A correction method for laser micro tin ore sample hafnium isotope determination

Abstract

The application discloses a correction method for laser micro-area tin stone sample hafnium isotope determination, which comprises the following steps: arranging a first tin stone standard substance into a first row, arranging a second tin stone standard substance into a second row, arranging a tin stone sample into a third row, embedding them into the same epoxy resin respectively, so as to prepare a sample target; obtaining a first detection signal at a first time; obtaining a second detection signal at a second time; obtaining a third detection signal at a third time; obtaining initial hafnium isotopes in the first tin stone standard substance according to the first detection signal, obtaining initial hafnium isotopes in the second tin stone standard substance according to the second detection signal, and obtaining initial hafnium isotopes in the tin stone sample according to the third detection signal; and correcting the initial hafnium isotopes in the tin stone sample by using the initial hafnium isotopes in the first tin stone standard substance and the initial hafnium isotopes in the second tin stone standard substance, so as to obtain a correction result of the initial hafnium isotope determination in the tin stone sample.

Description

Technical Field

[0001] This invention relates to the field of hafnium isotope technology in isotope geochemistry, and particularly to a calibration method for hafnium isotope determination of cassiterite samples in a laser micro-area. Background Technology

[0002] Cassiterite (SnO2) belongs to the rutile mineral group and is a tetragonal oxide-type uranium-bearing mineral. It is not only the main ore mineral in various tin polymetallic deposits, but also a common accessory mineral, associated with tungsten deposits related to granites, lithium-beryllium-niobium-tantalum deposits related to pegmatites, and volcanogenic massive sulfide deposits.

[0003] Early determinations of the mineralization age of tin deposits primarily relied on measuring the crystallization ages of tin-related granites (such as zircon uranium-lead, mica argon-argon, whole-rock rubidium-strontium, etc.) or using isotopic age data from gangue minerals. However, due to differences in the minerals and testing methods chosen by different researchers, the mineralization ages of the same deposit can vary significantly, leading to differing understandings of the deposit's genesis.

[0004] Cassiterite has a high sealing temperature, and its crystallization age can directly represent the mineralization age, making it the most effective means of directly determining the formation time of tin deposits. Due to its relatively high uranium / lead ratio and low lead content, cassiterite is an ideal material for uranium-lead isotope dating. To better constrain the formation age of tin deposits, a deep understanding of their geological genesis is necessary. The formation age is a crucial genetic factor. Accurately obtaining the age of cassiterite is a prerequisite for studying the mineralization background and comparing it with known geological events.

[0005] Besides the mineralization epoch of tin deposits, the source of tin minerals is another very important parameter in its isotopic geochemistry. Cassiterite contains a certain amount of hafnium (100–600 micrograms / gram), making it a potential target for hafnium isotope determination. This provides a new means for isotopic geochemical tracing of tin-forming mineral source areas, and offers new insights and perspectives for the study of tin deposit geochronology and the genesis of material source areas.

[0006] Currently, the instrument used for hafnium isotope determination is a multiple-collector inductively coupled plasma mass spectrometer (MCP-MS). Since cassiterite is a solid, granular mineral, the entire cassiterite particle must be dissolved in acid at high temperature, followed by chemical separation techniques to remove impurities and interfering elements, yielding a pure hafnium solution. Finally, the hafnium isotopes in the cassiterite are measured. This method yields whole cassiterite particles (approximately 10-1 granules). -3 The information obtained by collecting large quantities of samples (in grams) yields highly accurate hafnium isotopes, typically less than 0.001%. For example, the hafnium isotope of cassiterite can be obtained as 0.282190 ± 0.000010, making it the most accurate method currently available.

[0007] The above chemical methods require dissolving cassiterite particles, thus yielding an average hafnium isotope value for the cassiterite sample. However, the geological processes of cassiterite growth are highly complex, potentially involving alteration. Furthermore, cassiterite often contains numerous inclusions or is associated with or coexists with high-hafnium minerals (such as zircon and niobite). Therefore, cassiterite may not possess uniform hafnium isotopes on a large scale. If only chemical methods are used to obtain cassiterite hafnium isotopes, the resulting average value cannot truly reflect the actual hafnium isotopes at the microscale (~100 micrometers). Therefore, chemical methods are only suitable for hafnium isotope determination of cassiterite samples with simple and homogeneous growth processes, such as for the determination and calibration of cassiterite hafnium isotope standards. Moreover, the biggest challenge with current chemical methods is the difficulty in dissolving cassiterite; 20–30 milligrams of cassiterite requires high temperature and pressure dissolution for thirty days, which is the fundamental reason why no chemical method exists for cassiterite hafnium isotope determination.

[0008] Over the past two decades, with the rapid development of technology, laser micro-area hafnium isotope methods (such as zircon) have been widely used, becoming an important tool for exploring Earth's evolution and various geological processes. Compared with chemical methods, laser micro-area methods have significant advantages such as simple sample preparation, rapid analysis, and higher spatial resolution, while also avoiding cumbersome chemical experiments. Therefore, laser micro-area hafnium isotope technology has developed rapidly, greatly promoting the application research of hafnium isotope geochemistry.

[0009] However, laser micro-area hafnium isotope techniques have mainly focused on minerals with high hafnium content (greater than 1000 μg / g), such as zircon, while cassiterite typically has a hafnium content of 100–600 μg / g. Currently, there is no detailed literature reporting on cassiterite hafnium isotope analysis. Whether the laser micro-area zircon hafnium isotope determination method is suitable for cassiterite, whether there is a matrix effect between zircon and cassiterite, and isotopic analysis are all questions that need to be addressed. 176 Lu and 176 Yb will interfere 176 Key technical issues such as how to calculate Hf interference correction were not discussed or studied in detail.

[0010] Furthermore, the laser micro-area method is a relative analysis technique that relies on the same mineral as a standard material for laser micro-area analysis. Based on the inventors' research and understanding of the relevant technical field, there is currently no laser micro-area standard material for cassiterite hafnium isotopes. Therefore, only by fundamentally solving the above technical challenges can laser micro-area cassiterite hafnium isotope technology truly enter the practical application stage. Summary of the Invention

[0011] This invention provides a calibration method for hafnium isotope determination of cassiterite samples in a laser micro-area to solve at least one of the above-mentioned technical problems and other potential technical problems.

