共查询到20条相似文献，搜索用时 765 毫秒
1.
Concealed and fossilized geothermal systems are not characterized by obvious surface manifestations like hotsprings and fumaroles, therefore, could not be easily identifiable using conventional techniques. In this investigation, the applicability of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Hyperion data-sets were evaluated in discriminating hydrothermal alteration minerals associated with geothermal systems as a proxy in identifying subtle Geothermal systems at Yankari Park, Nigeria. Feature-oriented principal component selection, spectral angle mapper, linear spectral unmixing were applied to ASTER data based on spectral characteristics of hydrothermal alteration key minerals for a systematic selective extraction of the information of interest. Analytical imaging and geophysics-developed processing methods were applied to Hyperion data for mapping iron oxide/hydroxide minerals and clay mineral assemblages in hydrothermal alteration zones. The results indicate that ASTER and Hyperion could be complemented for reconnaissance stage of targeting subtle alteration mineral assemblages associated with geothermal systems. 相似文献
2.
AbstractThe Shahr-e-Babak region located in the Kerman metallogenic belt is one of the high potential segments of Urumieh–Dokhtar magmatic arc for porphyry copper and epithermal gold mineralization in the south of Iran. This high potential zone encompasses several porphyry copper deposits under exploitation, development and exploration stages. The aim of this study is to evaluate Landsat-8 data and comparison with the Advanced Spaceborne Thermal Emission and Reflection Radiometer data-sets for mapping hydrothermal alteration zones related to Cenozoic magmatic intrusions in Shahr-e-Babak region. Previous studies have proven the robust application of ASTER in lithological mapping and mineral exploration; nonetheless, the Landsat-8 data have high capability to map and detect hydrothermal alteration zones associated with porphyry copper and epithermal gold mineralization. In this investigation, several band combinations and multiplications, developed selective principal component analysis and image transformations were developed for discriminating hydrothermal alteration zones associated with porphyry copper mineralization using Landsat-8 data. 相似文献
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Melanie Brandmeier 《国际地球制图》2013,28(8):629-648
A combined approach to detect hydrothermal alteration zones and their mineral distribution is proposed for a relatively remote area around the Carhuarazo volcanic complex in southern Peru encompassing 2222 km2. In this region, tertiary volcanic structures associated with hydrothermal alteration are well known to host epithermal ore deposits. We make an attempt to detect and to quantify alteration minerals based on spectral analysis using ASTER reflectance data product provided by LP-DAAC. Besides commonly used ratio images, mineral indices (MI) and relative band depth images (RBD), we also extracted endmember spectra using Pixel-Purity-Processing preceded by minimum noise fraction transformation. These spectra are thought to represent the spectrally purest pixel of the image and show the typical absorption features of the main constituents. Based on this assumption, we used different spectral analysis methods in order to extract the most important alteration minerals for such an environment. These minerals were then used for matched filter processing in areas showing high values in MIs and RBDs. Using this method, we detected and mapped argillic alteration and variations in the distribution of important minerals like alunite, kaolinite or nacrite. There were no indications for the presence of propilitization at ASTER spatial resolutions. Our method can be applied easily to any ASTER scene and provides information about the intensity of alteration and the character of alteration zones. The intensity is highest in the centre of the Carhuarazo volcanic complex and is mostly argillic with a high content of alunite, dickite and other clay minerals. 相似文献
4.
Kaveh Pazand Jamal Fereidoni Sarvestani M. Reza S. Ravasan 《Journal of the Indian Society of Remote Sensing》2013,41(2):379-389
The Ahar area is located in East Azarbaijan province, and covers an area of about 2,500 km2. Spectral mapping techniques were applied on VNIR and SWIR of ASTER data for discriminating between hydrothermal alteration zones and the identification of high potential mineralized lithological unit associated with hydrothermal porphyry copper mineralization in the Ahar. In this research to remove atmospheric and topographic effects from ASTER data, the log-residual method (LRM) was used. Four methods, Relative Band Depth Ratios (RBD), Principal Component Analysis (PCA), Minimum Noise Fraction (MNF) and matched filtering (MF), were used to processing and interpretation of remote sensing data in the study area. Results show that ASTER images provide preliminary mineralogy information and geo-referenced alteration maps at low cost and with high accuracy for reconnaissance porphyry copper mineralizations. 相似文献
5.
