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1.
A. A. Bakheit G. Z. Abdel Aal A. E. El-Haddad M. A. Ibrahim 《Arabian Journal of Geosciences》2014,7(6):2165-2178
The study area lies to the south of El-Dakhla Oasis in the central part of the western desert, Egypt. It is limited by the latitudes 24–25°?N and the longitudes 28–30°?E. The main purpose of this work is the investigation of the subsurface structure and the delineation of the main structural elements at different subsurface levels. This study aims also to estimate the basement depth, the basement relief, and consequently, the thickness of the sedimentary cover. The study is based on acquired aeromagnetic data prepared by "La Compagnie General De Géophysique" for the Egyptian General Petroleum Company and Conoco (1977), geological information and results of previous studies in the region. The study involves the analysis for the aeromagnetic data and generating of reduced to pole magnetic map from which different magnetic maps are calculated. The calculated maps are first vertical derivative map and downward continuation map at depth level 400 m. Trend analysis technique is used to define the fault pattern affecting the studied area at different subsurface levels. It is applied to the reduced to pole magnetic map, the first vertical derivative map, and the downward continuation map at depth level 400 m of the study area. All results obtained from the interpretation process were combined together to draw the general view of the subsurface structures of the area. The NE–SW, E–W, and N–S trends are important surface and subsurface (basement) structural trends. This is attributed to the rejuvenation of movements on these old (basement) tectonic trends after the deposition of the sedimentary cover. Basement depth calculation from the aeromagnetic data is achieved using different techniques. The applied techniques included natural spectral analysis and Euler deconvolution. The depth values obtained vary from 400 to 1,700 m. 相似文献
2.
为验证低飞航磁技术在推断断裂带和预测成矿远景区中的应用效果,以江西朱溪矿区以往的地质构造、物化探工作为背景,对朱溪测区的低飞航磁数据进行向上延拓和梯度处理,即总梯度模、斜导数和垂向一阶导数计算。将计算后的多幅异常等值线图与测区的区域地质构造及江西矿区成矿特点相结合,在该地区共推断出地质断裂8条,构造走向为NE向、近EW向及NW向。其中,NE向断裂为该区域主要的深大断裂,形成于下扬子板块和上华夏板块之间由于推覆构造所产生的压挤作用,主要位于塔前—赋春断裂带和双田—石劈山断裂带附近;近EW向和NW向断裂为次生断裂,近EW向断裂可能由九江—德兴断裂带产生。同时,通过分析朱溪矿区矽卡岩矿床所具有的特殊磁梯度异常现象,共推断成矿远景区4个,主要位于断裂带附近。 相似文献
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The gravity map of the Aveiro Basin, North West Portugal was produced in 2000/2001 and some limited two dimensional (2D) interpretation was carried out. It is intended in this article to advance the interpretation and modelling of the original Aveiro basin gravity data. Thus, the data were processed and the horizontal gradient, the second vertical derivative and downward continued field computed. The corresponding maps have been processed and a new interpretation of the basin tectonic features has been proposed. This is compared with the previous geological and tectonic information obtained from former surveys and local boreholes. As the next step a more detailed modelling of the Aveiro Basin took place. Bearing the interpretation of the basin tectonic features in mind, several north–south and east–west gravity profiles were established and modelled. The proposed models were presented and discussed. As a result, a comprehensive mass distribution model for the basin was proposed. Finally, comparison was made between the new gravity model and the previously published tectonic features map. This modelling is particularly useful for groundwater protection, exploration and exploitation and also for the dimensioning of drilling operations. Bearing in mind the geomorphology of the basin the gravity method is a very economical tool for the investigation of basin structures. 相似文献
6.
