基于ASTER数据的蛇绿岩组分识别：以德尔尼矿区为例

本文运用高级星载热辐射和反射探测器(ASTER)反射率数据对青海德尔尼蛇绿岩的主要岩石组成和蚀变矿物进行探测。以现有的标准光谱库数据作为参照,采用光谱角制图法来提取感兴趣的岩性和矿物信息,并通过与现有地质图对比,验证结果的精度。实验结果表明,运用ASTER数据和标准的光谱库数据,可较有效地识别蛇绿岩的主要岩性和相关矿物成分,但不同岩性的识别精度不同。     

Validated surface mineralogy from high-spectral resolution remote sensing: a review and a novel approach applied to gold exploration using AVIRIS data

Remote sensing's main limitation to date was that geological surface information lacked detail due to the broad bandwidth of the operational scanners. Imaging spectrometers now allow acquisition of image data in many contiguous spectral bands, with the aim of producing laboratory-like reflectance spectra for each pixel in the scene which can be directly compared with spectra of known materials measured in the field or laboratory to allow mineral identification on the Earth surface. The advent of satellite-based imaging spectrometer systems justifies the surge for techniques that allow the automatic preparation of validated surface mineralogy maps. We show an extension of a procedure known as cross-correlogram spectral matching to retrieve accuracy assessed surface mineralogy from Airborne Visible/InfraRed Imaging Spectrometer data (AVIRIS). The procedure is based on the spectral cross-correlation of known mineral spectra with unknown pixel spectra from AVIRIS. The validation is performed through a root-mean square calculation of expected correlograms and pixel correlograms. Results obtained in the study outlined allow an accurate delineation of zones of hydrothermal alteration in an area of active gold exploration.     

Thermal transformations of akaganéite and lepidocrocite to hematite: assessment of possible precursors to Martian crystalline hematite

We examine the possibility that crystalline hematite (α-Fe₂O₃) deposits on Mars were derived from the precursor iron oxyhydroxide minerals akaganéite (β-FeOOH) or lepidocrocite (γ-FeOOH) and compare them to an earlier study of goethite (α-FeOOH) and magnetite (Fe₃O₄) precursors. Both the mid-infrared and visible/near infrared spectra of hematite are dependent upon the hematite precursor mineral and the temperature of transformation. Laboratory spectra are compared to spectra from the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES) and the Mars Exploration Rover (MER) Opportunity Mini-TES and Pancam experiments, allowing us to infer the formation environment of Martian crystalline hematite deposits. Akaganéite and lepidocrocite readily transform to hematite at temperatures of 300 and 500°C, respectively. The visible/near-infrared and mid-infrared spectra of akaganéite-derived hematite are poor matches to data returned from TES, Mini-TES, and Pancam. The spectra of lepidocrocite-derived hematite are slightly better fits, but previously published spectra of goethite-derived hematite still represent the best match to MGS and MER spectral data. The experiments demonstrate that hematite precursor mineralogy, temperature of formation, and crystal shape exert a strong control on the hematite spectra.     

应用多光谱ASTER数据对ETM遥感异常的定性判别研究——以东昆仑五龙沟为例

文中讨论了新的找矿参数——蚀变遥感异常的地质基础和光谱前提,在矿床地质学和蚀变矿物光谱参数特征的基础上,编制了一张用于遥感异常提取及对其地质解释的表格。ETM遥感异常提取技术已在全国推广,ASTER数据可以在三个方面对已推广的ETM起到重要的补充作用：1.利用短波红外增设的波段,对某些矿致异常区分其矿化（矿床）类型;2.利用增设的热红外波段区分某些岩性;3.可有助于解决ETM因第7波段太宽而产生的许多疑难问题。本文以东昆仑五龙沟为例讨论了ASTER对于解决ETM遥感异常性质判别困难方面的作用。     

Geological mapping of the Francistown area in northeastern Botswana by surface temperature and spectral emissivity information derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) thermal infrared data

