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Pramod Kumar Yadav P K Adhikari Shalivahan Srivastava Ved P Maurya Anurag Tripathi Shailendra Singh Roshan K Singh Ashish K Bage 《Journal of Earth System Science》2018,127(2):17
Dalma volcanics (DVs) has intruded the older Singhbhum Group of Metapelites. Despite DVs being rich in mineralisation, its boundaries are not clearly demarcated. Gravity and magnetic surveys have been attempted for mapping the boundaries in DVs. These surveys were made in the northern fringe of the DVs over an area of \(\sim \)0.70 \(\hbox {km}^{2}\) along 13 parallel lines at 50 m spacing. The data was acquired at \(\sim \)25 \(\hbox {m}\) spacing. The surveys were taken for determination of lithological boundaries, depths and nature of causative source using Euler depth solutions and radially averaged power spectrum (RAPS). Residual anomaly maps of gravity and magnetic intensity show the same trend as that of Bouguer gravity anomaly and total magnetic intensity anomaly map indicating towards shallow sources. The magnetic map in general follows the same pattern as that of gravity anomaly maps. The map shows coincident high gravity and magnetic anomalies. These anomalies together with resistivity signatures confirm that the northern fringe of DVs hosts volcanogenic massive sulphide settings. The Euler depth solution delineated the lateral boundaries and nature of the source. It seems that the source is of spherical nature lying within a depth range of 25–40 m. The obtained lithological (vertical) units from RAPS are between Lower DVs, Upper DVs and Singhbhum Group Metapelites at depths of \(\sim \)15, \(~\sim \)25 and \(\sim \)40 \(\hbox {m}\), respectively. The metallogeny is associated with the Upper DVs and the corresponding delineated lithological (vertical) unit is indicative of the top of the ore body. Good agreement is observed with the geological succession from the drilling data and resistivity data. The findings suggest that the northern fringe of DVs could be a preferred target for drilling. 相似文献
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杨桥孜铜金矿是皖北覆盖区以地质理论为指导通过综合物探手段发现的一处中型矽卡岩型矿床。该矿床是皖北地区迄今为止发现的规模最大金矿床,对三铺岩体成矿预测、皖北地区找矿、研究华北陆块找金方向具有重要意义,为覆盖区综合找矿方法提供了成功经验。重磁勘探在该矿床的发现过程中发挥了重要作用,重磁组合异常特征倍受关注。杨桥孜金铜矿位于重力梯级带的次级鼻状重力高异常区,重力二阶导数异常与矿体分布相吻合;地磁场以正异常为背景,局部叠加明显的强磁异常,强磁异常与铁矿体分布一致,铜金矿体对应于磁力梯级带。重高磁高、重高磁梯组合异常在矿床普查过程中发挥了作用。 相似文献
