A method for determining the control factors of cathodoluminescence intensity based on laser surface scanning

Abstract

This invention provides a method for determining the controlling factors of cathodoluminescence intensity based on laser surface scanning. The method includes: sampling and preparing thin sections; observing and identifying key areas using polarizing microscopy and cathodoluminescence microscopy; in-situ laser surface scanning of micro-areas using LA-ICP-MS; combining the cathodoluminescence microscopy images with the LA-ICP-MS in-situ laser surface scanning imaging results to determine representative line segments and points; quantitatively correcting the elemental content using relative sensitivity factors to obtain the corrected elemental content at the representative line segments and points; obtaining the quantitative relationship between cathodoluminescence intensity and the type and content of elements, and determining the controlling factors of cathodoluminescence intensity. This method can obtain the quantitative relationship between the cathodoluminescence intensity of diagenetic minerals and the type and content of multiple elements, thereby determining the controlling factors of cathodoluminescence intensity. It has the advantages of simplicity, efficiency, and wide applicability.

Description

Technical Field

[0001] This invention relates to a method for determining the control factors of cathodic emission intensity based on laser surface scanning, belonging to the field of rock analysis technology. Background Technology

[0002] Cathodoluminescence is an indispensable technique in sedimentary petrology research. The cathodoluminescence of diagenetic minerals is closely related to their formation environment and diagenetic fluid medium, and is an effective method for studying diagenetic evolution and reservoir formation conditions.

[0003] Regarding the controlling factors of cathodoluminescence intensity in diagenetic minerals, researchers generally agree that Mn acts as an activator and Fe as a quencher in carbonate minerals (Liu Jie et al., 2000; Sun Jing et al., 2009; Liu Jinlian et al., 2010). Using techniques such as electron probe microanalysis and atomic absorption spectrometry, certain rare earth elements (REEs) have been found to act as activators, quenchers, and sensitizers for cathodoluminescence. However, due to the low concentration of REEs in minerals and limitations in instrument detection limits and testing accuracy, quantitative analysis of the relationship between REE concentration and cathodoluminescence intensity has not been conducted (Zhou Lingdi et al., 1981; Huang Sijing, 1992). With the widespread adoption of LA-ICP-MS technology, researchers have discovered that the content of REEs Sm, Eu, Tb, and Dy in carbonate minerals has a controlling effect on cathodoluminescence (Pan Liyin et al. Determination of Controlling Factors of Cathodoluminescence Intensity in Carbonate Minerals [P].; CN110530961B).

[0004] Diagenetic minerals are generally diverse and complex, exhibiting inclusions, zonal structures, and irregularly bounded mineral textures. Analyzing only single points delineated under polarizing and cathodoluminescence microscopy can easily miss information from unselected areas. Furthermore, the detection limit for rare earth elements activating cathodoluminescence is typically 10-20 ppm (RAMason & A.N. Mariano. Cathodoluminescence activation in manganese-bearing and rare earth-bearing synthetic calcites. Chemical Geology, 1990, 88: 191-206), while carbonate minerals generally have low rare earth element content. Therefore, analyzing only the controlling effects of Sm, Eu, Tb, and Dy elements on cathodoluminescence is far from sufficient. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a method for determining cathodoluminescence intensity control factors based on laser surface scanning. This method can obtain a quantitative relationship between the cathodoluminescence intensity of diagenetic minerals and the types and contents of various elements, thereby determining the cathodoluminescence intensity control factors. It has the advantages of simplicity, efficiency, and wide applicability.

[0006] To achieve the above objectives, the present invention provides a method for determining the control factors of cathode luminescence intensity based on laser surface scanning, which includes the following steps:

[0007] Step 1: Obtain the rock sample to be tested and prepare a thin section sample;

[0008] Step 2: Observe the thin section sample using a polarizing microscope and a cathodoluminescence microscope. Based on the polarizing microscopy characteristics and cathodoluminescence characteristics, determine the key areas, take pictures and record them to obtain polarizing microscope photos and cathodoluminescence microscope photos.