B. K. Bhadra Suparn Pathak G. Karunakar J. R. Sharma 《Journal of the Indian Society of Remote Sensing》2013,41(2):391-404
Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) SWIR bands are used in identification of alteration zones which have developed during hydrothermal activity. Among the available methods of hyperspectral data analysis, PCA and RBD techniques are found to be useful in delineation of clay alteration and iron oxide zones. ASTER data analysis by PCA and RBD of (B5+B7)/B6 shows delineation of two distinct alteration zones with characteristic mineral assemblages viz. propylitic zone (chlorite, epidote, montmorillonite and calcite) and phyllic zone (illite, kaolinite, white mica and quartz). Iron oxide rich zones (gossans) have been delineated using ASTER band ratio technique (B2/B1). Geochemical dispersion of soil samples shows that Pb and Zn concentration is higher in phyllic and propylitic zones around Sawar and Malpura area respectively. Thus, ASTER data shows the potential in discrimination of metasedimentary rocks and delineation of alteration zones for targeting base metals around Sawar-Malpura area in central Rajasthan. 相似文献
6.
Hyperspectral remote sensing/imaging spectroscopy has enabled precise identification and mapping of hydrothermal alteration mineral assemblages based on diagnostic absorption features of minerals. In the present study, we use Airborne Visible InfraRed Imaging Spectrometer-Next Generation (AVIRIS-NG) datasets acquired over Rishabdev ultramafic suite to derive surficial mineral map using least square based spectral shape matching in wavelength range of diagnostic absorption features of minerals. Resulting mineral map revealed presence of hydrothermally altered serpentine group of minerals and associated alteration products (talc and dolomite) along with clays and phyllosilicates. Mineral maps are validated using field spectral measurements and published geological map. Involvement of low temperature (<350 °C) hydrothermal fluid in serpentinization of ultramafic rocks in the region is inferred from analysis of deepest absorption features of muscovites at 2.20 μm, spectral abundance of lizardite and absence of prenhite-pumpyllite facies mineral assemblages. Talc was found to be the most common alteration product of serpentines followed by dolomites. Intense alteration of serpentines to talc along the fracture zone is attributed to the circulation of carbon dioxide rich hydrothermal fluids along these conduits. Kaolinite and halloysite are primarily associated with granites and are the result of hydrothermal alteration of plagioclase feldspar in granites while muscovite and illites are generally associated with phyllites and quartzites . The study demonstrates the potential of imaging spectroscopy for mapping hydrothermal alteration mineral assemblages in ultramafic complex. 相似文献
7.
AbstractGeological mapping is one of the primary tasks of remote sensing. Remote sensing applications are especially useful when extreme environmental conditions inhibit direct survey such as in Antarctica. In this investigation, a satellite-based remote sensing approach was used for mapping alteration mineral zones and lithological units using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data in the Oscar II coast area, north-eastern Graham Land, Antarctic Peninsula. Specialized band ratios and band combinations were developed using visible and near infrared, shortwave infrared (SWIR) and thermal infrared spectral bands of ASTER for detecting alteration mineral assemblages and lithological units in Antarctic environments. Constrained Energy Minimization, Orthogonal Subspace Projection and Adaptive Coherence Estimator algorithms were tested to ASTER SWIR bands for detecting sub-pixels’ abundance of spectral features related to muscovite, kaolinite, illite, montmorillonite, epidote, chlorite and biotite. Results indicate valuable applicability of ASTER data for Antarctic geological mapping. 相似文献
8.
ASTER short-wave infrared bands were used to investigate the spectral discrimination of hydrothermally altered materials, based on the presence of minerals with diagnostic spectral features in wavelengths around 2200 nm (e.g. kaolinite and K-micas). Due to the presence of widespread albitized-greisenized materials, the Serra do Mendes granitoid, located in area of tropical savannah environment in Central Brazil, was selected for this study. The Spectral Angle Mapper (SAM) technique was used as an attempt to detect the presence of hydroxyl-bearing minerals in the domain of the hydrothermally altered materials. Results indicated that areas of altered materials were discriminated from the surrounding mainly due to the high overall reflectance of the whitish lithosols in these areas. The detection of hydroxyl-bearing minerals was blurred by the presence of a sparse grass cover in the alteration zone, which caused a slight increase in the SAM classification angles. As a consequence, the remote detection of hydroxyl-bearing minerals was restricted to a small number of pixels from barren areas. Results indicate that, for the environmental conditions of the study area, ASTER data are more efficacious for spectral characterization of rock–soil-vegetation associations than for the detection of alteration-derived minerals. 相似文献
9.