A. K. Chaturvedi M. Sridhar R. Murlidharan K. Shrivastava R. Pavan Guru 《Journal of the Geological Society of India》2014,84(4):385-396
Surface exploration techniques have been key contributors in discovering mineral deposits over the past three decades. However, in the last decade there has been a growing emphasis on integrating remote sensing, geological, geophysical and geochemical exploration techniques to compliment them in identifying concealed deposits. Successful integrated exploration requires putting mappable petrophysical property contrasts in terms of geological and geochemical process that could be associated with different mineralisation environment. The Precambrian Gangpur basin comprising volcanic free sedimentary sequence is considered as a potential geological setting for hosting uranium mineralisation. The Gangpur basin with metasediments of low to medium metamorphic grade classified as the Gangpur Group are known for hosting manganese, limestone and lead-zinc deposits. Uranium mineralization is reported in limonitic carbonaceous phyllite and sheared quartzite of Kumarmunda Formation at Jhamankele-Bhalulata areas. Several uranium anomalies have been associated with gossan at Kaedarpani, Jamdra and in ferruginised laterite at Badekachar, Jarmal, Jhagarpur, Kadorpani, Karamabahal, Tetelkela & Kumtinunda. In the present study geological, geophysical and remote sensing data sets are processed and integrated with other available data to delineate target zones for uranium exploration. Even though direct detection of uranium mineralisation remains unresolved in exploration strategy, instead it is becoming increasingly instructive to focus on mapping suitable depositional environments. The enhanced satellite imagery is interpreted in terms of thematic layers viz. trend lines, lineaments, faults and geological contacts. The aeromagnetic data is processed and interpreted thematic layers of magnetic breaks and linears from total magnetic intensity (TMI), the reduced to pole (RTP), tilt derivative and amplitude of analytical signal grid images. The radiometric data is processed based on their broad lithology and radio-elemental distribution maps viz. count maps, ratio maps, ternary (%K-eTh-eU) and eU/K ? eU/eTh ? eU images are generated to aid in mapping uranium favourability zones. The favourability image zones with high eU/K, eU/eTh and eU counts zones are classified into class based on statistics and anomalous high zones are picked up as uranium favourable locales. The thematic layers of geological contacts, lineaments and faults interpreted from satellite imagery, magnetic linears interpreted from aeromagnetic data and uranium favourability zone extracted from Airborne Gamma Ray Spectrometric (AGRS) data are overlaid. Based on spatial association of favourable features few locals are delineated for uranium exploration. 相似文献
7.
为更加清晰和准确地利用磁梯度数据获得地质体的分布特征,笔者采用解析信号总水平导数法和梯度欧拉反褶积技术组合实现磁梯度数据的解释,解析信号总水平导数的极值可有效地圈定出矿体的分布范围,梯度欧拉反褶积法可有效地避免背景异常的干扰,从而准确地给出磁性体的位置和深度信息。理论模型证明解析信号水平导数法和梯度欧拉反褶积法的组合可准确地获得磁性体的水平范围和深度。应用于河北迁安地区磁梯度数据的解释,圈定出5个呈条带状分布的较大型铁矿藏,埋深在200~450 m。 相似文献
