Cathode luminescence intensity control factor determination method based on laser surface scanning

Abstract

The invention provides a cathode luminescence intensity control factor determination method based on laser surface scanning. The method comprises the following steps: sampling and preparing a slice; observing and determining a key area through a polarizing microscope and a cathode luminescence microscope; carrying out LA-ICP-MS micro-area in-situ laser surface scanning; determining representative line segments and point locations by combining cathode luminescence microscope pictures and LA-ICP-MS microcell in-situ laser surface scanning imaging results, and performing relative sensitivity factor quantitative correction on element contents to obtain element contents on the corrected representative line segments and point locations; and obtaining a quantitative relation of correlation between the cathode luminescence intensity and the element types and contents, and determining cathode luminescence intensity control factors. According to the method, the quantitative relation of correlation between the diagenesis mineral cathode luminescence intensity and the types and contents of various elements can be obtained, then the cathode luminescence intensity control factors are determined, and the method has the advantages of being simple, convenient, efficient, wide in applicability and the like.

Description

Technical Field

[0001] The present invention relates to a method for determining the control factors of cathodoluminescence intensity based on laser surface scanning, belonging to the technical field of rock analysis. Background Art

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

[0003] Regarding the control factors of the cathodoluminescence intensity of diagenetic minerals, researchers generally recognize that Mn is an activator and Fe is a quencher in carbonate minerals (Liu Jie et al., 2000; Sun Jing et al., 2009; Liu Jinlian et al., 2010). Through technical means such as electron probe and atomic absorption spectroscopy, it is found that certain rare earth elements can act as activators, quenchers, and sensitizers for cathodoluminescence. However, due to the low concentration of rare earth elements in minerals, restricted by factors such as the detection limit and test accuracy of instruments, quantitative analysis of the relationship between rare earth element concentration and cathodoluminescence intensity has not been carried out (Zhou Lingdi et al., 1981; Huang Sijing, 1992). With the popularization of LA-ICP-MS technology, researchers have found that the contents of rare earth elements Sm, Eu, Tb, and Dy in carbonate minerals have a controlling effect on cathodoluminescence (Pan Liyin et al. Determination method and device for control factors of cathodoluminescence intensity of carbonate minerals [P]; CN110530961B).

[0004] Diagenetic minerals generally have diversity and complexity, such as mineral textures with inclusions, zonation structures, and irregular boundaries. If only the single points delineated under polarized light microscopy and cathodoluminescence microscopy are analyzed, it is easy to miss the information in the unselected areas. Moreover, the detection lower limit of the content of rare earth elements activating cathodoluminescence is generally 10-20 ppm (R.A. Mason & A.N. Mariano. Cathodoluminescence activation in manganese-bearing and rare-earth-bearing synthetic calcites. Chemical Geology, 1990, 88: 191-206), and the content of rare earth elements in carbonate minerals is generally low. Therefore, only analyzing the control effect of Sm, Eu, Tb, and Dy elements on cathodoluminescence is far from enough. Summary of the Invention

[0005] To solve the above technical problems, the purpose of the present invention is to provide a method for determining the control factors of cathodoluminescence intensity based on laser surface scanning. This method can obtain the quantitative relationship between the cathodoluminescence intensity of diagenetic minerals and the types and contents of various elements, and then determine the control factors of cathodoluminescence intensity, with the advantages of simplicity, high efficiency, wide applicability, etc.

