Method for determining mineralization age of Kangyunnan earth axis coarse-grained uraninite

Abstract

The invention discloses a Kangyunnan earth axis coarse-grained crystalline uranium ore metallogenic age determination method, and relates to the technical field of uranium ore geological exploration, and the method comprises the following steps: sample collection and pretreatment; chemical dating with an electronic probe; carrying out major element analysis on the uraninite, and calculating age by adopting an empirical formula; carrying out LA-ICP-MS in-situ U-Pb dating; performing microcell isotope analysis on the symbiotic sphene, and combining standard sample correction and common lead deduction; zircon U-Pb dating is carried out; determining the age of zircon in the mixed rocks, and constraining the age of mixed rocks; performing Nd isotope tracing; analyzing Nd isotope composition of the uranite and the sphene, and verifying the consistency of a mineral source and a dating result; comprehensively analyzing data; according to the method, a plurality of groups of age data and regional geological events are combined to determine the metallogenic age, so that the problems of low precision and weak anti-interference capability during use of an existing coarse-grained uranium ore metallogenic age determination method are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of uranium geological exploration, in particular to a method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian geoaxis. Background Art

[0002] The Kangdian axis is a major uranium mineralization belt in my country. The discovery of coarse-grained crystalline uranium deposits provides key samples for studying Neoproterozoic uranium mineralization. Accurately determining the age of uranium mineralization in this region is crucial for understanding uranium mineralization and guiding uranium exploration. However, this research currently faces numerous challenges.

[0003] Traditional methods for dating uranium mineralization ages, such as chemical dissolution, suffer from high sample consumption, the introduction of impurities, and the inability to distinguish elements from different sources. This makes it difficult to accurately reflect the true mineralization age of samples modified by later geological processes. Emerging micro-area in situ analytical techniques, such as electron microprobe dating and LA-ICP-MS, while offering certain advantages, also have significant drawbacks. Electron microprobe dating relies on empirical formulas that fail to fully account for later perturbations in the U-Pb system and exhibit limited spatial resolution. LA-ICP-MS requires calibration with standard samples and is less adaptable to complex mineral structures, hindering the accurate determination of mineralization ages.

[0004] Furthermore, existing methods mostly focus on analyzing the minerals themselves, lacking effective coupling with regional tectonic evolutionary events (such as the breakup of the Rodinia supercontinent and the activity of the Emeishan mantle plume). This makes it difficult to fully understand the dynamic background of uranium mineralization and provide effective guidance for uranium exploration and development. Therefore, an efficient, accurate determination method that comprehensively considers the geological background is urgently needed. Summary of the Invention

[0005] Based on this, in response to the above problems, the present invention proposes a method for determining the mineralization age of coarse-grained uranium deposits in the Kangdian axis, which solves the problems of low accuracy and weak anti-interference ability of the current method for determining the mineralization age of coarse-grained uranium deposits.

[0006] The technical solution of the present invention is: A method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian axis comprises the following steps: A: Sample collection and pretreatment; Select uranium-rich veins and surrounding rocks, separate crystalline uranium ore, paragenetic titanite and zircon, and prepare epoxy resin targets; B: Electron probe chemical dating; The major element analysis of crystalline uranium ore was carried out and the age was calculated using empirical formula; C: LA-ICP-MS in situ U-Pb dating; Micro-area isotope analysis of paragenetic sphene was conducted, combining standard sample calibration with common lead subtraction; D: zircon U-Pb dating; Determine the age of zircons in migmatites to constrain the age of migmatization; E: Nd isotope tracer; Analyze the Nd isotope composition of uraninite and titanite to verify the consistency of the ore-forming material source and dating results; F: comprehensive data analysis; The mineralization era is determined by combining multiple sets of age data and regional geological events.

[0007] Preferably, in step A, sample pretreatment comprises: A1: Obtain single minerals through heavy liquid separation and magnetic separation; A2: Prepare epoxy resin targets, polish them to 1 μm accuracy, and perform backscattered electron imaging.

[0008] Preferably, in step B, the specific parameters of the electron probe chemical dating are: accelerating voltage 15 kV, beam current 20 nA, beam spot diameter 1 μm, and ZAF correction; The empirical formula is as follows: Where t represents the calculated age of the crystalline uranium ore, Pb% represents the mass percentage content of lead in the crystalline uranium ore, U% represents the mass percentage content of uranium in the crystalline uranium ore, and Th% represents the mass percentage content of thorium in the crystalline uranium ore. The weighted average age of more than 20 groups of measuring points is calculated.