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三塘湖盆地是我国西部典型的火山岩油气盆地。本文基于1：5万高精度航磁资料,结合区域地质、区域重力、地面踏勘和物性资料,对三塘湖盆地进行了航磁综合解释;详细分析了磁场和重力场特征及其与区域构造的对应关系,圈定了盆地火山岩分布范围,采用欧拉反褶积方法计算了磁性体埋深,初步揭示了盆地磁性基底起伏情况;结合盆地火山岩油气成藏模式,开展了航磁油气远景预测。结果表明,三塘湖盆地中央坳陷内有隐伏火山岩存在的次级凹陷中心具有寻找火山岩油藏的良好前景：汉水泉凹陷区中的2个次级凹陷中心、条湖凹陷区北段次级凹陷中心应作为油气勘探重点区域;石头梅凸起和岔哈泉凸起区可作为重要油气勘探方向;方方梁凸起及其以南区域可作为下一步油气勘探工作的预研区。研究结果可为盆地油气资源后续勘探开发提供指导。 相似文献
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The present study aims mainly to delineate and outline the regional subsurface structural and tectonic framework of the buried basement rocks of Abu El Gharadig Basin, Northern Western Desert, Egypt. The potential field data (Bouguer gravity and total intensity aeromagnetic maps) carried out in the Abu El Gharadig Basin had been analyzed together with other geophysical and geological studies. The execution of this study is initiated by transformation of the total intensity aeromagnetic data to the reduced to pole (RTP) magnetic map. This is followed by applying several transformation techniques and various filtering processes through qualitative and quantitative analyses on both of the gravity and magnetic data. These techniques include the qualitative interpretation of gravity, total intensity magnetic and RTP magnetic maps. Regional–residual separation is carried out using the power spectrum. Also, the analytic signal and second vertical derivative techniques are applied to delineate the hidden anomalies. Aeromagnetic anomalies in the area reflect significant features on the basement tectonics, on the deep-seated structures and on the shallow-seated ones. Major faults and intrusions in the area are indicated to be mainly along the NE–SW, NW–SE, ENE–WSW and E–W directions. The Bouguer gravity map indicates major basement fracturing, as well as variations in the sedimentary basins and ridges and subsequent tectonic disturbances. The most obvious anomalous trends on the gravity map, based on their frequencies and amplitudes, are along the NE–SW, ENE–WSW, E–W and NW–SE trends. The main of Abu EL Gharadig Basin depositional center does not show sharp variations, because of the homogeneity of the marine rocks and the great basement depths. 相似文献
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依据重力与航磁异常,在地壳分层、正演模拟以及多种不同方法的处理结果基础上,重点认识天津断裂、沧东断裂与天津西部断裂等深大断层的深部延展特征,分析其活动规律,从不同侧面认识本区地壳在渤海湾裂谷盆地发育中的地质过程。研究结果认为:天津地区存在超壳断裂的可能性不大;天津断裂带西部新生代盖层下部存在规模较大的产状较陡的隐伏断裂,该断裂的活动性对本地区地壳稳定性影响更大。 相似文献
11.
珠江口盆地是南海北部陆坡最大的前新生代沉积盆地,油气资源丰富,由于新的地球物理资料未得以充分应用等问题导致盆地内部构造单元分布特征存在诸多不同看法,这些问题制约了盆地的进一步勘探和开发。本文以最新实测1∶10万高精度航磁数据为基础,采用切线法对研究区航磁异常深度进行反演计算,结合钻井、地震及南海北部陆域物性资料研究珠江口盆地磁性基底分布特征。在充分调研珠江口盆地已有构造单元划分的基础上,以盆地磁性基底展布特征为基础,结合断裂、区域构造等对珠江口盆地内部构造单元进行研究。研究表明:珠江口盆地磁性基底深度在0～9 km之间,磁性基底呈"三隆两坳"构造格局,整个坳陷区具有"南北分带,东西分块"的特征; NE向深大断裂为控盆断裂,常为盆地二级构造单元的边界,NW向断裂常控制次一级构造单元并影响其展布形态。 相似文献
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以江苏南部1∶50万航磁资料为基础,通过对区内岩矿石磁性特征的归纳与分析,对区内航磁异常形成的地质因素作了讨论,并对区内航磁异常进行了分类、分区及地质解释。通过进一步对区内航磁资料的数据处理,对区内深变质磁性基底面的埋深、形态特征及其地质意义作了讨论,对区内构造岩基带平面分布及垂向分布特征,特别是对长江断裂带也一并作了推断解释。 相似文献