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

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

[0008] Step 2: Observe the thin section sample with a polarized light microscope and a cathodoluminescence microscope, determine the key areas according to the polarized light microscopic characteristics and cathodoluminescence characteristics, take pictures and record them to obtain polarized light 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 the key areas of the thin section sample to obtain the LA-ICP-MS micro-area in-situ laser surface scanning imaging result;

[0010] Step 4: Combine the cathodoluminescence microscope photo with the LA-ICP-MS micro-area in-situ laser surface scanning imaging result, determine the representative line segments and points, and read the element contents in the LA-ICP-MS micro-area in-situ laser surface scanning imaging result corresponding to the representative line segments and points in the cathodoluminescence microscope photo; perform relative sensitivity factor (RSF) quantitative correction on the element contents to obtain the corrected element contents on the representative line segments and points;

[0011] Step 5: Based on the corrected element contents on the representative line segments and points, draw the element content curves on the representative line segments and points, classify the cathodoluminescence intensities of each element according to the element content curves on the representative line segments and points, determine the element content interval values in different luminescence intensity regions, and then obtain the quantitative relationship between the cathodoluminescence intensity and the types and contents of elements, and determine the control factors of cathodoluminescence intensity.

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

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

[0014] In the above method, preferably, in step 2, the key areas include one or more of: the mineral fabric transition zone, the mineral containing inclusions, the mineral with zonal structure, and the area of recrystallized minerals, and the areas showing different luminescence intensities 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, determine the surface scanning parameters that meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time consumption according to the characteristics of the mineral fabric in the surface scanning area;

[0018] Step 303, based on the types of elements and the 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 the key areas of the thin section sample, process the data, and obtain the LA-ICP-MS micro-area in-situ laser surface scanning imaging result.

[0019] In the above method, preferably, in step 301, for carbonate rock samples, the types of elements to be tested include 25 Mg, 43 Ca, 55 Mn, 57 Fe, 59 Co, 66 Zn, 88 Sr, 60 Ni, 89 Y, REEs and 208 Pb, etc., in combinations of one or more; among them, 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, etc., in combinations of one or more.

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

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

[0022] In the above method, preferably, in step 302, the surface scanning parameters include parameters such as scanning beam spot 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 several of the line segments passing through the zonal structure, the line segments passing through the boundary between dolomite and calcite or other boundaries of different fabrics, the line segments passing through inclusions, the line segments passing through recrystallized minerals, the line segments with large changes in element content, etc., and the bright points in the cathodoluminescence microscope photos.

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

[0025] In the above method, preferably, in steps 4 and 5, multiple representative line segments and points are determined, the element contents at the multiple corrected representative line segments and points are obtained, and the element content curves at the 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 observing the cathodoluminescence microscope photos according to experience and conventional methods.

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

[0028] In the above method, preferably, 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 that in the weak luminescence region, then the element is a cathodoluminescence activator.

[0029] The present invention provides a method for determining the control factors of cathodoluminescence intensity based on laser surface scanning. The present invention adopts the LA-ICP-MS micro-area in-situ laser surface scanning technology, which can not only quickly, comprehensively and accurately obtain the planar spatial distribution characteristics of the elemental composition of each diagenetic fabric, but also obtain the semi-quantitative results of elements linearly corrected by the external standard method. The present invention adopts relative sensitivity factor (RSF) quantitative correction, and for a single element or element ratio, quantitative data of any line segment and any orientation can be obtained. The surface scanning data obtained therefrom can be used in combination with the results of LA-ICP-MS micro-area in-situ point ablation. By combining the planar distribution characteristics of cathodoluminescence with the results of LA-ICP-MS micro-area in-situ laser surface scanning imaging, the present invention quantitatively analyzes the relationship between the cathodoluminescence intensity of minerals and various trace rare earth elements from different levels of point-line-plane imaging, providing a technical method for in-depth research and identification of the types and contents of elements controlling the 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 on micron-scale fabrics with element contents at the ppb level.

[0032] ② It realizes the quantitative analysis of the correlation between the cathodoluminescence intensity of diagenetic minerals and various trace rare earth elements in different forms of point-line-plane imaging.

[0033] ③ It makes up for the defect of missing important information due to analyzing local data at a single point.

[0034] ④ It solves the disadvantages of high requirements for element content, low detection accuracy, or difficult sampling in solution chemical analysis in electron probe and atomic absorption spectroscopy analysis.

