A method for analyzing occurrence state of rare earth elements in sedimentary rock and indicating ore prospecting direction

Abstract

The application provides a rare earth element occurrence state analysis and ore prospecting direction indication method in sedimentary rock, and belongs to the technical field of REE occurrence analysis, and comprises the following steps: preparing a laser sheet at a position with strong alteration of a rare earth element-containing sedimentary rock sample; performing full-spectrum element surface scanning on the laser sheet by using mu-XRF to obtain element spatial distribution information of the laser sheet; obtaining a backscattering BSE image by using a scanning electron microscope, and performing energy spectrum analysis on a high-BSE-intensity area; performing mineral phase analysis on a key area with rare earth mineral distribution; performing in-situ micro-area U-Pb dating of rare earth mineral types by using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS); and performing neodymium isotope analysis on in-situ micro-areas of rare earth minerals or associated accessory minerals. The rare earth element occurrence state analysis and ore prospecting direction indication method is used to solve the problems of low analysis efficiency, low intelligent degree of the analysis process and poor reliability of analysis results, and provides a scientific basis for ore prospecting work.

Description

Technical Field

[0001] This invention relates to the field of REE occurrence analysis technology, and in particular to a method for analyzing the occurrence state of rare earth elements in sedimentary rocks and indicating the direction of mineral exploration. Background Technology

[0002] Rare earth elements, due to their special uses and importance, are known as "industrial vitamins" or "industrial MSG." They are now widely used in many fields such as national defense, aerospace, special materials, metallurgy, energy, and agriculture. As a strategic mineral resource, they have received high attention from the state.

[0003] Based on the different geological processes involved in rare earth enrichment, rare earth deposits can be divided into endogenous and exogenous deposits. Among them, alkaline rock-carbonate rock type and ion adsorption type rare earth deposits are the two most important types of rare earth deposits in my country. Their ore body occurrence characteristics, rare earth element (REE) occurrence state, deposit genesis, and utilization evaluation have been studied in depth. Studies suggest that the ore bodies and mineralization of alkaline rock-carbonate rock type deposits are mainly developed in carbonatite bodies or appear as rare earth-bearing vein-like to veinlet-like carbonatite superimposed on alkaline complexes. Among them, bastnaesite, apatite, monazite, epidote, amphibole, and bastnaesite are commonly seen rare earth element (REE)-bearing minerals, with bastnaesite being the most common. Ion-adsorption type rare earth ore bodies are mostly hosted in siliceous-aluminous clay weathering crusts that have undergone moderate to strong weathering under subtropical climate conditions. The underlying parent rocks of these ore-bearing weathering crusts are mainly granites. In the weathering products, rare earth elements (REEs) are mainly fixed by clay minerals such as kaolinite and halloysite through interfacial reactions such as electrostatic adsorption, surface complexation or ion exchange. The occurrence states are various phases such as water-soluble phase, ion-exchange state, organically combined state, single mineral phase, isomorphous phase or micro-encapsulation dispersed phase.

[0004] However, compared to alkaline-carbonate rock and ion-adsorption type rare earth deposits, which have a higher level of research, clearer occurrence states of rare earth elements (REEs), and more mature exploration models, the research on the occurrence state of REEs in sedimentary rocks is relatively weak both domestically and internationally. Furthermore, the methods used are relatively simple and lack accuracy. Currently, the main analytical method used by domestic exploration units is to perform optical / thin section processing and optical microscopy to identify sedimentary rocks with high REE content discovered during exploration. Scanning electron microscopy may also be conducted to search for potential rare earth minerals and determine the occurrence state of REEs, aiming to support further mineral exploration and assess their utilization value. However, this method has the following problems: 1. Sedimentary rocks collected during the exploration stage mostly come from the surface or shallow trenches. Due to weathering, sedimentary rocks may undergo limonite or kaolinization, causing the primary minerals in the sedimentary rocks to darken in color and become less clear in structure, which is not conducive to conducting rock and mineral identification using optical microscopy; 2. Using optical microscopy to conduct rock and mineral identification requires a high level of expertise and experience from the identification personnel, the identification process may be time-consuming, and the reliability of the identification results is poor; 3. This method can only provide qualitative textual identification reports and cannot display the occurrence state of rare earth elements (REE) in the form of "comprehensive maps + quantitative data", and its role in indicating the direction of mineral exploration is poor. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the purpose of this invention is to provide a method for analyzing the occurrence state of rare earth elements in sedimentary rocks and indicating the direction of mineral exploration, so as to solve the problems of low analysis efficiency, low level of intelligence in the analysis process and poor reliability of analysis results, and to provide a certain scientific basis for guiding mineral exploration.

