A method for predicting the pegmatite lithium mineralization potential based on the spectral characteristics of tourmaline

Abstract

The present invention discloses a method for predicting the pegmatite lithium mineralization potential based on the spectral characteristics of tourmaline, belonging to the technical field of mineral exploration. The method includes: taking pegmatite samples at different drilling depths and classifying the tourmaline samples in the taken pegmatite samples under the microscope; measuring the elements of the classified tourmaline; performing spectral measurement on the classified tourmaline using a spectrometer to obtain spectral data; extracting and processing spectral characteristic parameters; thereby obtaining the spectral characteristics of different types of tourmaline, and then establishing a spectral database; establishing a correlation diagram between spectral characteristic values and lithium content based on the spectral database; and finally obtaining the potential evaluation result of pegmatite-type lithium mineralization based on the spectral characteristic values of different types of tourmaline. The present invention can achieve accurate discrimination of pegmatite-type lithium mineralization, without a large amount of data calculation, and has the advantages of wide application range and high precision, providing a powerful tool for the research of geological evolution and metallogenic mechanism.

Description

Technical Field

[0001] The present invention relates to the technical field of mineral exploration, and particularly relates to a method for predicting the potential of pegmatite lithium mineralization based on the spectral characteristics of tourmaline. Background Art

[0002] Pegmatite is generally formed in the magma stage and is closely related to various plutonic rocks in terms of origin. There are vein-like or massive rock bodies with coarse to very coarse grains in pegmatite, and tourmaline exists in the form of coarse to very coarse crystals in pegmatite. In the early stage of pegmatite mineralization, tourmaline coexists with minerals such as mica, quartz, and feldspar; in the late stage, tourmaline with compositional zoning is formed, which is characterized by being rich in more trace elements and rare elements (such as Li, Be, La, Nb, Ta, W, Sn, U, Th, etc.).

[0003] Pegmatite-type lithium resources have gradually become the main source of lithium due to their advantages such as large thickness, high grade, convenient mining, and high comprehensive development and utilization value. At present, there is a lack of an intuitive judgment method for the evolution process of pegmatite and the corresponding mineralization conditions. Different types of pegmatite tourmaline usually form accompanied by rare metal mineralization; based on the above changes, the degree of rare metal mineralization can be discriminated by geochemical methods, geophysical methods, geological modeling and spatial analysis, machine learning and data mining, and comprehensive methods, etc. From this, the origin of pegmatite can be revealed, mineral exploration can be guided, the geological evolution process can be reflected, and the development of mineral resources can be promoted. It can also reduce the blind exploration work in the early stage, narrow the exploration scope, delineate the target area rich in mineral resources, and optimize the mining plan.

[0004] (1) Geochemical methods: A series of technical means for studying the chemical properties and geochemical processes of geological bodies by analyzing the chemical elements and their isotope compositions in rocks, soils, waters, and other geological materials, and then identifying mineralization anomalies and predicting the location of ore deposits. Such as: whole-rock analysis, trace element analysis, isotope analysis, fluid inclusion analysis, and soil geochemical survey methods. These methods can help determine the chemical composition of rocks, the distribution law of elements, and the geochemical characteristics related to mineralization: ① Whole-rock analysis: By analyzing the overall chemical composition of pegmatite, the content and distribution of lithium are determined; this method has high test costs, long time consumption, and requires a large number of samples for analysis;

[0005] ② Trace element analysis: Analyze trace elements in pegmatite, such as rubidium (Rb), cesium (Cs), etc. These elements are often associated with lithium and can be used as indicator elements for lithium mineralization; however, it requires complex analysis techniques and may require professional knowledge when interpreting the results;

[0006] ③ Isotope analysis: Using lithium isotopes (such as 7 Li and 6By analyzing the ratio changes of lithium isotopes (Li), the source and enrichment process of lithium can be identified; however, due to its complex technology and high cost, specialized laboratory equipment is required for testing.

