Carbon isotope composition analysis method for gas inclusions in mantle mineral rocks

Abstract

The application provides an innovative method for analyzing carbon isotope composition of trace gas inclusions in mantle mineral rocks. The cavity of the ball mill and the mineral rock sample in the cavity are cleaned by a protective gas to remove possible gas impurities; the mantle mineral rock sample is placed in the micro-cavity of a three-dimensional high-energy vibration ball mill for vibration ball milling treatment. The released gas inclusions are transferred to a gas chromatography-isotope ratio mass spectrometry analysis system through a sealed rotary three-way valve for accurate carbon isotope composition analysis. The risk of non-native gas pollution can be significantly reduced through normal temperature crushing technology. Combined with ultra-trace gas extraction technology and efficient pre-concentration technology, the effective recovery and enrichment of trace gas in the gas inclusions in the mantle mineral rock are realized. By using high-sensitivity and high-precision isotope ratio measurement technology, the detection limit is improved, the background interference is effectively reduced, and the reliability of the analysis result is ensured.

Description

Technical Field

[0001] This invention relates to the field of mantle minerals and rocks, specifically to a method for analyzing the carbon isotope composition of gas inclusions in mantle minerals and rocks. Background Technology

[0002] Currently, the techniques for analyzing gas inclusions in common minerals and rocks include thermal detonation and vacuum fracturing. These two methods are used in geology, petroleum geology, and mineral deposit research to study the composition of gases, especially trace gas inclusions trapped within rocks. Below is a brief description of these two techniques:

[0003] Thermal detonation: This method involves heating a common sample containing gas inclusions to high temperatures (typically several hundred to thousands of degrees Celsius), causing the inclusions to rupture and release the gas. The released gas is then collected and analyzed. Advantages: It can handle inclusions that are difficult to break down physically and is suitable for studying gaseous components that may exist under high-temperature conditions. Disadvantages: Non-native gaseous components may be generated during the heating process, such as due to the decomposition of minerals or the pyrolysis of organic matter at high temperatures, leading to contamination of the analytical results and not a true reflection of the original fluid.

[0004] Vacuum fragmentation: This method involves mechanically fragmenting ordinary geological samples in a vacuum environment to release gases from gas inclusions. These gases are then collected and analyzed while maintaining the vacuum. Advantages: Compared to thermal fragmentation, this method reduces the possibility of pyrolysis reactions, more accurately reflects the original gas composition, and is suitable for detecting low-concentration gases. Disadvantages: Although it reduces thermal contamination, other forms of contamination, such as background contamination, may still exist. Furthermore, for very small or extremely hard inclusions, strong fragmentation forces may be required, which may be technically difficult to achieve, and it may still be challenging to reach extremely low levels of analytical sensitivity.

[0005] Existing mineral and rock gas inclusion analysis techniques primarily focus on crustal rocks, especially samples with relatively high gas content, such as sedimentary rocks. For these samples, commonly used vacuum fracturing techniques can extract gas inclusions in a low-oxygen environment, reducing oxidation reactions and external contamination. However, for the analysis of trace alkane inclusions in mantle rocks, this technique has certain limitations: ① Background contamination: The gas inclusion content in mantle rocks is extremely low, and conventional vacuum fracturing techniques easily introduce background contamination because nitrogen in the air readily mixes in, especially during processing. Even trace amounts of contamination can significantly affect the analytical results. Tiny gas inclusions in mantle samples are more easily exposed to contaminants during processing, making it difficult for the analytical results to reflect the true composition of the original mantle gases. ② Non-primitive gas release due to heating: Heating rock samples to release gases is a common method, but this is particularly challenging in mantle rocks. Mantle rocks have undergone extreme high-temperature and high-pressure conditions, resulting in a compact structure and the potential presence of high-pressure phase minerals. Heating may not only release the original inclusion gases, but also induce the decomposition of organic matter in the mineral structure, leading to the mixing of non-original gases and affecting the accuracy of the analytical results.