[0012] Exemplary embodiments of the present invention provide a calibration method for hafnium isotope determination of laser-guided micro-area cassiterite samples, comprising:

[0013] The first cassiterite standard material in granular form is arranged in the first row, the second cassiterite standard material in granular form is arranged in the second row, and the cassiterite sample in granular form is arranged in the third row. All of them are embedded in the same epoxy resin to make a sample target with a diameter of 1 inch to 2 inches. The sample target is then placed in the sample cavity of the laser ablation cell.

[0014] In the first instant, an excimer laser source is used to focus the first cassiterite standard material onto the sample target in a parallel light manner to perform laser micro-area ablation, so as to generate aerosol particles of the first cassiterite standard material; wherein, the aerosol particles of the first cassiterite standard material pass through the electric field and magnetic field in the multi-receiver inductively coupled plasma mass spectrometer to achieve dual focusing of angle and velocity and reach the ion signal detection system, thereby obtaining the first detection signal.

[0015] At the second time, an excimer laser source is used to focus the second cassiterite standard material onto the sample target in a parallel light manner to perform laser micro-area ablation, so as to generate aerosol particles of the second cassiterite standard material; wherein, the aerosol particles of the second cassiterite standard material pass through the electric field and magnetic field in the multi-receiver inductively coupled plasma mass spectrometer to achieve dual focusing of angle and velocity and reach the ion signal detection system, thereby obtaining a second detection signal.

[0016] In the third time, an excimer laser source is used and focused onto the cassiterite sample on the sample target in a parallel light manner to perform laser micro-area ablation, so as to generate aerosol particles of the cassiterite sample; wherein, the aerosol particles of the cassiterite sample pass through the electric field and magnetic field in the multi-receiver inductively coupled plasma mass spectrometer to achieve dual focusing of angle and velocity and reach the ion signal detection system, thereby obtaining a third detection signal.

[0017] The initial hafnium isotope in the first cassiterite standard material is obtained based on the first detection signal, the initial hafnium isotope in the second cassiterite standard material is obtained based on the second detection signal, and the initial hafnium isotope in the cassiterite sample is obtained based on the third detection signal.

[0018] The initial hafnium isotopes in the cassiterite sample are corrected using the initial hafnium isotopes in the first cassiterite standard material and the second cassiterite standard material, so as to obtain the correction results of the initial hafnium isotope determination in the cassiterite sample.

[0019] According to an embodiment of this disclosure, the total number of particles in the first cassiterite standard material is X, the total number of particles in the second cassiterite standard material is Y, and the total number of particles in the cassiterite sample is Z, where X, Y, and Z are natural numbers greater than or equal to 1.

[0020] According to an embodiment of this disclosure, when X and Y are even numbers and Z is a multiple of 5, two of the first cassiterite standard materials are focused and subjected to laser micro-etching at a first time, two of the second cassiterite standard materials are focused and subjected to laser micro-etching at a second time, and five of the cassiterite samples are focused and subjected to laser micro-etching at a third time, and this process is repeated until all particles are detected.

[0021] According to embodiments of this disclosure, the ion signal detection system is a Faraday cup; the magnetic field strength of the magnetic field can be adjusted to ensure that the primary ions... 172 Yb, 173 Yb, 175 Lu, 176 Yb+ 176 Lu+ 176 Hf, 177 Hf, 178 Hf, 179 Hf and 180 Hf sequentially reaches the ion signal detection system through an electric field and a magnetic field; where Yb is ytterbium, Lu is lutetium, and Hf is hafnium; wherein, the primary ion is the primary ion of the first cassiterite standard material at the first time and is detected as the first detection signal, the primary ion of the second cassiterite standard material at the second time and is detected as the second detection signal, and the primary ion of the cassiterite sample at the third time and is detected as the third detection signal.

[0022] According to embodiments of this disclosure, obtaining the initial hafnium isotope in the first cassiterite standard material based on the first detection signal includes calculation according to the following formulas (1) to (4):

[0023] 176 Yb 测 = 172 Yb 测 × ( 176 Yb / 172 Yb) 真 × (M 176 / M 172 ) βYb (1)

[0024] 176 Lu 测 = 175 Lu 测 × ( 176 Lu / 175 Lu) 真 × (M 176 / M 175 ) βLu (2)

[0025] 176 Hf 测 = ( 176 Yb 测 + 176 Lu 测 + 176 Hf 测 ) - 176 Yb 测 - 176 Lu 测 (3)

[0026] [ 176 Hf / 177 Hf] 测量 =[ 176 Hf / 177 Hf] 初始 + [ 176 Lu / 177 Hf] 测量 *(e λ176t -1) (4)

[0027] Formula (1) is used to calculate 176 Yb 测 ;In formula (1) ( 176 Yb / 172 Yb) 真 Among the first cassiterite standard materials, the known ones 176 Yb / 172 Theoretical truth value of Yb, M 176 / M 172 for 176 The mass number of Yb and 172 The ratio of the mass number of Yb βYb The Yb fractionation factor in the first cassiterite standard; 172 Yb 测 The one detected in the first detection signal 172 Yb measurement value.

[0028] Formula (2) is used to calculate 176 Lu 测 ;In formula (1) ( 176 Lu / 175 Lu) 真 Among the first cassiterite standard materials, the known ones 176 Lu / 175 Lu's theoretical truth value, M 176 / M 175 for 176 The mass number of Lu and 175 The ratio of the mass number of Lu βLu The Lu fractionation factor in the first cassiterite standard material; 175 Lu 测 The one detected in the first detection signal 175 Lu measurement value.

[0029] Formula (3) is calculated based on the results of formulas (1) and (2). 176 Hf 测 ;and 176 Yb 测 + 176 Lu 测 + 176 Hf 测 The one detected in the first detection signal 176 Yb+ 176 Lu+ 176 Hf measurement value.