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在野外1∶1万地质测量、井下大量坑道观察和编录基础上,对冀东峪耳崖金矿床矿区1∶1万高精度磁法测量数据进行化极、延拓、求导处理,将峪耳崖矿区的高磁异常划分为低缓正异常场、低缓负异常场和中高正异常场3种场区,解译出不同方向线性断裂构造31条,以北东向、北西向构造为主,构成矿区构造格架;磁化极异常进行4个高度50 m、100 m、200 m、500 m垂向二阶导数计算,形态受北东向、北西向及南北向构造综合控制,沿北东方向带状分布。结合已知矿体的构造控矿规律及岩体控矿特征,确定区内成矿远景区圈定依据为成矿磁性体形态、产状变化地段;北东向构造面与北西向、南北向、东西向构造交汇复合部位;黄铁矿化、硅化、大理岩化及绢云母化等蚀变发育部位。 相似文献
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Genesis of superimposed hypogene and supergene Fe orebodies in BIF at the Madoonga deposit, Yilgarn Craton, Western Australia 总被引:1,自引:0,他引:1
The Madoonga iron ore body hosted by banded iron formation (BIF) in the Weld Range greenstone belt of Western Australia is a blend of four genetically and compositionally distinct types of high-grade (>55 wt% Fe) iron ore that includes: (1) hypogene magnetite–talc veins, (2) hypogene specular hematite–quartz veins, (3) supergene goethite–hematite, and (4) supergene-modified, goethite–hematite-rich detrital ores. The spatial coincidence of these different ore types is a major factor controlling the overall size of the Madoonga ore body, but results in a compositionally heterogeneous ore deposit. Hypogene magnetite–talc veins that are up to 3 m thick and 50 m long formed within mylonite and shear zones located along the limbs of isoclinal, recumbent F1 folds. Relative to least-altered BIF, the magnetite–talc veins are enriched in Fe2O3(total), P2O5, MgO, Sc, Ga, Al2O3, Cl, and Zr; and depleted in SiO2 and MnO2. Mafic igneous countryrocks located within 10 m of the northern contact of the mineralised BIF display the replacement of primary igneous amphibole and plagioclase, and metamorphic chlorite by hypogene ferroan chlorite, talc, and magnetite. Later-forming, hypogene specular hematite–quartz veins and their associated alteration halos partly replace magnetite–talc veins in BIF and formed during, to shortly after, the F2-folding and tilting of the Weld Range tectono-stratigraphy. Supergene goethite–hematite ore zones that are up to 150 m wide, 400 m long, and extend to depths of 300 m replace least-altered BIF and existing hypogene alteration zones. The supergene ore zones formed as a result of the circulation of surface oxidised fluids through late NNW- to NNE-trending, subvertical brittle faults. Flat-lying, supergene goethite–hematite-altered, detrital sediments are concentrated in a paleo-topographic depression along the southern side of the main ENE-trending ridge at Madoonga. Iron ore deposits of the Weld Range greenstone belt record remarkably similar deformation histories, overprinting hypogene alteration events, and high-grade Fe ore types to other Fe ore deposits in