[0006] Despite significant technological advancements over the past few decades, the extraction and isotopic analysis of gases (especially trace gases) from mantle minerals and rocks remains a complex technique. The main reasons include: ① Difficulty in sample acquisition: Directly obtaining mantle samples is challenging, limiting the scope and reproducibility of research. ② Trace gas capture and preservation: The gas content in mantle gas inclusions is extremely low; effectively extracting these trace gases and preventing external contamination is a major technical challenge. ③ Accuracy of isotopic analysis: Isotopic ratios of mantle gases provide crucial geochemical information, but require analytical techniques with extremely high sensitivity and accuracy. Isotopic analysis techniques, especially for high-precision isotopic ratio determination of alkanes such as methane, still face challenges.

[0007] Current challenges in methane gas inclusion analysis of minerals and rocks primarily include two core difficulties: ① Low methane inclusion content in mantle rocks necessitates highly sensitive and precise extraction techniques to ensure sufficient gas separation for analysis. This not only tests the precision of sampling and processing techniques but also requires innovative pre-concentration strategies to enrich these minute gas components. ② Strict pollution control: Since nitrogen is a major component of the atmosphere, avoiding modern atmospheric nitrogen pollution during collection, processing, and analysis is an extremely difficult task. Any minute pollution can distort analytical results, severely affecting the judgment of the true gas composition and isotope ratios of the mantle. This requires a highly pure experimental environment, strict nitrogen-free or ultra-clean operating procedures, and methods such as isotope tracing and blank tests to monitor and correct for potential contamination. Summary of the Invention

[0008] The present invention aims to solve the above-mentioned technical problems by providing a method for analyzing the carbon isotope composition of gas inclusions in mantle minerals and rocks.

[0009] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0010] A method for analyzing the carbon isotopic composition of gas inclusions in mantle minerals and rocks includes the following steps:

[0011] S1. Sample preparation:

[0012] Select mantle minerals and rocks, choosing those with uniformly sized grains, 0.5-1mm in size;

[0013] S2. Preparation of the high-energy microcavity vibration ball mill:

[0014] Grinding balls are added to a high-energy microcavity vibrating ball mill, and a dispersant is added before grinding. Mantle minerals and rocks are then placed into the high-energy microcavity vibrating ball mill for grinding.

[0015] S3, Inert gas flushing:

[0016] The cavity of the high-energy microcavity vibrating ball mill is repeatedly flushed with inert gas for 10-30 minutes to completely replace the original air in the cavity.

[0017] S4. Gas Analysis:

[0018] After the ball milling process, the crushed sample is collected, and any gas inclusions that may have been released are recovered using separation technology. The gas inclusions are then transferred to a gas chromatography-isotope ratio mass spectrometry system via a closed three-way rotary valve for precise analysis of components and isotope ratios.

[0019] Preferably, the ratio of the grinding balls to mantle mineral rocks is 1:3.

[0020] Preferably, the purity of the inert gas is 99.9999%.

[0021] Preferably, the mantle mineral rock is olivine, pyroxene, or garnet.

[0022] Preferably, the grinding balls are stainless steel balls, ceramic balls, or zirconium beads. The grinding balls are made of a high-hardness material.

[0023] Preferably, the gas chromatography-isotope ratio mass spectrometry analysis system consists of a gas inclusion passing through a sealed three-way rotary valve sequentially through a gas chromatograph, an oxidation furnace, a dehydration device, and an isotope ratio mass spectrometer.

[0024] Preferably, the gas chromatography parameters are: initial temperature 30-40°C, hold for 3-7 min, heating rate 8-12°C / min, final temperature 200°C, hold for 26-32 min, split ratio 5:1, carrier gas helium, flow rate 5 ml / min, and isotope ratio mass spectrometry monitoring. 12 CO2 / 13 The ratio of CO2, calculate δ 13 C value.

[0025] Preferably, the high-energy microcavity vibrating ball mill includes a base plate and a motor and bearing housing connected to the base plate. A rotating shaft is installed inside the bearing housing. The motor and the rotating shaft are connected by a belt and a pulley. A rocker arm is connected to one end of the rotating shaft. A fixed plate is installed on one side of the rocker arm. A ball milling jar is installed inside the fixed plate. A spring is installed between the rocker arm and the base plate.

[0026] Preferably, the high-energy microcavity vibrating ball mill has a rotation speed of 1500-1800 r / min, the temperature inside the ball mill jar does not exceed 60°C, and the frequency is 20-50 Hz.