[0030] Formula (4) is obtained from formula (1) - formula (3). 176 Lu 测 and 176 Hf 测 Then, combined with the detected signal from the first detection signal 177 The Hf measurement value was used to obtain the initial hafnium isotope in the first cassiterite standard. 176 Hf / 177 Hf] 初始 In formula (4), the decay constant λ 176 =1.867*10 -11 t is a known constant, and t is the known age of the first cassiterite standard.

[0031] According to embodiments of this disclosure, obtaining the initial hafnium isotope in the second cassiterite standard material based on the second detection signal includes calculation according to the following formulas (5) to (8):

[0032] 176 Yb 测 = 172 Yb 测 ×( 176 Yb / 172 Yb) 真 ×(M 176 / M 172 ) βYb (5)

[0033] 176 Lu 测 =175 Lu 测 ×( 176 Lu / 175 Lu) 真 ×(M 176 / M 175 ) βLu (6)

[0034] 176 Hf 测 =( 176 Yb 测 + 176 Lu 测 + 176 Hf 测 )- 176 Yb 测 - 176 Lu 测 (7)

[0035] [ 176 Hf / 177 Hf] 测量 =[ 176 Hf / 177 Hf] 初始 +[ 176 Lu / 177 Hf] 测量 *(e λ176t -1) (8)

[0036] Formula (5) is used to calculate 176 Yb 测 ;In formula (5) ( 176 Yb / 172 Yb) 真 The second cassiterite standard material is known to be among the known ones. 176 Yb / 172 Theoretical truth value of Yb, M 176 / M 172 for 176 The mass number of Yb and 172 The ratio of the mass number of Yb βYb The Yb fractionation factor in the second cassiterite standard; 172 Yb 测 Detected in the second detection signal 172 Yb measurement value.

[0037] Formula (6) is used to calculate 176 Lu 测 ; In formula (6) ( 176 Lu / 175 Lu) 真 The second cassiterite standard material is known to be among the known ones. 176Lu / 175 Lu's theoretical truth value, M 176 / M 175 for 176 The mass number of Lu and 175 The ratio of the mass number of Lu βLu The Lu fractionation factor in the second cassiterite standard; 175 Lu 测 Detected in the second detection signal 175 Lu measurement value.

[0038] Formula (7) is calculated based on the results of formulas (5) and (6). 176 Hf 测 ;and 176 Yb 测 + 176 Lu 测 + 176 Hf 测 Detected in the second detection signal 176 Yb+ 176 Lu+ 176 Hf measurement value.

[0039] Formula (8) is obtained from formula (5) - formula (7). 176 Lu 测 and 176 Hf 测 Then, combined with the detected signal from the second detection signal 177 The Hf measurement value was used to obtain the initial hafnium isotope in the second cassiterite standard. 176 Hf / 177 Hf] 初始 In formula (8), the decay constant λ 176 =1.867*10 -11 t is a known constant, and t is the known age of the second cassiterite standard.

[0040] According to embodiments of this disclosure, obtaining the initial hafnium isotope in the cassiterite sample based on the third detection signal includes calculation according to the following formulas (9) to (12):

[0041] 176 Yb 测 = 172 Yb 测 ×( 176 Yb / 172 Yb) 真 ×(M 176 / M 172 ) βYb (9)

[0042] 176 Lu 测 = 175 Lu 测 ×( 176 Lu / 175 Lu) 真 ×(M 176 / M 175 ) βLu (10)

[0043] 176 Hf 测 =( 176 Yb 测 + 176 Lu 测 + 176 Hf 测 )- 176 Yb 测 - 176 Lu 测 (11)

[0044] [ 176 Hf / 177 Hf] 测量 =[ 176 Hf / 177 Hf] 初始 +[ 176 Lu / 177 Hf] 测量 *(e λ176t -1) (12)

[0045] Formula (9) is used to calculate 176 Yb 测 ; In formula (9) ( 176 Yb / 172 Yb) 真 The first cassiterite standard or the second cassiterite standard is known. 176 Yb / 172 Theoretical truth value of Yb, M 176 / M 172 for 176 The mass number of Yb and 172 The ratio of the mass number of Yb βYb The Yb fractionation factor in the first cassiterite standard material or the second cassiterite standard material; 172 Yb 测 The third detection signal detected 172 Yb measurement value.

[0046] Formula (10) is used to calculate 176 Lu 测 ; In formula (10) (176 Lu / 175 Lu) 真 The first cassiterite standard or the second cassiterite standard is known. 176 Lu / 175 Lu's theoretical truth value, M 176 / M 175 for 176 The mass number of Lu and 175 The ratio of the mass number of Lu βLu The Lu fractionation factor is either the first cassiterite standard substance or the second cassiterite standard substance. 175 Lu 测 The third detection signal detected 175 Lu measurement value.

[0047] Formula (11) is calculated based on the results of formulas (9) and (10). 176 Hf 测 ;and 176 Yb 测 + 176 Lu 测 + 176 Hf 测 The third detection signal detected 176 Yb+ 176 Lu+ 176 Hf measurement value.

[0048] Formula (12) is obtained from formula (9) - formula (11). 176 Lu 测 and 176 Hf 测 Then, combined with the detected signal in the third detection signal 177 The initial hafnium isotope in the cassiterite sample was obtained by measuring the Hf value. 176 Hf / 177 Hf] 初始 In formula (12), the decay constant λ 176 =1.867*10 -11 is a known constant, and t is the known age of the cassiterite sample.

[0049] According to embodiments of this disclosure, the step of using the initial hafnium isotopes in the first cassiterite standard material and the second cassiterite standard material to correct the initial hafnium isotopes in the cassiterite sample in order to obtain the correction result of the initial hafnium isotope measurement in the cassiterite sample includes: performing linear fitting on the initial hafnium isotopes in the first cassiterite standard material obtained from multiple measurements to obtain a first correction coefficient K1; performing linear fitting on the initial hafnium isotopes in the second cassiterite standard material obtained from multiple measurements to obtain a second correction coefficient K2; and averaging the first correction coefficient K1 and the second correction coefficient K2, and multiplying the initial hafnium isotopes in the cassiterite sample by the average value to obtain the correction result of the initial hafnium isotope measurement in the cassiterite sample.