[0009] Step 3: Perform LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) micro-area in-situ laser surface scanning on key areas of the thin-film sample to obtain LA-ICP-MS micro-area in-situ laser surface scanning imaging results;

[0010] Step 4: Combine the cathodoluminescence microscopy image with the LA-ICP-MS micro-area in-situ laser surface scanning imaging results to determine representative line segments and points. Read the element content in the LA-ICP-MS micro-area in-situ laser surface scanning imaging results corresponding to the representative line segments and points in the cathodoluminescence microscopy image. Perform relative sensitivity factor (RSF) quantitative correction on the element content to obtain the corrected element content on the representative line segments and points.

[0011] Step 5: Based on the element content of the corrected representative line segments and points, draw the element content curves of the representative line segments and points. According to the element content curves of the representative line segments and points, classify the cathodic emission intensity of each element, determine the element content range of different emission intensity regions, and then obtain the quantitative relationship between the cathodic emission intensity and the element type and content, and determine the cathodic emission intensity control factors.

[0012] In the above method, preferably, in step 1, the thin sheet sample is prepared by grinding and polishing.

[0013] In the above method, preferably, in step 1, the thickness of the sheet sample is 60-100 μm.

[0014] In the above method, preferably, in step 2, the key region includes one or more of the following: mineral texture transition zone, region containing inclusion minerals, region with ring structure and recrystallized minerals, and region exhibiting different luminescence in cathodoluminescence.

[0015] In the above method, preferably, step 3 specifically includes:

[0016] Step 301: Determine the types of elements to be tested and the element integration time;

[0017] Step 302: Based on the characteristics of the mineral fabric in the area being scanned, determine the area scanning parameters that meet the requirements for area scanning spatial resolution, area scanning area, and area scanning time.

[0018] Step 303: Based on the element types and element integration time determined in step 301 and the surface scanning parameters determined in step 302, perform LA-ICP-MS micro-area in-situ laser surface scanning on key areas of the thin-film sample, process the data, and obtain LA-ICP-MS micro-area in-situ laser surface scanning imaging results.

[0019] In the above method, preferably, in step 301, for the carbonate rock sample, the types of elements tested include 25 Mg 43 Ca, 55 Mn, 57 Fe、 59 Co、 66 Zn, 88 Sr、 60 Ni、 89 Y, REEs and 208 One or more of Pb, etc.; wherein, REEs include 139 La、 140 Ce、 141 Pr、 146 Nd, 147 Sm、 153 Eu、 157 Gd, 159 Tb, 163 Dy、 165 Ho、 166 Er、 169 Tm、 172 Yb and 175 One or more of Lu et al.

[0020] In the above method, preferably, in step 301, the element integration time includes: element 25 Mg 43 Ca, 55 Mn, 57 Fe and88 The integration times for Sr are 3ms-7ms, and the element... 59 Co、 66 Zn, 60 Ni、 89 Y, REEs and 208 The integration time for Pb is 8ms-10ms.

[0021] In the above method, preferably, step 302 specifically includes: performing laser surface scanning based on the characteristics of the mineral composition in the surface scanning area under preset scanning parameters, and determining the surface scanning spatial resolution, surface scanning area, and surface scanning time under the preset scanning parameters, and selecting surface scanning parameters that meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time.

[0022] In the above method, preferably, in step 302, the surface scanning parameters include parameters such as scanning beam size, energy density, moving speed, ablation frequency, and scanning line spacing.

[0023] In the above method, preferably, in step 4, the representative line segments and points include one or more of the following: line segments passing through zonal structures, line segments passing through the boundary between dolomite and calcite or other different structures, line segments passing through inclusions, line segments passing through recrystallized minerals, line segments with large variations in elemental content, and bright points in cathodoluminescence micrographs.

[0024] In the above method, preferably, in step 4, the quantitative correction of the relative sensitivity factor is performed using a standard substance that matches the matrix of the rock sample to be tested.

[0025] In the above method, preferably, in steps 4 and 5, multiple representative line segments and points are determined to obtain the element content on multiple corrected representative line segments and points, and element content curves on multiple representative line segments and points are plotted.

[0026] In the above method, preferably, in step 5, the different luminescence intensity regions include: weak luminescence regions and strong luminescence regions. It should be noted that these luminescence intensity regions can be determined by those skilled in the art through observation of cathodoluminescence microscope images using experience and conventional methods.