[0027] Preferably, the gas inclusion gas chromatography-isotope ratio mass spectrometry analysis system is used to analyze methane gas, nitrogen gas, hydrogen gas, carbon dioxide, ethane components and their respective isotope ratios.

[0028] By employing the above method, the present invention has the following advantages:

[0029] This invention enables the safe collection of gas inclusions from trace and difficult-to-obtain mantle rock samples, while minimizing sample damage and the risk of external contamination. Combining ultra-micro extraction with high-efficiency pre-concentration techniques, trace gases can be effectively recovered and enriched from extremely small amounts of mantle gas inclusions. High-sensitivity, high-precision isotope ratio measurement techniques for mantle gases, utilizing isotope ratio mass spectrometry coupled with or modified mass spectrometry, improve the detection limit, reduce background interference, and ensure data accuracy.

[0030] The above overview is intended to be illustrative only and is not intended to be limiting in any way. Other embodiments and features of the invention, in addition to the exemplary aspects, implementations, and features described above, will become clearer with reference to the accompanying drawings and the following detailed description. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a diagram showing the detection results of the gas inclusions of this invention;

[0033] Figure 2 This is a schematic diagram of the high-energy microcavity vibration ball mill of the present invention;

[0034] Figure 3 This is a schematic diagram of the structure of the sealed three-way rotary valve of the present invention;

[0035] Figure 4 This is a schematic diagram of the gas chromatography-isotope ratio mass spectrometry analysis system of the present invention.

[0036] As shown in the figure: 1. Base plate; 2. Motor; 4. Bearing housing; 5. Rocker arm; 6. Belt; 7. Fixing plate;

[0037] A. Rotary handle; B. Syringe port; C. Three-way valve outlet; D. Three-way valve body; E. Three-way valve front outlet; F. Needle. Detailed Implementation

[0038] Specific embodiments of the invention will now be described in detail. Although the invention is described in conjunction with these specific embodiments, it should be understood that it is not intended to limit the invention to these specific embodiments. Rather, these embodiments are intended to cover alternative, modified, or equivalent embodiments that may be included within the spirit and scope of the invention as defined by the claims. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. The invention may be practiced without some or all of these specific details. In other instances, well-known processes have not been described in detail in order not to unnecessarily obscure the invention.

[0039] When used in conjunction with the terms "comprising," "method comprising," or similar language in this specification and the appended claims, the singular forms "a," "some," and "the" include plural references unless the context clearly indicates otherwise. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0040] The present invention will now be described in further detail with reference to the full text.

[0041] Combined with appendix Figures 1-4A method for analyzing the carbon isotopic composition of gas inclusions in mantle minerals and rocks, comprising the following steps:

[0042] S1. Sample preparation:

[0043] Select mantle minerals and rocks, choosing those with uniformly sized grains, 0.5-1mm in size;

[0044] S2. Preparation of the high-energy microcavity vibration ball mill:

[0045] Grinding balls are added to a high-energy microcavity vibrating ball mill, and a dispersant is added before grinding. Mantle minerals and rocks are then placed into the high-energy microcavity vibrating ball mill for grinding.

[0046] S3, Inert gas flushing:

[0047] The cavity of the high-energy microcavity vibrating ball mill is repeatedly flushed with an inert gas for 10-30 minutes to completely replace the original air in the cavity; helium, hydrogen or other inert gases can be used.

[0048] S4. Gas Analysis:

[0049] After the ball milling process, the crushed sample is collected, and any gas inclusions that may have been released are recovered using separation technology. The gas inclusions are then transferred to a gas chromatography-isotope ratio mass spectrometry system via a closed three-way rotary valve for precise analysis of components and isotope ratios.

[0050] The ratio of the grinding balls to the mantle mineral rocks is 1:3.

[0051] The purity of the inert gas is 99.9999%.

[0052] The mantle minerals and rocks mentioned are olivine, pyroxene, or garnet, etc.

[0053] The grinding balls are stainless steel balls, ceramic balls, or zirconium beads, and the grinding balls are high-hardness grinding balls.

