遥感矿化蚀变分带弱信息增强提取方法研究——以普朗斑岩型铜矿区为例

为弥补以往研究中遥感矿化蚀变信息提取精细化程度不高、对西南三江斑岩型铜矿深部找矿勘查推进支撑作用有限的不足,针对西南三江成矿带中南段滇西北普朗斑岩型铜矿区矿化蚀变分带从外至内呈青磐岩化—硅化绢云母化—钾化硅化分布的特点,分析斑岩型铜矿矿化蚀变分带的特征矿物组成、诊断性波谱及其ASTER遥感波谱响应;采用多重分形"广义自相似性"和"局部奇异性"理论与能谱面积法(S-A法),探索复杂地质背景条件下斑岩型铜矿蚀变分带特征矿物,即青磐岩化(绿泥石、绿帘石)、硅化绢云母化(石英、绢云母)和钾化(钾长石)硅化(石英)等弱信息增强与提取方法;通过对遥感蚀变分带结果进行实地查证及岩矿鉴定,印证了本文构建的斑岩型铜矿蚀变分带遥感异常增强和提取方法的可靠性。     

高光谱蚀变信息在金矿找矿预测中的应用研究——以北山方山口金矿线索为例

航空高光谱数据具有丰富的光谱信息和高空间分辨率,在矿化蚀变带识别中发挥着重要作用。成矿地质条件分析表明,北山成矿带方山口—老金场地区存在与中酸性岩体有关的金矿床成矿潜力。覆盖该区的航空高光谱(CASI/SASI)遥感数据蚀变矿物异常提取结果显示,区内发育高铝绢云母、中铝绢云母、低铝绢云母、褐铁矿、白云石、绿泥石、绿帘石和方解石等蚀变矿物。对金滩子金矿床光谱信息的剖析表明,"中—高铝绢云母+褐铁矿"为其标志性蚀变矿物组合;对区内高光谱异常信息进行筛选,圈定出方山口找矿预测区;对预测区内标志性蚀变矿物组合发育地段进行野外查证,发现3条金矿化黄铁绢英岩脉。实践表明,通过针对性地筛选高光谱蚀变矿物异常组合,可以有效地指导下一步的金矿找矿工作。     

绢云母的光谱特征变异分析及成像光谱地质成因信息提取

鉴于绢云母(和白云母)类粘土矿物对于研究与矿化紧密相关的中低温热液蚀变机制、与温压有关的地质成因过程等的重要意义,开展了绢云母的岩矿光谱特征变异分析和成像光谱矿物识别,并对岩石、矿物的试验室光谱和影像光谱所反映的地质成因信息的提取进行探讨。     

基于ASTER数据的金川铜镍矿床外围遥感找矿预测

为了对甘肃省金昌市金川铜镍矿床外围地区进行遥感找矿预测,首先根据ASTER数据不同波段的特性分别提取岩性信息和蚀变信息,对热红外(TIR)波段,在采用波段比值法定量提取二氧化硅含量的基础上,利用波段比值计算的岩性指数(lithological index,LI)定量提取基性-超基性岩信息;对可见光-近红外(VNIR)及短波红外(SWIR)波段,运用主成分分析法定性提取高岭土-绢云母化、绿泥石化和蛇纹石化等矿化蚀变信息;然后在ArcGIS平台上,对所提取的矿化蚀变信息进行量化定级和叠加处理,制作综合矿化蚀变异常信息图(其反映的异常范围和强度与已知矿区十分一致);最后利用综合矿化蚀变异常信息,对金川铜镍矿床外围地区进行找矿预测,共圈定出3个找矿预测区,可为寻找同类型的矿床提供参考。     

板桥稀土矿遥感找矿信息提取与矿产预测研究

通过对离子吸附型稀土矿成矿规律的分析,从浙江省板桥地区的遥感地质特征研究入手,在研究区地表范围内进行稀土遥感找矿信息的提取。首先利用SPOT图像和DEM数据构建的坡度数据对与稀土成矿相关的地貌单元进行解译;然后通过光谱特征分析和基于ASTER图像的矿物遥感异常提取,获取与成矿相关的高岭土、绢云母、绿泥石等风化特征矿物的分布信息;最后叠合分析地貌、坡度及异常提取结果,进行稀土遥感找矿预测。与地质调查资料及化探数据的对比分析证实,上述方法对圈定1∶5万的大比例尺离子吸附型稀土矿分布范围是有效的,可为更详细的稀土矿产资源潜力评价提供依据。     