[0009] Preferably, in step C, the specific parameters of LA-ICP-MSU-Pb dating are as follows: laser ablation system: 193 nm ArF excimer laser, energy density 3.5 J / cm², beam spot diameter 33 μm, frequency 5 Hz; external standard is NIST610 glass, internal standard is 8 U; Concordant age was calculated by deducting common lead using the Tera–Wasserburg diagram.

[0010] Preferably, in step C, the selection criteria for paragenetic titanite are: having a distinct core-rim structure, with the core inheriting the age of the surrounding rock and the rim representing the mineralization age; and a flat rare earth element distribution pattern, indicating a high-temperature mineralization environment.

[0011] Preferably, in step D, the specific parameters for zircon U-Pb dating are: laser beam spot diameter of 30 μm, analysis object is metamorphic zircon with Th / U<0.1; Isoplot4.15 software is used to fit the upper intersection age, representing the age of migmatization.

[0012] Preferably, in step E, the specific parameters of Nd isotope tracing are: using Nu Plasma MC-ICP-MS, a laser beam spot of 23 μm, an energy density of 4.5 J / cm²; the standard sample is monazite, and the εNd(t) value and the TDM mode age are calculated.

[0013] Preferably, in step F, the comprehensive data analysis includes: F1: weighted average of the electron microprobe age of uraninite and the U-Pb age of sphene; F2: Time difference analysis between migmatization era and mineralization era; F3: Analyze the mineralization dynamics background in combination with the Rodinia supercontinent breakup event.

[0014] Preferably, a quality control step is also included: The repetition rate of the electronic probe measurement point is >90%; LA-ICP-MS data concordance >95%; The deviation of Nd isotope test standard is <0.5%.

[0015] Preferably, late thermal event interference correction is also included: Excluding electronic probe age outliers; Explain age differences in conjunction with regional geological events.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention adopts multiple technologies for collaborative dating: electron probe chemical dating for crystalline uranium ore, and LA-ICP-MS in situ U-Pb dating for paragenetic titanite. The two are mutually verified, which greatly improves the accuracy of the determination of the mineralization age. By comparing and comprehensively analyzing multiple groups of data, the error that may be caused by a single method can be effectively reduced, making the determination results more reliable, and the accuracy can be improved to ±5Ma. When comprehensively analyzing the data, judgments are made in combination with regional geological events. For abnormal age data, the reasons for their generation can be reasonably explained by comparing them with known geological events, eliminating the influence of interference factors of later thermal events on the determination of the mineralization age. This solves the problems of low accuracy and weak anti-interference ability of the current method for determining the mineralization age of coarse-grained crystalline uranium ore when it is used. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the process framework structure of a method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian axis described in an embodiment of the present invention. DETAILED DESCRIPTION

[0018] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0019] Example: like Figure 1 As shown, this embodiment discloses a method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian axis, comprising the following steps: A: Sample collection and pretreatment; Select uranium-rich veins and surrounding rocks, separate crystalline uranium ore, paragenetic titanite and zircon, and prepare epoxy resin targets; B: Electron probe chemical dating; The major element analysis of crystalline uranium ore was carried out and the age was calculated using empirical formula; C: LA-ICP-MS in situ U-Pb dating; Micro-area isotope analysis of paragenetic sphene was conducted, combining standard sample calibration with common lead subtraction; D: zircon U-Pb dating; Determine the age of zircons in migmatites to constrain the age of migmatization; E: Nd isotope tracer; Analyze the Nd isotope composition of uraninite and titanite to verify the consistency of the ore-forming material source and dating results; F: comprehensive data analysis; The mineralization era is determined by combining multiple sets of age data and regional geological events.

[0020] The present invention adopts multiple technologies for collaborative dating: electron probe chemical dating for crystalline uranium ore, and LA-ICP-MS in situ U-Pb dating for paragenetic titanite. The two are mutually verified, which greatly improves the accuracy of the determination of the mineralization age. By comparing and comprehensively analyzing multiple groups of data, the error that may be caused by a single method can be effectively reduced, making the determination results more reliable, and the accuracy can be improved to ±5Ma. When comprehensively analyzing the data, judgments are made in combination with regional geological events. For abnormal age data, the reasons for their generation can be reasonably explained by comparing them with known geological events, eliminating the influence of interference factors of later thermal events on the determination of the mineralization age. This solves the problems of low accuracy and weak anti-interference ability of the current method for determining the mineralization age of coarse-grained crystalline uranium ore when it is used.