[0050] According to embodiments of this disclosure, the surface of the sample target is further polished and cleaned; the multi-receiver inductively coupled plasma mass spectrometer is a Neptune Plus equipped with a Jet sample cone and an X-trap cone, and is supplemented with 2-4 mL / min of high-purity nitrogen gas to improve the sensitivity of the multi-receiver inductively coupled plasma mass spectrometer; the parameters of the multi-receiver inductively coupled plasma mass spectrometer include: the output intensity of the laser beam is 100 mJ, the laser energy density of the sample target surface is 5 joules / cm², the laser beam spot size is 160 μm, and the laser ablation frequency is 6-8 Hz.

[0051] According to an embodiment of this disclosure, the first cassiterite standard is Rond-A, a major cassiterite standard with a known initial hafnium isotope ratio, and the second cassiterite standard is BB#7, a monitoring cassiterite standard with a known initial hafnium isotope ratio; the initial hafnium isotope ratio of the major cassiterite Rond-A is 0.28217 ± 0.00003; and the initial hafnium isotope ratio of the monitoring cassiterite BB#7 is 0.28189 ± 0.00003. Attached Figure Description

[0052] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying 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.

[0053] Figure 1 This invention presents a comparison of hafnium isotope determination results and solution method results for a laser-guided micro-area cassiterite sample, with the sample being Rond-A.

[0054] Figure 2This invention provides a comparison of hafnium isotope determination results in a laser-guided micro-area cassiterite sample with results obtained using the solution method. The sample in question is BB#7. Detailed Implementation

[0055] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0056] The exemplary embodiments of the present invention provide a calibration method for hafnium isotope determination of cassiterite samples in a laser micro-area, including steps S100, S102, S104, S106, S108, and S110, which are described below.

[0057] In step S100, the granular first cassiterite standard material is arranged in the first row, the granular second cassiterite standard material is arranged in the second row, and the granular cassiterite sample is arranged in the third row, and all of them are embedded in the same epoxy resin to make a sample target with a diameter of 1 inch to 2 inches (where 1 inch is 2.54 cm, which can be a disc placed in the sample cavity, called a target), and the sample target is placed in the sample cavity of the laser ablation pool.

[0058] For example, the sample surface can be polished and cleaned (polishing to smooth the sample surface, and cleaning to remove any potential contaminants) before being placed in the laser ablation chamber for more accurate measurements. Cassiterite samples and cassiterite standards have very small particles, approximately 100–200 micrometers. These small particles of cassiterite samples of unknown age can be arranged in one row, and the small particles of cassiterite standards (first cassiterite standard, second cassiterite standard) in another row, all embedded in, for example, a 1-inch sample target. Then, during testing, a laser beam of approximately 100 or 120 micrometers can be used for ablation sampling. For example, an automated testing sequence can be used to test multiple sample or standard particles separately.

[0059] For example, the cassiterite standard material in this disclosure can be cassiterite whose hafnium isotopes are known in advance (e.g., it can be measured in advance using a solution method to know its true value). It is understood that the role of the cassiterite standard material is to serve as a standard sample, thereby facilitating the correction and adjustment of the measurement results of the cassiterite sample to obtain more accurate results. Since the cassiterite standard material and the cassiterite sample are prepared on the same sample target and placed in the laser ablation cell sample chamber, they are in the same detection environment and can be used as mutual references. Even if the testing equipment or testing environment changes, the measurement results will change synchronously because the environments of both will change simultaneously, and they can still be used as mutual references. For example, even if there are slight changes in the instrument conditions (e.g., multi-collector plasma mass spectrometer), the state of the standard material and the unknown sample is similar, and the unknown sample can be corrected using the standard material, resulting in more accurate test results.

[0060] According to an embodiment of this disclosure, the first cassiterite standard is Rond-A, a major cassiterite standard with a known initial hafnium isotope ratio, and the second cassiterite standard is BB#7, a monitoring cassiterite standard with a known initial hafnium isotope ratio; the initial hafnium isotope ratio of the major cassiterite Rond-A is 0.28217±0.00003; and the initial hafnium isotope ratio of the monitoring cassiterite BB#7 is 0.28189±0.00003.

[0061] Understandably, the advantage of using two standard reference materials is that it allows for effective monitoring of the instrument's condition and determination of the reliability and validity of the measurement results. The hafnium isotope ratios of both the primary and monitoring standard reference materials are known (e.g., they can be determined in advance using chemical methods). If their in-situ laser micro-area results are consistent with the known values ​​within the error range, the instrument is considered to be functioning normally, and the measurement results for unknown cassiterite samples are reliable and credible. Otherwise, the instrument needs to be adjusted and its parameters optimized until the in-situ laser micro-area results of the standard reference materials are consistent with the known values ​​within the error range.

[0062] Therefore, this disclosure employs two cassiterite reference materials (a first cassiterite reference material and a second cassiterite reference material). These two reference materials can be used as the primary reference material and the monitoring reference material, respectively, to effectively monitor the state of the instrument and determine whether the measurement results are reliable and effective, thereby preventing deviations or inaccuracies in results caused by relying on only one reference material.

[0063] According to an embodiment of this disclosure, the total number of particles in the first cassiterite standard material is X, the total number of particles in the second cassiterite standard material is Y, and the total number of particles in the cassiterite sample is Z, where X, Y, and Z are natural numbers greater than or equal to 1.

[0064] For example, X, Y, and Z can be natural numbers from 2 to 100. By measuring multiple samples and groups, the overall measurement results can be considered more accurately.

[0065] According to an embodiment of this disclosure, when X and Y are even numbers and Z is a multiple of 5, two of the first cassiterite standard materials are focused and subjected to laser micro-etching at a first time, two of the second cassiterite standard materials are focused and subjected to laser micro-etching at a second time, and five of the cassiterite samples are focused and subjected to laser micro-etching at a third time, and this process is repeated until all particles are detected.