[0006] To achieve the above objectives, the present invention provides the following solution: a method for analyzing the occurrence state of rare earth elements in sedimentary rocks, comprising the following steps:

[0007] Step 1: Select sedimentary rock samples containing rare earth elements obtained during the mineral exploration stage, and prepare the sedimentary rock samples containing rare earth elements into laser sheets;

[0008] Step 2: After fabricating the laser sheet, perform a full-spectrum elemental surface scan on the laser sheet using a micro-area X-ray fluorescence spectrometer (μ-XRF) to obtain the elemental spatial distribution information of the laser sheet;

[0009] Step 3: Obtain backscattered BSE images using a scanning electron microscope and perform energy dispersive spectroscopy analysis on the high BSE intensity regions;

[0010] Step 4: Use the TESCAN TIMA automated mineral analysis system to perform mineral phase analysis on the key areas of rare earth mineral distribution delineated in Steps 2 and 3.

[0011] Preferably, in step one, before the laser sheet is made, the rare earth element-containing sedimentary rock sample is cut, glued, mechanically ground and polished according to the location of the hydrothermal veins with strong alteration.

[0012] Preferably, the laser sheet has a size of 2cm × 3cm and a thickness of 100–200μm.

[0013] Preferably, in step two, the obtained spatial distribution information of elements is analyzed, and based on the rare earth element types and the distribution patterns and characteristics of rare earth elements and other elements, the category of rare earth minerals and their distribution patterns in the laser sheet are preliminarily determined.

[0014] Preferably, in step three, before acquiring the backscattered electron (BSE) image using a scanning electron microscope, the surface of the laser sheet needs to be carbon-sprayed.

[0015] Preferably, in step three, the high BSE intensity region is analyzed by energy dispersive spectroscopy (EDS) to qualitatively obtain the chemical composition data of the analyzed minerals, thereby determining the types of rare earth minerals.

[0016] Preferably, in step four, the TESCAN automated mineral analysis system TIMA is used to perform mineral phase TIMA analysis on key areas of rare earth mineral distribution to obtain the rare earth mineral types, contents, and combination characteristics with other minerals in the rare earth element sedimentary rock sample.

[0017] This invention also provides a mineral exploration direction indication technology based on the analytical method of rare earth element occurrence in sedimentary rocks, comprising the following steps:

[0018] Step 5: Based on the rare earth mineral types obtained in Step 4, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used to perform in-situ micro-area U-Pb dating on the rare earth mineral types to obtain the age of mineralization.

[0019] Step 6: Based on the LA-ICP-MS in-situ micro-area U-Pb dating in Step 5, perform laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) in-situ micro-area Nd isotope analysis on rare earth minerals or associated accessory minerals in the rare earth element-bearing sedimentary rock samples to infer the origin of the ore-forming materials.

[0020] Preferably, in step five, the rare earth-rich sedimentary rock sample contains six rare earth-rich minerals: monazite, xenotime, bastnaesite, sphene, epidote, and apatite. The mineralization age is obtained based on LA-ICP-MS in-situ micro-area U-Pb dating of these six minerals, specifically including the following:

[0021] If the rare earth mineral in the sedimentary rock sample containing rare earth elements is one of the above six minerals, in-situ micro-area U-Pb dating is performed directly to obtain the mineralization age.

[0022] If the rare earth minerals in the rare earth element-bearing sedimentary rock sample do not contain the above six minerals, but the accessory minerals associated with the rare earth minerals are the above six minerals, then the associated accessory minerals are subjected to in-situ micro-area U-Pb dating to indirectly determine the mineralization age.

[0023] Preferably, in step six, the obtained rare earth mineralization age and the results obtained from LA-MC-ICP-MS in-situ micro-area analysis are used... 143 Nd / 144 The Nd ratio calculation yields the εNd(t) values ​​of rare earth minerals or associated accessory minerals, specifically including the following:

[0024] If the value of εNd(t) is greater than zero, then the rare earth minerals originate from the depleted mantle.

