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Dewashish Kumar D. V. Subba Rao Setbandhu Mondal K. Sridhar K. Rajesh M. Satyanarayanan 《Journal of the Geological Society of India》2017,90(2):147-153
Time Domain Induced Polarization (TDIP) investigation in conjunction with high resolution electrical resistivity tomography surveys carried out at seven sites along a 5.2 km line in Jashpur and Raigarh districts of Chhattisgarh State yielded promising results leading to the demarcation of mineralized zones. These sites are confined to ultramafic-mafic-felsic intrusive complexes representing gabbro-pyroxenite-granite sequences characterized by gold - sulphide mineralization. Two dimensional (2D) geophysical datasets yielded interesting results and a good correlation is found between 2D inverted resistivity tomography and time domain induced polarization (IP) models. Both high resistivity-high chargeability as well as low resistivity-high chargeability conditions have been inferred from these datasets. This observation is consistent with conductive metallic mineralization. Interpretation of the Pharsabahar-Pandripani site, reveals a chargeability magnitude of 9-14 mV/V, which represents a strong metallic conductor associated with gold-sulphide ore body. The results at Samarkachar site are equally significant, showing a good correlation with the presence of a low resistivity and high chargeability zone. Hence, the present study suggests a new scope for application of resistivity and IP tomography surveys for mineral prospecting in favourable geological settings. 相似文献
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冀北地区岩石极化率特征及其找矿意义 总被引：1，自引：1，他引：1
介绍在东经114°～120°和北纬39°00′～42°30′的范围内岩石极化率研究的成果。数值统计结果显示,798件沉积岩的平均极化率为2.40%,1149件火成岩的极化率为2.99%,436件变质岩的极化率为3.59%,因此,变质岩是本区较好的金属矿矿源。空间分布上,与沉积作用密切相关的煤矿主要分布在沉积岩高极化率地区,变质铁矿主要分布在变质岩高极化率地区,内生金矿则主要分布在火成岩高极化率地区。因此认为,主要矿产地的分布与极化率高值区的分布在空间上大体一致,岩石极化率反映了矿源物质的总体背景。 相似文献
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介绍了不对称测深法装置的测深原理;在吉林某地进行了激电测深勘探,结果显示:正向单极-偶极和反向偶极-单极采集的视电阻率、视充电率原始数据在拟断面图的分布特征,和大地电磁测深原始数据受到的静态效应类似,视电阻率、视充电率受局部地形和电磁噪声的影响,在拟断面图中呈假的带状异常。正向单极-偶极、反向偶极-单极装置获取的视电阻率、视充电率数据也可分别进行二维反演,但联合单极-偶极/偶极-单极装置测深二维反演地质结果最好,具有采集的数据量大、激电信号强 、穿透深度大、勘探精度高等优点,根据视电阻率、视充电率二维反演在地电断面成像技术,能够准确确定电性异常体的空间分布,为钻探验证电异常提供准确的地球物理依据。 相似文献
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F. Darabi-Golestan R. Ghavami-Riabi R. Khalokakaie H. Asadi-Haroni M. Seyedrahimi-Nyaragh 《Arabian Journal of Geosciences》2013,6(11):4499-4509
Geochemical and statistical analyses of 165 soil samples led to Cu-Au anomaly separation in Dalli-Northern Hill by using fractal geometry and U-spatial statistic. There was a good correlation between the anomaly areas and outcrops of quartz diorite porphyry (QDP) in the study area. Based on the interpretation of soil data and anomaly areas determination, one trench was suggested in NE-SW direction for follow-up exploration. Based on the rock sample analyses from the trenches in QDP rocks, the ratio of $ \frac{{{\mathrm{Ba}} \times {\mathrm{K}}}}{{{\mathrm{Ca}} \times {\mathrm{Zn}}}} $ clearly separated the mineralization area and considered as an index ratio for follow-up exploration stage. Dalli-Northern Hill anomaly includes pyrite/chalcopyrite/bornite, which is dominantly abundant in the ore body. Three IP profiles (IP04, IP05, and IP06) confirmed the conductivity of the sulfide zone. The background chargeability in the study area was about 5.4 mV/V and the average of maximum apparent chargeability in the study area was 44.4 mV/V, which could be related to the higher intensity of Cu-Fe sulfide minerals. The contact of andesite and quartz diorite has shown the strongest chargeability (71 mV/V) and high magnetic anomalies in the study area. DDH03 and DDH04 boreholes mostly confirmed that the IP/magnetic/geochemical anomalies were related