首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:从到   被引次数:从到   他引次数:从到 提示：输入*表示无穷大
全文获取类型
  收费全文   10篇
  免费   0篇
专业分类
地球物理   2篇
地质学   8篇
出版年
  2021年   1篇
  2020年   1篇
  2016年   5篇
  2014年   1篇
  2013年   1篇
  2008年   1篇
排序方式： 共有10条查询结果，搜索用时 31 毫秒
1
1.
Ibrahim  Elkhedr  Mogren  Saad  Qaysi  Saleh  Abdelrahman  Kamal  Ghrefat  Habes  Zaidi  Faisal  Hakami  Ahmed 《Natural Hazards》2021,108(3):2613-2628
Natural Hazards - The main objective of this study is to detect the subsurface extension of salt diapirs and structural deformations in the city of Jazan and its suburbs using gravity data. Salt...  相似文献   
2.
Seismicity constraints on stress regimes along Sinai subplate boundaries   总被引：1，自引：0，他引：1  
The relative movement between African, Arabian and Eurasian plates has significantly controlled the tectonic process of Sinai subplate region, although its kinematics and precise boundaries are still doubtful. The respective subplate bounded on both sides by the Aqaba-Dead Sea transform fault to the east and the Gulf of Suez, the only defined part, to the west. Seismicity parameters, moment magnitude relation and fault plane solutions were combined to determine the active tectonics along the aforementioned boundaries. Seven shallow seismogenic zones were defined by the heterogeneity in stress field orientations. Along the eastern boundary, the average fault plane solution obtained from the moment tensor summation (MTS) reveals a sinistral strike-slip faulting mechanism. The corresponding seismic strain rate tensor showed that the present tectonic stress producing earthquakes along the boundary is dominated by both NW-SE compression and NE-SW dilatation. Towards the north, the average focal mechanism showed a normal faulting mechanism of N185°E compression and an N94°E extension in the Carmel Fairi seismic zone. On the other hand, the active crustal deformation along the western boundary (Gulf of Suez region) showed a prevailing tensional stress regime of NE to ENE orientations; producing an average fault plane solution of normal faulting mechanism. The seismic strain rate tensor reveals a dominant stress regime of N58°E extension and N145°E compression in consistence with the general tectonic nature in northeastern Africa. Finally, the extensional to strike-slip stress regimes obtained in the present study emphasize that the deformation accommodated along the Sinai subplate boundaries are in consistence with the kinematics models along the plate boundaries representing the northern extremity part of the Red Sea region.  相似文献   
3.
In this study, a comprehensive assessment on the generation mechanism, distribution characteristics, and extension rules of structure cracks was conducted by in situ monitoring and field investigation in the Chengchao Iron Mine. Structure cracks are affected by many factors, e.g., surface deformation, structure strength, occurrence position, and machine vibration. They initially occur in a structure when the strength of the structure is not enough to resist the inner strain as surface deformation increases. In contrast, increases in width and length of structure crack exert stress release in the structure and thus decrease structure deformation surrounding the crack. A great ground crack may adversely aggravate structure cracking and release the stress of surrounding rock masses. In addition, micro cracks in rock masses provide favorable conditions for the generation and extension of cracks, resulting that cracks occur in shaft walls more easily and extend towards the deeper. The initial distribution of cracks is generally consistent with such micro cracks. Subsequently, cracks in deep rock masses will extend along the strike of the mined-out area as surface deformation increases. Sensibilities to cracking of structures are changed by their different strain resistances and become stronger from bolt-shotcrete shaft, bolt-shotcrete tunnel, and brick-concrete building to brick wall. Based on distribution characteristics of cracks and wave velocity in rock masses, the overlaying strata affected by underground mining can be divided into four zones: broken zone, broken transition zone, crack generation zone, and micro deformation zone.  相似文献   
4.
Ten global positioning system (GPS)–gravity profiles were conducted to provide sub-surface geometry of two sections of the Najd Fault System (NFS) Ruwah and Ar Rika faults, six in the Afif and four in the Al Muwayh area about 500 and 650 km west of Riyadh, respectively. GPS surveys were collected in differential GPS (DGPS) mode, allowing a large area to be covered in limited time. DGPS is utilized for the advantages of accuracy, economy, and speed. Output DGPS location coordinates were used in free-air and Bouguer reductions; terrain corrections were applied using a 3-arcsecond digital elevation model; finally, isostatic and decompensative corrections were applied. Integration of the resulting decompensative isostatic residual anomalies and aeromagnetic map has mapped the NFS very accurately. Modeling the gravity field crossing the Ruwah fault zone revealed that it is associated with low gravity anomalies probably due to a complex of lower density crushed rocks and modeled the geometry of the subsurface structure of Ar Rika fault as an inclined fault with reverse movement that would imply a compression component (post-dated the shearing) parallel to the plane of the cross-section.  相似文献   
5.