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

[0036] Figure 1 It is a flow schematic diagram of the method for determining the control factors of cathodoluminescence intensity based on laser surface scanning in the specific embodiment of the present invention.

[0037] Figure 2 It is a polarized light microscope photo, a cathodoluminescence microscope photo and an optical photo of the key area in the embodiment.

[0038] Figure 3 It is a cathodoluminescence microscope photo and the results of LA-ICP-MS micro-area in-situ laser surface scanning imaging in the embodiment.

[0039] Figure 4Element content curves at representative line segments and points in the embodiments. Detailed implementation manners

[0040] For a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the technical solutions of the present invention will be described in detail below, but it should not be construed as a limitation on the scope of implementation of the present invention.

[0041] According to the specific implementation manners of the present invention, the present invention provides a method for determining the control factors of cathodoluminescence intensity based on laser surface scanning, as Figure 1 shown, which includes the following steps:

[0042] Step 1: Obtain a rock sample to be measured and prepare a thin-section sample.

[0043] Step 2: Observe the thin-section sample with a polarized light microscope and a cathodoluminescence microscope. According to the polarized light microscopic characteristics and cathodoluminescence characteristics, determine the key areas, take pictures and record them to obtain polarized light microscope photos and cathodoluminescence microscope photos.

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

[0045] Step 4: Combine the cathodoluminescence microscope photos with the LA-ICP-MS micro-area in-situ laser surface scanning imaging results to determine representative line segments and points, and read (software Iolite can be used) the element contents 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 microscope photos; perform relative sensitivity factor (RSF) quantitative correction on the element contents to obtain the corrected element contents at the representative line segments and points.

[0046] Step 5: Based on the corrected element contents at the representative line segments and points, draw element content curves at the representative line segments and points. According to the element content curves at the representative line segments and points, classify the cathodoluminescence intensities of each element, determine the element content interval values in different luminescence intensity regions, and further obtain the quantitative relationship between the cathodoluminescence intensity and the types and contents of elements (especially trace rare earth elements), and determine the cathodoluminescence intensity control factors, that is, determine the types and contents of the main elements (especially trace rare earth elements) that control the cathodoluminescence intensity.

[0047] In some embodiments, in Step 1, the thin-section sample is prepared by grinding and polishing.

[0048] In some embodiments, in step 1, the thickness of the thin slice 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 areas include one or several of the microstructural feature complex areas such as the mineral fabric transition zone, minerals containing inclusions, minerals with zonal structures, and recrystallized minerals affected by multi-stage diagenetic fluid activities, and the areas presenting different luminescence intensities 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: Determine the surface scanning parameters that meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time consumption according to the characteristics of the mineral fabric in the surface scanning area;

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

[0054] In some embodiments, in step 301, for carbonate rock samples, the types of elements to be tested include 25 Mg, 43 Ca, 55 Mn, 57 Fe, 59 Co, 66 Zn, 88 Sr, 60 Ni, 89 Y, REEs and 208 Pb, etc., in combinations of one or several; 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 175A combination of one or more of Lu, etc.

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

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

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

[0058] In some embodiments, in step 302, the characteristics of the mineral fabric are classified as: larger fabric: area ≥ 15 mm 2 ; medium fabric: 1 mm 2 ≤ area < 15 mm 2 ; ultra - fine fabric: area < 1 mm 2; Usually, the larger fabric components include pisolites, cloudy-core bright-edge coarse crystals - gravel crystals, gravel debris, crystals with zoned structures under cathodoluminescence, etc.; the medium fabric components include ooids, cloudy-core bright-edge medium crystals - fine crystals, sand debris, crystals with zoned structures under cathodoluminescence, etc.; the ultra-fine fabric components include small ooids, silt - clay crystals, silt debris - sand debris, crystals with zoned structures under cathodoluminescence, etc. Further, the scanning parameters preset based on the characteristics of the mineral fabric in the area of the surface scan include: for the larger fabric components: a beam spot of 40 - 50 μm, an energy density of 3 J / cm 2 , an erosion frequency of 20 Hz, a moving speed of 0.04 - 0.05 mm / s, and a line spacing of 40 - 50 μm; for the medium fabric components: a beam spot of 20 - 30 μm, an energy density of 3 J / cm 2 , an erosion frequency of 20 Hz, a moving speed of 0.02 - 0.03 mm / s, and a line spacing of 20 - 30 μm; for the ultra-fine fabric components: a beam spot of 5 - 10 μm, an energy density of 3 J / cm 2 , an erosion frequency of 20 Hz, a moving speed of 0.005 - 0.01 mm / s, and a line spacing of 5 - 10 μm.