to the contact of intrusive rocks and the wall rock of andesite. The combination of geochemical information from soil and rock together with geophysical data (induced polarization/resistivity) led to the subsurface geological cross sections and location of the mineralized zone enriched of sulfide. The mineralized zone in Dalli-Northern Hill distinct could be identified by potassic to weak sericitic and trace chloritic alteration, high values of the $ \frac{{{\mathrm{Ba}} \times {\mathrm{K}}}}{{{\mathrm{Ca}} \times {\mathrm{Zn}}}} $ ratio accompanied with high gold and copper values and enrichment from magnetite minerals. The high magnetic susceptibility, low resistivity, and high chargeability are considered as geophysical properties of the mineralized zones. 相似文献
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这里简述并图示了单极～偶极和对称四极装置测深原理及野外布极方式。根据单极～偶极装置视电阻率与施伦贝格尔装置视电阻率存在的内在关系,以及"等效电阻率法",给出了施伦贝格尔装置视极化率与单极～偶极装置视极化率的数学式,即时域激电单极～偶极装置测得的电性参数数据,可以转换为施伦贝格尔装置电性参数的数据,并对这两种测深装置视电阻率、视充电率分别进行二维反演、成图及对比,结合测区简单的地质特征,显示出两种装置测深具有相同的地质勘探效果。 相似文献
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为准确评价敦化团北地区激电异常,研究其产生机制,采用提取激电二次信息的视金属因素(Js)方法,突出与电子导体相关的低阻极化体异常,压制与电子导体不相关的激电异常。结果表明:测区西北角视金属因素异常与强激电异常相吻合,与电子导体(金属矿化或矿化)相关,而大范围低缓激电异常区没有视金属因素异常显示,说明与电子导体不相关。在敦化团北地区利用视金属因素压制干扰因素所引起的异常,突出与电子导电体相关的低阻极化体异常效果明显,结合地质揭露工程得出低缓激电异常是由受轻微矿染的花岗斑岩所引起的结论。 相似文献
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锦州东港电力有限公司矿泉水水源地位于辽西中部断陷盆地锦州盆地的北端。地处中新生代上侏罗统及白垩系构成的对称向斜,NNE新华夏系断裂构造经由锦州盆地通过。工作区第四系覆盖6-14m,下伏孙家湾组(K2S)砂质泥岩、砂砾岩和义县组(K1y)火山碎屑岩、英安岩、安山岩及火山凝灰角砾岩。对该区进行地质水文资料综合分析的基础上,采用电阻率联合剖面、高密度电阻率法、电测深(电阻率、衰减时及极化率)多种物探电法综合勘查,确定断裂构造位置、产状及赋水性。经验证获得涌水量312t/d具有商业价值的矿泉水水源地。这一工作方法在辽西火山岩贫水区进行水资源勘查具有推广意义。 相似文献
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这里研究层状极化介质激发极化效应特征。首先,在忽略电磁效应的情况下,用柯尔～柯尔模型表征极化介质复电阻率,计算三层不同地电断面复电阻率的振幅和相位随极距变化的曲线;然后,分析极化层不同充电率和不同时间常数、不同激发频率和极化层不同埋深,对测深曲线的影响规律,并提出了具有实际指导意义的极化层埋深与极距的对应关系。这些工作都能够为野外开展复电阻率测量和资料解释起到参考作用。 相似文献
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运用美国生产的高密度电法仪器对峪耳崖金矿区16~28线进行了测量。该仪器可同时测得视电阻率和视充电率2种数据,并可自动成图和地形改正。通过高密度电法工作圈定了地表较浅部的矿化异常区,除主要矿化异常赋存于岩体接触带外,在灰岩中也发现高极化异常区,表明在灰岩地层内也存在金属硫化物矿化现象,这为下一步找矿工作提供了新的思路和方向。通过钻探结果确定该矿区异常区有2种类型,即高阻高充电异常和低阻高充电异常,主要分布在岩性的接触带附近,尤其是内接触带。 相似文献
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时频电磁法(TFEM)作为一项比较成熟的油气检测技术,在国内外已得到了广泛的应用.在时频电磁解释过程中,主要采用电阻率和极化率联合定性检测,不能给出含油气的定量评价,并把地层电阻率视作与温度、压力无关的量.但随着地层深度增加,地层的温度、压力变化会对电阻率产生影响.由温度、压力的变化引起的电性变化会给储层解释带来误差.通过对岩石的频散测试,分析岩石电性参数随频率变化的规律,并结合岩石的频散性质研究了地层电阻率受温度、压力影响后的变化特征,而后通过拟合获得岩石电阻率与温度、压力的近似关系式.利用恰当的温压-电阻率函数,对时频电磁储层数据进行电阻率校正;利用校正后的电阻率数据,基于Archie公式计算研究区储层目标段的饱和度,并对储层进行了定量评价. 相似文献
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Induced polarization,resistivity, and self-potential: a case history of contamination evaluation due to landfill leakage 总被引：2，自引：1，他引：1
José Domingos Faraco Gallas Fabio Taioli Walter Malagutti Filho 《Environmental Earth Sciences》2011,63(2):251-261
This article compares the efficiency of induced polarization (IP) and resistivity in characterizing a contamination plume
due to landfill leakage in a typical tropical environment. The resistivity survey revealed denser electrical current flow
that induced lower resistivity values due to the high ionic content. The increased ionic concentration diminished the distance
of the ionic charges close to the membrane, causing a decrease in the IP phenomena. In addition, the self-potential (SP) method
was used to characterize the preferential flow direction of the area. The SP method proved to be effective at determining
the flow direction; it is also fast and economical. In this study, the resistivity results were better correlated with the
presence of contamination (lower resistivity) than the IP (lower chargeability) data. 相似文献