[0021] Wherein, in step A, sample pretreatment includes: A1: Obtain single minerals through heavy liquid separation and magnetic separation; A2: Prepare epoxy resin targets, polish them to 1 μm accuracy, and perform backscattered electron (BSE) imaging.

[0022] In step B, the specific parameters of electron probe chemical dating are: accelerating voltage 15 kV, beam current 20 nA, beam spot diameter 1 μm, and ZAF correction; The empirical formula is as follows: Where t is the calculated age of the crystalline uranium ore (unit: million years, Ma), Pb% is the mass percentage content of lead (Pb) in the crystalline uranium ore, U% is the mass percentage content of uranium (U) in the crystalline uranium ore, and Th% is the mass percentage content of thorium (Th) in the crystalline uranium ore. The weighted average age of more than 20 groups of measuring points is calculated.

[0023] In step C, the specific parameters for LA-ICP-MSU-Pb dating are as follows: laser ablation system: 193 nm ArF excimer laser, energy density 3.5 J / cm², beam spot diameter 33 μm, frequency 5 Hz; external standard: NIST 610 glass, internal standard: 8 U; Concordant age (MSWD < 5) was calculated by deducting common lead using the Tera–Wasserburg diagram.

[0024] The selection criteria for paragenetic titanites are: a distinct core-rim structure (such as Ttn-I and Ttn-II), with the core inheriting the age of the surrounding rock and the rim representing the mineralization age; and a flat rare earth element distribution pattern, indicating a high-temperature mineralization environment.

[0025] Among them, in step D, the specific parameters of zircon U-Pb dating are: laser beam spot diameter 30μm, analysis object is metamorphic zircon with Th / U <0.1; use Isoplot4.15 software to fit the upper intersection age, representing the age of migmatization.

[0026] In step E, the specific parameters for Nd isotope tracing are: using Nu Plasma MC-ICP-MS, a laser beam spot size of 23 μm, and an energy density of 4.5 J / cm²; the standard sample is monazite (e.g., 44069, M2), and the εNd(t) value and TDM mode age are calculated.

[0027] In step F, the comprehensive data analysis includes: F1: weighted average of the electron microprobe age of uraninite and the U-Pb age of sphene (error < 5%); F2: Time difference analysis between the migmatization age (830-860 Ma) and the mineralization age (770-790 Ma); F3: Analyze the mineralization dynamics background in combination with the Rodinia supercontinent breakup event (~750Ma).

[0028] As a further preferred aspect, a quality control step is further included: The repetition rate of the electronic probe measurement point is >90%; LA-ICP-MS data concordance >95%; The deviation of Nd isotope test standard is <0.5%.

[0029] As a further preferred embodiment, it also includes a late thermal event interference correction: Exclude outliers in electron probe ages (e.g., points around 240 Ma); The age differences are explained in combination with regional geological events (such as the Emeishan mantle plume event ~250Ma).

[0030] Specifically: Sample collection and pretreatment: Sampling Strategy: Uranium-rich veins (quartz veins and albite veins) and host rocks (migmatized gneiss) were sampled from representative uranium deposits at Miyi Haita 2811 / A19, Panzhihua Datian 505, and Mouding 1101. Priority was given to sampling unaltered coarse-grained crystalline uranium ore and associated sphene to ensure the integrity of the mineral assemblage.

[0031] Sample preparation process: The sample is crushed to 200 mesh, and single minerals (crystalline uraninite, titanite, and zircon) are obtained through heavy liquid separation and magnetic separation. Epoxy resin targets are prepared and polished to 1μm accuracy for backscattered electron (BSE) imaging and rock and mineral identification.

[0032] Multi-technique collaborative determination: Electron Probe Machining (EPMA) dating: Instrument parameters: JEOL JXA-8230 electron probe, accelerating voltage 15 kV, beam current 20 nA, beam spot diameter 1 μm, ZAF correction.

[0033] Analytical elements: major elements U, Th, Pb, the scanning range covers the core to the edge of the crystalline uranium ore.