[0007] (2) Geophysical methods: A technical means that uses the changes in geophysical fields (such as gravity fields, magnetic fields, electric fields, etc.) to detect the differences in underground geological structures and physical properties. By measuring and analyzing the anomalies of these physical fields, the types, structures, and distributions of underground rocks can be inferred, as well as the physical characteristics related to mineralization can be identified:

[0008] ① Magnetic exploration: By identifying the distribution of magnetic minerals in pegmatite bodies through magnetic anomalies, the distribution and structure of pegmatites can be indirectly inferred; the interpretation of such magnetic anomalies requires professional knowledge and is greatly affected by the environment;

[0009] ② Electrical exploration: Using methods such as resistivity and induced polarization to identify the electrical characteristics of pegmatite bodies and evaluate the lithium mineralization potential; this method requires complex equipment and data processing techniques and has a relatively high cost;

[0010] (3) Geological modeling and spatial analysis: Geological modeling is to construct a three-dimensional geological model using geological data (such as boreholes, outcrops, geophysical and geochemical data, etc.) to visually display the spatial distribution and structural characteristics of geological bodies. Spatial analysis is to process and analyze geological data through tools such as geographic information systems (GIS) to identify the spatial relationships and patterns between geological bodies and provide a basis for predicting mineralization potential:

[0011] ① Three-dimensional geological modeling: Construct a three-dimensional geological model of pegmatite bodies, integrate geological, geophysical, and geochemical data, and predict lithium mineralization areas; this method requires a large amount of preliminary data and the modeling process is complex;

[0012] ② GIS spatial analysis: Using geographic information system (GIS) technology to analyze the distribution law of pegmatites and the spatial relationships of geological factors related to lithium mineralization; this method requires high-quality geological data, and data processing and analysis require professional knowledge;

[0013] ③ Tectonic analysis: Studying the tectonic background of pegmatites, such as fault zones, magmatic activities, etc., to identify favorable ore-forming tectonic environments; this method requires detailed geological background knowledge and the interpretation results may be subjective.

[0014] (4) Remote sensing and spectral analysis:

[0015] ① Hyperspectral remote sensing: Using hyperspectral remote sensing data to identify the spectral characteristics of specific minerals (such as tourmaline, lepidolite, etc.) in pegmatites and evaluate the lithium mineralization potential; this method has complex data processing and is greatly affected by weather and terrain;

[0016] ②Thermal infrared remote sensing: By using thermal infrared remote sensing data, identify the thermal anomalies of pegmatite and infer the lithium enrichment areas; this method is vulnerable to external environmental influences and has low resolution, making it unable to accurately identify minerals;

[0017] (5) Machine learning and data mining: Machine learning is an artificial intelligence technology that automatically learns patterns and rules from large amounts of data by constructing algorithm models. Data mining is the process of extracting useful information and knowledge from large amounts of data. In the prediction of mineralization potential, machine learning and data mining technologies can integrate various geological, geophysical, and geochemical data, identify features and patterns related to mineralization, and establish prediction models:

[0018] ①Supervised learning: Use the geological, geophysical, and geochemical data of known lithium mineralization areas to train machine learning models and predict the lithium mineralization potential of unknown areas; this method requires a large amount of training data and the interpretability of the model is poor;

[0019] ②Unsupervised learning: Identify geological features and patterns related to lithium mineralization through methods such as cluster analysis; the interpretation of the results of this method requires professional knowledge and may require multiple iterations;

[0020] ③Multi-source data fusion: Integrate multiple data sources (such as geological, geophysical, geochemical, and remote sensing data), and use data mining techniques to identify potential lithium mineralization areas; the data fusion process of this method is complex and requires professional technologies and tools.

[0021] In summary, the current methods for predicting the lithium mineralization potential of pegmatite have at least the following disadvantages:

[0022] (1) It is necessary to conduct a large amount of data sampling and complex processing and calculations, and establish relevant mathematical models based on the processed data;

[0023] (2) The cost is too high and the data interpretation is subjective;

[0024] (3) It cannot accurately reflect and simulate the mineralization conditions formed;

[0025] (4) It is necessary to combine a large amount of geological information for comprehensive analysis. SUMMARY OF THE INVENTION

[0026] The object of the present invention is to provide a method for predicting the lithium mineralization potential of pegmatite based on the spectral characteristics of tourmaline to solve the above problems.

