Hyperspectral mineral mapping technology and application research

introduction

The development of Earth observation technology has enabled humans to truly analyze the Earth as a unified system and reveal the interconnections and interactions of various layers of the Earth at different levels. At present, remote sensing technology has become an indispensable means of geological work.

The rise of imaging spectroscopy theory and technology has brought geostationary technology to a new stage. If the significant improvement of spectral resolution enhances the ability of remote sensing to distinguish and identify the ground objects, then the direct spectral characteristics of the features, composition and even the features of the ground objects based on the continuous spectral features obtained by hyperspectral will make the remote sensing technology happen. A qualitative leap: from identification (classification) to direct identification of features, from the detection of macroscopic features to the detection of components and chemical composition. The remote sensing method has also changed from image analysis to a combination of spectrum analysis based on spectrum analysis; remote sensing applications have gradually got rid of the stage of “seeing literacy” and increasingly rely on the understanding and quantitative analysis of spectral features of ground objects. .

Mineral mapping can be said to be the most successful and best-performing application of hyperspectral technology. It enables the development of remote sensing geology from the identification of lithology to the identification of single minerals to the chemical composition and crystal structure of minerals. In the visible short-wave infrared spectrum, the identified minerals are mainly oxides and hydroxides of transition elements such as Fe and Mn, hydroxyl-containing minerals, carbonate minerals and partially hydrated sulfate minerals, up to nearly 40 species, and Most of them belong to altered minerals closely related to mineralization, which are used to delineate mineralized alteration zones, analyze altered mineral combinations and altered phases, quantitatively or semi-quantitatively estimate relative alteration strength and altered mineral content, and The soot mineralization hydrothermal alteration center and the delineation of the prospecting target area all play an important role; the use of the mid-thermal infrared spectrum can identify most mineral types including rock-forming minerals and ore minerals. Hyperspectral remote sensing can also detect the composition and structural characteristics of some altered minerals and some rock-forming minerals, to analyze the temperature and pressure conditions of the ore-forming diagenesis, the thermodynamic process and the space-time evolution of hydrothermal migration, and restore the diagenetic ore-forming history. Establish mineralization models and prospecting models for different deposits. Hyperspectral mineral identification technology has also played an important role in soil soil surveys, soil degradation (desertification and salinization) monitoring, mine environmental monitoring, lunar and planetary exploration. Hyperspectral mineral mapping technology will be one of the important high-tech technologies supporting China's strategic mineral exploration, environmental monitoring and prevention and lunar exploration programs.

Supported by the Science and Technology Department of the Ministry of Land and Resources, the China Geological Survey, and the “863 Program” information acquisition and processing topics, the China Land and Resources Aviation Geophysical and Remote Sensing Center has systematically carried out high-spectral mineral mapping and application research since the “Ninth Five-Year Plan”. In the main rock, ore reflectance spectral characteristics and influencing factors, hyperspectral data processing, mineral mapping and its geological applications have been systematically studied, so that China's high-spectral mineral mapping technology quickly catch up or close to the world's advanced level .

I. Analysis of influencing factors of spectral characteristics of rocks and mines

The spectral characteristics and variation laws of rock and ore and their influencing factors are the basis and basis for mineral identification. Although there are some databases of rock and ore spectrum that can be publicly available in foreign countries, the composition, structure and spectral characteristics of the same kind of rocks and minerals will be different, and their spectra will have geographical characteristics. However, it is these changes that allow us to study the composition and structural changes of minerals using hyperspectral remote sensing, analyze the spatio-temporal evolution characteristics of thermodynamic processes and hydrothermal migration, and predict the ore-forming sequence.