[0034] Age calculation: Use the empirical formula to calculate the weighted average age of more than 20 groups of measurement points; The empirical formula is as follows: Where t is the calculated age of the crystalline uranium ore (unit: million years, Ma), Pb% is the mass percentage content of lead (Pb) in the crystalline uranium ore, U% is the mass percentage content of uranium (U) in the crystalline uranium ore, and Th% is the mass percentage content of thorium (Th) in the crystalline uranium ore. The weighted average age of more than 20 groups of measuring points is calculated.

[0035] Data screening: exclude measurement points with abnormal U / Th values (such as U / Th>1000) and uneven element distribution.

[0036] LA-ICP-MSU-Pb dating: Instrument parameters: Laser ablation system: 193 nm ArF excimer laser (ResolutionLR), energy density 3.5 J / cm², beam spot diameter 33 μm, frequency 5 Hz.

[0037] ICP-MS: Agilent 7700X, external standard: NIST 610 glass, internal standard: ²³ 8 U.

[0038] Standard calibration: Sphene standards: BLR-1 (1047 Ma), Ontario (1056 Ma); Zircon standards: GJ-600, Ple-337.

[0039] Data processing: Concordant ages (MSWD < 5) were calculated using the Tera–Wasserburg diagram to deduct common lead.

[0040] Combined with the core-edge structure of sphene (such as Ttn-I and Ttn-II), the inherited age and the mineralization age are distinguished.

[0041] Zircon U-Pb dating (constraining the age of migmatization): Instrument parameters: Same as LA-ICP-MS, beam spot diameter 30 μm.

[0042] Analysis object: Metamorphic zircons in migmatized gneiss, those with Th / U < 0.1 are determined to be metamorphic in origin.

[0043] Age calculation: Isoplot4.15 software was used to fit the upper intersection age, which represents the age of migmatization.

[0044] Nd isotope tracer: Instrument parameters: NuPlasma II MC-ICP-MS, laser beam spot size 23 μm, energy density 4.5 J / cm².

[0045] Analysis objects: crystalline uranium ore and associated titanite, the standard sample is monazite (such as 44069, M2).

[0046] Data verification: Calculate the εNd(t) value and TDM model age, and verify the source of mineralization materials by combining regional crustal evolution models (such as the basement age of the Yangtze Plate).

[0047] Comprehensive data analysis: Age comparison: The consistency of electron microprobe ages of uraninite and sphene U-Pb ages (error < 5%).

[0048] The time difference between the migmatization age (zircon U-Pb) and the mineralization age (e.g. 830-860 Ma vs. 770-790 Ma).

[0049] Coupling of geological events: Combining the regional tectonic events of the Rodinia supercontinent breakup (~750Ma) and the Emeishan mantle plume event (~250Ma) to analyze the mineralization dynamics background.

[0050] Error correction: The chi-square test was used to screen the Concordia age data and exclude the measurement points affected by later hydrothermal disturbances (e.g., abnormally high / low electron probe ages).

[0051] Taking the Miyihaita 2811 uranium mine as an example, the details are as follows: Electron microprobe age of uraninite: 231-257 Ma (interference from late thermal events).

[0052] LA-ICP-MS age of intergenetic sphene: 778±12Ma (Neoproterozoic).

[0053] Migmatization age: zircon U-Pb age 832±20Ma.

[0054] Conclusion: The mineralization age is 770-790Ma, and it was later modified by the Emeishan mantle plume event.

[0055] Data analysis process Data input: Electron probe data (Excel), LA-ICP-MS raw data (.csv).

[0056] Processing software: Electron probe: ZAF correction program (ProbeforEPMA).

[0057] LA-ICP-MS: ICPMS-DataCal10.5, Isoplot4.15.

[0058] Nd isotope: ISOPLOT / Ex_ver3.

[0059] Quality Control: The repetition rate of the electronic probe measurement point is >90%; LA-ICP-MS data concordance >95%; The deviation of Nd isotope test standard is <0.5%.

[0060] Working principle and beneficial effects of the present invention: The method for determining the mineralization age of the coarse-grained crystalline uranium deposit in the Kangdian geoaxis of the present invention is based on the synergistic effect of multiple modern analytical techniques and combines the radioactive isotope decay principle and geological evolution law to determine the mineralization age.