the wider Yilgarn Craton (e.g. Koolyanobbing and Windarling deposits) despite these Fe camps being presently located more than 400 km apart and in different tectono-stratigraphic domains. Rather than the existence of a synchronous, Yilgarn-wide, Fe mineralisation event affecting BIF throughout the Yilgarn, it is more likely that these geographically isolated Fe ore districts experienced similar tectonic histories, whereby hypogene fluids were sourced from commonly available fluid reservoirs (e.g. metamorphic, magmatic, or both) and channelled along evolving structures during progressive deformation, resulting in several generations of Fe ore. 相似文献
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根据高精度磁法测量在龙岩马坑铁矿磁异常的分布情况,圈定测区东南段为规模较大的正负伴生异常,大致以官寮坑—太保林为界,东南为正异常,西北为负异常.走向北东,西南向未闭合.△T磁异常长度大于3 200 m,宽度800~2 300m.通过磁异常反演情况推测地下磁性体呈板状体,埋深在标高-200~-400 m,磁性体厚度约30 m,倾角约30°.经钻孔验证,磁铁矿体出现在标高-200~-400m,视厚度30.68 m.根据地质验证结果,工作区东南部的△T磁异常证实是由地下磁铁矿体所致,从而证实了高精度磁法在寻找磁铁矿床具有较高的应用效果. 相似文献
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本溪大台沟铁矿床位于本溪市桥头镇,是近年来发现的最大的鞍山式铁矿床。该矿床为隐伏的超大型铁矿床,埋深1100~1200m,已控制矿体延长2000m,最大延深840m,最宽处1100m。矿体总体为近直立的厚板状体,夹石很少,为单一矿体。矿石类型为磁铁石英岩(磁铁矿石)、赤铁石英岩(赤铁矿石)及其过渡类型的磁铁赤铁石英岩(混合矿石)。矿石品位较均匀,矿床有害杂质含量低。初步估算333+332类资源量约34亿t。 相似文献
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在河北省铁矿资源潜力评价及成矿预测中,对重力场、磁场特征进行了总结和归纳,认为规模较大的航磁正异常主要是出露或隐伏侵入岩基的反映;大面积分布的低缓正磁异常区则主要反映了太古宙变质岩系或基底隆起的边缘,沉积变质型铁矿主要密集分布在此区域;负磁场区主要出现在中上元古界、古生界碳酸盐岩和中生界酸性火山—沉积岩系;强度高、梯度大、或有明显负值伴生的局部磁异常则可能是磁性铁矿的反映。从重力场特征看,磁性铁矿主要分布在布格重力异常的梯级带或异常扭曲处,以及正、负异常的交界处,这些地方多与地质构造强烈变形密切相关。只有对重磁场进行深入地质剖析,结合典型矿床上建立的识别标志进行对比分析,才能得出一个符合客观实际的地质解释。 相似文献
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郎和都格矿区地表沙土和草原覆盖严重,直接寻找钨多金属矿的信息较少。地质地球化学研究结果表明,与钨多金属矿关系密切的是早白垩世钾长花岗岩,赋矿围岩主要是二叠纪辉石闪长岩。根据围岩与矿体之间的物性差异,完成了矿区1∶1万地质填图、磁法和重力测量,对数据进行重磁联合反演,识别出3条走向北东、长度800~3 000 m、宽度50~100 m的重要的构造蚀变带(分别对应于负磁异常带),均分布在矿区西北侧的辉石闪长岩中,且平行于辉石闪长岩和钾长花岗岩的接触带。预测了6个综合物探异常区,也位于矿区西北侧的辉石闪长岩分布区,单个异常面积为500 800 m2,异常深度不超过1 000 m。经钻探工程验证,在3个异常部位发现了隐伏的构造破碎带型钨多金属找矿靶区,钨多金属矿体埋藏深度为150~650 m,单个矿体厚度为2~4 m。表明成矿地质条件分析与重磁联合反演相结合的定位预测方法,在覆盖区寻找钨矿效果明显,值得进一步推广。 相似文献
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应用重磁方法勘查铁矿的效果——以辽宁建昌县马道铁矿为例 总被引:12,自引:0,他引:12
文章运用重磁方法以辽宁建昌县马道铁矿找矿为例,说明了重磁法的找矿效果,特别指出重力、磁法的科学组合是勘查评价铁矿、区分磁异常性质、寻找富铁矿的有效综合找矿方法。通过对一磁异常进行重新解释和评价,最终验证该异常为一大型鞍山式沉积变质磁铁矿引起的。同时说明GIS、MRAS计算技术模拟、判别分析等现代先进勘探技术的综合运用,是在老矿山的深部和外围铁矿勘查过程中的重要手段。因此,在对危机矿山的研究中,对如何加深地球物理异常的解释和评价等问题,应予以高度重视。 相似文献
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邯邢式铁矿深部探测技术及综合找矿模式研究——以河北省沙河市白涧铁矿床为例 总被引:4,自引:0,他引:4