[0027] To achieve the above object, the technical solution adopted by the present invention is as follows: A method for predicting the lithium mineralization potential of pegmatite based on the spectral characteristics of tourmaline, comprising the following steps:

[0028] 1) Take pegmatite samples with different drilling depths, classify the taken samples under the microscope using a mineralogical microscope, and measure the elements of tourmaline in the classified pegmatite samples;

[0029] 2) Use a spectrometer to measure the spectrum of tourmaline in the classified pegmatite samples to obtain spectral data;

[0030] 3) Extract and process the spectral characteristic parameters;

[0031] 4) Obtain the spectral characteristics of different types of tourmaline, and then establish a spectral database;

[0032] 5) Establish a diagram of the mutual relationship between the spectrum and the lithium content;

[0033] 6) According to the mutual relationship diagram obtained in step 5), obtain the potential evaluation result of pegmatite-type lithium mineralization based on the spectral characteristics of tourmaline.

[0034] As a preferred technical solution, in step 1), the mineralogical microscope is a digital polarizing microscope, different types of tourmaline are classified through microscopic characteristics, and different types of tourmaline are subjected to element measurement; the element measurement is major element measurement and trace element measurement; among them, the microscopic characteristics include interference color, structure, texture, associated minerals, etc.

[0035] As a further preferred technical solution, the measurement of major elements is carried out using a JXA-iSP100 type electron probe microanalyzer of JEOL, Japan, and the measurement of trace elements is carried out using an inductively coupled plasma mass spectrometer FininganMAT LA-ICP-MS (Element Ⅰ type).

[0036] As a preferred technical solution, in step 2), the specific method of analysis is: the sample needs to be washed and dried before testing to avoid the influence of impurities on the spectral characteristics; a CSD350 full-spectrum ground object spectrometer is used to perform fixed-point spectral measurement on the classified tourmaline samples, and at least three spectral measurements are carried out on the samples. It is preferred to test three times and take the average value to ensure the accuracy of the sample data.

[0037] As a preferred technical solution, in step 3), a mineral spectral analysis expert system (hereinafter referred to as MSA) developed by the Jiangsu Institute of Spectral Detection and Intelligent Sensing Technology, China, and a spectral geologist analysis software (hereinafter referred to as TSG) developed by the Commonwealth Scientific and Industrial Research Organization of Australia and first introduced by Zhongke Remote Sensing Information Technology Co., Ltd. are used to extract and process the spectral characteristic parameters. The spectral data is processed by MSA to obtain the spectral characteristics and reflectivity values, and the absorption depth values are obtained using TSG.

[0038] As a preferred technical solution, in step 4), based on MSA and TSG, the spectral characteristics of different types of tourmaline are obtained, and its spectral database is established; the spectral characteristics of different types of tourmaline obtained are statistically analyzed, and the spectral bands with indicative significance for different types of tourmaline are summarized.

[0039] As a preferred technical solution, in step 5), the method for establishing the diagram of the mutual relationship between the spectrum and the lithium content is as follows:

[0040] First, establish the coupling relationship between different indicative bands and the lithium content, that is, conduct a coupling relationship study on the spectral characteristic values of different types of tourmaline and the lithium content, and then obtain the quantitative inversion model of the spectral characteristic values of different indicative bands and the lithium content, that is, the diagram of the mutual relationship between the spectrum and the lithium content.

[0041] As a preferred technical solution, in step 6), the method for evaluating the potential of pegmatite-type lithium mineralization is as follows:

[0042] Based on the above diagram, classify tourmaline with different lithium contents. The classification is re-divided according to the lithium content, and is divided into tourmaline without ore, poor ore and rich ore, and the potential evaluation of pegmatite-type lithium mineralization by the spectral characteristics of tourmaline is obtained.

[0043] The formation of tourmaline is affected by geological conditions such as temperature and pressure. Under different geological conditions, the chemical composition and short-wave infrared spectral characteristics of tourmaline will change accordingly. The increase in the lithium content in tourmaline results in a larger absorption peak in its short-wave infrared, the H2O wavelength (1900 nm) shifts towards the long-wave direction, and the Al-OH wavelength (2200 nm) shifts towards the short-wave direction. By measuring and analyzing the short-wave infrared spectral characteristics of tourmaline, identifying the characteristic absorption bands related to the lithium content, establishing the quantitative relationship between the spectral characteristics and the lithium content, and predicting the lithium mineralization potential of pegmatite.