We identified geological units in the Francistown area in northeastern Botswana by using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) thermal infrared (TIR) data, which contains both surface temperature and spectral emissivity information. A scatter plot of ASTER L1B daytime TIR digital values and L2 daytime temperature indicates that in the ASTER L1B daytime TIR data, bands 10, 11, and 12 contain spectral emissivity and temperature information, whereas surface temperature dominates the spectral emissivity information in bands 13 and 14. Visual interpretation of the ASTER TIR false color composite (FCC) images generated by assigning red, green, and blue to band 14:band 12:band 10 using L1B daytime data allowed us to identify mafic-to-ultramafic units and quartz-rich felsic units. Mafic-to-ultramafic units such as gabbro, dolerite, and dunite appear white in ASTER L1B daytime TIR FCC images due to their high spectral emissivities in the 8–9 μm region (bands 10 and 12) and high surface temperatures. Mafic-to-ultramafic units have higher surface temperatures than other geological units because they absorb more solar radiation due to their lower albedos and they have a lower thermal inertia. Quartz-rich felsic units such as granite and dry river sand appear reddish in the ASTER L1B daytime TIR FCC image because the spectral emissivity of quartz is lower in the 8–9 μm region (bands 10 and 12) than in the 10–12 μm region (band 14). Mafic-to-ultramafic and granitic units are important targets for mineral exploration because they are potential geological units to host or accompany mineralization. The proposed ASTER L1B daytime TIR FCC images can be prepared very simply and they provide valuable information for geological mapping and mineral exploration.     

Copper Ore Identification using Spectral Similarity Measurement from Hyperion Image,Mapping of Porphyry Copper Mineralized Zone

This work illustrates the effectiveness of hyperspectal image spectroscopy and lab spectroscopy in identification techniques of minerals in alteration zone of ore body. The adopted procedure involves testing of Hyperion image spectra, their processing for noise, spectral matching and spectral similarity measurement with selected library spectra. Average weighted spectral similarity; visual and statistical matching techniques were used to select end-members from image spectra. Minimum noise fraction and pixel purity index technique were used to retrieve end-member spectra from hyperion image. Hyperspectral image like hyperion has the capability to deliver laboratory standard spectroscopic result. This paper illustrates the capability of hyperion image spectra in copper ore identification and mapping of chalcopyrite outcrop. A systematic approach has been made in this paper. This approach describes how image end member spectra and laboratory spectra can be co-related to fetch accurate spectral form of chalcopyrite ores. Thus, statistical and graphical comparison has been carried out between image derived end member spectra and laboratory spectra of chalcopyrite for better accuracy. The visual measurements is satisfactory, R = 0.973 for fine and 0.976 for medium grained chalcopyrite ore. Excellent statistical significance levels (90–97%) are found while comparing these spectra. There are many success stories of sub-pixel and N-dimensional feature space methods to separate the hydrothermal alteration zones from iron oxide mixed ore bodies. Thus, unmixing methods are very useful for mapping of most dominating mineral parts of a pixel from hyperspectral images which have coarse spatial resolution. Finally, mapping of mineralized zone has been achieved through sub-pixel based classifiers like spectral angle mapper (SAM), constrained energy minimization (CEM) and adaptive coherence estimator (ACE) techniques.     

多光谱遥感技术预测矿产资源的潜能——以蒙古国欧玉陶勒盖铜金矿床为例

建议把蚀变遥感异常作为一个新的找矿参数,文中讨论了蚀变遥感异常的地质基础和光谱前提。在矿床地质学和蚀变矿物光谱参数特征的基础上,编制了一张用于蚀变遥感异常提取及对其地质解释的表格。设计了从ETM+和ASTER数据中提取羟基蚀变矿物组合信息的独特流程方案。这个方案称之为"去干扰异常主分量门限化技术",文中示以简化的流程图。ETM+数据用来研究位于欧玉陶勒盖铜金矿床东北部的汉保各德中酸性火成杂岩体岩性特征,ASTER近红外和短波红外数据用来提取欧玉陶勒盖斑岩铜金矿矿床及其近区的羟基异常,通过选择性主分量分析判断欧玉陶勒盖铜金矿矿床的矿床类型为斑岩型。已知矿区各矿体的羟基异常都十分清晰,此外在矿床西部还发现了三个新的有希望的羟基异常。此工作进一步展示出多光谱遥感技术对于金属矿床的预测具有极好的潜能。     

ASTER Spectral Analysis for Host Rock Associated with Porphyry Copper-molybdenum Mineralization