[0054] The gas chromatography-isotope ratio mass spectrometry analysis system described herein involves a gas inclusion passing sequentially through a gas chromatograph, an oxidation furnace, a dehydration device, and an isotope ratio mass spectrometer via a sealed three-way rotary valve.

[0055] The gas chromatography method described is as follows: initial chromatographic temperature 30-40°C, held for 3-7 min, heating rate 8-12°C / min, final temperature 200°C, held for 26-32 min, split ratio 5:1, helium as carrier gas, flow rate 5 ml / min, followed by isotope ratio mass spectrometry monitoring. 12 CO2 / 13 The ratio of CO2, calculate δ 13 C value.

[0056] The high-energy microcavity vibrating ball mill includes a base plate and a motor and bearing housing connected to the base plate. A rotating shaft is installed inside the bearing housing. The motor and rotating shaft are connected by a belt and a pulley. One end of the rotating shaft is connected to a rocker arm. A fixed plate is installed on one side of the rocker arm. A grinding jar is installed inside the fixed plate. A spring is installed between the rocker arm and the base plate. When the motor operates, it drives the rocker arm to rotate via the rotating shaft. The fixed plate is fixedly connected to the grinding jar via a flange. The grinding jar and the rotating shaft are set at an inclined angle.

[0057] The core of high-energy vibration ball milling technology in high-energy microcavity vibratory ball mills lies in their unique vibration mechanism, ensuring that the grinding balls and samples within the milling chamber are always in a highly dynamic state of motion. This continuous, high-intensity motion is key to achieving efficient grinding. Specifically, this motion state is mainly reflected in the following aspects: ① Three-dimensional motion: Unlike the single-axis rotation of traditional high-energy microcavity vibratory ball mills, high-energy microcavity vibratory ball mills typically employ a three-dimensional motion mode. The grinding balls not only rotate around the central axis of the container but also undergo complex vibrations and oscillations in the vertical and horizontal directions. This multi-dimensional motion significantly increases the collision frequency and energy between the grinding balls, accelerating the grinding process. ② High-frequency vibration: Driven by a motor, high-frequency vibration is generated, causing the grinding balls to continuously jump, roll, and collide within the milling chamber. High-frequency vibration not only improves grinding efficiency but also reduces the formation of large particles, ensuring more uniform grinding.

[0058] Within the grinding chamber, the grinding balls not only revolve with the entire container, ensuring that each grinding ball surface contacts the sample, but also improve the comprehensiveness and uniformity of grinding. ④ Dynamic balance: Although the grinding balls and sample move at high speed, a well-designed high-energy vibration ball mill ensures that collisions between grinding balls and between the grinding balls and the chamber wall occur in a relatively gentle manner, avoiding excessive wear and equipment damage, while also guaranteeing the stability and safety of the grinding process. ⑤ Continuous renewal of contact surfaces: Due to the continuous movement of the grinding balls and sample, new contact surfaces are constantly created, which helps to break down the material structure more quickly, promotes the generation of fine particles, and improves grinding efficiency and fineness.

[0059] The high-energy microcavity vibratory ball mill operates at a speed of 1500-1800 r / min, with the temperature inside the milling jar not exceeding 60°C and a frequency of 20-50 Hz. The milling program is designed to start the mill and monitor key temperature parameters during the grinding process (temperature is monitored using an infrared thermometer to ensure the jar temperature does not exceed 60°C). This ensures the temperature does not rise too rapidly during grinding; grinding is stopped when the temperature exceeds 60°C to avoid generating interfering gases, ensuring safe operation and achieving the desired grinding effect.

[0060] The gas inclusion gas chromatography-isotope ratio mass spectrometry system described above is used to analyze methane, nitrogen, hydrogen, carbon dioxide, ethane and their respective isotope ratios.

[0061] Operating Procedures: ① Sample Preparation: First, carefully select suitable portions from mantle-derived rock samples to ensure representativeness and research value. ② Microcavity: Crush the selected mineral and rock samples into appropriate particle sizes. The cavity is designed to minimize sample contact with the external environment and is filled with inert gas to exclude oxygen and moisture, protecting the sample from oxidation or hydrolysis. ③ High-Energy Vibratory Ball Milling: At room temperature, use a microcavity vibratory ball mill equipped with hard grinding balls to subject the sample within the microcavity to high-intensity mechanical vibration and rotation. Through high-frequency collisions and friction between the balls, the mineral and rock are gradually physically crushed into smaller particles, even releasing internal gas inclusions. ④ Collection and Analysis: After the ball milling process, collect the crushed sample and recover any released gas inclusions using appropriate separation techniques (such as centrifugation and sieving). Subsequently, perform chemical composition analysis on these gases to reveal geological information from deep within the mantle, such as mantle composition, temperature, pressure conditions, and the Earth's early evolutionary history.