[0027] In the above method, preferably, step 5 further includes: determining the element content range for concentration quenching luminescence based on the element content range values ​​of different luminescence intensity regions.

[0028] In the above method, preferably, in step 5, the cathodic emission intensity control factor is determined at least by the following means: if the content of an element in the strong emission region is greater than the content in the weak emission region, then the element is a cathodic emission activator.

[0029] This invention provides a method for determining the controlling factors of cathodoluminescence intensity based on laser surface scanning. This invention employs LA-ICP-MS micro-area in-situ laser surface scanning technology, which can not only rapidly, comprehensively, and with high precision obtain the planar spatial distribution characteristics of various diagenetic fabric elements, but also obtain semi-quantitative results of elements with external standard linear correction. This invention uses relative sensitivity factor (RSF) quantitative correction, which can obtain quantitative data for any line segment and any orientation for a single element or element ratio. The resulting surface scanning data can be matched with LA-ICP-MS micro-area in-situ ablation results. By combining the planar distribution characteristics of cathodoluminescence with LA-ICP-MS micro-area in-situ laser surface scanning imaging results, this invention quantitatively analyzes the relationship between the cathodoluminescence intensity of minerals and various trace rare earth elements from different levels of point-line-planar imaging, providing a technical method for in-depth research and identification of the types and contents of elements controlling cathodoluminescence intensity.

[0030] The technical solution of the present invention has at least the following beneficial effects:

[0031] ① It can perform high-precision quantitative detection of micron-level structure at the ppb level of element content.

[0032] ②Quantitative analysis of the correlation between cathodic luminescence intensity of diagenetic minerals and various trace rare earth elements was achieved using different forms of point-line-plane imaging.

[0033] ③ It compensates for the deficiency of missing important information due to single-point analysis of local data.

[0034] ④ It solves the drawbacks of electron probe and atomic absorption spectrometry, such as high requirements for element content, low detection accuracy, or difficulty in sampling for solution chemical analysis.

[0035] ⑤ This method is simple, efficient, and widely applicable. It can be applied not only to carbonate minerals but also to other types of minerals. Attached Figure Description

[0036] Figure 1 This is a flowchart illustrating the method for determining the control factors of cathode luminescence intensity based on laser surface scanning in a specific embodiment of the present invention.

[0037] Figure 2 The images shown are polarizing microscope images, cathodoluminescence microscope images, and optical images of key areas in the embodiments.

[0038] Figure 3 The images shown are cathodoluminescence microscopy images and LA-ICP-MS micro-area in-situ laser surface scanning imaging results from the examples.

[0039] Figure 4The figures show the element content curves at representative line segments and points in the examples. Detailed Implementation

[0040] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0041] According to specific embodiments of the present invention, the present invention provides a method for determining the control factors of cathode luminescence intensity based on laser surface scanning, such as... Figure 1 As shown, it includes the following steps:

[0042] Step 1: Obtain the rock sample to be tested and prepare a thin section sample;

[0043] Step 2: Observe the thin section sample using a polarizing microscope and a cathodoluminescence microscope. Based on the polarizing microscopy characteristics and cathodoluminescence characteristics, determine the key areas, take pictures and record them to obtain polarizing microscope photos and cathodoluminescence microscope photos.

[0044] Step 3: Perform LA-ICP-MS micro-area in-situ laser surface scanning on key areas of the thin-film sample to obtain LA-ICP-MS micro-area in-situ laser surface scanning imaging results;

[0045] Step 4: Combine the cathodoluminescence microscopy image with the LA-ICP-MS micro-area in-situ laser surface scanning imaging results to determine representative line segments and points. Read (using software Iolite) the element content in the LA-ICP-MS micro-area in-situ laser surface scanning imaging results corresponding to the representative line segments and points in the cathodoluminescence microscopy image; perform relative sensitivity factor (RSF) quantitative correction on the element content to obtain the corrected element content at the representative line segments and points.

[0046] Step 5: Based on the element content of the corrected representative line segments and points, draw the element content curves of the representative line segments and points. According to the element content curves of the representative line segments and points, classify the cathodic emission intensity of each element, determine the element content range of different emission intensity regions, and then obtain the quantitative relationship between the cathodic emission intensity and the type and content of elements (especially trace rare earth elements). Determine the controlling factors of cathodic emission intensity, that is, determine the type and content of the main elements (especially trace rare earth elements) that control the cathodic emission intensity.