[0059] In some embodiments, in step 4, the representative line segments and points include: one or several of the line segments passing through the zoned structure, the line segments passing through the junction of dolomite and calcite or other junctions of different fabrics, the line segments passing through the inclusions, the line segments passing through the recrystallized minerals, the line segments with large changes in element content, etc., and the bright points in the cathodoluminescence microscope photographs.

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

[0061] In some embodiments, in steps 4 and 5, multiple representative line segments and points are determined, the element contents at the corrected multiple representative line segments and points are obtained, and the element content curves at the multiple representative line segments and points are plotted. Specifically, based on the fabric characteristics of the rock sample to be measured, multiple representative line segments and points are selected at different positions in the cathodoluminescence microscope photographs and the LA-ICP-MS micro-area in-situ laser surface scan imaging results, the element contents are obtained and RSF quantitative correction is performed to obtain the element contents at the corrected multiple representative line segments and points, and the element content curves at the multiple representative line segments and points are plotted, making the data results more comprehensive and reliable and realizing the quantitative analysis of the correlation between the cathodoluminescence intensity and the element content of point - line - plane.

[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 observing the cathodoluminescence microscope photographs according to experience and conventional methods.

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

[0064] In some embodiments, in step 5, the cathode luminescence 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 that in the weak luminescence region, then the element is a cathode luminescence activator.

[0065] Embodiment

[0066] This embodiment provides a method for determining the cathode luminescence intensity control factor based on laser surface scanning, which determines the cathode luminescence control factor of calcite minerals in the dolomitic carbonate rock wall with high rare earth content, and specifically includes the following steps:

[0067] Step 1: Obtain a rock sample to be measured, and prepare a thin slice sample with a thickness of 100 μm through grinding and polishing.

[0068] Step 2: Observe the thin slice sample with a polarized light microscope and a cathode luminescence microscope, determine the key areas according to the polarized light microscopic characteristics and cathode luminescence characteristics, take pictures and record them to obtain polarized light microscope photos and cathode luminescence microscope photos; the polarized light microscope photos, cathode luminescence microscope photos and optical photos of the key areas are as Figure 2 shown; in this embodiment, the coexisting area of calcite and dolomite (i.e., the mineral texture transition zone area) is selected, and the areas with different luminescence intensities (strong luminescence, weak luminescence, non-luminescence) in the cathode luminescence are used as key areas; Figure 2 where a in is the polarized light microscope photo of the sample, Figure 2 b in is the cathode luminescence microscope photo of the sample, Figure 2 c in is the ordinary optical photo of the sample, Figure 2 the solid line frame in c of is the microscopic observation area, and the dotted line frame is the laser surface scanning area; this embodiment involves three cathode luminescence intensities, namely weak luminescence ( Figure 2 ① in b of), strong luminescence ( Figure 2 ② in b of), non-luminescence ( Figure 2 ③ in b of);

[0069] Step 3: Conduct LA-ICP-MS micro-area in-situ laser surface scanning imaging test and mapping on the key areas of the thin slice sample:

[0070] Step 301: Determine the types of elements to be tested and the integration time for each element. In this embodiment, the sample to be tested is a carbonate rock, and the types of elements to be tested include 25 Mg, 43 Ca, 55 Mn, 57 Fe, 88 Sr, 59 Co, 60 Ni, 89 Y, 208 Pb, and REEs. Among them, 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 integration time for each element includes: the integration times for elements 25 Mg, 43 Ca are 4 ms respectively, the integration times for elements 55 Mn, 57 Fe, 88 Sr are 6 ms respectively, the integration times for elements 59 Co, 60 Ni, 89 Y, 208 Pb are 10 ms respectively, and the integration times for elements REEs ( 139 La - 175 Lu) are 8 ms respectively;

[0071] Step 302: Determine the surface scanning parameters that meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time consumption according to the characteristics of the mineral texture in the surface scanning area. The surface scanning parameters include parameters such as laser scanning spot 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 surface scanning area, laser surface scanning is performed under preset scanning parameters, and the surface scanning spatial resolution, surface scanning area, and surface scanning time consumption under the preset scanning parameters are determined. The surface scanning parameters that meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time consumption are screened out. If the preset scanning parameters meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time consumption, the preset scanning parameters are used as the surface scanning parameters for the mineral fabric with such characteristics. If the preset scanning parameters do not meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time consumption, the preset scanning parameters are modified, and laser surface scanning is performed again. The surface scanning spatial resolution, surface scanning area, and surface scanning time consumption under the modified preset scanning parameters are determined again until the modified preset scanning parameters can meet the requirements of surface scanning spatial resolution, surface scanning area, and surface scanning time consumption.

[0073] The characteristics of the mineral fabric are classified as: larger fabric: area ≥ 15 mm 2 ; medium fabric: 1 mm 2 ≤ area < 15 mm 2 ; ultra-fine fabric: area < 1 mm 2 ; Generally, the larger fabric includes pisolites, cloudy core bright edge coarse crystals - gravel crystals, gravel debris, crystals with zoned structure in cathodoluminescence, etc.; the medium fabric includes ooids, cloudy core bright edge medium crystals - fine crystals, sand debris, crystals with zoned structure in cathodoluminescence, etc.; the ultra-fine fabric includes small ooids, fine powder crystals - muddy crystals, powder debris - sand debris, crystals with zoned structure in cathodoluminescence, etc.

[0074] The scanning parameters preset based on the characteristics of the mineral fabric in the surface scanning area include: larger fabric: beam spot of 40 - 50 μm, energy density of 3 J / cm 2 , erosion frequency of 20 Hz, moving speed of 0.04 - 0.05 mm / s, line spacing of 40 - 50 μm; medium fabric: beam spot of 20 - 30 μm, energy density of 3 J / cm 2 , erosion frequency of 20 Hz, moving speed of 0.02 - 0.03 mm / s, line spacing of 20 - 30 μm; ultra-fine fabric: beam spot of 5 - 10 μm, energy density of 3 J / cm 2 , erosion frequency of 20 Hz, moving speed of 0.005 - 0.01 mm / s, line spacing of 5 - 10 μm;

[0075] In this embodiment, the selected surface scanning area is 920 μm × 920 μm, and the determined surface scanning parameters are: scanning beam spot size of 20 μm × 20 μm, energy density of 3 J / cm 2 , moving speed of 0.02 mm / s, erosion frequency of 20 Hz, scanning line spacing of 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 in-situ laser surface scanning imaging test on the key area of the thin slice sample by LA-ICP-MS, and use software Iolite to process the data to obtain the LA-ICP-MS in-situ laser surface scanning imaging results;

[0077] Step 4: Compare the cathodoluminescence microscope photos with the LA-ICP-MS in-situ laser surface scanning imaging results. As Figure 3 shown, determine the representative line segments and points. In this embodiment, select the line segment that passes through the boundary between calcite and dolomite and has large changes in the contents of elements such as Mn, Fe, Pb, Co, Ni, and REE. At the same time, this representative line segment has bright points in the cathodoluminescence microscope photos as representative points. The representative line segment and points are as shown by the solid line in CL in Figure 4 . Use software Iolite to read the element contents in the LA-ICP-MS in-situ laser surface scanning imaging results corresponding to the representative line segments and points in the cathodoluminescence microscope photos; perform relative sensitivity factor (RSF) quantitative correction on the element contents. Since the results read by software Iolite are semi-quantitative results calibrated by the element external standard method, RSF quantitative correction of the reference material for matrix matching is required. In this embodiment, the lithology of the tested rock is carbonate rock, and the reference material MACS-3 is selected as the RSF calibration reference material.