(I) Analysis of factors and stability of rock and mineral spectrum

The characteristics and laws of rock spectral variation caused by factors such as observation angle, particle size, weathering degree and chemical composition were studied comprehensively. Some commonly used spectral parameters (strength, overall shape, absorption characteristics, etc.) were analyzed and evaluated. The influence of mass sensitivity and stability on mineral identification under different conditions is proposed. The technical idea of ​​high-spectrum rock and ore identification should be as follows to extract the characteristics of the absorption spectrum band and other stable global spectral features. It is believed that among the parameters describing many bands, the most stable ones are the position (wavelength) of the band and the primary and secondary sequence relationships. In the absorption band of altered minerals, in addition to the water near the 1400 nm and 1900 nm wavelengths and the 0H-group absorption band, there is generally a stronger band called the main band or diagnostic band. The band combination feature refers to the symbiotic relationship formed by the combination of the main band, the minor band and the associated band in the mineral spectrum in the studied spectral interval and the primary and secondary sequence relationship determined according to the absorption intensity. The main band and band combination characteristics are important indicators for identifying and distinguishing specific mineral types. The reflection intensity and overall shape of the spectrum are most affected by environmental factors, mixed spectra and data quality, and generally only play a supporting role in mineral identification.

(II) Study on the characteristics of mineral mixed spectrum

Rocks are generally composed of a variety of minerals, and the rock spectrum is a comprehensive reflection of the compositional mineral spectrum. Studying mineral mixed spectral characteristics has important guiding significance for mineral identification and quantitative inversion.

Based on laboratory simulation, mineral mixed spectral features and model studies were carried out. OH-containing minerals and rock-forming minerals, OH-containing minerals and OH-containing minerals, OH-containing minerals and carbonate minerals, carbonate minerals and different weight ratios are used in different weight ratios. carbonate minerals, minerals and iron quality three mineral composition of the five types of mixed mineral or OH- containing carbonate minerals, variation of synthetic spectra.

The experimental results show that the spectral characteristics of the rock are not a simple superposition of the mineral spectra of the components. The spectral characteristics of the minerals of each component tend to strengthen and cover each other. Sometimes a mineral spectrum may even change the spectral characteristics of another mineral in the rock. The performance in the spectrum; the mixed spectral effect of minerals not only affects the intensity of spectral features, but also causes spectral position shifts and morphological changes, especially in the case where the spectral absorption features are similar. The spectral recognition of minerals must take full account of the effects of the mixed spectrum. On the other hand, natural minerals have their symbiotic combination rules. In practical applications, it is sometimes more practical to identify symbiotic combinations of specific minerals.

It can be seen that in the visible near-infrared range, the mixed spectrum of mineral reflectance exhibits obvious nonlinear characteristics; in the short-wave infrared range, the mixed spectrum of mineral reflectivity approximates linear characteristics. The mixture of mineral single albedo spectra is linearly mixed. The Hapke model is used to convert the emissivity into a single scattering albedo, which linearizes the mixed spectrum of minerals, which can effectively improve the accuracy of spectral linear demixing and mineral abundance inversion. The results of linear dissolving experiments of mixed ratios of kaolinite and montmorillonite show that the mineral abundance inversion error is reduced from 18.01% of reflectivity to 5.2% of single scattering albedo.

(III) Spectral characteristics analysis of symbiotic combination of alteration type and altered mineral

Alteration type, alteration mineral combination and alteration zoning are important indicators of geological prospecting, and are products of water-rock interaction, thermodynamic action and thermal metamorphism in the process of metallogenic diagenesis. Studying the type of alteration, the spectral characteristics of the altered mineral combination and the direct identification method have important guiding and decision-making significance for remote sensing geological prospecting.

The variation of the mixed spectrum using a spectral library mineral typical spectrum, semi-quantitative method of digital simulation and laboratory simulation of the combination, respectively, from a mineral ion or ionic group (metal cations, different types of water, OH a The group, the type of mineralized alteration, the symbiotic combination of altered zone and altered mineral, and the similarity of minerals are analyzed and summarized. The characteristics of the main minerals are analyzed and summarized: Fe 2+ and Fe 3 are analyzed. Spectral behavior of metal cations such as + and Al 3+ and metal-OH groups; summarizing the spectral characteristics of major alteration types of low, medium and high temperature, spectral behavior of mainly altered minerals, mineral alteration and isomorphism Spectral variation characteristics caused by the combination of mineral symbiosis and the combined effects of the altered mineral absorption bands of the main alteration types and their effects on mineral identification; proposed for identification of slate lithology and secondary quartz Dominant spectral characteristics and spectral composition of the rock, hydrothermal alteration force other types of clay minerals in different combinations alteration. According to the symbiotic combination of alteration bands and minerals of different mineralization alteration types, the Hapke radiation transfer model is used to quantitatively simulate the mixed spectra of different alteration types and different mineral symbiosis combinations, study the characteristics of mixed spectra, and establish corresponding search. Table, which lays the foundation for the direct identification of hyperspectral alteration bands. Currently, this work is still in progress.