[0066] For example, as shown in Table 1, the first cassiterite standard is Rond-A (e.g., Figure 1 The standard used is Rond-A, while the second cassiterite standard is BB#7 (e.g., Rond-A). Figure 2 As shown, BB#7 was used as the monitoring standard. Each type of cassiterite standard was measured individually in groups of two or two particles; while cassiterite samples were measured in groups of five or five particles, in order to save standard materials while ensuring the measurement efficiency of cassiterite samples.

[0067] For example, referring to Table 1, at the first time, two of the first cassiterite standard materials are focused and subjected to laser micro-etching; at the second time, two of the second cassiterite standard materials are focused and subjected to laser micro-etching; at the third time, five of the cassiterite samples are focused and subjected to laser micro-etching, and so on, until all the first cassiterite standard materials (e.g., Rond-A 01…Rond-A 06), the second cassiterite standard materials (e.g., BB#7 01…BB#7 06), and the cassiterite samples (e.g., sample 01…sample 15) have been measured.

[0068] Table 1. Test sequence of standard materials and actual samples in laser micro-area hafnium isotope determination of cassiterite samples.

[0069]

[0070]

[0071] In step S102, at a first time, an excimer laser source is used to focus the first cassiterite standard material onto the sample target in a parallel light manner to perform laser micro-area ablation, so as to generate aerosol particles of the first cassiterite standard material; wherein, the aerosol particles of the first cassiterite standard material pass through the electric field and magnetic field in the multi-receiver inductively coupled plasma mass spectrometer to achieve dual focusing of angle and velocity and reach the ion signal detection system, thereby obtaining the first detection signal.

[0072] According to embodiments of this disclosure, the surface of the sample target is further polished and cleaned; the multi-receiver inductively coupled plasma mass spectrometer is a Neptune Plus equipped with a Jet sample cone and an X-trap cone, and is supplemented with 2-4 mL / min of high-purity nitrogen gas to improve the sensitivity of the multi-receiver inductively coupled plasma mass spectrometer; the parameters of the multi-receiver inductively coupled plasma mass spectrometer include: the output intensity of the laser beam is 100 mJ, the laser energy density of the sample target surface is 5 joules / cm², the laser beam spot size is 160 μm, and the laser ablation frequency is 6-8 Hz.

[0073] For example, the parameters of the laser micro-area multi-receiver inductively coupled plasma mass spectrometer include: the laser is a parallel-focused excimer laser, the output intensity of the laser beam is 100 millijoules, the laser energy density on the surface of the cassiterite sample is 4 joules / square centimeter, the laser spot size is 100–120 micrometers, and the laser ablation frequency is 6–8 Hz; the multi-receiver plasma mass spectrometer is Neptune Plus, the accelerating voltage is -10 kV, the number of measurement groups is 200, the single-point analysis accuracy is 0.0008%, the total single-point analysis time is approximately 60 seconds, and the mass resolution of the multi-receiver plasma mass spectrometer is approximately 400.

[0074] According to embodiments of this disclosure, the ion signal detection system is a Faraday cup; the magnetic field strength of the magnetic field can be adjusted to ensure that the primary ions... 172 Yb, 173 Yb, 175 Lu, 176 Yb+ 176 Lu+ 176 Hf, 177 Hf, 178 Hf, 179 Hf and 180 Hf sequentially reaches the ion signal detection system through an electric field and a magnetic field; where Yb is ytterbium, Lu is lutetium, and Hf is hafnium; wherein the primary ion is the primary ion of the first cassiterite standard substance at the first moment and is detected as the first detection signal.

[0075] For example, at the first time t1, the first cassiterite standard material undergoes laser micro-area ablation to obtain aerosol particles (containing primary ions) of the first cassiterite standard material. These particles then pass through the electric and magnetic fields of a multi-receiver inductively coupled plasma mass spectrometer to reach the ion signal detection system. At this time, the magnetic field can guide the primary ions... 172 Yb, 173 Yb, 175 Lu, 176 Yb+ 176 Lu+ 176 Hf, 177 Hf,178 Hf, 179 Hf and 180 Hf passes through the electric field and magnetic field sequentially to reach the ion signal detection system, thereby obtaining the detection result, which can then be used as the first detection signal of the first cassiterite standard material.

[0076] In step S104, at the second time, an excimer laser source is used to focus the second cassiterite standard material onto the sample target in a parallel light manner to perform laser micro-area ablation, so as to generate aerosol particles of the second cassiterite standard material; wherein, the aerosol particles of the second cassiterite standard material pass through the electric field and magnetic field in the multi-receiver inductively coupled plasma mass spectrometer to achieve dual focusing of angle and velocity and reach the ion signal detection system, thereby obtaining a second detection signal.

[0077] According to embodiments of this disclosure, the magnetic field strength can be adjusted to allow the primary ions to... 172 Yb, 173 Yb, 175 Lu, 176 Yb+ 176 Lu+ 176 Hf, 177 Hf, 178 Hf, 179 Hf and 180 Hf sequentially passes through an electric field and a magnetic field to reach the ion signal detection system; where Yb is ytterbium, Lu is lutetium, and Hf is hafnium; wherein the primary ion is the primary ion of the second cassiterite standard substance at the second time and is detected as the second detection signal.

[0078] For example, at a second time t2, the second cassiterite standard material is then subjected to laser micro-area ablation to obtain aerosol particles (containing primary ions) of the second cassiterite standard material. These particles then pass through the electric and magnetic fields of a multi-receiver inductively coupled plasma mass spectrometer to reach the ion signal detection system. At this time, the magnetic field can guide the primary ions... 172 Yb, 173 Yb, 175 Lu, 176 Yb+ 176 Lu+ 176 Hf, 177 Hf, 178 Hf, 179 Hf and 180 Hf passes through the electric field and magnetic field sequentially to reach the ion signal detection system, thereby obtaining the detection result, which can then be used as the second detection signal of the second cassiterite standard material.

[0079] In step S106, at the third time, an excimer laser source is used to focus the cassiterite sample onto the sample target in a parallel light manner to perform laser micro-area ablation, so as to generate aerosol particles of the cassiterite sample; wherein, the aerosol particles of the cassiterite sample pass through the electric field and magnetic field in the multi-receiver inductively coupled plasma mass spectrometer to achieve dual focusing of angle and velocity and reach the ion signal detection system, thereby obtaining a third detection signal.