This study is an attempt to understand the application of spectral image processing methods to ASTER data for mapping host rock associated with porphyry copper-molybdenum mineralization. The application of remote sensing in identifying variations in surface mineralogy, structural elements, and lithologic contacts can help in identifying such relations. Signatures collected from the Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) data is used to map the host rock of Zafarqand area. The study area is located in the central segment of the Urumieh–Dokhtar volcanic belt of Iran. The Urumieh-Dokhtar is a potential zone for exploration of new porphyry copper deposits. Band ratio, band math, false colour composites and principal component analysis techniques are used to refine the different lithologic units in the area. These methods showed the discrimination of acidic igneous rock from intermediate igneous rock and the boundary between igneous rocks using the shortwave infrared bands (SWIR) of ASTER at regional scale. Results have proven to be effective and in accordance with the results of field observations, ore microscopy examination and with reference geological map. In conclusion, the image processing methods used can provide cost-effective information to discover possible locations of porphyry copper and epithermal gold mineralization prior to detailed and costly ground investigations. The extraction of spectral information from ASTER data can produce comprehensive and accurate information for copper and gold resource investigations around the world, including those yet to be discovered.     

Paths of development in mineralogy

The authors suggest that mineralogy has become a stepdaughter in the family of Earth disciplines and that the methods on which mineralogy is based - the crystallochemical and the genetic - be examined. The basis for modern mineralogy and its future development should be the historic-genetic method from which it would be possible to attack problems in the history of mineral bodies and their evolution on a planetary scale, and the causes of high mineral concentrations in segments, provinces, and belts within the Earth's crust. — IGR Staff.     

基于ASTER的雅鲁藏布江缝合带泽当-罗布莎蛇绿岩套分析和组分识别

本文通过对西藏雅鲁藏布江缝合带泽当-罗布莎地区蛇绿岩套的主要岩石组成和蚀变矿物的标准波谱吸收特征分析,比较了标准光谱库的相应岩性光谱吸收特征和ASTER数据波段特征之间的关系,采用连续统去除、比值法和光谱角制图法对ASTER影像数据进行处理及相关岩性和矿物提取。结果表明,蛇绿岩组分岩性中亚铁离子和Fe-OH,Mg-OH的可见-短波红外吸收特征显著,而且有一个宽波长范围的Si-O热红外光谱特征,基于这些光谱特征采用ASTER数据和比值法与光谱角制图法可有效地识别蛇绿岩的主要岩性和相关矿物成分及其空间分布,结果与地质资料基本吻合。     

Application of Spectral Angle Mapper Classification to Discriminate Hydrothermal Alteration in Southwest Birjand,Iran, Using Advanced Spaceborne Thermal Emission and Reflection Radiometer Image Processing

The purpose of this study is to evaluate the Spectral Angle Mapper (SAM) classification method for determining the optimum threshold (maximum spectral angle) to unveil the hydrothermal mineral assemblages related to mineral deposits. The study area indicates good potential for Cu-Au porphyry, epithermal gold deposits and hydrothermal alteration well developed in arid and semiarid climates, which makes this region significant for Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image processing analysis. Given that achieving an acceptable mineral mapping requires knowing the alteration patterns, petrochemistry and petrogenesis of the igneous rocks while considering the effect of weathering, overprinting of supergene alteration, overprinting of hypogene alteration and host rock spectral mixing, SAM classification was implemented for argillic, sericitic, propylitic, alunitization, silicification and iron oxide zones of six previously known mineral deposits: Maherabad, a Cu-Au porphyry system; Sheikhabad, an upper part of Cu-Au porphyry system; Khoonik, an Intrusion related Au system; Barmazid, a low sulfidation epithermal system; Khopik, a Cu-Au porphyry system; and Hanish, an epithermal Au system. Thus, the investigation showed that although the whole alteration zones are affected by mixing, it is also possible to produce a favorable hydrothermal mineral map by such complementary data as petrology, petrochemistry and alteration patterns.     

ETM+和ASTER数据在遥感矿化蚀变信息提取应用中的比较——以安徽铜陵凤凰山矿田为例

在利用遥感技术找矿中,矿化蚀变信息识别与提取起着重要作用。选择具有典型蚀变特征的安徽铜陵凤凰山矿田作为研究区,从分析地物波谱,尤其是岩矿光谱特征出发,根据ETM+和ASTER数据的光谱特征,采用主成分分析（PCA）,设计了相应的粘土矿化蚀变信息提取方案,成功地进行信息提取。对两者的提取结果进行比较后表明,ASTER数据较之ETM数据在粘土类矿化蚀变信息提取中具有更大的优势。     