[0044] The method of the present invention can establish a more intuitive revelation of the geological process of pegmatite formation, study the formation conditions and evolution history of minerals in pegmatite, and the metallogenic law of rare metal minerals by calculating the spectral characteristics and lithium content of pegmatite-type tourmaline.

[0045] The present invention adopts methods such as short-wave external spectral technology, microscopic observation, electron probe, etc., establishes the relevant diagram and quantitative inversion schematic diagram of the lithium content, and judges the coupling relationship between the spectral characteristics and the lithium content based on the physical model method.

[0046] Compared with the prior art, the advantages of the present invention are as follows: The short-wave infrared prediction method has the ability of on-site rapid measurement; through the combination of MSA and TSG, spectral data can be converted into intuitive charts and models, thus simplifying data interpretation and reducing subjectivity. Through spectral feature analysis, mineral and wall rock information can be effectively extracted without relying on dating or element analysis steps; a quantitative relationship between spectral features and lithium content is established to realize the inversion and speculation of lithium content, thereby effectively evaluating the lithium mineralization potential. Compared with other traditional methods, the inversion process of the short-wave infrared prediction method of the present invention is more efficient and direct, the result interpretation is simple and easy to understand, and it is not restricted by the environment, thus reducing the unnecessary field verification workload. It reduces more than 85% of lithological sampling and experimental analysis and improves the prediction accuracy by more than 35%, as shown in Table 1.

[0047] Table 1 Comparison of different prediction methods for lithium content

[0048] 。 Brief Description of the Drawings

[0049] Figure 1 is the flow chart of the present invention;

[0050] Figure 2 is the relationship diagram between the H2O wavelength (1900 nm) and lithium content of different types of tourmaline in pegmatite-type lithium deposits in the embodiments of the present invention;

[0051] Figure 3 is the relationship diagram between the Al-OH wavelength (2200 nm) and lithium content of different types of tourmaline in pegmatite-type lithium deposits in the embodiments of the present invention;

[0052] Figure 4 is the diagram for distinguishing ore-bearing types of tourmaline with different wavelength characteristics in the embodiments of the present invention. Detailed Embodiments

[0053] The present invention will be further described below in conjunction with embodiments and the accompanying drawings.

[0054] Embodiment:

[0055] A method for predicting the pegmatite lithium mineralization potential based on tourmaline spectral characteristics successively includes the following steps:

[0056] 1) Take pegmatite samples with different drilling depths, classify the samples taken under the microscope and measure the elements. The microscopic instrument used is a digital polarized light microscope. According to the microscopic characteristics, tourmaline is divided into three categories: magmatic stage, magmatic-hydrothermal stage; the measurement of major elements is completed using a JXA-iSP100 type electron probe microanalyzer, and the measurement of trace elements is carried out using an inductively coupled plasma mass spectrometer Finingan MAT LA-ICP-MS (Element Ⅰ type); among them, the cation numbers of different types of tourmaline are shown in Table 2;

[0057] Table 2 Cation numbers of different types of tourmaline

[0058] ,

[0059] 2) Before testing, the samples need to be washed and dried in the sun to avoid the influence of impurities on the spectral characteristics; use a CSD350 full-spectrum ground object spectrometer to conduct fixed-point spectral measurements on the classified tourmaline samples, and conduct three spectral measurements on the samples to ensure the accuracy of the sample data. The spectral information is recorded according to the sorting of the drilling depths where the samples are located;

[0060] 3) Use MSA and TSG to extract and process the spectral characteristic parameters. Through MSA processing of the spectral data, the spectral characteristics and reflectance values are obtained, and the absorption depth values are obtained using TSG; the spectral wavelength characteristics of different classified tourmalines are shown in Table 3;

[0061] Table 3 Spectral characteristics of different types of tourmaline

[0062] ,

[0063] 4) Based on MSA and TSG, obtain the spectral characteristics of different types of tourmaline and establish its spectral database; statistically analyze the spectral characteristics of different types of tourmaline obtained, and summarize the bands with indicative significance for different types of tourmaline,

[0064] 5) Establish the coupling relationship between different indicative bands and lithium content, that is, conduct a coupling relationship study on the spectral characteristic values and lithium content of different types of tourmaline (Table 4), and obtain the inversion model diagram of the spectral characteristic values and lithium content of different indicative bands;

[0065] Table 4 Spectral characteristics and lithium content of different types of tourmaline

[0066] ;