[0025] If the value of εNd(t) is less than zero, then the rare earth minerals originate from the Earth's crust or enriched mantle.

[0026] According to the specific technical solution provided by the present invention, the present invention discloses the following technical effects:

[0027] This invention provides a method for analyzing the occurrence state of rare earth elements in sedimentary rocks and a method for indicating mineral exploration direction, which solves the problems of low analysis efficiency, low level of intelligence in the analysis process, and poor reliability of analysis results in existing methods, and provides a certain scientific basis for the deployment of the next mineral exploration work. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a flowchart illustrating a method for analyzing the occurrence state of rare earth elements in sedimentary rocks and indicating mineral exploration directions according to the present invention.

[0030] Figure 2 This is a schematic diagram of the principle provided in Embodiment 1 of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The purpose of this invention is to provide a method for analyzing the occurrence state of rare earth elements in sedimentary rocks and indicating the direction of mineral exploration, so as to solve the problems of low analysis efficiency, low level of intelligence in the analysis process and poor reliability of analysis results in existing methods, and to provide a certain scientific basis for guiding mineral exploration.

[0033] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Figure 1 This is a flowchart illustrating a method for analyzing the occurrence state of rare earth elements in sedimentary rocks and indicating mineral exploration directions according to the present invention. Figure 1 As shown, this invention provides a method for analyzing the occurrence state of rare earth elements in sedimentary rocks and indicating the direction of mineral exploration, specifically implemented through the following scheme:

[0035] Step 1: Select rare earth element (REE) sedimentary rock samples obtained during the mineral exploration stage, and prepare the rare earth element (REE) sedimentary rock samples into laser sections;

[0036] Before fabricating the laser sheet, the rare earth element (REE) sedimentary rock sample is cut, glued, mechanically ground, and polished according to the location of well-developed hydrothermal veins and strong alteration. The laser sheet has a size of 2cm × 3cm and a thickness of 100–200μm. For some samples with well-developed sedimentary bedding or many fractures and are fragile, thermoplastic resin is used to effectively fix them on the outside to prevent the sedimentary rock from breaking during the grinding and polishing process.

[0037] Step 2: After fabricating the laser sheet, a full-spectrum elemental surface scan is performed on the laser sheet using a micro-area X-ray fluorescence spectrometer (μ-XRF) to obtain the elemental spatial distribution information of the laser sheet;

[0038] Among them, the spatial distribution information of the acquired elements is analyzed. Based on the rare earth element types and the distribution patterns and characteristics of rare earth elements and other elements, and with reference to the table of common industrially valuable rare earth minerals, as shown in Table 1, the categories of rare earth minerals and their distribution patterns in the laser sheet are preliminarily determined.

[0039] Table 1 Common rare earth minerals with industrial value

[0040]

[0041]

[0042] Step 3: Obtain backscattered electron (BSE) images using a scanning electron microscope and perform energy dispersive spectroscopy analysis on the high BSE intensity regions;

[0043] Before acquiring backscattered electron (BSE) images using a scanning electron microscope (SEM), the surface of the laser sheet needs to be carbonized. Then, the areas with high rare earth content revealed by micro-area X-ray fluorescence spectrometry (XRF) analysis images of the laser sheet are observed in detail using a SEM. By adjusting the grayscale of the backscattered electron images acquired by the SEM, the grayscale changes in the study area are observed; the brighter the area in the image, the higher the atomic number. Generally, rare earth elements have higher atomic numbers, and minerals rich in rare earth elements also have higher brightness in the backscattered images. The obtained backscattered images are compared and analyzed with elemental surface scan images obtained by XRF to identify the possible distribution areas of rare earth minerals in the laser sheet. The high BSE intensity areas are then analyzed by energy dispersive spectroscopy (EDS), and the chemical composition data of the analyzed minerals are qualitatively obtained. Referring to Table 1, the types of rare earth-containing minerals are determined.

[0044] Step 4: Use the TESCAN Automated Mineral Analysis System (TIMA) to perform mineral phase analysis on the key areas of rare earth mineral distribution delineated in Steps 2 and 3.