[0061] Electron probe chemical dating works by analyzing the radioactive decay of uranium (U) and thorium (Th) in crystalline uranium ore to form lead (Pb). Electron probe dating analyzes the U, Th, and Pb content in crystalline uranium ore using an empirical formula to calculate its age. This formula, derived from the radioactive decay patterns of uranium, thorium, and lead and extensive experimental data, estimates the age of crystalline uranium ore by measuring the ratio of these elements.

[0062] LA-ICP-MS in situ U-Pb dating principle: In the coexisting sphene, uranium (U) decays into different isotopes of lead (Pb) with a certain decay constant (such as ² 06 Pb,² 07 Pb). LA-ICP-MS technology can perform in-situ U-Pb isotope analysis on sphene micro-areas. After comparison and correction with standard samples of known age and deduction of the interference of common lead, the formation age of sphene can be calculated based on the U-Pb isotope ratio and the law of radioactive decay, thus providing an important reference for the mineralization era.

[0063] Zircon U-Pb dating principles: Zircon is a relatively stable mineral in geological processes, and its internal U-Pb isotope system is also relatively stable. Metamorphic zircons in migmatized gneiss can record the age of migmatization. U-Pb dating of zircons and fitting of upper intersection ages using Isoplot software reveal the timing of migmatization, providing an upper limit constraint on the age of uranium mineralization, as uranium mineralization generally occurs after migmatization.

[0064] Nd isotope tracing principle: Different geological bodies have different Nd isotope compositions. By analyzing the Nd isotope compositions of crystalline uraninite and titanite, and calculating εNd(t) values and TDM model ages, we can understand the origin of the ore-forming material. If the ore-forming material originates from ancient crust, its Nd isotope signature will be similar to that of corresponding crustal materials. Comparative analysis can verify the consistency between the ore-forming material source and the dating results, further supporting the accuracy of the mineralization era.

[0065] Principle of Comprehensive Data Analysis: A comprehensive comparative analysis of multiple age data sets obtained using electron microprobe, LA-ICP-MS, zircon U-Pb dating, and Nd isotope tracing is performed. Furthermore, geological events in the Kangdian axis region, such as the breakup of the Rodinia supercontinent and the Emeishan mantle plume, are combined to determine the temporal relationship and interaction between these events and uranium mineralization, thereby more accurately determining the mineralization age of the uranium deposits.

[0066] This method uses multiple dating techniques in tandem: electron microprobe dating of crystalline uranium ores and LA-ICP-MS in situ U-Pb dating of intergrowth sphene. The two techniques mutually validate each other, significantly improving the accuracy of mineralization age determination. By comparing and comprehensively analyzing multiple data sets, the error that could be introduced by a single method can be effectively reduced, making the results more reliable and achieving an accuracy of ±5 Ma.

[0067] During the data processing process, strict quality control measures were implemented, such as electron probe measurement point reproducibility >90%, LA-ICP-MS data concordance >95%, and Nd isotope test standard deviation <0.5%, further ensuring the accuracy of the measurement results.

[0068] This method utilizes in-situ microanalysis techniques, such as electron microprobe and LA-ICP-MS, to analyze minerals at microscale, avoiding the information averaging problem associated with traditional methods that dissolve the entire sample. Backscattered electron (BSE) imaging and mineral structure analysis (such as the core-edge structure of sphene) can accurately identify and exclude areas affected by later alteration and hydrothermal disturbance, thereby reducing interference from external factors on the measurement results.

[0069] When comprehensively analyzing the data, we combine it with regional geological events to make judgments. For abnormal age data, we can reasonably explain the reasons for their occurrence by comparing them with known geological events, and eliminate the influence of interference factors of later thermal events on the determination of mineralization age.

[0070] This study not only focuses on mineral age determination but also, through Nd isotope tracing, further investigates the sources of ore-forming materials. Combined with the regional tectonic evolution, this study reveals the intrinsic connection between uranium mineralization and geological events. For example, ancient crustal remelting may have provided the material source for uranium mineralization, and the breakup of the Rodinia supercontinent may have provided the driving force and tectonic conditions for uranium mineralization. This coupled geological and geochemical analysis has provided a more comprehensive and in-depth understanding of the uranium mineralization mechanism and provided a more scientific theoretical basis for uranium exploration and research in the region.

[0071] During sample pretreatment, a rational method was used to separate crystalline uraninite, paragenetic titanite, and zircon, and epoxy resin targets were prepared, enabling multi-mineral analysis within the same sample. This comprehensive sample utilization approach improves sample utilization and reduces the demand for precious samples, making it particularly suitable for the Kangdian geocentric region, where sample acquisition is difficult.

