic resources, which therefore, worth further detailed studies. 相似文献
12.
Abdullah Arik 《Geotechnical and Geological Engineering》1990,8(4):305-318
Summary Reliable ore reserve estimates for deposits with highly skewed grade distributions are difficult tasks to perform. Although some recent geostatistical techniques are available to handle problems with these estimations, ordinary kriging or conventional interpolation methods are still widely used to estimate the ore reserves for such deposits. The estimation results can be very sensitive to the search parameters used during the interpolation of grades with these methods.This paper compares the ore reserve estimates from ordinary kriging using several cases in which certain search parameters are varied. The comparisons are extended to different mineralizations to show the changing effects of these parameters. 相似文献
13.
Abdullah N. Alwelaie 《GeoJournal》1994,34(4):383-392
The present paper reviews the conservation movement in Saudi Arabia as measured against the established protected areas, as well as the basic philosophy regarding natural resource management. The degree of representation of the biophysical diversity of Saudi Arabia in the established protected areas is discussed by using three areas as case studies: Harrat Al-Harrah (lava field), Urug Bani Mu'arid (Cuesta and Sand), and Raydah Escarpment (High Mountain). 相似文献
14.
The concentration of cadmium in sexually mature Nucella lapillus was investigated around the coast of Wales. Higher concentrations of cadmium were found in whelks located in the Bristol Channel compared with Cardigan Bay Nucella. Accumulation and toxicity of cadmium were investigated at 50–600 μg Cd l−1 over a period of 21 days. At the lower concentrations of 50–100 μg Cd l−1 all Nucella survived the 21 days of experimentation. The rate of cadmium uptake after exposure to cadmium was inconsistent and not related to the degree of site contamination. At all sites the concentration of cadmium in Nucella, after treatment with 50–600 μg Cd l−1 for 21 days, was significantly different from controls, but after 7 days it varied with the site and cadmium concentration. Only samples collected at Fishguard, Dale, and Swansea survived 21 days at 600 μg Cd l−1. Tissue cadmium concentrations did not significantly effect the whole body concentration of zinc. 相似文献
15.
Anomaly analysis is used for various geophysics applications such as determination of geophysical structure's location and
border detections. Besides the classical geophysical techniques, artificial intelligence based image processing algorithms
have been found attractive for geophysical anomaly analysis. Recently, cellular neural networks (CNN) have been applied to
geophysical data and satisfactory results are reported. CNN provides fast and parallel computational capability for geophysical
image processing applications due to its filtering structure. The behavior of CNN is defined by two template matrices that
are adjusted by a properly supervised learning algorithm. After training stage for geophysical data, Bouguer anomaly maps
can be processed and analyzed sequentially. In this paper, CNN learning and processing capability have been improved, combining
Wavelet functions and backpropagation learning algorithms. The new architecture is denoted as Wavelet-Cellular Neural networks
(Wave-CNN) and it is employed to analyze Bouguer anomaly maps which are important to extract useful information in geophysics.
At first, Wave-CNN performance is tested on synthetic geophysical data, which are created by a computer environment. Then,
Bouguer anomaly maps of the Dumluca iron ore field have been analyzed and results are reported in comparison to real drilling
results. 相似文献
16.
The dynamic response of tall civil structures due to earthquakes is very important to civil engineers. Structures exposed to earthquakes experience vibrations that are detrimental to their structural components. Structural pounding is an additional problem that occurs when buildings experience earthquake excitation. This phenomena occurs when adjacent structures collide from their out‐of‐phase vibrations. Many energy dissipation devices are presently being used to reduce the system response. Tuned mass dampers (TMD) are commonly used to improve the response of structures. The stiffness and damping properties of the TMD are designed to be a function of the natural frequency of the building to which it is connected. This research involves attaching adjacent structures with a shared tuned mass damper (STMD) to reduce both the structures vibration and probability of pounding. Because the STMD is connected to both buildings, the problem of tuning the STMD stiffness and damping parameters becomes an issue. A design procedure utilizing a performance function is used to obtain the STMD parameters to result in the best overall system response. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
17.
A. Z. Aris M. H. Abdullah B.Sc. M.Sc. Ph.D. A. Ahmed B.Sc. M.Sc. Ph.D. K. K. Woong B.Sc. M.Sc. Ph.D. 《International Journal of Environmental Science and Technology》2007,4(4):441-450
Factor analysis was applied to the hydrochemical data set of Manukan Island in order to extract the principal factors corresponding to the different sources of variation in the hydrochemistry. The application of varimax rotation was to ensure the clear definition of the main sources of variation in the hydrochemistry. The geochemical data of dissolved major, minor and trace constituents in the groundwater samples indicates the main processes responsible for the geochemistry evolution. By using Kaiser normalization, principal factors were extracted from the data for each location. The analysis reveals that there are four sources of solutes: (1) seawater intrusion; (2) leaching process of underlying rock mediated by pH; (3) minerals weathering process and (4) dissolution of carbonate minerals characterized by high loadings of Ca, Zn and Mg. Such processes are dominated by the significant role of anthropogenic impact from the over abstraction of fresh water from the aquifer. Those factors contributed to the changes of the groundwater geochemistry behavior explain the effect of rising extraction of freshwater from the aquifer. 相似文献
18.