[0062] In specific implementation of this invention, such as Figure 4 As shown, for the analysis of carbon isotope ratios (focusing on δ13C) of methane (CH4) inclusions in gases, the experimental conditions for using gas chromatography-isotope ratio mass spectrometry (GC-IRMS) can be summarized as follows: Before injection, ensure that the gas sample is free of moisture and impurities that may interfere with the analysis. Standard preparation: Prepare methane standards with known δ13C values ​​for instrument calibration.

[0063] Chromatographic conditions (GC section): A permanent gas analysis column (J&W HP-PLOT-Q; 30m, 0.53mm, 40.00μm) was used. Column temperature: initial temperature 35°C, hold for 5 min, heating rate 10°C / min, final temperature 200°C, hold for 30 min. Split ratio: 5:1. Carrier gas: high-purity helium, flow rate 5 ml / min, ensuring effective sample transfer to the mass spectrometer. Isotope ratio mass spectrometry conditions (DELTAVPlus) or a similar high-precision isotope ratio mass spectrometer. Isotope ratio monitoring: 44 / 45 (corresponding to...) 12 CO2 / 13 The ratio of CO2 to δ is used to calculate δ. 13 C-value. Calibration: Run standards before and after analysis to calibrate the instrument and ensure the accuracy of the results.

[0064] To avoid contamination, this invention employs an inert gas shielding system to effectively prevent chemical contamination of the sample during processing. High-energy vibratory ball milling at room temperature achieves efficient and precise physical fragmentation without altering the sample's chemical properties, releasing gas inclusions. This helps preserve the original state of the gas inclusions, improving the accuracy and reliability of subsequent gas composition analysis. This method is applicable to the study of various mantle minerals and is of great significance for understanding deep Earth processes. In summary, this technology is an important tool for exploring the secrets of the Earth's depths, enabling scientists to obtain crucial information about mantle material composition and geodynamic processes without damaging the original properties of the sample.

[0065] Microcavity design is particularly suitable for processing extremely small amounts of samples, reducing sample loss and improving the sensitivity and accuracy of gas analysis.

[0066] The sealed microcavity environment combined with efficient vibration grinding facilitates the release, concentration, and enrichment of trace gases in the sample, which is crucial for the analysis of rare or trace gases. The microcavity structure allows for direct connection to gas chromatography-mass spectrometry instruments, simplifying sample processing and reducing contamination and loss during transfer.

[0067] Helium, as an inert gas, effectively isolates oxygen and other reactive gases, preventing unnecessary chemical reactions during grinding and preserving the sample's original state. A helium environment helps create stable grinding conditions, especially for oxygen-sensitive samples such as easily oxidized substances, resulting in purer grinding products. In some cases, helium flow can also help promote the release of gas inclusions in the sample, improving the efficiency and recovery rate of gas analysis. It facilitates the transfer and analysis of gas inclusion samples: the microcavity design simplifies the transition from sample preparation to analysis, allowing samples to be directly transferred to the analytical system under a protective atmosphere, reducing external interference. By reducing sample preparation steps and external contact, the original information of gas inclusions is better preserved, improving the accuracy and reliability of the final analytical results. High-energy microcavity vibratory ball milling technology combined with a helium protective atmosphere not only improves the efficiency and accuracy of ultra-micro gas processing.