顾及太空风化效应的虹湾地区矿物含量反演

月表矿物含量反演是研究月球地质起源和演化的关键.太空风化作用普遍发生在月球表面,对矿物纯净光谱造成了不可忽视的影响,它弱化光谱吸收特征, 降低反射率,影响矿物含量遥感反演精度.基于Relab光谱库和Hapke辐射传输模型,将月表 4种矿物(单斜辉石、斜方辉石、斜长石、橄榄石)的二向性反射率转换成同向性的单次散射反照率,然后计算矿物的光学常数;再根据亚微观金属铁SMFe(submicroscopic metallic iron)的质量分数模拟6种不同程度太空风化效应,得到端元矿物的反射率光谱;最后基于上述方法,利用多端元线性分解方法和M3(moon mineralogy mapper,月球矿物绘图仪)高光谱数据反演不同风化程度下的矿物含量,得到月表虹湾地区辉石、斜长石、橄榄石3种矿物的含量分布.实验表明,利用多端元线性分解可以有效模拟太空风化效应对矿物光谱的影响,是研究太空风化效应影响下矿物识别及含量反演的一种行之有效的方法.      

Mapping hydrocarbon‐induced mineralogical alteration in the northern Tian Shan using ASTER multispectral data

Seepage from hydrocarbon reservoirs can cause a number of chemical and/or mineralogical changes in overlying rocks and soils. These surface changes can be detected by remote sensing imaging systems. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is an advanced multispectral imaging system in the visible and near infrared (VNIR) to shortwave infrared (SWIR) region. Band ratios of ASTER VNIR and SWIR data to detect red bed bleaching and secondary carbonate formation induced by hydrocarbon seepage are proposed through analysis of the spectral properties of rock samples. Results show that ASTER band ratios of 2/1 and 4/8 can discriminate bleached red beds and secondary carbonate minerals due to hydrocarbon seepage in the northern Tian Shan. They are in good agreement with mineral identification using X‐ray diffraction. The ratio technique derived from ASTER data may provide a potential approach for hydrocarbon exploration in areas with sparse vegetation cover.     

矿物学研究的新进展

概括述评了近年来矿物学的重要进展和发展趋势,重点对矿物显微构造分析、矿物环境研究、天体矿物研究、粘土矿物研究和矿物应用研究作了详细介绍。也对新矿物、矿物相变热力学、矿物结晶学、矿物计算物理学、矿物测试新技术和矿物化学同位素分带研究等做了简要介绍,最后指出矿物学研究的5个趋势。     

Application of Principal Component Analysis and Spectral Angle Mapper in the Mapping of Hydrothermal Alteration in the Jebal–Barez Area,Southeastern Iran

The southeastern part of the central Iranian Cenozoic magmatic belt contains many areas with copper mineralization. In an analysis of this region, we used the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Enhanced Thematic Mapper plus (ETM⁺) images to map the distribution of hydrothermally altered rocks, based on their mineral assemblages. The spectral measurements, based on the field samples and satellite‐image‐derived spectra, show dominantly Al–OH (sericite and clays) and Fe–O absorption features in the visible–near infrared to shortwave infrared regions of the spectrum. Silica–bearing rocks, as well as silicic alteration, show an intense Si–O vibrational feature in the thermal infrared wavelength region. We analyzed ASTER/ETM⁺ images, performed a directed principal component analysis, and used spectral angle mapper to map areas of hydrothermal alteration and iron oxide/hydroxide minerals. The individual principal component images compiled by directed principal component analysis reveal the distribution of individual alteration minerals such as sericite, kaolinite, chlorite, epidote, and quartz. The best results, in terms of mapping the distribution of alteration, were obtained using the spectral angle mapper method. The altered areas were then sampled and the samples subjected to X–ray diffraction analysis, spectral analysis, and thin sections were observed under a microscope. Field observations reveal that more than 98% of the known copper mineralization occurs within the interpreted alteration areas. The present results indicate the great potential of ASTER and ETM⁺ data for mapping the distribution of alteration and exploring for copper mineralization in areas with a similar climate and geological setting to those of the present study.     