Irfan Temizel Mehmet Arslan Cem Yücel Emel Abdioğlu Yazar Abdullah Kaygusuz Zafer Aslan 《International Geology Review》2020,62(9):1131-1158
ABSTRACT Eocene intermediate to felsic plutons of different sizes and compositions are widespread in the Eastern Pontides Orogenic Belt in northern Turkey. Of these, the Ta?l?k Tepe pluton in the Havza (Samsun) area is fine-to-medium-grained, with granular, porphyritic, and micrographic textures, and include mafic microgranular enclaves (MMEs). LA-ICP-MS U-Pb zircon dating yielded emplacement ages of 42.9 (± 1.4) and 40.5 (± 1.3) Ma for the host granodioritic pluton and the dioritic MMEs, respectively. Petrochemically, the host pluton has I-type, high-K calc-alkaline, and metaluminous-to-slightly peraluminous features (A/CNK = 0.95–1.06). The host pluton also shows geochemical features of adakite-like rocks with high SiO2 (67–68 wt%) and Al2O3 (15.5–16.0 wt%) content and Ba/La (17–23), Sr/Y (40.7–61.6), and LaN/YbN (14.4–23.7) ratios and low Y (8.2–9.9 ppm) and YbN (3.1–4.4) contents. Whole-rock major and trace element variations suggest that fractional crystallisation played a significant role in the pluton evolution. The N-MORB normalised trace element patterns of the pluton are similar to those of MMEs with enrichment in large-ion lithophile elements, Th and Ce, and negative Nb and Ti anomalies. Chondrite-normalised rare earth element plots show moderate-to-highly enriched concave patterns (LaN/LuN = 14.2–21.6) with insignificant negative Eu anomalies (EuN/Eu* = 0.86–1.14), all of which imply hornblende fractionation during magmatic evolution. The pluton samples have 87Sr/86Sr ratios of 0.704767 to 0.704927, 143Nd/144Nd ratios of 0.512767–0.512774, εNd values of (+2.52) – (+2.65), and δ18O values of 7.9–9.7‰. The isotopic compositions of the host pluton and MMEs are similar to I-type granitoids derived from mantle sources. The MMEs show incomplete magma mixing/mingling, representing small bodies of mafic parental magma. Combined with regional studies, these new data suggest that the parental magma of the studied adakite-like pluton was generated from the lithospheric mantle and then modified by fractional crystallisation and assimilation in a post-collisional setting. 相似文献
19.
Abdullah I. Al-Mhaidib 《Geotechnical and Geological Engineering》1998,16(4):291-307
Severe and widespread damage in residential buildings, sidewalks and pavements in various parts of the middle region of Saudi Arabia is caused by the development of heave and swelling pressure in the expansive shales in the region. This paper presents the problems and the geotechnical and physicochemical properties of the tested shales. The swelling potential was determined using various methods. Swell tests were conducted under different loading conditions and following different procedures to quantify the amount of vertical swell and swelling pressure. The conventional one-dimensional oedometer swell tests were performed using three different procedures, namely, free swell, constant volume swell and swell overburden. In addition, swell tests were performed in the stress path triaxial apparatus. Tests under different vertical stresses and confinements were conducted. Vertical swell and swelling pressure obtained from the various methods were compared. The reliability of the different methods for estimation of swelling potential is discussed. 相似文献
20.
A considerable portion of the territory of Afghanistan, having structures of the Mediterranean folded belt, has been subjected to a general tectonomagmatic activization over the Miocene through to the present, resulting in different (predominantly oscillating) tectonic movements, intrusive magmatism, terrestrial volcanism, mineral occurrences, and springs of carbonated and nitrous thermal water.Three types of young magmatism and volcanism products have been recognized in Afghanistan:
- 1. (1) Miocene alkaline granite intrusions, described as the Share—Arman Complex, resulted from the early orogenic stage of the Late Alpine geosynclinal troughs development and were restricted to transversal uplifts, in both the geosynclinal structures and on their extension, in the surrounding median masses. These transversal uplifts also play the role of mineralization-controlling structures.
- 2. (2) Late orogenic—Early Quaternary volcanics (the Dash-i-Nawar Complex) cropping out by the periphery of median masses and at the marginal uplifts of the Late Alpine folded area and also restricted to the transversal uplifts with the confined fault zones to them.
- 3. (3) Alkaline carbonatitic (the Khanneshin Complex) and trachybasaltic (the SarLogh Complex) Early—Middle Quaternary volcanics in the inner parts of the Central Afghanistan Median Mass and in the southeastern segment of the Turan Plateau.