[0080] According to embodiments of this disclosure, the magnetic field strength can be adjusted to allow the primary ions to... 172 Yb, 173 Yb, 175 Lu, 176 Yb+ 176 Lu+ 176 Hf, 177 Hf, 178 Hf, 179 Hf and 180 Hf sequentially passes through an electric field and a magnetic field to reach the ion signal detection system; where Yb is ytterbium, Lu is lutetium, and Hf is hafnium; wherein the primary ion is the primary ion of the cassiterite sample at the third time and is detected as the third detection signal.

[0081] For example, at the third time t3, the cassiterite sample is then subjected to laser micro-area ablation to obtain aerosol particles (containing primary ions) from the cassiterite sample. These particles then pass through the electric and magnetic fields of a multi-receiver inductively coupled plasma mass spectrometer to reach the ion signal detection system. At this time, the magnetic field can guide the primary ions... 172 Yb, 173 Yb, 175 Lu, 176 Yb+ 176 Lu+ 176 Hf, 177 Hf, 178 Hf, 179 Hf and 180 Hf passes through the electric field and magnetic field sequentially to reach the ion signal detection system, thereby obtaining the detection result, which can then be used as the third detection signal for the cassiterite sample.

[0082] In step S108, the initial hafnium isotope (usually a ratio) in the first cassiterite standard material is obtained according to the first detection signal, the initial hafnium isotope (usually a ratio) in the second cassiterite standard material is obtained according to the second detection signal, and the initial hafnium isotope (usually a ratio) in the cassiterite sample is obtained according to the third detection signal.

[0083] According to embodiments of this disclosure, obtaining the initial hafnium isotope in the first cassiterite standard material based on the first detection signal includes calculation according to the following formulas (1) to (4):

[0084] 176 Yb 测 = 172 Yb 测 × ( 176 Yb / 172 Yb) 真 × (M 176 / M 172 ) βYb (1)

[0085] 176 Lu 测 = 175 Lu 测 × ( 176 Lu / 175 Lu) 真 × (M 176 / M 175 ) βLu (2)

[0086] 176 Hf 测 = ( 176 Yb 测 + 176 Lu 测 + 176 Hf 测 ) - 176 Yb 测 - 176 Lu 测 (3)

[0087] [ 176 Hf / 177 Hf] 测量 =[ 176 Hf / 177 Hf] 初始 + [ 176 Lu / 177 Hf] 测量 *(e λ176t -1) (4)

[0088] Formula (1) is used to calculate 176 Yb 测 ;In formula (1) ( 176 Yb / 172 Yb) 真 Among the first cassiterite standard materials, the known ones 176 Yb / 172Theoretical truth value of Yb, M 176 / M 172 for 176 The mass number of Yb and 172 The ratio of the mass number of Yb βYb The Yb fractionation factor in the first cassiterite standard; 172 Yb 测 The one detected in the first detection signal 172 Yb measurement value. It can be understood that the fractionation factor typically represents the deviation between the measured value and the theoretical value.

[0089] Formula (2) is used to calculate 176 Lu 测 ;In formula (1) ( 176 Lu / 175 Lu) 真 Among the first cassiterite standard materials, the known ones 176 Lu / 175 Lu's theoretical truth value, M 176 / M 175 for 176 The mass number of Lu and 175 The ratio of the mass number of Lu βLu The Lu fractionation factor in the first cassiterite standard material; 175 Lu 测 The one detected in the first detection signal 175 Lu measurement value.

[0090] Formula (3) is calculated based on the results of formulas (1) and (2). 176 Hf 测 ;and 176 Yb 测 + 176 Lu 测 + 176 Hf 测 The one detected in the first detection signal 176 Yb+ 176 Lu+ 176 Hf measurement value.

[0091] Understandable. 176 Yb, 176 Lu as 176 The isotopic interference of Hf, when the first detection signal is obtained, yields... 176 Yb 测 + 176 Lu 测 + 176 Hf 测 The measured value is a holistic detection value, that is... 176 Yb,176 Lu, 176 Hf was not measured separately. Therefore, it needs to be eliminated. 176 Yb, 176 Lu 176 Isotopic interference of Hf. Accordingly, in this disclosure, formulas (1) and (2) are used to obtain 176 Yb 测 and 176 Lu 测 Then, use formula (3) to obtain 176 Hf, in order to eliminate interference from isotopes.

[0092] Formula (4) is obtained from formula (1) - formula (3). 176 Lu 测 and 176 Hf 测 Then, combined with the detected signal from the first detection signal 177 The Hf measurement value was used to obtain the initial hafnium isotope in the first cassiterite standard. 176 Hf / 177 Hf] 初始 In formula (4), the decay constant λ 176 =1.867*10 -11 t is a known constant, and t is the known age of the first cassiterite standard.

[0093] According to embodiments of this disclosure, obtaining the initial hafnium isotope in the second cassiterite standard material based on the second detection signal includes calculation according to the following formulas (5) to (8):

[0094] 176 Yb 测 = 172 Yb 测 × ( 176 Yb / 172 Yb) 真 × (M 176 / M 172 ) βYb (5)

[0095] 176 Lu 测 = 175 Lu 测 × ( 176 Lu / 175 Lu) 真 × (M 176 / M 175 ) βLu (6)

[0096] 176 Hf 测 = ( 176 Yb 测 + 176 Lu 测 + 176 Hf 测 ) - 176 Yb 测 - 176 Lu 测 (7)

[0097] [ 176 Hf / 177 Hf] 测量 =[ 176 Hf / 177 Hf] 初始 + [ 176 Lu / 177 Hf] 测量 *(e λ176t -1) (8)

[0098] Formula (5) is used to calculate 176 Yb 测 ;In formula (5) ( 176 Yb / 172 Yb) 真 The second cassiterite standard material is known to be among the known ones. 176 Yb / 172 Theoretical truth value of Yb, M 176 / M 172 for 176 The mass number of Yb and 172 The ratio of the mass number of Yb βYb The Yb fractionation factor in the second cassiterite standard; 172 Yb 测 Detected in the second detection signal 172 Yb measurement value.