[0047] In some embodiments, in step 1, the sheet sample is prepared by grinding and polishing.

[0048] In some embodiments, in step 1, the thickness of the thin-film sample is 60-100 μm. This thickness can simultaneously meet the requirements of cathodoluminescence microscopy analysis and LA-ICP-MS micro-area in-situ laser surface scanning analysis.

[0049] In some embodiments, in step 2, the key region includes one or more of the following regions with complex microscopic features: mineral fabric transition zone, minerals containing inclusions, minerals with zonal structures, and recrystallized minerals affected by multiple phases of diagenetic fluid activity, and regions exhibiting different luminescence in cathodoluminescence.

[0050] In some embodiments, step 3 specifically includes:

[0051] Step 301: Determine the types of elements to be tested and the element integration time;

[0052] Step 302: Based on the characteristics of the mineral fabric in the area being scanned, determine the area scanning parameters that meet the requirements for area scanning spatial resolution, area scanning area, and area scanning time.

[0053] Step 303: Based on the element types and element integration time determined in step 301 and the surface scanning parameters determined in step 302, perform LA-ICP-MS micro-area in-situ laser surface scanning on key areas of the thin-film sample, process the data (using software Iolite), and obtain LA-ICP-MS micro-area in-situ laser surface scanning imaging results.

[0054] In some embodiments, in step 301, for the carbonate rock sample, the types of elements tested include 25 Mg 43 Ca, 55 Mn, 57 Fe、 59 Co、 66 Zn, 88 Sr、 60 Ni、 89 Y, REEs and 208 One or more of Pb, etc.; wherein, REEs include 139 La、 140 Ce、 141 Pr、 146 Nd, 147 Sm、 153 Eu、 157 Gd, 159 Tb, 163 Dy、 165 Ho、 166 Er、 169 Tm、 172 Yb and 175One or more of Lu et al.

[0055] In some embodiments, in step 301, the element integration time includes: element 25 Mg 43 Ca, 55 Mn, 57 Fe and 88 The integration times for Sr are 3ms-7ms, and the element... 59 Co、 66 Zn, 60 Ni、 89 Y, REEs and 208 The integration time for Pb is 8ms-10ms.

[0056] In some embodiments, step 302 specifically includes: performing laser surface scanning based on the characteristics (including type and size) of the mineral fabric in the surface scanning area under preset scanning parameters, and determining the surface scanning spatial resolution, surface scanning area, and surface scanning time under the preset scanning parameters, and filtering out surface scanning parameters that meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time. Specifically, if the preset scanning parameters meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time, then the preset scanning parameters are used as the surface scanning parameters for the mineral fabric with that characteristic; if the preset scanning parameters do not meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time, then the preset scanning parameters are modified, laser surface scanning is performed again, and the surface scanning spatial resolution, surface scanning area, and surface scanning time under the modified preset scanning parameters are re-determined, until the modified preset scanning parameters can meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time.

[0057] In some embodiments, in step 302, the surface scanning parameters include parameters such as scanning beam size, energy density, moving speed, ablation frequency, and scanning line spacing.

[0058] In some embodiments, in step 302, the mineral texture is characterized as follows: larger texture: area ≥ 15 mm 2 Medium structure: 1mm 2 ≤Area<15mm 2 Ultrafine structure: area <1mm 2Typically, larger textures include granules, coarse-grained to gravelly grains with a hazy core and bright edge, gravel fragments, and cathodoluminescent crystals with zonal structures; medium textures include oolitic grains, medium-fine-grained to hazy-core crystals with a bright edge, sand fragments, and cathodoluminescent crystals with zonal structures; ultrafine textures include small oolitic grains, fine-grained to muddy grains, powder fragments to sand fragments, and cathodoluminescent crystals with zonal structures. Furthermore, the preset scanning parameters based on the characteristics of the mineral texture in the area scan region include: larger textures: 40-50 μm beam spot, energy density 3 J / cm². 2 1. Ablation frequency 20Hz, moving speed 0.04-0.05mm / s, row spacing 40-50μm; medium structure: 20-30μm beam spot, energy density 3J / cm² 2 1. Ablation frequency 20Hz, moving speed 0.02-0.03mm / s, row spacing 20-30μm; 2. Microstructure: 5-10μm beam spot, energy density 3J / cm² 2 The etching frequency is 20Hz, the moving speed is 0.005-0.01mm / s, and the row spacing is 5-10μm.