Second, mineral identification method and recognition model

Hyperspectral mineral identification and mineral mapping can be divided into three levels, namely mineral species identification, abundance inversion and component identification. Species identification is to identify the mineral composition in the rock; abundance inversion is to reflect the relative content or percentage of the target mineral in the rock; component identification generally identifies the relative content of metal ions in the mineral or the content ratio of different metal ions.

(I) Identification of mineral species - mineral stratification identification pedigree

The basic principle of hyperspectral mineral identification is the quantitative analysis of the reconstructed spectra of hyperspectral remote sensing data with mineral standard spectra or measured spectra. From the perspective of rock and mineral information extraction, the spectral recognition methods developed at home and abroad can be summarized into two types: spectral matching methods based on reconstructed spectra and standard spectral similarity measures, and mineralogy and mineral spectroscopy knowledge. Based on intelligent identification methods.

Spectral matching is a method of identifying a mineral by comparing the reconstructed spectrum with a reference spectrum and measuring the similarity or correlation between them using a measure function. The similarity measure function may be a distance function (Euclidean distance, Mahalanobis distance, etc.), a similarity index, a correlation coefficient, a spectral vector angle, and a spectral information divergence.

The intelligent identification method is based on the knowledge of mineralogy and mineral spectroscopy, and selects appropriate spectral features or spectral parameters with discriminative ability, and combines expert system methods to establish identification rules to identify minerals. Representatively, the Tricorder system developed by the United States Geodetic Regulation Bureau is based on the fitting degree of the characteristic band, the size and gradient of the continuum at the diagnostic band, and the auxiliary spectral features as the discriminant indicators for comprehensive discrimination. In the decision-making, the normalization of feature intensity, the different weights of different identification capabilities, the influence of water-gas band on mineral absorption characteristics, etc. are also considered. The types and correctness of identified minerals are relatively high, and the identifiable minerals are up to 40 or so. However, due to the small difference in the spectral characteristics of some minerals, especially the hydrothermal alteration minerals related to mineralization, the Tricorder system is still confused with some minerals with similar spectral characteristics. And misjudgment.

Aiming at the many uncertainties in pixel mixed spectrum and spectral unmixing and the difficulty in selecting endmembers, the Spearman correlation coefficient and Kendall consistency are obtained from the similar é™› probability theory of mixed spectra and endmember spectra. The coefficient was introduced into the recognition of hyperspectral minerals, and the mineral identification method with great correlation of spectral mixing was developed to identify the dominant minerals in the mixed spectrum, and a good recognition effect was obtained, and the invention patent was obtained based on the spectral mixture composition. Hyperspectral minerals are highly correlated with identification methods."

At present, based on spectral matching, the mineral identification process including sub-pixel matching treats each mineral as an individual that is isolated from each other. The use of spectral parameters in recognition is treated equally and equally, regardless of the pair. Mineral sensitivity and stability under different conditions. In fact, according to the knowledge of mineralogy and mineral taxonomy, similar and homogenous minerals have different degrees of similarity in chemical composition, crystal structure and spectral characteristics. To this end, the idea of ​​establishing a hierarchical system of mineral identification is proposed: in the system of analyzing the variation law of mineral spectrum, evaluating the sensitivity and stability of spectral parameters, referring to or referring to the classification method of mineralogy, visible-reflection infrared spectroscopy The interval is based on the main absorption band, band combination characteristics, band fine features and band variation characteristics, and the minerals are identified layer by layer according to the “mineral group one species and one subspecies”, forming the imaging spectrum minerals. The layer identification spectrum system constitutes the tree structure of the actual discriminant decision process. In the identification decision from class to specific mineral, the fineness of the features used is getting higher and higher, but its stability and diagnostics for minerals are gradually reduced, so that the uncertainty of recognition is controlled at a certain level. In general, the credibility of mineral identification is improved, and the automation level and batch processing capacity of the treatment are improved. The achievement obtained the national invention patent "method of identification of hierarchical spectrum of hyperspectral minerals".