[0045] Mineral phase analysis was performed on key areas of rare earth mineral distribution using the TESCAN Automated Mineral Analysis System (TIMA). TIMA identifies rare earth minerals by comparing the energy dispersive spectral curves of all minerals in the area with those of a standard mineral library. The system obtains the composition, content, and co-occurrence relationships of different minerals in the key study area using laser sections. By fully combining the μ-XRF elemental surface scans, BSE images, and TIMA mineral phase analysis maps of the key areas of the studied laser sections, the types and occurrence states of rare earth minerals in sedimentary rock samples with industrial-grade rare earth element (REE) content obtained during the mineral exploration stage can be accurately determined.

[0046] Step 5: Based on the rare earth mineral types obtained in Step 4, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) in-situ micro-area U-Pb dating is performed on the rare earth mineral types to obtain the age of mineralization.

[0047] The rare earth-rich sedimentary rock samples contained six rare earth-rich minerals: monazite, xenotime, bastnaesite, sphene, epidote, and apatite. The mineralization age was determined based on LA-ICP-MS in-situ micro-area U-Pb dating of these six minerals, specifically as follows:

[0048] If the rare earth mineral in the rare earth element (REE) sedimentary rock sample is one of the above six minerals, in-situ micro-area U-Pb dating can be performed directly to obtain the mineralization age.

[0049] If the rare earth minerals in the rare earth element (REE) sedimentary rock sample do not contain the above six minerals, but the accessory minerals associated with the rare earth minerals are the above six minerals, then the associated accessory minerals are dated in situ using micro-area U-Pb dating to indirectly determine the mineralization age.

[0050] During in-situ analysis, the analysis points were numbered and their locations recorded for subsequent in-situ micro-area neodymium (Nd) isotope analysis. Information on the metallogenic epoch, magmatic epoch, stratigraphic sedimentary sequence, and tectonic events of other known deposits in the exploration area and surrounding regions was fully collected. The mineralization ages of rare earth mineralization in the sedimentary rock samples obtained in the study were compared with the aforementioned geological time series data to preliminarily determine the geological events and geological bodies related to the rare earth mineralization in the exploration area.

[0051] Step 6: Based on the LA-ICP-MS in-situ micro-area U-Pb dating in Step 5, perform laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) in-situ micro-area neodymium (Nd) isotope analysis on rare earth minerals or associated accessory minerals in the rare earth element (REE) sedimentary rock samples to infer the origin of the ore-forming materials.

[0052] Among them, the rare earth mineralization age and LA-MC-ICP-MS in-situ micro-area analysis were used to obtain 143 Nd / 144 The Nd ratio calculation yields the εNd(t) values ​​of rare earth minerals or associated accessory minerals, specifically including the following:

[0053] If the value of εNd(t) is greater than zero, then the rare earth minerals originate from the depleted mantle.

[0054] If the value of εNd(t) is less than zero, then the rare earth minerals originate from the Earth's crust or enriched mantle.

[0055] By combining the rare earth mineralization age and εNd(t) value in sedimentary rocks, we can infer the source of rare earth mineralization ore-forming materials and potential ore-forming geological bodies, which is of guiding significance for determining the direction of the next mineral exploration.

[0056] In this invention, the micro-area X-ray fluorescence spectrometer (μ-XRF) is an M4 TORNADO micro-area X-ray fluorescence spectrometer, which integrates the M4 TORNADO spectrometer for ultra-fast, high-resolution elemental distribution analysis manufactured and developed by Bruker, Germany; the TESCAN automated mineral analysis system (TIMA) consists of a TESCAN MIRA-3 field emission scanning electron microscope, four EDAX Element30 energy dispersive spectroscopy probes, and TIMA automated processing software; the GeolasPro laser ablation system in the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) consists of a COMPexPro 102ArF 193nm excimer laser and a MicroLas optical system, and the ICP-MS model is Agilent 7900; the laser ablation multi-receiver inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) uses the Geolas HD laser ablation system from Coherent, Germany, and the MC-ICP-MS uses the Neptune Plus from Thermo Fisher Scientific, Germany.

[0057] The present invention will be further described below through specific implementation methods.