矿物科学的概念

本文阐述了矿物科学的概念,包括矿物科学的产生背景、基本涵义与特点、主要研究内容及其与其它学科之间的关系等,并对中国的矿物科学做了简要介绍。矿物科学是研究矿物及其性质的一门交叉学科。它的研究对象是天然矿物和人工晶体材料。它不仅是为地球科学服务的学科,而且是为材料科学、环境科学以及工程科学与技术等学科服务的学科。矿物科学的主要研究内容包括矿物及其性质两大方面。矿物研究既是传统矿物学的研究领域,也是矿物科学基础的重要组成部分。矿物性质及其变换过程研究则是当前矿物科学中最为活跃的研究领域之一。矿物科学是以矿物学等分支学科为基础并具有众多交叉分支学科的学科体系,具有比传统矿物学更加广阔的科学范畴,具有一级学科的概念。矿物学既是地质科学的一门分科,同时也是矿物科学的一门分科。中国已在矿物科学的许多学科领域取得了丰硕的研究成果,已形成较为完整的理论与学科体系。     

Reconnaissance assessment of the Stenian-Tonian granitoids of southern Tanzania for metal resources by using geological remote sensing and geochemical techniques

This study presents the use of geological remote sensing and geochemistry to determine spatial extents, geochemical characteristics and petrogenetic origin of Ndanda-Masasi metagranitoids in order to explore for important metals (Sn, W, Ta and Nb) in the metagranitoids. Geological remote sensing was done using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data, and major and trace elements were analysed using a combination of Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and Inductively Coupled Plasma Emission Spectrometer (ICP-ES). It has been revealed that the metagranitoids and other rocks in the Ndanda-Masasi area crop out in a larger spatial coverage than how it is depicted in available geological maps. Moreover, the meta-granitoids have variable SiO₂ contents, low Mg, Ni and Cr concentrations and moderate to large Fe-numbers. They classify mainly as magnesian- and ferroan-type granites and minor granodiorite and quartz monzonite. The chondrite normalized Rare Earth Elements (REE) patterns of the rocks show slight to strong enrichment of light REE over middle REE and heavy REE ((La/Yb)_N = 4.2–289.1), due to their variable contents of MREE and HREE. The rocks show flat patterns of middle REE and heavy REE and have negative Eu-anomalies (mean Eu/Eu* = 0.7), with the exception few rocks in some localities yielding positive Eu-anomalies. They are characterised by variable Sr/Y (4.7–356.7), Nb/Ta (2.6–44.5) and well correlated trends with negative slopes of SiO₂ vs MgO, TiO₂, CaO, and Al₂O₃ diagrams. These geochemical features reflects a most likely magmatic formation of the rocks in the presence of plagioclase, hornblende, garnet and rutile, or/and fractionation of the phases at variable crustal depths. Numerous myrmekites forming convex grain boundaries around K-feldspar in the rocks indicate Ca- and Na-metasomatism as an important process affecting the rocks in their evolution. The omnipresent retrograde assemblage of titanite, chlorite, epidote and muscovite forming at the expense of plagioclase, hornblende, biotite and opaque (Fe-Ti-oxides?) reflects their formation during uplifting history of the rocks. Contrary to granitoids of similar age such as those of the Karagwe-Ankolean Belt, which are metalliferous, our reconnaissance survey found that the Ndanda-Masasi meta-granitoids have uneconomic concentration of most important metals.     

多源遥感数据图谱协同岩石单元分类方法

岩石单元的结构、构造、差异风化和出露状况在遥感图像上综合表现为图形纹理特征即“图”标志，其矿物成分和组合则表现为光谱特征即“谱”标志.传统遥感岩石单元分类以利用其光谱特征为主，图形纹理特征为辅，因此分类精度有限.以新疆维吾尔自治区与甘肃省交界的北山西段为研究区，开展岩石单元图形指数和光谱指数协同分类方法研究.基于Worldview-2全色图像构建的图形指数，能够量化岩石单元的层理、构造、展布形态和微地貌等特征，包括0°和45°定向滤波图像及灰度共生矩阵计算出的同质性和异质性特征图像、熵特征图像；光谱指数基于Worldview-2多光谱图像和ASTER（Advanced Spaceborne Thermal Emission and Reflection Radiometer）短波红外波段图像利用比值、和-差方法构建.多源遥感图像构建的光谱指数其光谱波段涵盖可见光-近红外及短波红外，包括RI（Ratio index）_ASTER、SI（Spectral index）_ASTER、SI_Worldview-2.采用面向对象方法对建立的图谱指数进行多尺度分割，依据不同岩石单元出露规模建立适宜的分割尺度，利用光谱指数自动提取相应岩石信息，实现岩石单元自动分类.结果表明，实验区基于图谱协同方法共划分出17类岩石单元，总体精度达到83.62%，而单独利用Worldview-2和ASTER图像，仅划分出13类和14类岩石单元.提出的图谱协同岩石分类方法可为我国西部高海拔深切割无人区地质调查及找矿工作提供新思路和遥感技术支撑.