In the application process, through the analysis of the fine spectral characteristics of similar minerals, further development and introduction of spectral similarity matching, spectral index and mixed decomposition in the identification pedigree, further refine and expand the hierarchical recognition rules of hyperspectral minerals. A recognition framework that integrates different recognition algorithms into different levels has been established, increasing the number of identifiable minerals to more than 30.

(2) Mineral abundance recognition

Mineral abundance spectral identification is a method of qualitatively or quantitatively retrieving the relative content (abundance) of minerals in a geological body based on certain characteristics of the measured spectrum. At present, quantitative inversion methods for mineral abundance are mainly based on the depth of diagnostic absorption bands, spectral mixture decomposition and mathematical statistics.

The intensity of the reflected light absorption band is a function of the mineral's Intrinsic Absorption Strength, scattering properties, and mineral abundance. The results of mineral mixed spectral characteristics show that the intensity of mineral characteristic bands is linearly related to the percentage of minerals. The relative content of minerals can be approximated by the intensity variation of the absorption bands. Due to the influence of mixed spectra, the relationship between the intensity of minerals in different rocks and the percentage of minerals is different. The depth of the bands is also affected by environmental factors and spectral reconstruction accuracy, and has certain uncertainty.

The most commonly used statistical analysis methods are regression analysis and partial least squares regression analysis, which play the role of “regularization” or “calibration”, and convert the “relative content” of the inversion into “true content”, but need to be measured. And analyze a large number of samples.

Mixed pixel decomposition is a commonly used method for inverting mineral abundance, but there are two main problems: First, the current mixed decomposition is basically a linear model, but in the reflection spectrum interval, the mineral spectral mixture is a compact mixture. The non-linear characteristics are obvious; the second is that the "abundance" information obtained by the mixed spectral decomposition is the specific gravity of each endmember spectrum in the mixed spectrum, and is the "spectral abundance" of the mineral. In response to these two problems, we have taken three major measures to improve the spectral linear hybrid decomposition: one is to convert the spectral reflectance into a single scattering albedo using the Hapke radiation transmission model, and convert the nonlinear mixture of the spectrum into "linear mixing". Second, the continuum removal method is used to separate the absorption band and background to reduce the influence of illumination and environmental factors. The third is to add the endmembers of the spectrum single-scattering albedo representing the non-absorbed characteristic minerals to participate in the decomposition, so that the inversion The abundance is close to its true abundance and improves the reliability of abundance inversion.

(III) Analysis of mineral chemical composition inversion and geological genesis information

White mica, chlorite are two causes of mineralogy and mineralogy of the ore minerals important feature. Two kinds of samples with different locations, different lithologies and different genesis were collected for laboratory testing to study the relationship between spectral characteristics and mineral composition and structure, and to analyze the genesis and temperature and pressure information during formation.

Collected in east Tianshan mountain Huangshandong copper-nickel mine ultrabasic rocks to chlorite-based Pennines, gabbro Xiangshanxi Huangshan copper and nickel ore, diabase mafic rocks iron, magnesium chlorite, gold red Beach gabbro, diabase luminance chlorite group of rocks, diorite Xiangshanxi neutral copper nickel and iron in the Pennine magnesium chlorite, Samples such as iron-magnesium chlorite in the chlorite slate were measured in the laboratory and analyzed by chemical analysis using an electron probe. Based on the analysis results of chlorite particles, the structural formula of chlorite was calculated based on 28 oxygen atoms. At the same time, the spectral data of chlorite in the USGS spectral library and the corresponding chemical analysis results were collected to study the relationship between the spectral characteristics of chlorite and its chemical composition and formation temperature. The analysis results show that the Mg octahedral coordination number, ω (Fe)/ω(Fe+Mg), A1IV plasma number and the band position and spectral absorption depth of the Mg-OH/Fe-OH group are present. A certain correlation, and with the increase of chlorite formation temperature, the characteristic absorption position of Mg-OH/Fe-OH groups drifts to the long-wave direction.