基于ASTER数据的蚀变矿物信息提取——以哈密黄山铜镍矿区为例 总被引：1，自引：0，他引：1
在分析哈密黄山铜镍矿区典型地物波谱特征的基础上,设计了基于ASTER数据的蚀变信息提取流程,详细论述了对4组含不同离子或基团的常见蚀变矿物应用主成分分析(PCA)进行蚀变信息提取、采用光谱角制图法(spectral angle mapper,SAM)进行干扰异常筛选的“SAM去干扰异常主分量门限技术”.4组(9种)蚀变矿物包括:含Fe离子的矿物(针铁矿、赤铁矿)、含CO23-基团的矿物(方解石、白云石)、含Al - OH基团的矿物(白云母、蒙脱石、高岭石)以及含Mg - OH基团的矿物(绿泥石、绿帘石).蚀变矿物信息提取结果表明,“SAM去干扰异常主分量门限技术”方法可行,对ASTER数据的应用效果与实际情况比较吻合,充分证明ASTER在短波红外范围内具有很强的矿物刻画能力. 相似文献
10.
为了利用遥感影像进行更加精确的找矿预测,本文选择新疆东天山尾亚地区ASTER数据进行矿化蚀变信息提取方法研究。为了提高信息提取精度,本文提出了结合主成分分析(PCA)、多尺度分割和支持向量机(SVM)的遥感矿化蚀变信息提取方法。首先,分析ASTER数据的特征,选取各矿化蚀变信息的特征波段,对组合波段进行主成分分析,获得主分量图像;然后,对各主分量图像进行多尺度分割,并获得分割之后的均值图像;接着,提取训练样本,利用SVM对训练样本进行训练,采用试验方法求得最优核参数和松弛变量,构造最优SVM模型;最后,运用最优SVM模型完成矿化蚀变信息的提取。进行主成分分析时,铁染蚀变信息选择Band1、2、3、4组合,Al-OH基团蚀变信息选择Band 1、4、6、7组合,OH和CO32-基团蚀变信息采用Band 1、2、8、9组合。在运行SVM时采用了序列最小优化算法(SMO)进行求解,速度提高了12%。实验结果表明,与波段比值法、主成分分析法及基于光谱角和SVM的方法等3种方法相比,本文方法提取铁染蚀变信息、Al-OH基团蚀变信息及OH和CO32-基团蚀变信息的总体精度可达到87.98%、 90.01%及88.93%,Kappa系数分别为0.8011、0.8134及0.8023,与成矿区带、已知矿点和已有不同地质背景成矿特征相关性较好。 相似文献
11.
遥感光谱研究是遥感地质的基础研究工作之一,主要用于地质领域中岩石、矿物、地质构造、地质演变过程[1]的研究以及找矿勘查(确定蚀变矿化带)。结合研究课题,本文主要介绍了相山铀矿田地面光谱测量数据的处理与分析方法,从定性和定量两个方面确定蚀变矿物的特征光谱,建立相应的识别光谱模型,为利用高光谱成像技术圈定热液矿化蚀变带,分析蚀变矿物组合,圈定找矿靶区打下基础。 相似文献
12.
为了追索朝鲜北部惠山-利原成矿带是否延入玄武岩覆盖下的中国长白山地区,采用航空彩色红外像片和经过处理的TM数据,解译惠山-长白县一带的构造、岩性展布和蚀变现象。发现控制惠山-利原成矿带的构造(地层已延入我国长白县,但为玄武岩覆盖。采用TM5/TM7,TM4/TM3,TM3/TM4比值合成图像,压抑了植被干扰,突出了粘土类矿物蚀变岩信息。结合重力、航磁资料分析,推断沿江村-万宝岗及马鹿沟以北一带存在隐伏斑岩体,确定此二处为找矿靶区。通过地面地质验证及物化探普查工作,在沿江村一带,获得了良好的找矿效果,发现了大量辉绿玢岩、低温热液蚀变岩石和铜化探异常,并于马鹿沟以北,圈定出3km2金异常区。 相似文献
13.