[0058] Example 1

[0059] In this embodiment, the Huishishan Rare Earth-Niobium Polymetallic Exploration Area in Ejin Banner, Inner Mongolia Autonomous Region, is selected as the test area. Specifically, rare earth mineralization in this area is mainly hosted in the shallow marine clastic and carbonate rocks of the Lower Permian Shuangbaotang Formation. However, the occurrence state of rare earth elements in this area has not been determined during the mineral exploration phase, and further exploration work lacks sufficient geological basis. Therefore, this embodiment selects sedimentary rock samples with REE content reaching industrial grade in the Huishishan exploration area to analyze the occurrence state of REE elements in the sedimentary rocks and provide preliminary guidance for mineral exploration.

[0060] Figure 2 This is a schematic diagram of the principle provided in Embodiment 1 of the present invention, as shown below. Figure 2 As shown, it includes the following steps:

[0061] Step 1: Select locations in the sedimentary rock sample where hydrothermal veins and alteration are well-developed, and then cut and prepare sections.

[0062] Step 2: The entire area of ​​the laser sheet was scanned using a micro-area X-ray fluorescence spectrometer (μ-XRF). The obtained image showed that the three elements La, Ce and P were well matched, and the rare earth elements were distributed in fine veins almost along the siliceous sedimentary rocks. Based on Table 1, it is inferred that the rare earth minerals may be mainly monazite.

[0063] Step 3: Using a micro-area X-ray fluorescence spectrometer (μ-XRF), a full-spectrum elemental surface scan image of the entire laser sheet is obtained. The grayscale is adjusted using a scanning electron microscope to observe the brighter areas in the laser sheet and acquire backscattered images. At the same time, energy dispersive spectroscopy analysis is performed on the rare earth-rich areas in the μ-XRF scan image and the bright areas in the backscattered image to qualitatively determine the mineral composition of rare earth minerals. Energy dispersive spectroscopy analysis identifies two main rare earth minerals in the sedimentary rock sample: monazite and xenotime.

[0064] Step 4: For the key areas identified in Steps 2 and 3, perform mineral phase analysis using the TESCAN Automated Mineral Analysis System (TIMA). By comparing with standard mineral samples, the rare earth minerals in the sedimentary rocks are further identified as monazite and xenotime. The images show that the rare earth minerals occur in vein-like, nearly parastratified forms and are associated with pyrite and hematite.

[0065] Step 5: LA-ICP-MS in-situ micro-area U-Pb dating was performed on monazite, a rare earth mineral, in the sedimentary rocks of the Huishishan exploration area. The lower node age was obtained as 297±37 M. 207 Pb correction 208 Pb / 232 The weighted average age of Th is 293.9±3.9 Ma, indicating that the rare earth deposit was mainly formed in the Early Permian, which is consistent with the age of the Late Paleozoic granitic intrusive rocks widely distributed in the Yagan and Zhusileng-Hangwula areas on the northern edge of Alashan. Therefore, it is inferred that the rare earth mineralization in this exploration area is an Early Permian mineralization product under the background of the subduction of the Paleo-Asian Ocean into the Yagan and Zhusileng-Hangwula areas.

[0066] Step Six: LA-MC-ICP-MS in-situ micro-area Nd isotope analysis was conducted on the monazite samples that had undergone geochronological analysis. The εNd(t) values ​​of monazite, a rare earth mineral in the Huishishan exploration area, were all concentrated negative values ​​(-10.4 to -11.7), indicating that the source region of the rare earth elements may be ancient crustal material. Therefore, it is inferred that crustal granite is the key area for further rare earth mineral exploration in this region. Simultaneously, attention should be paid to fractures connecting deep granites, as ore-forming fluids tend to ascend along these fractures, which are also prone to mineralization.

[0067] Therefore, the above-mentioned method for analyzing the occurrence state of rare earth elements in sedimentary rocks and indicating the direction of mineral exploration is adopted to solve the problems of low analysis efficiency, low level of intelligence in the analysis process, and poor reliability of analysis results, and to provide a certain scientific basis for the deployment of the next mineral exploration work.