陕西柞水冷水沟地区遥感地质特征及找矿预测

陕西柞水县冷水沟地区中酸性小岩体发育,与之相关的矿产丰富。为加速冷水沟地区找矿工作的突破,应用World View-I,ASTER等多源遥感数据开展大比例尺遥感地质解译。厘定了斜长花岗岩、闪长岩、石英闪长岩和花岗岩等4类不同岩性的侵入体,线性断裂构造、断裂破碎带及构造密集带等3类遥感线性构造以及环形构造的遥感地质特征;通过对区内蚀变矿物的分类及光谱特征的分析,应用主成分分析方法直接提取了区内与矽卡岩化有关的"榴石类矿物-透闪石-透辉石-阳起石"和"绿泥石-绿帘石-阳起石-透闪石-透辉石"2类遥感蚀变矿物组合异常。遥感地质特征揭示,冷水沟岩体深部具有较大的岩浆穹窿,外围存在隐伏岩体,遥感异常信息矿致性明显。通过综合分析,在研究区内预测了阳沟凹—吊庄梁和青定坪2个遥感找矿预测区。     

新疆哈密三种典型蚀变矿物的HyMap高光谱遥感信息提取

利用机载的可见光、近红外及短波红外成像光谱(ＨyMap)数据,对新疆哈密地区岩矿信息识别方法进行研究。基于方解石、 绿泥石和绢云母3种常见蚀变矿物的光谱特征,在遥感数据定标和反射率图像转换的基础上,应用光谱角度模型（SAM）分类法进行自 动匹配识别和信息提取。通过掩膜技术进行方解石、绿泥石和绢云母矿物填图,并结合实验室光谱数据库光谱进行了验证。     

新疆白杨河铀铍矿区航空高光谱矿物填图及蚀变特征分析

以新疆白杨河铀铍矿区为研究区,通过建立航空高光谱数据CASI/SASI矿物填图处理流程,运用混合调制匹配滤波技术实现了多种蚀变矿物的填图。填图结果的野外验证表明,3种绢云母亚类的准确性高于85%,其他各类矿物的准确性高于90%。叠加研究区铀矿点资料,发现白杨河矿区赤铁矿化和高铝绢云母的空间分布特征与铀矿点分布高度相关,主要位于杨庄岩体与外围火山岩的北接触带附近,呈明显分带性。并且,高、中、低铝绢云母的空间分布指示矿床北部和南部的热液活动温度可能存在差异,区域上存在多期热液活动作用。这为矿区外围找矿预测和区域地质成因研究提供了参考和依据。     

灵泉盆地多源地学信息综合岩性识别方法探讨

以满洲里灵泉盆地为例,研究探讨了利用航空γ能谱数据、航磁资料、遥感资料(包括TM数据和MSS数据)进行岩性识别的方法,即①利用γ能谱和MSS数据,通过K-L变换提取岩性信息的方法;②利用γ能谱和TM数据,通过IHS变换提取岩性信息的方法。     

分维变点法在遥感蚀变异常提取中的应用

从遥感蚀变异常主分量图像中提取异常信息,目前主要基于数据的正态分布特征,并未考虑地质异常的非线性特征。针对此问题,提出了分维变点提取算法(fractal dimension-change point method,FDCPM)。首先利用分形模型计算蚀变异常的自相似性参数值,再采用变点模型计算蚀变异常的突变性参数值,然后确定蚀变异常临界阈值,达到有效区分地质背景和蚀变异常的目的。以甘肃北山方山口地区为研究区,对识别的ASTER蚀变异常进行测试和验证,并对其提取精度进行初步评价和比较。结果表明:对于实验中的褐铁矿、绢云母和绿泥石3种蚀变矿物来说,分维变点法的总体提取精度略高于门限化方法。利用分维变点法提取3种蚀变矿物的正确率均超过83%,且遥感蚀变异常的分布与化探及重砂异常有较高的吻合度,已知金属矿(化)点也几乎都落在遥感蚀变异常区内或其边缘,表明分维变点法行之有效,可作为今后划分地质背景和蚀变异常的方法之一。     