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A. Markandeyulu I. Patra B. V. S. N. Raju A. K. Chaturvedi P. S. Parihar 《Journal of the Geological Society of India》2012,80(3):382-392
The Paleo-Meso Proterozoic Gwalior basin (E - W), lying to NW fringe of Bundelkhand massif is represented by litho-package of lower arenaceous Par Formation and upper chemogenic Morar Formation. It is bounded by Indo-Gangetic alluvium in north and east, Kaimur sediments in west and Bundelkhand granitoids in south. Gwalior Basin has been the exploration target for uranium mineralization right from early 60’s. Surface radioactivity anomalies due to uranium has been reported in both Par and Morar Formations of Gwalior Group and Vindhyan sediments. Besides presence of syngenetic uranium in the system, presence of post-depositional faults and fractures are the favorable factors. Aeromagnetic survey was carried out by AMD in 2002 with N-S lines of 500 m interval covering 9406 line km. The data with sampling interval of 0.1 sec was corrected for spikes, diurnal variation, IGRF, heading and lag. Final processed images are prepared after suitable leveling and gridding. First vertical derivative of TMI-RTP and tilt-angle derivative images are used to map the litho-contacts, lineaments and structural features. Numerous NE-SW trending low amplitude and NW-SE trending high amplitude magnetic linears corroborate with quartz reefs and basic dykes respectively. Besides, E-W to WNW-ESE and ENE-WSW trending fractures are also evident from the processed image maps. Further, the Euler’s depth solution of gridded aeromagnetic data calculated for structural indices of 0 and 1 are very consistent in locating the position of the causative sources. Based on the amplitude and textural character of processed aeromagnetic data, alteration zone is delineated well within the Morar Formation. Enhanced Thematic Mapper (ETM+) image with 30m resolution was merged with IRS PAN 1D (5.8 m resolution) for better spatial/radiometric resolution to extract litho-contacts and lineament patterns. Merged PAN band-4 after linear contrast and edge enhancement techniques deciphered detailed lineament pattern, which corroborate the magnetic data. Merged ETM+ (RGB 751) and PC (PC1-PC2-PC5) images depict litho-logical contrast. Integration of aeromagnetic and satellite imagery data helped in understanding the structural fabric of the Gwalior Basin and to identify favorable loci of uranium mineralization. 相似文献
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巴里坤盆地夹持于麦钦乌拉岛弧和哈尔里克岛弧之间,其地层展布、断裂构造、油气成藏、盆山关系均不明确.使用大地电磁测深、航磁、地震等方法对其开展综合研究.研究表明:新生界沉积较薄,中生界及上二叠统地层从盆地中心向四周逐渐减薄,下二叠统和石炭系地层山前沉积略厚、向南逐渐变薄;盆地内部存在12条断裂,大多数为近东西走向的逆冲断裂,这些断裂构成研究区的基本构造格架;盆地可划分为北部斜坡、哈尔里克逆冲带、巴里坤坳陷三个二级构造单元;巴里坤坳陷大河构造为油气成藏的有利区域;南边哈尔里克山呈北西向向盆地内逆冲推覆,与盆地以哈尔里克断裂为界,盆地与北边麦钦乌拉山与以麦钦乌拉断裂为界,与西边博格达山以冬屋断裂为界. 相似文献
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由于断裂两侧的磁性、密度的纵横向差异在重力、磁力异常上有所表现,因此所获得的重力、磁力数据为深入研究关键的地质课题提供了科学基础,如郯庐断裂带的基底性质、断裂形成特征和岩浆岩分布。利用最新的高精度航空重力和磁力数据以及地面重力数据,绘制了郯庐断裂带地区的1∶50 000重力和磁力异常图,并结合区域地质数据分析了重力和磁力异常特征。分析结果认为:存在连体的郯庐—大别古老构造带,郯庐断裂带南段是元古宙和燕山中期岩浆活动的复合反映带;郯庐断裂带为中元古—新元古代时期南华北陆块与下扬子陆块的界限;磁力、重力异常图对比说明,合肥盆地范围由老到新向东扩展。 相似文献