Feizollah Masoumi Taymour Eslamkish Mehdi Honarmand Ali Akbar Abkar 《Journal of the Indian Society of Remote Sensing》2017,45(6):1039-1055
This study attempts to evaluate the capability of the advanced spaceborne thermal emission and reflection radiometer (ASTER) and the advantages of ground knowledge for generating maps portraying hydrothermally altered areas in relation to porphyry copper deposits. The northern part of the Rabor area in the Urumieh–Dokhtar magmatic belt, containing some copper mineralization occurrences, was investigated as a case study. Several image processing techniques, namely minimum noise fraction, pixel purity index, and n-dimensional visualization, contributed to the extraction of pure pixels as endmembers. The spectra of some rock samples collected around the well-known altered zones of the study area were resampled to ASTER bands and used to identify the image-extracted endmembers. Spectral analysis of the endmembers and ground sample spectra led to the identification of three types of hydrothermal alterations: (1) phyllic, (2) propylitic, and (3) argillic. The identified endmembers were used as the specified targets for mapping hydrothermal alteration zones over the study area by using a mixture tuned match filtering algorithm. Results demonstrate that high abundances within pixels correspond closely to the altered areas. Field observations, thin section, and X-ray diffraction of collected samples confirmed the accuracy of the alteration maps prepared by the application of the proposed methods. The final classified hydrothermal alteration maps showed the overall accuracy and kappa coefficient values of 85.41 and 0.72%, respectively. These results ascertain that ASTER data that use suitable image processing techniques appear consistent in mapping out the distribution of hydrothermally altered areas. In addition, ground knowledge data can act as a valuable information source to increase the image classification accuracy and reliability. 相似文献
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利用ASTER热红外遥感数据开展岩石化学成分填图的初步研究 总被引：14，自引：0，他引：14
ASTER遥感成像仪的发射提供了廉价的多光谱热红外数据,是热红外遥感数据的一个重要来源。ASU热红外光谱库提供了多种矿物的热红外发射率波谱的同时,还提供了矿物的化学成分即氧化物含量的分析结果。把ASU波谱库的矿物波谱重采样至ASTER各热红外波段,对矿物的波谱进行波段比值处理,与各矿物成分进行相关分析,选择波段比值与各氧化物含量最大相关系数,进行对数模拟,从而可以确定出发射率光谱与化学成分的数值关系。本文分别对SiO2,MgO,Al2O3,CaO,K2O,Na2O进行了数值分析及公式模拟。统计是根据各矿物做出的,模拟公式同样适用于岩石,进而可以在遥感热红外数据中得以应用。在四川省西范坪矿区利用模拟公式对SiO2,Na2O,K2O三种氧化物进行了岩石填图,在野外大部分得到了证实;利用SiO2进行了硅化蚀变带填图,在异常带内发现了砂岩型铜矿化。 相似文献
17.
Abstract In this paper we present the use of ASTER data for the creation of a Digital Terrain Model (DMT) of high accuracy. Using a stereo pair of ASTER satellite images with 15m resolution we created two DMTs: one with a 30m pixel size and another one with a 15m pixel size. Then we made a statistical verification of the two DTMs accuracy. We created another DTM with 30m pixel size from digitized contours of 1:50000 scale topographic maps. We first made an optical comparison of the two DTMs with 30m pixel size. Then we subtracted the two DTMs and we presented their difference. Finally, we verified the DTMs accuracy using 68 points of a well‐known elevation. All the results demonstrated that DTMs derived from ASTER data have very good accuracy. 相似文献
18.
This study investigates the effect of spatial subsets of Advanced Spaceborne Thermal Emission and Reflection radiometer (ASTER) L1B visible-near infrared and short wave-infrared (VNIR-SWIR) data on matched filtering results at the central part of Kerman magmatic arc, where abundant porphyry copper deposits exist. The matched filtering (MF) procedure was run separately at sites containing hydrothermal minerals such as sericite, kaolinite, chlorite, and jarosite to map the abundances of these minerals on spatial subsets containing 100, 75, 50, and 25 percent of the original scene. Results were evaluated by comparing the matched filtering scores with the mineral abundances obtained by semi-quantitative XRD analysis of corresponding field samples. It was concluded that MF method should be applied to the whole scene prior to any data subsetting. 相似文献
19.
Zahra Yazdi Alireza Jafari Rad Mehraj Aghazadeh Peyman Afzal 《Journal of the Indian Society of Remote Sensing》2018,46(10):1581-1593
The Sonajeel prospect is located in the Arasbaran belt which is one of the significant copper mineralization belts in NW Iran. There are mostly Eocene volcano-sedimentary rocks and Post Eocene intrusive units which are the source for mineralization in the area. ASTER multispectral images were used for delineation of alteration zones as a key feature of porphyry copper mineralization. Due to the need for geometric correction and ortho-rectification of the ASTER images, a high resolution QuickBird image with pixel width of about 60 cm (in PAN) was employed as a reference image in order to boost the rectification process. Ortho-rectification has been done by using digital elevation model which is created by topographic map in scale 1:1000. Potassic alteration as one of the essential alteration types in porphyry copper deposits, distributed mostly in the north of the Sonajeel prospect that determined by Thermal infrared bands processing. Phyllic and argillic alteration zones detected by creating relative absorption band-depth grids which are comparable to field observations. Moreover, silica rich areas which are remnants of hydrothermal circulation and form at the top of porphyry copper systems were detected for recognition of epithermal deposits (with 1 km distance from Sonajeel porphyry system). Finally, Remote Sensing results were compared by field evidences especially for determination of an epithermal system. Most parts of the alteration zones were observed of the surface confirmed with the remote sensing alteration (in average about 75% matched fittingly), displayed concentrations anomalous in the NE and NW parts of the studied area. 相似文献