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火炉岭脚-棚坞多金属矿区开展的电法综合勘探工作和矿区内视极化率、视电阻率异常特征综合分析表明,该异常体为高极化高阻体,并推断出其产状变化和分布范围;同时结合矿区的区域地质情况以及已实施的槽探和钻孔资料,判定出该矿化赋存于岩体接触带内,且呈浸染状矿化。由于推断区内矿化体的产状和岩体接触面产状不一致,且矿化体的产状自东向西变化较大,因此认为该区多金属成矿不仅受到区内接触带蚀变的影响,更主要受到断裂构造的控制。 相似文献
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The application of electrical imaging and very low frequency (VLF) electromagnetics was investigated for the purpose of delineating basement fracture zones, and to show how incorporating a priori information in numerical modelling would facilitate the location of fractured zones within a basement rock more precisely. To this end, direct current (DC) dipole–dipole resistivity and VLF modelling and inversion experiments were carried out to evaluate the efficacy of the methods in detecting low-resistivity fracture zones in a typical crystalline basement rock that is favourable for groundwater accumulation. Most wells drilled in such an environment usually have low yields. Results of the numerical experiment generally indicate that fractures covered by moderate overburden, and having considerable depth, extent, and thickness compared to the depth of fracture burial, produce good responses resulting in high-resolution resistivity images. Lower resolution resistivity images were obtained as the thickness of the overburden increased. Also, the model investigations indicate that width of the fracture zone plays a major role in controlling image resolution. Conclusions from the synthetic modelling were confirmed by resistivity and VLF data gathered across a suspected fault in a hard rock terrain of southwestern Nigeria. The results from the field data are in general agreement with the numerical modelling experiments.Integración de métodos geofísicos superficiales para la detección de fracturas en macizos rocosos cristalinos del suroeste de Nigeria. 相似文献
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新疆白干湖钨锡矿床简介 总被引：5，自引：0，他引：5
介绍了白干湖钨锡矿床地质特征、含矿围岩特征、矿体类型及各类型特点,确定了围岩蚀变类型及分带现象,指出了硅化、电气石化、金属硫化物矿化是寻找钨、锡矿的找矿标志。最后探讨了矿床成因,展望了发现该矿床的意义。 相似文献
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Subash Chandra V. A. Rao N. S. Krishnamurthy S. Dutta Shakeel Ahmed 《Hydrogeology Journal》2006,14(5):767-776
An integrated study was carried out to investigate the subsurface geological conditions in a hard rock environment, with the aim of identifying zones with groundwater resource potential. The study, in Bairasagara watershed, Karnataka, India, considered geomorphology, water level, resistivity imaging, self potential, total magnetic field and susceptibility. The signatures due to lineaments have been clearly identified and their role in groundwater movement has been documented. Synthetic simulation methods were used to model the electrical response of the lineament using finite differential modeling scheme. The inverted image of the field data is compared with the synthetic image and iteration were performed on the initial model until a best match was obtained resulting on the generation of the calibrated resistivity image of the subsurface. Resistivity imaging revealed that the dykes are weathered/fractured to a depth of 6–8 m and are compact at deeper levels, and that they behave as barriers to groundwater movement, yet facilitate a good groundwater potential zone on the upgradient side. The results of magnetic surveys were utilized in differentiating granites and dolerite dykes with an insignificant resistivity contrast. Geomorphological expression alone cannot reveal the groundwater potential associated with a lineament. However, characterizing the nature of the feature at depth with integrated geophysical methods provides essential information for assessing that potential.An erratum to this article can be found at 相似文献
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用MT方法对一维地质体的探测能力进行研究。结果表明 ,在合适条件下MT方法的探测深度可达几千公里。但具体探测深度与异常体的电性、规模、围岩电性有关。一般来说 ,异常体规模越大 ,可探测深度越大 ;异常体与围岩的电性差越大 ,可探测深度越大 相似文献