Interpretation of aeromagnetic and gravity data in East Qattara Depression, North Western Desert, Egypt     

Mohamed H. Saad  Mansour A. Al-Garni  Hamdy I. E. Hassanein 《Arabian Journal of Geosciences》2012,5(4):747-756

The study area lies to the east of Qattara Depression at the north of the Western Desert, Egypt. It is bounded by latitudes 29°00?? and 30°00?? N and longitudes 28°00?? and 29°30?? E, including Abu Gharadig basin, which is the most petroliferous basin in the Egyptian Western Desert. Numerous exploratory wells show that the area is characterized by a thick sedimentary section, unconformably overlying the basement rocks. The main objective of the present study is to outline the structural parameters controlling the area under consideration. Aeromagnetic and gravity data were subjected to the analytic signal, 3D Euler deconvolution and edge enhancement techniques. The Analytic signal and 3D Euler deconvolution were utilized mainly to locate the main subsurface contact zones and to determine the depth and structural indices of the expected causative subsurface structural elements. However, the edge enhancement technique was used with various windows to enhance the edges of subsurface structures. The structural indices were estimated to be ranging between 0.16 and 0.26, indicating that the area is mainly controlled by faults. The depth of these structural elements was also estimated to be ranging between <1.37 and 5.29?km. It has been shown that the structural elements of the study area have different directions, trending E-W, ENE, NW, and N-S.  相似文献   

Neuro-fuzzy modeling based genetic algorithms for identification of geochemical anomalies in mining geochemistry     

Mansour Ziaii  Faramarz Doulati Ardejani  Mahdi Ziaei  Ali A. Soleymani 《Applied Geochemistry》2012

A genetic algorithm (GA)-based neuro-fuzzy approach is used for identification of geochemical anomalies by implementing a Takagi, Sugeno and Kang (TSK) type fuzzy inference system in a 5-layered feed-forward adaptive artificial neural network. This paper investigates the effectiveness of GA-based neuro-fuzzy for separating zone dispersed mineralization (ZDM) from blind mineralization, and its application for identification of geochemical anomalies in the arid landscape of the Lut metallogenic province in eastern Iran. Other classification algorithms such as metallometry, zonality, criteria, and back-propagation artificial neural network classifiers are also used for comparison. The genetic operators are carefully designed to optimize the artificial neural network, avoiding premature convergence and permutation problems. The results show that the GA-based hybrid neuro-fuzzy model can provide accurate results in comparison with those results obtained by other techniques. Neuro-fuzzy and GA-based neuro-fuzzy techniques appear to be well-suited for routine exploration geochemistry applications. In conjunction with statistics and conventional mathematical methods, hybrid approaches can be developed and may prove a step forward in the practice of applied geochemistry.  相似文献   

Response of wheat plants to sodium and calcium ion interaction under saline environment     

B. Zaman  B. H. Niazi  M. Athar  M. Ahmad 《International Journal of Environmental Science and Technology》2005,2(1):7-12

Wheat being a glycophyte crop, responds differently to saline-sodic soil environmental conditions. The application of calcium is multidimensional with respect to sodium ion and plant part response. This study was conducted to record the response of shoot and root to sodium and calcium interaction under saline environment. Wheat seed of variety Punjab 85 were raised in quartz sand. Later on the seedlings were transplanted to pots containing Hoagland’s nutrient solution along with NaCl at 0 mM. and 50 mM. Calcium was applied as CaSO₂ 2H₂O at 3 mM. and 6 mM. Under saline conditions shoot showed positive response to sodium ion in the presence of higher calcium. Relative water contents were higher in the root system at 6 mM of CaSO₄. 2H₂O under saline condition. Growth responses to potassium and Magnesium in the presence of sodium induced salinity with calcium ion interaction remained variable.  相似文献   

Variability of the Sea Surface Salinity (SSS) in the Western Tropical Pacific: On the Ability of an OGCM to Simulate the SSS, and on the Sampling of an Operating Merchant Ship SSS Network     

Mansour Ioualalen  Yoshinobu Wakata  Yoshikazu Kawahara  Yves Gouriou  David Varillon 《Journal of Oceanography》2003,59(1):105-111

The sea surface salinity (SSS) derived from a network developed at Institut de Recherche pour le Développement (IRD/Nouméa) has been analyzed during the period 1995–1998 in the tropical western Pacific. The measurements were made with thermosalinographs installed on merchant ships selected for their regularity and routes. The western tropical Pacific was sampled mainly along three regular routes across the equator leading to an average of a one month frequency. We analyze here how such a network can be efficient in monitoring the SSS at time scales longer than one month. For this purpose we have used results derived from the Princeton Ocean Model (POM) which is forced by the surface flux of National Centers for Environmental Prediction (NCEP) reanalysis data. The interannual variability of the simulated SSS exhibits very similar features to (sub-sampled) observations despite its being weakly damped to a climatology in order to avoid biases. Even smaller time scale phenomena can be simulated, like the erosion/reconstruction of the region composed of low density waters lying within the Pacific warm pool. The agreement between the observational data and the simulations indicate that the network sampling is sufficient to monitor the SSS variability of the western tropical Pacific from three-month to interannual time scales. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Source geometry and mechanism of 1978 Tabas, Iran, earthquake from well located aftershocks     

Mansour Niazi  Jafar Shoja-Taheri 《Tectonophysics》1985,115(1-2)

Aftershocks of the September 16, 1978 Tabas earthquake located from close-in observations made during a four-week fielding of temporary stations have been analyzed for the purpose of delineating detailed source geometry of the 1978 earthquake. Spatial distribution of aftershocks and their composite focal mechanism suggest that the geometry of faulting is far from planar. Aftershocks define two prominent alignment. The southern alignment strikes E-W to WNW-ESE, whereas the northern alignment strikes in a N-S to NNW-SSE direction with an abrupt change of nearly 55–60 degrees near 33.4°N latitude. Both field observations of surface faulting pattern and systematic variation of principal directions of stress axes computed from aftershock focal mechanisms are consistent with the upthrusting and imbrication of a wedge shaped crustal block with the wedge angle of about 120 degrees. Both geological and seismological evidence suggest that the deformed zone is truncated at the southern edge by preexisting E-W fault structures. New observations may provide a partial answer to the unexplained farfield asymmetry of the long period Rayleigh wave radiation pattern recently observed for the mainshock across IDA network.  相似文献