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南黄海北部重力场信息丰富、梯级带发育、异常特征明显,充分反映了该区隆坳构造格局、断裂展布等地质特征。综合研究认为: NE向断裂构成了南黄海北部主体构造格架,嘉山-响水断裂、南黄海北缘断裂共同构成了苏鲁造山带南部边界; 依据航空重磁资料新发现的NW向宫家岛深大断裂对南黄海北部基底构成、岩浆岩分布具有重要的控制作用; 通过重磁联合反演,发现在南黄海北部坳陷的东北凹陷存在着前寒武系稳定的结晶基底; 航空重力资料表明,胶莱盆地向东延伸进入南黄海,在海域内其最大沉积厚度可达3 km。上述地质认识和发现为南黄海北部海洋区域地质调查、油气资源调查及重大基础地质问题的解决提供了借鉴。 相似文献
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本文根据最新的航磁资料,将东昆仑-阿尔金山地区按照不同的磁异常面貌特征进行了分区描述,其总体展布以北东和近东西向为主,磁异常具有明显的分区、分带性。同时辅以卫星重力资料,通过解析延拓、任意水平方向导数计算等处理,得到大量与断裂相关的地球物理场信息,并结合地质资料综合分析,揭示了研究区内断裂构造尤其是深大断裂在磁场上的特征。这些特征主要以不同磁场分界线、磁异常梯度带和串珠状异常等形式呈现,明显的表现为磁场分区、分带的界线。在此基础上,根据航磁资料解释和实际应用结果对深大断裂与成矿的关系进行了探讨。本文实例揭示已知的中小型矿床多位于深大断裂附近。 相似文献
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为了解不同时代火成岩的航磁异常特征,对东北地区1∶20万的航磁资料进行了化极、向上延拓及垂向导数的处理。通过与地质图进行对比分析,总结出研究区火成岩的航磁特征:区内广泛分布的各时代花岗岩表现出了不同的磁异常特征,寒武纪、石炭纪、三叠纪等时代的花岗岩表现为高磁异常,而二叠纪及侏罗纪花岗岩表现为低磁异常,其中磁异常最高的岩性为石炭纪花岗岩,磁异常最低的是二叠纪花岗岩。测区内存在的喷出岩-古近纪玄武岩磁异常较高,而更新统玄武岩并未见明显的异常特征。 相似文献
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With the help of aerial photographs, satellite photographs and imageries, contour maps, geological and geomorphological information
(personal correspondence and unpublished works), geophysical regional data, and field work, it has been possible to map a
network of fractures, alignments, and faults in 26 areas (distinguishing them quantitatively and hierarchically). Links with
known regional structures were also studied. Interpretation of the linear relief elements confirms the very different density,
dimensions, strikes, and function of the fracturation and also, from a microtectonic perspective, explains the activity of
some active faults better. It has confirmed some previous results and improved on others; for example, the Oriente fault which
is the most active in Cuba with two segments (Western: Cabo Cruz—Santiago de Cuba; Eastern: Santiago de Cuba—Punta de Maisí,
the Western fault being the most active); the Nortecubana fault, forming the northern limit of the Cuban megablock, and divided
into three segments; and the Cauto—Nipe fault, forming the limit of the neotectonic units, presenting two segments with three
seismoactive knots. 相似文献
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Structural evaluation of the pegmatite-rich zones in a part of Lafiagi (Sheet 203), Central Nigeria, was carried out. It was aimed at identification of the structures responsible for the rich mineralization of the area. This work involved the qualitative and quantitative analysis of aeromagnetic data and pseudogravity transforms by using Oasis Montaj? software. The 3D Euler deconvolution results from acquired aeromagnetic data and pseudogravity transforms augmented with geological information obtained from reliable sources were employed in the structural interpretation work. The results have shown that the abundance of 2D and 3D structures that are commonly associated with gemstones and precious minerals explain why the study area is rich in mineral deposits. 相似文献