邯邢式铁矿是中国著名的铁矿类型之一.近年来,在邯邢地区采用深钻对白涧铁矿低缓磁异常区进行了验证,在孔深592.74~1 040.52 m处发现了厚度大、埋藏深、规模大、品位高的隐伏邯邢式铁矿,表明该区具有深部找矿的巨大潜力.通过对白涧矿区的综合找矿探测方法技术的应用研究和对白涧铁矿深部隐伏铁矿的预测分析,证实了高精度重、磁方法相结合是寻找该类铁矿最有效的方法.EH-4电磁测深方法通过探测深部隐伏岩体的起伏变化,进而预测和发现盲矿体,是一种间接预测隐伏矿分布的有效方法.针对邯邢地区地表及地下均存在不同程度的重、磁、电干扰,该研究加强了实地干扰源的详细调查和室内资料的相关滤波、圆滑处理、位场的转换、异常正反演解释的研究工作,认为加强赋矿地层、构造、岩浆岩、围岩蚀变和重、磁综合异常"五位一体"的深部综合找矿模式,是寻找邯邢式铁矿深部矿体的有效方法. 相似文献
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MARIELA磁铁矿矿床位于秘鲁南部成矿带上。矿体主要赋存于侏罗纪闪长岩体中,富矿体呈透镜状、脉状产出,而品位较低的矿石为浸染状和细脉状。矿石主要由阳起石(透辉石)-磁铁矿和磷灰石-磁铁矿组成,磁铁矿中V含量较高。该矿床具有玢岩型铁矿的特征,为岩浆期后热液交代充填成矿。运用多重分形理论建立模型,将地面磁异常分为低值异常与中值异常2级,它们分别作为一级找矿靶区和二级找矿靶区,较好地解释了已知矿体与磁异常的吻合关系,为下一步找矿提供了依据。 相似文献
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鲁西南单县地区赋存沉积变质型铁矿,近年来,该地区铁矿找矿取得了较大的进展。为了更好地指导区内铁矿勘查工作,通过介绍单县地区铁矿地质特征、地球物理特征,剖析大刘庄铁矿床、龙王庙铁矿的矿床特征,建立找矿标志,并对今后铁矿找矿方向进行研究。单县大刘庄、龙王庙铁矿赋存于新太古代泰山岩群山草峪组中;铁矿体总体呈层状、似层状,局部呈透镜状,铁矿体产状与围岩一致。通过分析认为,区内的铁矿总体受山草峪组控制,构造、侵入岩对铁矿有破坏作用。经过对重磁测量成果分析,总体认为磁异常及其化极明显部位是区内铁矿勘查中最重要的指示标志,重力梯度带是铁矿赋存的重点位置。通过对以往勘查成果的综合分析认为,辛羊庙异常区应为今后铁矿勘查工作的首选地区。 相似文献
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安徽凤凰山岩体岩浆侵位过程的磁性研究 总被引:2,自引:0,他引:2
通过对安徽省铜陵地区凤凰山岩体25个采样点302件岩石样品的磁性分析,认为研究区内所得的岩石磁组构能代表岩浆侵位时的流动型磁组构,它受岩浆形成之后的构造活动的影响较小;岩浆侵位过程是准静态过程,岩浆流动性较弱、分异作用和同化混染作用强烈;岩浆侵位过程的早期可能受北北东方向的最大主压应力的控制,后期受西南方向最大主压应力场的控制;凤凰山岩体的西南部(药园山矿床所在地段)是岩体的上盘,北东部(仙人冲矿床所在地)是岩体的下盘,即凤凰山岩体向西南方向倾伏;凤凰山岩体的西南部附近地区(如来龙山等地),可能有与凤凰山岩体侵位同时期形成的小岩株,是找矿的远景区段。 相似文献
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Qinglong-Dacalhang ore concentration area is one of the important antimony deposit areas in Guizhou Province, and the fault structures and magnetic activities have great influence on the antimony mineralization. Based on gravity data, geology, mineral and geochemical data, the authors analyzed the fault structures and 3D morphology of granite body synthetically, by processing and inverting the gravity data in this paper. Combined with the condition the fault structures, shape of the rock body and geology, mineral and Sb-Au element anomalies, the authors also deduced that the deep faults and shallow faults provided a migration pathway for the magmatic hydrothermal fluids and controlled the top surface of the rock body. The limestone of Maokou Formation, Emeishan Basalt and fault structures were well developed in Dachang-Bihen area of the clamping area between fault F8 and F11, along with fault F11. The Sb-Au element anomalies were high, with large scale, which were a favorable region for deep ore prospecting. This research would provide the geophysical basis for deep ore prospecting. 相似文献