A total of 72 water samples were collected from the sub-surface aquifer system in the Midyan basin and analyzed for 24 major, minor and trace elements. Histograms and normal quantile plots were used to delineate the sub-populations of the chemical constituents in the studied groundwater samples. Some of the elements such as Al, K, Ca, Mg, Na and Cl have concentrations that could be linked to the weathering of the surface rock strata. On the other hand, the elements like As, Pb and Sb have concentration, that can be linked to agricultural practices in the area. The use of simple statistical analysis, frequency histograms, and Q-Q plots were useful for the detection and evaluation of elemental constituents in the groundwater of the study area.  相似文献   
6.
  相似文献   
7.
  相似文献   
8.
This study integrates potential gravity and magnetic field data with remotely sensed images and geological data in an effort to understand the subsurface major geological structures in Afghanistan. Integrated analysis of Landsat SRTM data was applied for extraction of geological lineaments. The potential field data were analyzed using gradient interpretation techniques, such as analytic signal (AS), tilt derivative (TDR), horizontal gradient of the tilt derivative (HG-TDR), Euler Deconvolution (ED) and power spectrum methods, and results were correlated with known geological structures.The analysis of remote sensing data and potential field data reveals the regional geological structural characteristics of Afghanistan. The power spectrum analysis of magnetic and gravity data suggests shallow basement rocks at around 1 to 1.5 km depth. The results of TDR of potential field data are in agreement with the location of the major regional fault structures and also the location of the basins and swells, except in the Helmand region (SW Afghanistan) where many high potential field anomalies are observed and attributed to batholiths and near-surface volcanic rocks intrusions.A high-resolution airborne geophysical survey in the data sparse region of eastern Afghanistan is recommended in order to have a complete image of the potential field anomalies.  相似文献   
9.
Chemical characteristics of groundwater in the Midyan Basin (northwestern Saudi Arabia) were investigated and evaluated. A total of 72 water samples were collected from existing shallow wells and analyzed for different elements. Two multivariate statistical methods, hierarchical cluster analysis (HCA) and principal components analysis (PCA), were applied to a subgroup of the data set in terms of their usefulness for groundwater classification, and to identify the processes controlling groundwater geochemistry. The subgroup consisted of 46 water samples out of 72 samples and 24 variables included major elements (Ca2+, Na+, Mg2+, K+, Cl?, HCO3 ?, NO3 ?, SO4 2?), minor and trace element (SiO2, Al, As, B, Ba, Cd, Cr, F, Fe, Mo, P, Pb, Sb, Sn, Ti, and V). For water samples, four geochemically distinct clusters (i.e., C1, C2, C3 and C4) have been observed by hierarchical cluster analysis. Cr, F and Pb are the dominant ions in cluster C2. Al, As, Cd, Mo, Sb and Ti are the dominant ions in cluster C3, while B, Ca, Cl, HCO3, K, Mg, Na, SO4 and V are identified as dominant ions in the cluster C4. In the PCA, a total of five components are extracted form the data set, which explained 73.37 % of the total data variability. Among them the first component reveals strong associations between As, B, Cd, Cr, F, Mo, Pb, Sb and Ti. The second component reveals the associations between Ca, Cl, HCO3, Mg, Na, SO4 and V.  相似文献   
10.
Water samples for chemical analyses were collected in January 2012. A total of 72 samples of groundwater were collected from 72 boreholes in the Midyan Basin, northwestern Saudi Arabia. Samples were collected in polyethylene bottles and preserved and the used analytical techniques were in accordance with the standard methods from American public health association. Geochemical analyses of the groundwater samples from Midyan Basin reveal the concentration of fluoride (F) between 0.98 and 2.1 mg/l. Other parameters, e.g, pH, EC, TDS, HCO3, SO4, NO3, Cl, K, Na, Mg, and Ca have been found in a variable proportion. Among them, the concentration of EC, HCO3, K, Na and Mg is higher than the permissible limits. According to thermodynamical considerations, most of the analysed samples are graded under-saturated with respect to calcite and fluoride, while saturation has been observed in some samples. The under-saturation could probably be attributed to low concentration of calcite and fluoride in the studied wells. Fluoride concentration shows weak positive correlation with EC, TDS, Na, Cl, and SO4. Factors controlling the concentration of fluoride (F) in the studied samples are the area climate, water chemistry and the presence of accessory minerals in the rocks through which groundwater is circulating, besides the anthropogenic activities in the area.  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号