Methods of the same of different origins muscovite (sericite) the content of Al ions in tetrahedral, octahedral ion content of Al, A1 2 0 3 weight percent, ω (Si) / ω ( A1) with parameters band near 2210 nm The relationship between the positions shows that the position of the band shifts with the decrease of A1IV content in the muscovite and the value of ω(Si)/ω(A1IV) increases toward the long wave.

According to the experimental results, regression equations were used to establish a regression equation for the inversion of A1IV content, ω(Si)/ω(AlIV) in muscovite based on the position of the muscovite near the wavelength of 2 210 nm; according to chlorite 3330 The inversion model of the ratio of Fe, Mg mass fraction, ω(Fe)/ω(Fe+Mg), ω(Mg)/ω(Fe. 3+ +Fe 2+ ) in the vicinity of nm is inversed.

(4) S1 thermal infrared multi/hyperspectral data processing and mineral identification

Starting from the "Eleventh Five-Year Plan", China's Land and Resources Aeronautical Geophysical and Remote Sensing Center further researched the mineral identification method of emission spectra based on the study of mineral identification of reflectance spectra, and extended the spectral interval from visible to reflected infrared to medium one. The thermal infrared spectrum segment is used to establish a full-spectrum mineral mapping technology system, and many phased results have been achieved.

1. Quantitative study analyzes the influence of temperature profile error on emissivity inversion under different atmospheric modes. The main emission spectrum inversion methods developed at home and abroad, such as reference channel method, day and night method, gray body emissivity method, ratio method, residual method only, emissivity normalization method and temperature-emissivity separation method, are analyzed and compared. Summarized their application conditions and advantages and disadvantages, and developed corresponding processing procedures.

2. Using the emission spectra of 138 rock samples from JHU and ASU spectral data, and the collected thermal infrared hyperspectral data of Mars TES, study the mineral identification method using emission spectrum, and establish a similar idea with reflection spectrum mineral identification. Some criteria for the identification of rock-forming minerals and ore minerals.

The relationship between Christianis characteristics (CF) and rock SiO 2 content, SCFM index [ω(SiO 2 )/ω(SiO 2 +CaO+ FeO+MgO)] was analyzed and the correlation model was established.

According to the characteristics of ASTER thermal infrared multispectral data band, the SiO 2 index (ε12/ε13) was designed, and its statistical relationship with SiO 2 content was established. The SiO 2 index was used to quantitatively invert the ASTER thermal infrared multispectral data. Surface rock SiO 2 content. A pyroxenite rock mass not originally painted on the original geological map was found in the working area of ​​Dongtianshan, Xinjiang.

Third, the technical system and working methods of high-spectral mineral identification and mineral mapping

(1) Analysis of mineral identification limits and influencing factors

The mineral identification limit refers to the lowest pixel abundance of minerals that can be detected by hyperspectral, ie the minimum average abundance of the inner mineral. The identification limits of the hyperspectral minerals were estimated using correlation analysis between the inversion of mineral distribution intensity and the measured abundance of minerals. The results show that the sensitivity or detection limit of hyperspectral remote sensing mineral mapping is between 5% and 10%. Generally speaking, the dark mineral with lower reflectance is lower in sensitivity, and the recognition limit is generally about 8% to 10%, such as chlorite, epidote, etc.; the light color mineral with higher reflectance is higher in sensitivity, and the recognition limit is higher. Generally, it is about 5% to 6%, such as calcite . However, the identification limits of minerals are affected by many factors, including the actual content, distribution, range of the minerals in the rock, the contrast with the background, and the spatial resolution of the data. Low spatial resolution produces a dilution effect on the abundance of mineral elements. For minerals with small distribution scales, such as fine veined calcite veins and minerals in fine veins, minerals with very uneven spatial distribution, the actual recognition limit will be significantly reduced.

Using a combination of theoretical analysis, experiment and digital simulation, the non-Lambertian characteristics of the atmosphere and the ground, the geometric relationship of the solar-target-instrument, spectral resolution, spatial resolution, signal-to-noise ratio, etc. are systematically analyzed. The influence of technical parameters on the type, credibility and quantification of mineral boron .