[0068] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for analyzing the occurrence state of rare earth elements in sedimentary rocks, characterized in that, Includes the following steps: Step 1: Select sedimentary rock samples containing rare earth elements obtained during the mineral exploration stage, and prepare the sedimentary rock samples containing rare earth elements into laser sheets; Step 2: After fabricating the laser sheet, perform a full-spectrum elemental surface scan on the laser sheet using a micro-area X-ray fluorescence spectrometer (μ-XRF) to obtain the elemental spatial distribution information of the laser sheet; Step 3: Obtain backscattered BSE images using a scanning electron microscope and perform energy dispersive spectroscopy analysis on the high BSE intensity regions; Step 4: Use the TESCAN TIMA automated mineral analysis system to perform mineral phase analysis on the key areas of rare earth mineral distribution delineated in Steps 2 and 3.

2. The method for analyzing the occurrence state of rare earth elements in sedimentary rocks according to claim 1, characterized in that, In step one, before the laser sheet is made, the rare earth element-containing sedimentary rock sample is cut, glued, mechanically ground and polished according to the location of the hydrothermal veins with strong alteration.

3. The method for analyzing the occurrence state of rare earth elements in sedimentary rocks according to claim 2, characterized in that, The laser sheet has dimensions of 2cm × 3cm and a thickness of 100~200μm.

4. The method for analyzing the occurrence state of rare earth elements in sedimentary rocks according to claim 1, characterized in that, In step two, the obtained spatial distribution information of elements is analyzed. Based on the rare earth element types and the distribution patterns and characteristics of rare earth elements and other elements, the types of rare earth minerals and their distribution patterns in the laser sheet are preliminarily determined.

5. The method for analyzing the occurrence state of rare earth elements in sedimentary rocks according to claim 1, characterized in that, In step three, before acquiring backscattered electron (BSE) images using a scanning electron microscope, the surface of the laser sheet needs to be carbon-sprayed.

6. The method for analyzing the occurrence state of rare earth elements in sedimentary rocks according to claim 5, characterized in that, In step three, the high BSE intensity region is analyzed by energy dispersive spectroscopy (EDS), and the chemical composition data of the analyzed minerals are qualitatively obtained to determine the types of rare earth minerals.

7. The method for analyzing the occurrence state of rare earth elements in sedimentary rocks according to claim 1, characterized in that, In step four, the TESCAN automated mineral analysis system TIMA is used to perform mineral phase TIMA analysis on key areas of rare earth mineral distribution to obtain the types, contents, and combination characteristics of rare earth minerals with other minerals in the rare earth element sedimentary rock samples.

8. A mineral exploration direction indication method based on the analytical method for the occurrence state of rare earth elements in sedimentary rocks according to any one of claims 1-7, characterized in that, Includes the following steps: Step 5: Based on the rare earth mineral types obtained in Step 4, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is used to perform in-situ micro-area U-Pb dating on the rare earth mineral types to obtain the age of mineralization. Step 6: Based on the LA-ICP-MS in-situ micro-area U-Pb dating in Step 5, perform laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) in-situ micro-area Nd isotope analysis on rare earth minerals or associated accessory minerals in the rare earth element-bearing sedimentary rock samples to infer the origin of the ore-forming materials.

9. The mineral exploration direction indication method according to claim 8, characterized in that, In step five, the rare earth-rich sedimentary rock sample contains six rare earth-rich minerals: monazite, xenotime, bastnaesite, sphene, epidote, and apatite. The mineralization age is obtained based on LA-ICP-MS in-situ micro-area U-Pb dating of these six minerals, specifically including the following: If the rare earth mineral in the sedimentary rock sample containing rare earth elements is one of the above six minerals, in-situ micro-area U-Pb dating is performed directly to obtain the mineralization age. If the rare earth minerals in the rare earth element-bearing sedimentary rock sample do not contain the above six minerals, but the accessory minerals associated with the rare earth minerals are the above six minerals, then the associated accessory minerals are subjected to in-situ micro-area U-Pb dating to indirectly determine the mineralization age.

10. The mineral exploration direction indication method according to claim 8, characterized in that, In step six, the obtained rare earth mineralization age and LA-MC-ICP-MS in-situ micro-area analysis are used to obtain... 143 Nd / 144 The Nd ratio calculation yields the εNd(t) value of rare earth minerals or associated accessory minerals, specifically including... the following: If the value of εNd(t) is greater than zero, then the rare earth minerals originate from the depleted mantle. If the value of εNd(t) is less than zero, then the rare earth minerals originate from the Earth's crust or enriched mantle.

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