[0078] The element content correction formula is:

[0079]

[0080]

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

[0082] Based on the fabric characteristics of the rock sample to be tested, select multiple representative line segments and points as comprehensively as possible at different positions in the cathodoluminescence microscope photos and the LA-ICP-MS in-situ laser surface scanning imaging results, obtain the element contents and perform RSF quantitative correction, obtain the element contents at multiple corrected representative line segments and points, and draw the element content curves at multiple representative line segments and points to make the data results more comprehensive and reliable, and realize the quantitative analysis of the correlation between the cathodoluminescence intensity and the element content of point-line-plane.

[0083] Step 5: Organize the element contents at the corrected representative line segments and points in an Excel table, and plot the Mn, Fe, and REEs element content curves at the representative line segments and points. As Figure 4 shown, according to the element content curves at the representative line segments and points, classify the cathodoluminescence intensities of each element, and determine the element (especially trace rare earth element) content interval values in different luminescence intensity regions. The different luminescence intensity regions include: weak luminescence region, strong luminescence region. Furthermore, obtain the quantitative relationship between the cathodoluminescence intensity and the element content (especially trace rare earth elements), and determine the cathodoluminescence intensity control factors, that is, determine the types of main elements (especially trace rare earth elements) that control the cathodoluminescence intensity;

[0084] In the embodiment, the quantitative relationship between the cathodoluminescence intensity and the element content is shown in Table 1. The Mn content interval value in the weak luminescence region is 20 - 300 ppm, the Fe content interval value is 5000 - 50000 ppm, and the ΣREE (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) content interval value is 20 - 4000 ppm; the Mn content interval value in the strong luminescence region is 300 - 13000 ppm, the Fe content interval value is 95 - 5000 ppm, and the ΣREE content interval value is 4000 - 44000 ppm; it is obtained that the Mn content range for concentration quenching luminescence caused by the concentration reaching the quenching limit is >13000 ppm, the Fe content range is >50000 ppm, and the ΣREE content range is >44000 ppm; at the same time, it is determined that the cathodoluminescence intensity control factors are: Mn and rare earth element ΣREE with a content reaching the detection limit (20 ppm) are cathodoluminescence activators, and when the concentrations of Mn, Fe, and ΣREE exceed the limit, they are all quenchers.

[0085] Table 1

[0086]

[0087] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is impossible to list all the implementation manners here. Any obvious changes or variations derived from the technical solutions of the present invention still fall within the protection scope of the present invention.

Claims

1. A method for determining cathode luminescence intensity control factors 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 slice sample with a polarizing microscope and a cathode luminescence microscope, determine the key area according to the polarizing microscope characteristics and the cathode luminescence characteristics, take pictures and record them, and obtain polarizing microscope pictures and cathode luminescence microscope pictures; Step 3, performing LA-ICP-MS micro-area in-situ laser surface scanning on key areas of the thin slice sample to obtain LA-ICP-MS micro-area in-situ laser surface scanning imaging results; Step 4, combining the cathode luminescence microscope photograph with the LA-ICP-MS micro-area in-situ laser surface scanning imaging result, determining representative line segments and points, reading the element content in the LA-ICP-MS micro-area in-situ laser surface scanning imaging result corresponding to the representative line segments and points in the cathode luminescence microscope photograph; performing quantitative correction of the element content by relative sensitivity factor to obtain the corrected element content on the representative line segments and points; Step 5: Based on the element contents on the corrected representative line segments and points, draw element content curves on the representative line segments and points; classify the cathode luminescence intensity of each element according to the element content curves on the representative line segments and points; determine the element content interval values ​​in different luminescence intensity areas; and then obtain a quantitative relationship between the correlation between cathode luminescence intensity and the type and content of the element, and determine the cathode luminescence intensity control factors.