Delineation of geology of a part of bundelkhand complex around girar, distt. lalitpur, u.p., using remote sensing data

An attempt is made to mark regional geology of part of Lalitpur district. The area is characterized by flat topography gently sloping east ward with isolated hillocks. The well contrasted lithology has been marked on the basis of variation in tone, drainage pattern and texture. The main lithounits are foliated granites/gneiss, banded iron formation, granites, ultra basic, quartz reef and basic dykes. The structural elements of lineaments are visible on aerial photos and imagery which range in length from 1 to 10 km. The lineaments at places intersect with each other. The major trends are NNW- SSE. NE- SW. NNH- SSW. These NNW- SSE and NE-SW lineaments are retlected by well aligned body of quartz- sericite schist and quartz reef respectively.     

Mapping alteration mineral zones and lithological units in Antarctic regions using spectral bands of ASTER remote sensing data

Abstract

Geological 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.     

基于ASTER影像的蚀变异常提取方法研究——以赞比亚谦比希铜矿床地区为例

基于赞比亚谦比希(Chambishi)铜矿带中的多种蚀变矿物及其在ASTER影像VNIR - SWIR谱带的特征光谱分析,采用相对波段吸收深度(Relative absorption- Band Depth,RBD)和波段比值的方法对蚀变信息进行增强处理.用波段比值ASTER 2/ASTER 1和ASTER 3的RBD...     

西藏多不杂斑岩铜矿ASTER遥感蚀变异常特征

采用ASTER数据,利用"掩模+定向主成分分析"方法提取了多不杂斑岩铜矿的遥感蚀变异常。对蚀变异常的特征、蚀变异常与地面蚀变对应关系、蚀变异常与已知矿体的关系等几个方面进行了初步探讨,认为利用ASTER数据提取的蚀变异常效果较好,为西藏自治区矿产资源潜力评价多龙铜矿预测工作区的最小预测区圈定提供了遥感依据。     

Hydromorphogeology and Remote Sensing applications for groundwater exploration in agnigundala mineralised belt, Andhra Pradesh, India

Hydromorphogeological studies have been carried out around Agnigundala mineralised belt (longitude 70°.39′ - 16°.51′ and latitude 16°.2′ - 16°.15′) using remote sensing IRS-IB and SPOT data for ground water exploration. Based on erosional and depositional characters of various geomorphic units like Hills (Structural and denudational) Pediment, Buried pediment, plains and valley fills have been identified in various lithologies like granite, granite gneiss, biotite schist, phyllite,. quartzite and dolomite. The acclamations of individual geomorphic units through visual interpretation are verified from field data. The groundwater potentials of the individual geomorphologic units have been evaluated to obtain a complete hvdrogcological picture of the area. The field data have further helped in quanlifying various geomorphological units with reference to their potential for ground water occurrence.     

应用ASTER数据提取矽卡岩型锡矿蚀变遥感异常信息——以滇东南马关都龙锡矿为例

运用多光谱遥感数据进行矿化蚀变信息提取,对圈定找矿预测区具有重要意义.采用ASTER数据及其矿化蚀变信息提取原理,对滇东南马关都龙锡矿含矿岩体分布区分别提取了方解石化、白云岩化、绿泥石化等3类蚀变遥感异常信息.所提取的蚀变异常与野外调查发现的矿化点吻合性好,蚀变信息可靠,对指导找矿有较好的效果,为该地区矿产资源潜力评价...     

ASTER Data Analysis for Mineral Potential Mapping Around Sawar-Malpura Area, Central Rajasthan

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.     

Evaluating the effect of spatial subsetting on subpixel unmixing methodology applied to ASTER over a hydrothermally altered terrain

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.     

ASTER数据在北方铝土矿预普查中的应用——以豫西渑池地区为例

ASTER数据的光谱和空间分辨率均具有一定优势,适合于中等比例尺的矿产预普查。为了探讨ASTER数据应用于铝土矿预普查的效果,通过对ASTER图像彩色合成、地质解译及异常信息提取,对豫西渑池地区的铝土矿进行了预普查试验。结果表明,在北方基岩裸露地区,应用ASTER数据圈定"赋矿影像单元"和提取铝土矿遥感找矿信息能获得较好的效果。