[0072] The above-described embodiments merely represent specific implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, and all such variations and improvements fall within the scope of protection of the present invention.

Claims

1. A method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian axis, characterized in that: The following steps are involved: A: Sample collection and pretreatment; Select uranium-rich veins and surrounding rocks, separate crystalline uranium ore, paragenetic titanite and zircon, and prepare epoxy resin targets; B: Electron probe chemical dating; The major element analysis of crystalline uranium ore was carried out and the age was calculated using empirical formula; C: LA-ICP-MS in situ U-Pb dating; Micro-area isotope analysis of paragenetic sphene was conducted, combining standard sample calibration with common lead subtraction; D: zircon U-Pb dating; Determine the age of zircons in migmatites to constrain the age of migmatization; E: Nd isotope tracer; Analyze the Nd isotope composition of uraninite and titanite to verify the consistency of the ore-forming material source and dating results; F: comprehensive data analysis; The mineralization era is determined by combining multiple sets of age data and regional geological events.

2. The method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian Earth Axis according to claim 1, characterized in that: In step A, sample pretreatment includes: A1: Obtain single minerals through heavy liquid separation and magnetic separation; A2: Prepare epoxy resin targets, polish them to 1 μm accuracy, and perform backscattered electron imaging.

3. The method for determining the mineralization age of coarse-grained crystalline uranium deposits in Kangdian Earth Axis according to claim 2, characterized in that: In step B, the specific parameters of electron probe chemical dating are: accelerating voltage 15 kV, beam current 20 nA, beam spot diameter 1 μm, and ZAF correction; The empirical formula is as follows: Where t represents the calculated age of the crystalline uranium ore, Pb% represents the mass percentage content of lead in the crystalline uranium ore, U% represents the mass percentage content of uranium in the crystalline uranium ore, and Th% represents the mass percentage content of thorium in the crystalline uranium ore. The weighted average age of more than 20 groups of measuring points is calculated.

4. The method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian geoaxis according to claim 3, characterized in that: In step C, the specific parameters for LA-ICP-MSU-Pb dating were as follows: laser ablation system: 193 nm ArF excimer laser, energy density 3.5 J / cm², beam spot diameter 33 μm, frequency 5 Hz; external standard: NIST 610 glass, internal standard: 8 U; Concordant age was calculated by deducting common lead using the Tera–Wasserburg diagram.

5. The method for determining the mineralization age of coarse-grained uranium deposits in the Kangdian Earth Axis according to claim 4, characterized in that: In step C, the selection criteria for paragenetic sphene are: having a distinct core-rim structure, with the core inheriting the age of the surrounding rock and the rim representing the mineralization age; The rare earth element distribution pattern is flat, indicating a high-temperature mineralization environment.

6. The method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian geoaxis according to claim 5, characterized in that: In step D, the specific parameters for zircon U-Pb dating are: laser beam spot diameter of 30 μm, metamorphic zircons with Th / U < 0.1 as the analysis object; Isoplot4.15 software is used to fit the upper intersection age, which represents the age of migmatization.

7. The method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian Earth Axis according to claim 6, characterized in that: In Step E, the specific parameters for Nd isotope tracing are: Nu Plasma MC-ICP-MS, a laser beam spot size of 23 μm, and an energy density of 4.5 J / cm²; the standard sample is monazite, and the εNd(t) value and TDM mode age are calculated.

8. The method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian geoaxis according to claim 7, characterized in that: In step F, comprehensive data analysis includes: F1: weighted average of the electron microprobe age of uraninite and the U-Pb age of sphene; F2: Time difference analysis between migmatization era and mineralization era; F3: Analyze the mineralization dynamics background in combination with the Rodinia supercontinent breakup event.

9. The method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian Earth Axis according to claim 8, characterized in that: Quality control steps are also included: The repetition rate of the electronic probe measurement point is >90%; LA-ICP-MS data concordance >95%; The deviation of Nd isotope test standard is <0.5%.

10. The method for determining the mineralization age of coarse-grained crystalline uranium deposits in the Kangdian Earth Axis according to claim 9, characterized in that: Also includes late thermal event interference correction: Excluding electronic probe age outliers; Explain age differences in conjunction with regional geological events.

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