[0059] In some embodiments, in step 4, the representative line segments and points include one or more of the following: line segments passing through zonal structures, line segments passing through the boundary between dolomite and calcite or other different structures, line segments passing through inclusions, line segments passing through recrystallized minerals, line segments with large variations in elemental content, and bright points in cathodoluminescence micrographs.

[0060] In some embodiments, in step 4, the quantitative correction of the relative sensitivity factor is performed using a standard substance that matches the matrix of the rock sample to be tested.

[0061] In some embodiments, in steps 4 and 5, multiple representative line segments and points are determined to obtain the elemental content at multiple corrected representative line segments and points, and elemental content curves at multiple representative line segments and points are plotted. Specifically, based on the fabrication characteristics of the rock sample to be tested, multiple representative line segments and points can be selected at different locations in cathodoluminescence microscopy images and LA-ICP-MS micro-area in-situ laser surface scanning imaging results to obtain the elemental content and perform RSF quantitative correction, thereby obtaining the elemental content at multiple corrected representative line segments and points, and plotting elemental content curves at multiple representative line segments and points. This makes the data results more comprehensive and reliable, and realizes the quantitative analysis of the correlation between point-line-plane cathodoluminescence intensity and elemental content.

[0062] In some embodiments, in step 5, the different luminescence intensity regions include: weak luminescence regions and strong luminescence regions. It should be noted that these luminescence intensity regions can be determined by those skilled in the art through observation of cathodoluminescence microscopy images using experience and conventional methods.

[0063] In some embodiments, step 5 further includes: determining the element content range for concentration quenching luminescence based on the element content range values ​​of different luminescence intensity regions. It should be noted that the element content range exceeding the element content range values ​​of the strong luminescence region is the element content range for concentration quenching luminescence, and thus the element content range as the quenching agent can be derived.

[0064] In some embodiments, in step 5, the cathodoluminescence intensity control factor is determined at least by the following means: if the content of an element in the strong luminescence region is greater than its content in the weak luminescence region, then the element is a cathodoluminescence activator.

[0065] Example

[0066] This embodiment provides a method for determining cathodoluminescence intensity control factors based on laser surface scanning. It is used to determine the cathodoluminescence control factors of calcite minerals from the Bayan Obo carbonate dike with high rare earth element content. The method includes the following steps:

[0067] Step 1: Obtain the rock sample to be tested, and prepare a thin section sample with a thickness of 100 μm by grinding and polishing;

[0068] Step 2: Observe the thin-section sample using a polarizing microscope and a cathodoluminescence microscope. Based on the polarizing and cathodoluminescence microscopic characteristics, determine the key areas, take photos and record them, obtaining polarizing microscope images and cathodoluminescence microscope images; the polarizing microscope images, cathodoluminescence microscope images, and optical images of the key areas are as follows: Figure 2 As shown; in this embodiment, the region where calcite and dolomite coexist (i.e., the mineral fabric transition zone) is selected as the key region, and the region that exhibits different luminescence intensities (strong luminescence, weak luminescence, no luminescence) in cathodoluminescence is selected as the key region; Figure 2 In the image, a is a single-polarization microscope image of the sample. Figure 2 In the image, b is a cathodoluminescence micrograph of the sample. Figure 2 In the image, 'c' represents a standard optical photograph of the sample. Figure 2 In section c, the solid-lined box represents the microscopic observation area, and the dashed-lined box represents the laser surface scanning area; this embodiment involves three luminescence intensities of cathodic emission, namely weak emission ( Figure 2 ① in b), strong light emission ( Figure 2 ② in b), does not emit light ( Figure 2 ③ in b);

[0069] Step 3: Perform LA-ICP-MS micro-area in-situ laser surface scanning imaging test and image generation on key areas of the thin-film sample:

[0070] Step 301: Determine the types of elements to be tested and the element integration time; In this embodiment, a carbonate rock sample is being tested, and the types of elements tested include... 25 Mg 43 Ca, 55 Mn, 57 Fe、 88 Sr、 59 Co、 60 Ni、 89 Y、 208 Pb and REEs; where REEs include 139 La、 140 Ce、 141 Pr、 146 Nd, 147 Sm、 153 Eu、 157 Gd, 159 Tb, 163 Dy、 165 Ho、 166 Er、 169 Tm、 172 Yb and 175 Lu; the element integration time includes: element 25 Mg 43 The integration times for Ca are 4ms, and the element... 55 Mn, 57 Fe、 88 The Sr integration time is 6ms, and the element... 59 Co、 60 Ni、 89 Y、 208 The integration time for Pb is 10ms, and the element REEs ( 139 La- 175 The integration time for Lu is 8ms;

[0071] Step 302: Based on the characteristics of the mineral fabric in the area being scanned, determine the area scanning parameters that meet the requirements for area scanning spatial resolution, area scanning area, and area scanning time. The area scanning parameters include parameters such as laser scanning beam size, energy density, moving speed, ablation frequency, and scanning line spacing.

[0072] Specifically, based on the characteristics (including type and size) of the mineral fabric in the area being scanned, laser surface scanning is performed under preset scanning parameters. The spatial resolution, area, and time consumption of the surface scan under the preset scanning parameters are determined, and surface scanning parameters that meet the requirements of spatial resolution, area, and time consumption are selected. If the preset scanning parameters meet the requirements of spatial resolution, area, and time consumption, then the preset scanning parameters are used as the surface scanning parameters for the mineral fabric with that characteristic. If the preset scanning parameters do not meet the requirements of spatial resolution, area, and time consumption, then the preset scanning parameters are modified, laser surface scanning is performed again, and the spatial resolution, area, and time consumption of the surface scan under the modified preset scanning parameters are determined again, until the modified preset scanning parameters can meet the requirements of spatial resolution, area, and time consumption.

[0073] The mineral texture is characterized as follows: Larger texture: Area ≥ 15 mm 2 Medium structure: 1mm 2 ≤Area<15mm 2 Ultrafine structure: area <1mm 2 Generally, larger structures include granules, coarse-grained crystals with a hazy core and bright edge, gravel, and cathodic emission crystals with ring structures; medium structures include oolitic grains, medium-fine-grained crystals with a hazy core and bright edge, sand, and cathodic emission crystals with ring structures; ultrafine structures include small oolitic grains, fine-grained powder-mud crystals, powder-sand, and cathodic emission crystals with ring structures.

[0074] The preset scanning parameters based on the mineral fabric characteristics in the area scan region include: larger fabrics: 40-50 μm spot size, energy density 3 J / cm². 2 1. Ablation frequency 20Hz, moving speed 0.04-0.05mm / s, row spacing 40-50μm; medium structure: 20-30μm beam spot, energy density 3J / cm² 2 1. Ablation frequency 20Hz, moving speed 0.02-0.03mm / s, row spacing 20-30μm; 2. Microstructure: 5-10μm beam spot, energy density 3J / cm² 2 The etching frequency is 20Hz, the moving speed is 0.005-0.01mm / s, and the row spacing is 5-10μm.

[0075] In this embodiment, the area scanning region is selected as 920μm×920μm, and the determined area scanning parameters are: scanning beam size 20μm×20μm, energy density 3J / cm². 2 Movement speed 0.02 mm / s, ablation frequency 20 Hz, scan line spacing 20 μm;

[0076] Step 303: Based on the element types and element integration time determined in step 301 and the surface scanning parameters determined in step 302, perform LA-ICP-MS micro-area in-situ laser surface scanning imaging on key areas of the thin-film sample. Use Iolite software to process the data and obtain LA-ICP-MS micro-area in-situ laser surface scanning imaging results.