The study of mineral identification limits and influencing factors provides a basis for the selection of engineering arrangements and technical indicators for hyperspectral measurements.

(II) Two geological prospecting application modes for mapping hyperspectral minerals

Mineral composition in the same type of rock, mineral sequence of different mineral types, different genetic types of mineral deposits, symbiosis and associated combination of minerals, alteration type and altered mineral combination and zoning, standard minerals, etc. have certain internal law. In geological prospecting, altered mineral combinations and alteration zones are more instructive and decision-making than single altered minerals. In many cases, it is not necessary to identify individual mineral components one by one, and it is more necessary to identify the symbiotic combination of minerals and their zoning. Based on this, two application modes are proposed for prospecting applications, which can be used for different situations:

1. Recognition mode based on single mineral. Identify individual minerals one by one. According to the spatial distribution and combination of minerals, combined with the symbiotic combination of minerals and the geological environment and geological conditions of the working area, the spatial combination pattern and spatial variation of mineral distribution are analyzed, and different alteration zones, metamorphic zones, lithification zones or phases are classified. Belt for in-depth geological analysis.

2. Recognition mode based on combined minerals (alteration zone). According to the different alteration types and the mineral combination of the alteration zone, the alteration zone is directly identified according to the combined spectral characteristics, which is used for geological analysis and mineral resource evaluation, and the ore-targeting area is delineated.

(III) Basic working methods and technical processes for mapping hyperspectral minerals in arid exposed areas

Through theoretical analysis and typical experiments, the application conditions and application effects of different treatment methods or models in the main technical aspects such as atmospheric correction, spectral reconstruction, mineral spectral identification, end mineral selection and spectral unmixing are compared and analyzed. The effects of four kinds of imaging spectral atmospheric correction and spectral reconstruction methods, such as spectral synchronization measurement, geosynchronous measurement of point calibration point, non-synchronous measurement of calibration point spectrum and atmospheric transmission model, summarize and propose the follow-up of spectral reconstruction in engineering implementation. Working criteria, methods for judging the quality of reconstructed spectra and judgment criteria; proposed combinations of methods or methods to be adopted according to different mineral selection pathways and endmember types. On this basis, the basic working methods or working procedures of a series of systematic imaging spectral mineral mapping in the arid exposed area are summarized. The complete technology and application system (except data acquisition) can basically adapt to large-scale production. Need.

(4) Knowledge-based mineral mapping work strategy

The composition, traits and spectral characteristics of natural rock minerals are very complex. In practical work, mathematical methods and mathematical models are often difficult to achieve better recognition results. Familiar with or understand the geological background, geological environment and geological development history of the work area, master the knowledge and experience of mineralogy, mineral symbiosis and mineral spectroscopy, determine the identification target, select the diagnostic features, and apply the identification method. And the establishment of decision-making basis has important guiding role. Based on this, the working strategy and discriminant decision-making method of hyperspectral mineral mapping based on knowledge of geology, mineralogy and mineral physics are proposed.

(5) Technical system for high-spectral mineral identification and mineral mapping

Based on the above analysis and application demonstration, summarize and propose uncertainties and sensitivity analysis including data acquisition and standard product generation, data preprocessing, atmospheric correction and spectral reconstruction, image analysis, mineral spectral identification, mineral identification, Spectral recognition support system, application analysis and modeling, combined use of multiple data and other high-spectral mineral mapping technology system framework.

Fourth, application demonstration

(1) Regional mineral mapping

The working area of ​​the Tujiadong East and Sankoukou in Xinjiang is about 3000km 2 . It is located in the Chihu-Huangshan Yijingerquan copper-nickel- molybdenum gold metallogenic area in the Cu-Nu- Mo- Gold metallogenic belt of the Kanggurtage subduction zone. Copper-nickel deposits generally occur in the basic or ultrabasic lithofacies of the complex rock mass, which are accompanied by a certain scale of wall rock alteration. Applying the established identification lineage and identification rules, using HyMap airborne imaging spectral data to fill out serpentine, tremolite , limonite, aluminum- rich muscovite, aluminum-poor muscovite, montmorillonite, kaolinite, green More than 10 kinds of minerals such as mudstone, epidote, chlorite and epidote, calcite, salinization ( gypsum and thenardite ), and the distribution of minerals in the whole region and standard framing. The field field verification results show that the mineral identification rate (the ratio at which the content reaches the recognition limit) is 82%, and the recognition accuracy rate (the ratio of the identified sites to the presence of the mineral) is over 90%.