[0099] Formula (6) is used to calculate 176 Lu 测 ; In formula (6) ( 176 Lu / 175 Lu) 真 The second cassiterite standard material is known to be among the known ones. 176 Lu / 175 Lu's theoretical truth value, M 176 / M 175 for 176 The mass number of Lu and 175 The ratio of the mass number of Lu βLu The Lu fractionation factor in the second cassiterite standard; 175 Lu测 Detected in the second detection signal 175 Lu measurement value.

[0100] Formula (7) is calculated based on the results of formulas (5) and (6). 176 Hf 测 ;and 176 Yb 测 + 176 Lu 测 + 176 Hf 测 Detected in the second detection signal 176 Yb+ 176 Lu+ 176 Hf measurement value.

[0101] Understandable. 176 Yb, 176 Lu as 176 The isotopic interference of Hf, when the second detection signal is obtained, yields... 176 Yb 测 + 176 Lu 测 + 176 Hf 测 The measured value is a holistic detection value, that is... 176 Yb, 176 Lu, 176 Hf was not measured separately. Therefore, it needs to be eliminated. 176 Yb, 176 Lu 176 Isotopic interference of Hf. Accordingly, in this disclosure, formulas (5) and (6) are used to obtain 176 Yb 测 and 176 Lu 测 Then, use formula (7) to obtain 176 Hf, in order to eliminate interference from isotopes.

[0102] Formula (8) is obtained from formula (5) - formula (7). 176 Lu 测 and 176 Hf 测 Then, combined with the detected signal from the second detection signal 177 The Hf measurement value was used to obtain the initial hafnium isotope in the second cassiterite standard. 176 Hf / 177 Hf] 初始 In formula (8), the decay constant λ 176 =1.867*10 -11t is a known constant, and t is the known age of the second cassiterite standard.

[0103] According to embodiments of this disclosure, obtaining the initial hafnium isotope in the cassiterite sample based on the third detection signal includes calculation according to the following formulas (9) to (12):

[0104] 176 Yb 测 = 172 Yb 测 × ( 176 Yb / 172 Yb) 真 × (M 176 / M 172 ) βYb (9)

[0105] 176 Lu 测 = 175 Lu 测 × ( 176 Lu / 175 Lu) 真 × (M 176 / M 175 ) βLu (10)

[0106] 176 Hf 测 = ( 176 Yb 测 + 176 Lu 测 + 176 Hf 测 ) - 176 Yb 测 - 176 Lu 测 (11)

[0107] [ 176 Hf / 177 Hf] 测量 =[ 176 Hf / 177 Hf] 初始 + [ 176 Lu / 177 Hf] 测量 *(e λ176t -1) (12)

[0108] Formula (9) is used to calculate 176 Yb 测 ; In formula (9) ( 176 Yb / 172 Yb)真 The first cassiterite standard or the second cassiterite standard is known. 176 Yb / 172 The theoretical truth value of Yb (for simplicity, in this disclosure, the known values ​​of the first cassiterite or the second cassiterite can be used) 176 Yb / 172 The theoretical true value of Yb is used as a reference for cassiterite samples. 176 Yb / 172 Yb theoretical truth value), M 176 / M 172 for 176 The mass number of Yb and 172 The ratio of the mass number of Yb βYb The Yb fractionation factor is the Yb fractionation factor in the first cassiterite standard material or the second cassiterite standard material (for simplicity, the Yb fractionation factor in the first cassiterite standard material or the second cassiterite standard material can be used as the Yb fractionation factor of the cassiterite sample in this disclosure); 172 Yb 测 The third detection signal detected 172 Yb measurement value.

[0109] Formula (10) is used to calculate 176 Lu 测 ; In formula (10) ( 176 Lu / 175 Lu) 真 The first cassiterite standard or the second cassiterite standard is known. 176 Lu / 175 The truth value of Lu theory (for simplicity, in this disclosure, the known values ​​of the first cassiterite or the second cassiterite standard material can be used) 176 Lu / 175 The theoretical truth value of Lu is used for cassiterite samples. 176 Lu / 175 Lu's theoretical truth value), M 176 / M 175 for 176 The mass number of Lu and 175 The ratio of the mass number of Lu βLu The Lu fractionation factor is the first cassiterite standard material or the second cassiterite standard material (for simplicity, the Lu fractionation factor in the first cassiterite standard material or the second cassiterite standard material can be used as the Lu fractionation factor of the cassiterite sample in this disclosure); 175 Lu 测 The third detection signal detected 175 Lu measurement value.

[0110] Formula (11) is calculated based on the results of formulas (9) and (10). 176 Hf 测 ;and 176 Yb 测 + 176 Lu 测 + 176 Hf 测 The third detection signal detected 176 Yb+ 176 Lu+ 176 Hf measurement value.

[0111] Understandable. 176 Yb, 176 Lu as 176 The isotopic interference of Hf, when the third detection signal is obtained, yields... 176 Yb 测 + 176 Lu 测 + 176 Hf 测 The measured value is a holistic detection value, that is... 176 Yb, 176 Lu, 176 Hf was not measured separately. Therefore, it needs to be eliminated. 176 Yb, 176 Lu 176 Isotopic interference of Hf. Accordingly, in this disclosure, formulas (9) and (10) are used to obtain 176 Yb 测 and 176 Lu 测 Then, use formula (11) to obtain 176 Hf, in order to eliminate interference from isotopes.

[0112] Formula (12) is obtained from formula (9) - formula (11). 176 Lu 测 and 176 Hf 测 Then, combined with the detected signal in the third detection signal 177 The initial hafnium isotope in the cassiterite sample was obtained by measuring the Hf value. 176 Hf / 177 Hf] 初始 In formula (12), the decay constant λ 176 =1.867*10 -11 is a known constant, and t is the known age of the cassiterite sample.

[0113] In step S110, the initial hafnium isotopes in the cassiterite sample are corrected using the initial hafnium isotopes in the first cassiterite standard material and the second cassiterite standard material, so as to obtain the correction result of the initial hafnium isotope measurement in the cassiterite sample.