[0077] Step 4: Compare the cathode luminescence microscopy images with the LA-ICP-MS micro-area in-situ laser surface scanning imaging results, such as... Figure 3 As shown, representative line segments and points were determined. In this embodiment, a line segment passing through the boundary between calcite and dolomite and exhibiting significant variations in the content of elements such as Mn, Fe, Pb, Co, Ni, and REE was selected. This representative line segment also included bright spots in the cathodoluminescence microscopy image, which were then used as representative points. The representative line segments and points are shown in the figure. Figure 4 As shown by the solid line in CL, the elemental content of the LA-ICP-MS micro-area in-situ laser surface scanning imaging results corresponding to representative line segments and points in the cathodoluminescence microscopy images was read using the Iolite software. The elemental content was quantitatively corrected using the relative sensitivity factor (RSF). Because the results read by Iolite software are semi-quantitative results calibrated using the external standard method, matrix-matched standard material RSF quantitative correction is required. In this embodiment, the tested lithology is carbonate rock, and the standard material MACS-3 was selected as the RSF calibration reference material.

[0078] The formula for elemental content correction is:

[0079]

[0080]

[0081] C u.sam It is the content of the element u to be analyzed in the sample. This is a semi-quantitative content of the element u to be analyzed, extracted by the software Iolite. It refers to the content of element u in the calibration reference material. It is the semi-quantitative content of element u in the calibration reference material extracted by the software;

[0082] Based on the fabrication characteristics of the rock sample to be tested, multiple representative line segments and points were selected as comprehensively as possible at different locations in the cathodoluminescence microscopy images and LA-ICP-MS micro-area in-situ laser surface scanning imaging results. The elemental content was obtained and RSF quantitative correction was performed to obtain the elemental content at multiple corrected representative line segments and points. The elemental content curves at multiple representative line segments and points were plotted to make the data results more comprehensive and reliable, and to achieve quantitative analysis of the correlation between point-line-plane cathodoluminescence intensity and elemental content.

[0083] Step 5: Compile the elemental contents of the corrected representative line segments and points into an Excel spreadsheet, and plot the Mn, Fe, and REE elemental content curves for the representative line segments and points, as shown below. Figure 4 As shown, based on the element content curves on the representative line segments and points, the cathodic emission intensity of each element is classified, and the element (especially trace rare earth elements) content range values ​​in different emission intensity regions are determined. The different emission intensity regions include: weak emission regions and strong emission regions. Then, the quantitative relationship between cathodic emission intensity and element content (especially trace rare earth elements) is obtained, and the controlling factors of cathodic emission intensity are determined, that is, the types of main elements (especially trace rare earth elements) that control cathodic emission intensity are determined.

[0084] In the embodiments, the quantitative relationship between cathodic luminescence intensity and elemental content is shown in Table 1. In the weak luminescence region, the Mn content ranges from 20-300 ppm, the Fe content ranges from 5000-50000 ppm, and the ΣREE (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) content ranges from 20-4000 ppm. In the strong luminescence region, the Mn content ranges from 300-13000 ppm, and the Fe content ranges from 95%. -5000ppm, ΣREE content range 4000-44000ppm; it was found that the concentration range of Mn content >13000ppm, Fe content >50000ppm, and ΣREE content >44000ppm reached the quenching limit and caused concentration quenching luminescence. At the same time, it was determined that the controlling factors of cathodoluminescence intensity are: Mn and rare earth element ΣREE with content reaching the detection limit (20ppm) are cathodoluminescence activators, and Mn, Fe and ΣREE concentrations exceeding the limit are all quenchers.

[0085] Table 1

[0086]

[0087] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for determining the control factors of cathodic emission intensity based on laser surface scanning, comprising the following steps: Step 1: Obtain the rock sample to be tested and prepare a thin section sample; Step 2: Observe the thin section sample using a polarizing microscope and a cathodoluminescence microscope. Based on the polarizing microscopy characteristics and cathodoluminescence characteristics, determine the key areas, take pictures and record them to obtain polarizing microscope photos and cathodoluminescence microscope photos. Step 3: Perform LA-ICP-MS micro-area in-situ laser surface scanning on key areas of the thin section sample, determine the surface scanning parameters based on the mineral fabric characteristics in the surface scanning area, and obtain the LA-ICP-MS micro-area in-situ laser surface scanning imaging results; Step 4: Compare and combine the cathodoluminescence microscopy image with the LA-ICP-MS micro-area in-situ laser surface scanning imaging results to determine representative line segments and points. Read the element content in the LA-ICP-MS micro-area in-situ laser surface scanning imaging results corresponding to the representative line segments and points in the cathodoluminescence microscopy image. Perform relative sensitivity factor quantitative correction on the element content to obtain the corrected element content on the representative line segments and points. Step 5: Based on the element content of the corrected representative line segments and points, draw the element content curves of the representative line segments and points. According to the element content curves of the representative line segments and points, classify the cathodic emission intensity of each element, determine the element content range of different emission intensity regions, and then obtain the quantitative relationship between the cathodic emission intensity and the element type and content, and determine the cathodic emission intensity control factors.