2. The method according to claim 1, wherein: In step 1, the thin slice sample is prepared by grinding and polishing; Preferably, in step 1, the thickness of the thin slice sample is 60-100 μm.

3. The method according to claim 1, wherein: In step 2, the key areas include: one or more of the mineral fabric transition zone, inclusion-containing minerals, minerals with ring-band structures, and recrystallized minerals, and areas showing different luminescence intensities in cathode luminescence.

4. The method according to claim 1, wherein: Step 3 specifically includes: Step 301, determine the element type and element integration time to be tested; Step 302, determining surface scanning parameters that meet the surface scanning spatial resolution, surface scanning area, and surface scanning time requirements according to the characteristics of the mineral structure in the surface scanning area; Step 303: Based on the element type and element integration time determined in step 301 and the surface scanning parameters determined in step 302, LA-ICP-MS micro-area in-situ laser surface scanning is performed on the key area of ​​the thin-section sample, and the data is processed to obtain LA-ICP-MS micro-area in-situ laser surface scanning imaging results.

5. The method according to claim 4, wherein: In step 301, for carbonate rock samples, the elements tested include 25 Mg, 43 Ca, 55 Mn, 57 Fe, 59 Co. 66 Zn, 88 Sr. 60 You, 89 Y, REEs, and 208 One or a combination of Pb; REEs include 139 La, 140 Ce, 141 Pr, 146 Nd, 147 Sm, 153 Eu, 157 Gd, 159 Tb, 163 Dy, 165 Ho, 166 2. 169 Tm, 172 Yb and 175 One or a combination of Lu; Preferably, in step 301, the element integration time includes: element 25 Mg, 43 Ca, 55 Mn, 57 Fe and 88 The integration time of Sr is 3ms-7ms, and the element 59 Co. 66 Zn, 60 You, 89 Y, REEs, and 208 The integration time of Pb is 8ms-10ms respectively.

6. The method according to claim 4, wherein: Step 302 specifically includes: based on the characteristics of the mineral structure in the surface scanning area, performing laser surface scanning under preset scanning parameters, and determining the surface scanning spatial resolution, surface scanning area and surface scanning time under the preset scanning parameters, and screening out surface scanning parameters that meet the surface scanning spatial resolution, surface scanning area and surface scanning time requirements.

7. The method according to claim 4 or 6, wherein: In step 302, the surface scanning parameters include scanning beam spot size, energy density, moving speed, ablation frequency and scanning line spacing.

8. The method according to claim 1, wherein: In step 4, the representative line segments and points include: one or more of the line segments passing through the zoning structure, the line segments passing through the boundary between dolomite and calcite or other boundaries between different structures, the line segments passing through inclusions, the line segments passing through recrystallized minerals, the line segments with large changes in element content, and the bright spots in the cathode luminescence microscope photograph.

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

10. The method according to claim 1, wherein: In step 4 and step 5, a plurality of representative line segments and points are determined, the element contents on a plurality of corrected representative line segments and points are obtained, and element content curves on the plurality of representative line segments and points are drawn.

11. The method according to claim 1, wherein: In step 5, the different luminous intensity regions include: a weak luminous region and a strong luminous region.

12. The method according to claim 11, wherein: Step 5 further includes: determining the element content range of concentration quenching luminescence based on the element content interval values ​​in different luminescence intensity regions.

13. The method according to claim 11, wherein: In step 5, the cathode luminescence intensity control factor is determined at least in the following manner: if the content of an element in a strong luminescence region is greater than that in a weak luminescence region, then the element is a cathode luminescence activator.

Images