[0067] 6) Based on the spectral characteristics of tourmaline obtained in step 5), the potential evaluation of pegmatite-type lithium mineralization is as follows: if the wavelength of Al-OH in the short-wave infrared spectrum of the tourmaline sample is greater than 2200.8 nm, it indicates that the pegmatite in the area where the sample is located has no lithium mineralization potential, that is, there is no lithium mineralization; if the wavelength of Al-OH is between 2198.7 nm and 2199.8 nm, it indicates that the pegmatite in the area where the sample is located has relatively low lithium mineralization potential, that is, it shows poor lithium mineralization; if the wavelength of Al-OH is less than 2198.6 nm, it indicates that the pegmatite in the area where the sample is located has relatively high lithium mineralization potential, that is, it shows rich lithium mineralization; however, there is no good correlation between the spectral characteristic boundaries of tourmaline with poor lithium mineralization and rich lithium mineralization at 1900 nm ( Figure 2 , 3). Therefore, a spectral metallogenic model diagram of tourmaline is constructed based on the spectral characteristics at 2200 nm ( Figure 4 ), and this model diagram and prospecting criteria provide strong support for the further exploration of pegmatite-type lithium deposits.

[0068] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for predicting the pegmatite lithium mineralization potential based on the spectral characteristics of tourmaline, characterized in that, It includes the following steps: 1) Take pegmatite samples with different drilling depths, classify tourmaline in the taken pegmatite samples under a microscope using a mineralogical microscope, and measure the elements of the classified tourmaline; 2) Use a spectrometer to measure the spectrum of the classified tourmaline to obtain spectral data; 3) Extract and process spectral characteristic parameters; 4) Obtain the spectral characteristics of different types of tourmaline, and then establish a spectral database; 5) Establish a diagram of the mutual relationship between the spectrum and lithium content; 6) According to the mutual relationship diagram obtained in step 5), obtain the potential evaluation result of pegmatite-type lithium mineralization based on the spectral characteristics of tourmaline; among them, In step 1), the mineralogical microscope is a digital polarizing microscope, different types of tourmaline are classified through microscopic characteristics, and the elements of different types of tourmaline are measured; the element measurement includes major element measurement and trace element measurement; The specific method of the spectrum measurement is: wash and dry the sample before testing; use a CSD350 full-spectrum ground object spectrometer to perform fixed-point spectrum measurement on the classified tourmaline sample, and perform at least three spectrum measurements on the sample; In step 4), based on the mineral spectral analysis expert system and the spectral geologist analysis software, obtain the spectral characteristics of different types of tourmaline and establish its spectral database; statistically analyze the spectral characteristics of different types of tourmaline obtained, and summarize the spectral bands with indicative significance for different types of tourmaline; In step 5), the method for establishing a diagram of the mutual relationship between the spectrum and lithium content is: Conduct a coupling study on the spectral characteristic values of different types of tourmaline and lithium content, and obtain a quantitative inversion model of the spectral characteristic values and lithium content in different indicative bands, that is, a diagram of the mutual relationship between the spectrum and lithium content; In step 6), the method for evaluating the potential of pegmatite-type lithium mineralization is: Based on the mutual relationship diagram, classify tourmaline with different lithium contents, and reclassify according to lithium content, divided into non-ore, lean-ore and rich-ore tourmaline, and obtain the potential evaluation of pegmatite-type lithium mineralization by the spectral characteristics of tourmaline.

2. The method according to claim 1, characterized in that, The measurement of major elements is carried out using a JXA-iSP100 type electron probe microanalyzer of JEOL, Japan, and the measurement of trace elements is carried out using an inductively coupled plasma mass spectrometer Finingan MAT LA-ICP-MS, Element Ⅰ type.

3. The method according to claim 1, characterized in that In step 3), use the mineral spectral analysis expert system developed by the Jiangsu Institute of Spectral Detection and Intelligent Sensing Technology, China, and the spectral geologist analysis software developed by the Commonwealth Scientific and Industrial Research Organization of Australia and first introduced by Zhongke Remote Sensing Information Technology Co., Ltd. to extract and process spectral characteristic parameters. Through the mineral spectral analysis expert system, process the spectral data to obtain spectral characteristics and reflectivity values, and use the spectral geologist analysis software to obtain absorption depth values.

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