2. The method according to claim 1, wherein, In step 1, the thin sheet sample is prepared by grinding and polishing.

3. The method according to claim 1 or 2, wherein, In step 1, the thickness of the thin film sample is 60-100 μm.

4. The method according to claim 1, wherein, In step 2, the key regions include one or more of the following: mineral texture transition zones, regions containing inclusion minerals, minerals with zonal structures, and recrystallized minerals, and regions exhibiting different luminescence in cathodoluminescence.

5. The method according to claim 1, wherein, Step 3 specifically includes: Step 301: Determine the types of elements to be tested and the element integration time; Step 302: Based on the characteristics of the mineral fabric in the area being scanned, determine the area scanning parameters that meet the requirements for area scanning spatial resolution, area scanning area, and area scanning time. Step 303: Based on the element types and element integration time determined in step 301 and the surface scanning parameters determined in step 302, perform LA-ICP-MS micro-area in-situ laser surface scanning on key areas of the thin-film sample, process the data, and obtain LA-ICP-MS micro-area in-situ laser surface scanning imaging results.

6. The method according to claim 5, wherein, In step 301, for the carbonate rock sample, the types of elements tested include... 25 Mg 43 Ca, 55 Mn, 57 Fe、 59 Co、 66 Zn, 88 Sr、 60 Ni、 89 Y, REEs and 208 One or more of Pb; wherein, REEs include 139 La、 140 Ce、 141 Pr, 146 Nd, 147 Sm、 153 Eu、 157 Gd, 159 Tb, 163 Dy、 165 Ho、 166 Er、 169 Tm、 172 Yb and 175 One or more combinations of Lu.

7. The method according to claim 5, wherein, In step 301, the element integration time includes: element 25 Mg 43 Ca, 55 Mn, 57 Fe and 88 The integration times for Sr are 3ms-7ms, and the element... 59 Co、 66 Zn, 60 Ni、 89 Y, REEs and 208 The integration time for Pb is 8ms-10ms.

8. The method according to claim 5, wherein, Step 302 specifically includes: based on the characteristics of the mineral composition in the area being scanned, performing laser area scanning under preset scanning parameters, determining the area scanning spatial resolution, area scanning area, and scanning time under the preset scanning parameters, and selecting area scanning parameters that meet the requirements of area scanning spatial resolution, area scanning area, and scanning time.

9. The method according to claim 5 or 8, wherein, In step 302, the surface scanning parameters include scanning beam size, energy density, moving speed, ablation frequency, and scanning line spacing.

10. The method according to claim 1, wherein, In step 4, the representative line segments and points include one or more of the following: line segments passing through zonal structures, line segments passing through the boundary between dolomite and calcite or other different structures, line segments passing through inclusions, line segments passing through recrystallized minerals, line segments with large variations in elemental content, and bright points in cathodoluminescence micrographs.

11. The method according to claim 1, wherein, In step 4, the quantitative correction of the relative sensitivity factor is performed using a standard substance that matches the matrix of the rock sample to be tested.

12. The method according to claim 1, wherein, In steps 4 and 5, multiple representative line segments and points are determined, the element content on multiple corrected representative line segments and points is obtained, and element content curves on multiple representative line segments and points are plotted.

13. The method according to claim 1, wherein, In step 5, the different light emission intensity regions include: weak light emission regions and strong light emission regions.

14. The method according to claim 13, wherein, Step 5 further includes: determining the range of element content for concentration quenching luminescence based on the element content range values ​​in different luminescence intensity regions.

15. The method according to claim 13, wherein, In step 5, the cathodoluminescence intensity control factor is determined at least by the following method: if the content of an element in the strong luminescence region is greater than its content in the weak luminescence region, then the element is a cathodoluminescence activator.

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