[0068] Example 1:

[0069] Taking typical mantle peridotite as an example: ① Sample preparation: Pre-treat the mantle peridotite sample to an appropriate size to ensure it meets the feed particle size requirements of the high-energy microcavity vibrating ball mill (1 mm), thus reducing damage to the milling chamber from excessively large particles and improving grinding efficiency. ② Reasonable selection of grinding media: Use grinding balls of appropriate size, density, and hardness. Zirconia material is selected for the grinding balls. Oversized balls will result in excessive impact force and agglomeration; undersized balls will have low grinding efficiency. Simultaneously, the material of the grinding media should be compatible with the sample to avoid introducing impurities or reactions. ③ Optimization of ball-to-material ratio: The ball-to-material ratio (the mass ratio of grinding balls to sample) directly affects the grinding effect. An excessively high ratio may lead to over-grinding and agglomeration, while an excessively low ratio will result in insufficient grinding. Experiments determined the optimal ball-to-material ratio to be 1:3. ④ Use a dispersant: For samples prone to agglomeration, an appropriate amount of dispersant can be added before grinding to increase lubrication between samples and reduce agglomeration; ⑤ Set atmospheric conditions: Ensure good sealing performance of the ball mill chamber, and flush the sample with 99.9999% pure inert gas to remove oxygen, nitrogen, and other gas interferences from the air, creating an atmosphere that prevents oxidation during grinding; ⑥ Adjust vibration parameters: Appropriately adjust the vibration frequency and ball milling time to find the grinding conditions most suitable for the sample characteristics. High-frequency vibration helps reduce the mutual attraction between particles and lowers the risk of agglomeration.

[0070] High-energy three-dimensional vibration parameters: Based on the properties of the mantle peridotite and the target (such as releasing nitrogen inclusions), appropriate vibration frequency and amplitude are set, while three-dimensional vibration accelerates this process, making it easier for the gas to be released, avoiding sample agglomeration, and making the inclusions easier to release.

[0071] Subsequent processing and analysis: After ball milling, samples were collected and the released gases were detected and analyzed using appropriate methods (such as gas chromatography and mass spectrometry) to understand the composition and distribution characteristics of gas inclusions in mantle peridotite.

[0072] Example 2:

[0073] Gas isotope analysis procedure steps:

[0074] Step 1: Gas chromatography separation;

[0075] Sample injection: The purified and concentrated gas sample is injected into the gas chromatograph through a closed three-way rotary valve.

[0076] Column chromatography: Utilizing the differences in the partition coefficients of different gases on the stationary phase, gas components are separated by using a chromatographic column.

[0077] Step 4: Online Conversion

[0078] For gases requiring conversion (such as methane to CO2), the chemical reaction is carried out online via a catalytic converter. For gases that do not require conversion (such as nitrogen), they are directly fed into a mass spectrometer.

[0079] Step 5: Isotope ratio mass spectrometry analysis

[0080] Helium carrier gas: Helium is used as a carrier gas to carry the gas sample into the ion source.

[0081] Ionization: Sample molecules are ionized in an ion source and converted into charged ions.

[0082] Mass analysis: Ions are separated based on their mass-to-charge ratio (m / z) by passing through a magnetic or electric field.

[0083] Isotope ratio determination: Measure the abundance of different isotope ions and calculate the isotope ratio.

[0084] like Figure 1 As shown, the horizontal axis of the isotopic analysis spectrum of gas inclusions in mantle peridotite represents retention time in seconds; the vertical axis represents peak height (unit: millivolts mv).

[0085] In the field of isotope research, particularly in stable isotope geochemistry and environmental science, "δ" (delta) is a commonly used symbol to represent the deviation of an isotope ratio from a standard sample, usually expressed as parts per thousand (‰, permil). This representation allows for comparison of data between different laboratories.

[0086] Rsample is the ratio of two isotopes in a sample (e.g., 13C / 12C).

[0087] Rstandard is an internationally recognized standard substance.

[0088] The formula for calculating the δ value is as follows:

[0089]

[0090] The isotopic analysis data (PDB,‰) of methane and carbon dioxide gas inclusions are shown in the table below.