The geological analysis and field investigation of the results of the mapping revealed that there were strips, flakes or clumps, single minerals such as muscovite, chlorite, epidote and calcite, or one or two, distributed along the tectonic line. Mineral combinations are generally products of regional metamorphism; serpentine and tremolite can be used to delineate ultrabasic rocks; scattered around the edges of rock masses, contact belts, and fracture zones, with small plate-like, fine-striped, crystal-transparent The combination of serpentine, tremolite and other altered minerals, often in the form of mineralization, indicates the distribution of mineral deposits, ore deposits, and is a favorable area for prospecting. . Based on this, a number of favorable prospecting areas, target areas and prospecting areas for prospecting are proposed.

(2) Metallogenic and prospecting models of typical mining areas

In the Chongli working area of ​​Hebei Province, according to the characteristics of the discovered deposits related to the alkaline complex, the spectrum of the altered mineral complex in the known mining area is used as a reference, and the MAIS imaging spectral data of the working area is processed. Identification, using spectral matching method, circled 12 gold mineralization alteration anomalies. To 7 wherein the outlier field is checked, the quartz veins are seen closely related and Gold, quartz veins in the surrounding rock are developed or different degrees of potassium feldspar, silicification, epidotization chloritization Alteration of pyrite mineralization and limonite mineralization. In particular, the two gold mineralization anomalies at the west and west gullies of Xigou Kiln are strongly petrified and silicified, and the sulphide is very developed. After the analysis of the sorting block, the Xigou kiln east ditch contains gold 0.68g/t and silver 348g/t. Lead is 15.88%; Xigou Kiln Xigou contains 4.9g/t gold, 50g/t silver and 2.86% lead.

Using Hyperion aerospace imaging spectral data, four kinds of altered minerals such as high Al sericite, low Al sericite, kaolinite and chlorite were mapped in the prospective area of ​​the Tibet Longlong porphyry copper deposit.

Compared with the typical metallogenic model of porphyry copper deposits, the distribution of sericite, kaolinite and chlorite corresponds to the Yunying lithification, clayification and Qingpan lithology belt. The hyperspectral remote sensing prospecting model of the porphyry copper deposit in the working area was established, and many mineralization anomalies and some small alteration distribution areas which are very similar to the mineral combination characteristics of the known mining areas were found. After analysis and evaluation and ground verification , circled 3 prospecting targets, each confirmed by subsequent exploration work.

High Al sericite is distributed on the contact zone of the rock mass at the northern edge of the deposit. According to the theory of genetic mineralogy, low temperature and high pressure conditions are favorable for aluminum ions to replace other cations in six coordination. High Al sericite is formed in a relatively low temperature and high pressure environment, and its concentrated distribution on the contact zone of rock mass may reflect When the ore magma rises along the contact zone, it is produced after the temperature in the shallower part is lowered, or the result of multi-stage hydrothermal action.

V. Plant geochemical detection

The Bailukashan Work Area in Heilongjiang Province is located at the northeastern end of the delbugan precious metal and non-ferrous metal metallogenic belt. The area is densely populated and the rock outcrops are scarce, which brings great difficulties to remote sensing prospecting. In the first half of September 2000, high-spectrum plant biochemical information detection and plant geochemical detection were carried out in the region with PHI data of 5 nm spectral resolution.