[0091] Number of analyses Methane peak area (vs) <![CDATA[δ 13 C CH4 ]]> <![CDATA[C02 peak area (vs)]]> <![CDATA[δ 13 C CO2 ]]> 1 0.66 -42.35 0.26 -19.07 2 0.53 -42.04 0.26 -18.72 3 0.61 -43.09 0.22 -19.08

[0092] This invention safely collects gas inclusions from trace and difficult-to-obtain mantle rock samples, while minimizing sample damage and the risk of external contamination. Combining ultra-micro extraction with high-efficiency pre-concentration techniques, it effectively recovers and enriches trace gases, such as methane, from extremely small amounts of mantle gas inclusions, ensuring that the gas purity and concentration before analysis meet the requirements of high-precision isotope analysis. High-sensitivity and high-precision isotope ratio measurement techniques for mantle gases (especially methane) utilize isotope ratio mass spectrometry coupled with or improved mass spectrometry to improve detection limits, reduce background interference, and ensure data accuracy. This invention will greatly advance the boundaries of mantle fluid and gas inclusion research, providing richer and more accurate data support for understanding deep Earth processes, material cycles, mantle dynamics, and early Earth history. It also opens new avenues for exploring cutting-edge scientific questions such as the origin of life on Earth and climate change.

[0093] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown throughout are only one of the embodiments of the present invention. The actual structure is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for analyzing the carbon isotopic composition of gas inclusions in mantle minerals and rocks, characterized in that, Includes the following steps: S1. Sample preparation: Select mantle minerals and rocks, choosing those with uniformly sized grains, 0.5-1mm in size; S2. Preparation of the high-energy microcavity vibration ball mill: Grinding balls are added to a high-energy microcavity vibrating ball mill, and a dispersant is added before grinding. Mantle minerals and rocks are then placed into the high-energy microcavity vibrating ball mill for grinding. S3, Inert gas flushing: The cavity of the high-energy microcavity vibrating ball mill is repeatedly flushed with inert gas for 10-30 minutes to completely replace the original air in the cavity. S4. Gas Analysis: After the ball milling process, the crushed sample is collected, and any gas inclusions that may have been released are recovered using separation technology. The gas inclusions are then transferred to a gas chromatography-isotope ratio mass spectrometry system via a closed three-way rotary valve for precise analysis of components and isotope ratios. The ratio of the grinding balls to the mantle mineral rocks is 1:3; The purity of the inert gas is 99.9999%. The grinding balls are stainless steel balls, ceramic balls, or zirconium beads; The high-energy microcavity vibrating ball mill includes a base plate and a motor and bearing housing connected to the base plate. A rotating shaft is installed inside the bearing housing. The motor and the rotating shaft are connected by a belt and a pulley. A rocker arm is connected to one end of the rotating shaft. A fixed plate is installed on one side of the rocker arm. A ball milling jar is installed inside the fixed plate. A spring is installed between the rocker arm and the base plate.

2. The method for analyzing the carbon isotopic composition of gas inclusions in mantle minerals and rocks according to claim 1, characterized in that: The mantle minerals and rocks are olivine, pyroxene, or garnet.

3. The method for analyzing the carbon isotopic composition of gas inclusions in mantle minerals and rocks according to claim 1, characterized in that: The gas chromatography-isotope ratio mass spectrometry analysis system consists of a gas inclusion passing through a sealed three-way rotary valve sequentially through a gas chromatograph, an oxidation furnace, a water removal device, and an isotope ratio mass spectrometer.

4. The method for analyzing the carbon isotopic composition of gas inclusions in mantle minerals and rocks according to claim 3, characterized in that: The gas chromatographic parameters are as follows: initial temperature 30-40°C, hold for 3-7 min, heating rate 8-12°C / min, final temperature 200°C, hold for 26-32 min, split ratio 5:1, carrier gas helium, flow rate 5 ml / min, followed by isotope ratio mass spectrometry monitoring. 12 Calculate the δ¹³C value based on the ratio of CO₂ to ¹³CO₂.

5. The method for analyzing the carbon isotopic composition of gas inclusions in mantle minerals and rocks according to claim 1, characterized in that: The high-energy microcavity vibrating ball mill has a rotation speed of 1500-1800 r / min, the temperature inside the ball mill jar does not exceed 60°C, and the frequency is 20-50 Hz.

6. The method for analyzing the carbon isotopic composition of gas inclusions in mantle minerals and rocks according to claim 1, characterized in that: The gas inclusion gas chromatography-isotope ratio mass spectrometry system described above is used to analyze methane, nitrogen, hydrogen, carbon dioxide, ethane and their respective isotope ratios.

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