Through the spectral test and sampling analysis of the crown, the variation law of the spectrum of different growth plants in the high vegetation coverage area (red edge position and slope, green peak position and intensity, infrared reflection plate height, etc.) was summarized, and the plant metal content and spectrum were studied. The correlation between features and geochemical anomalies. On this basis, a multivariate inversion regression equation for the content of copper, lead, zinc , arsenic and molybdenum in the working area and the spectral absorption depth of 500-800 nm vegetation and a plant geochemical regression estimation model for the PHI imaging spectrum in the working area were established. According to the inversion results, a geochemical anomaly of the plant near the east-west direction was found in the middle of the survey area. It is located at the southern margin of the geochemical anomaly of Au and Ag. It is a combination of elements with high Hg and As and low Mo, and is a low-temperature hydrothermal geochemistry. Anomalous element combination feature.

Sixth, mine environmental monitoring

In the Dexing Copper Mine, the US Hyperion hyperspectral satellite data was used to conduct mine environmental investigation and monitoring application research. According to the research and analysis of different pollution types and spectral characteristics of solid waste, water and vegetation in the work area, the spectral identification rules of Fe 2+ , Fe 3+ minerals and their mixtures were established, and the solid waste in the mining area was identified and extracted. Distribution of Fe 2+ and Fe 3+ minerals and their diffusion to and around the water system; using band scatter plot analysis and classification and identification methods to distinguish acidic wastewater, acid heap leaching solution, alkaline tailing water and pollution River waters with different degrees; extracting remote sensing plant pollution information from the mining area by using the spectral red edge location and plant maximum absorption depth to obtain the general pollution distribution of remote sensing vegetation in the mining area; preliminary development of pollution diffusion and migration in the mining area Analysis and exploration of the spread and evolution of mining pollution in the catchment basin.

Seven, planetary exploration

Using the collected thermal infrared spectroscopic data of Mars TEs, the Mars mineral emission spectrum mapping test and Mars geological research were carried out.

Based on the study of the characteristics of the main mineral emission spectra, using the developed emission spectrum mineral identification method and identification criteria, from the TES thermal infrared hyperspectral data, the layered silicate and high Si glass, sulfate, Minerals such as plagioclase, potash feldspar, hematite, high-calcium pyroxene, low-calcium pyroxene and surface ash have accumulated experience in the systematic study of emission spectrum mineral mapping, as well as for geological exploration and research of the moon and planets. Useful for experimentation and practice.

Development and prospects

1. The promotion and scale application of hyperspectral mineral identification and mapping technology can play an important role in all stages of geological survey and prospecting exploration. However, the data sources currently available for use are extremely limited, and data source issues have become a major obstacle in hyperspectral applications. The development and construction of China's aviation and satellite hyperspectral data acquisition systems and ground application systems are urgent.

2. The characteristics of rock and ore spectra (reflection and emission) are the basis and basis for mineral identification. In addition to continuing to systematically study the rock and ore spectra of different regions, different strata and rocks, and different genetic types in China, establish a typical Chinese rock mineral spectrum database. It is also necessary to strengthen the research on the fine characteristics of mineral spectrum, the variation law with composition and structure, geological significance, identification characteristics and identification methods, especially under the guidance of geological theory and methods, to study certain characteristics in a targeted manner. Fine spectral characteristics and geological indications of minerals, minerals.

3. Constantly increase the types of identified minerals, further improve the reliability of detection, the sensitivity of detection, the fineness of recognition, and the level of quantification and intelligence, especially the identification of minerals that are difficult to identify, confuse, and identify with low accuracy. The method continuously expands and optimizes the identification spectrum and identification rules, accelerates the process maturity, standardization and ease of use of the technology, and forms large-scale production capacity as early as possible.

4. Under the guidance of theories and methods of ore mineralogy, genetic mineralogy, environmental mineralogy, ore-forming hydrothermal system and mineral fluid mapping, it will be more closely combined with geological prospecting and oil and gas exploration to develop different geology. Environmental, natural environment, deep geological application test or application demonstration of different application targets, and establish different application targets and different levels of geological application models based on mineral mapping.

5. Continue to carry out in-depth research on emission spectrum mineral identification technology, integrate and integrate reflection and emission spectrum identification methods, and establish a full-spectrum segment (visible-reflection infrared-medium thermal infrared), multi-level (censor, detailed investigation, exploration, mining), A three-dimensional (downhole, ground, aerospace, aerospace), seamless, multi-spectral and hyperspectral combination of mineral mapping technology.

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