[0114] According to embodiments of this disclosure, the step of using the initial hafnium isotopes in the first cassiterite standard material and the second cassiterite standard material to correct the initial hafnium isotopes in the cassiterite sample in order to obtain the correction result of the initial hafnium isotope measurement in the cassiterite sample includes: performing linear fitting on the initial hafnium isotopes in the first cassiterite standard material obtained from multiple measurements to obtain a first correction coefficient K1; performing linear fitting on the initial hafnium isotopes in the second cassiterite standard material obtained from multiple measurements to obtain a second correction coefficient K2; and averaging the first correction coefficient K1 and the second correction coefficient K2, and multiplying the initial hafnium isotopes in the cassiterite sample by the average value to obtain the correction result of the initial hafnium isotope measurement in the cassiterite sample.

[0115] It is understood that averaging the first correction coefficient K1 and the second correction coefficient K2 yields a more accurate result. In this case, multiplying the initial hafnium isotope in the cassiterite sample by the average value to obtain the corrected result of the initial hafnium isotope determination in the cassiterite sample results in a more accurate result, preventing errors from occurring due to relying solely on a single standard substance for correction.

[0116] From the above description of the embodiments, those skilled in the art will clearly understand that the present invention can also be implemented through other structures, and the features of the present invention are not limited to the preferred embodiments described above. Any variations or modifications that can be easily conceived by those skilled in the art within the technical field of the present invention should be covered within the patent protection scope of the present invention.

Claims

1. A correction method for laser microbeam tin mineral sample hafnium isotope determination, characterized in that, The method comprises the following steps: embedding a first tin ore standard material in a granular form into a first row, a second tin ore standard material in a granular form into a second row, and a tin ore sample in a granular form into a third row into the same epoxy resin to form a sample target with a diameter of 1 inch to 2 inches, and placing the sample target into a laser ablation cell sample chamber; at a first time, using an excimer laser source and focusing on the first tin ore standard material on the sample target in a parallel light mode to perform laser micro-area ablation, so as to generate aerosol particles of the first tin ore standard material; wherein the aerosol particles of the first tin ore standard material pass through an electric field and a magnetic field in a multi-receiving inductively coupled plasma mass spectrometer to realize angle and speed double focusing and reach an ion signal detection system, so as to obtain a first detection signal; at a second time, using an excimer laser source and focusing on the second tin ore standard material on the sample target in a parallel light mode to perform laser micro-area ablation, so as to generate aerosol particles of the second tin ore standard material; wherein the aerosol particles of the second tin ore standard material pass through an electric field and a magnetic field in a multi-receiving inductively coupled plasma mass spectrometer to realize angle and speed double focusing and reach an ion signal detection system, so as to obtain a second detection signal; at a third time, using an excimer laser source and focusing on the tin ore sample on the sample target in a parallel light mode to perform laser micro-area ablation, so as to generate aerosol particles of the tin ore sample; wherein the aerosol particles of the tin ore sample pass through an electric field and a magnetic field in a multi-receiving inductively coupled plasma mass spectrometer to realize angle and speed double focusing and reach an ion signal detection system, so as to obtain a third detection signal; obtaining initial hafnium isotopes in the first tin ore standard material according to the first detection signal, obtaining initial hafnium isotopes in the second tin ore standard material according to the second detection signal, and obtaining initial hafnium isotopes in the tin ore sample according to the third detection signal; and correcting the initial hafnium isotopes in the tin ore sample by using the initial hafnium isotopes in the first tin ore standard material and the initial hafnium isotopes in the second tin ore standard material, so as to obtain a correction result of the initial hafnium isotope determination in the tin ore sample; wherein the correction of the initial hafnium isotopes in the tin ore sample by using the initial hafnium isotopes in the first tin ore standard material and the initial hafnium isotopes in the second tin ore standard material, so as to obtain the correction result of the initial hafnium isotope determination in the tin ore sample, comprises: linearly fitting the initial hafnium isotopes in the first tin ore standard material obtained by multiple measurements to obtain a first correction coefficient K1, and linearly fitting the initial hafnium isotopes in the second tin ore standard material obtained by multiple measurements to obtain a second correction coefficient K2; and averaging the first correction coefficient K1 and the second correction coefficient K2, and multiplying the initial hafnium isotopes in the tin ore sample by the average value to obtain the correction result of the initial hafnium isotope determination in the tin ore sample. The first cassiterite standard substance is a cassiterite primary standard substance Rond-A with a known initial hafnium isotope ratio, and the second cassiterite standard substance is a cassiterite control standard substance BB#7 with a known initial hafnium isotope ratio; the initial hafnium isotope ratio of the cassiterite primary standard substance Rond-A is 0.28217 ± 0.00003; and the initial hafnium isotope ratio of the cassiterite control standard substance BB#7 is 0.28189 ± 0.00003.

2. The method for correction of laser microbeam tin stone sample Cm isotope measurement according to claim 1, characterized in that, The total number of particles of the first cassiterite standard substance is X, the total number of particles of the second cassiterite standard substance is Y, and the total number of particles of the cassiterite sample is Z, wherein X, Y and Z are natural numbers greater than or equal to 1.

3. The method for correction of laser microbeam tin stone sample Cm isotope measurement according to claim 2, characterized in that, When X and Y are even numbers and Z is a multiple of 5, 2 of the first cassiterite standard substances are focused and subjected to laser micro-area ablation at a first time, 2 of the second cassiterite standard substances are focused and subjected to laser micro-area ablation at a second time, 5 of the cassiterite samples are focused and subjected to laser micro-area ablation at a third time, and the process is sequentially repeated until all particles are detected.

4. The method for correction of laser microbeam tin stone sample Cm isotope measurement according to any one of claims 1-3, characterized in that, The ion signal detection system is a Faraday cup; the magnetic field strength of the magnetic field can be adjusted so that the first ions , , , , , , and pass through the electric field and the magnetic field in turn to reach the ion signal detection system; wherein Yb is ytterbium, Lu is lutetium, Hf is hafnium; The primary ions are primary ions of the first cassiterite standard substance and are detected as the first detection signal at a first time, are primary ions of the second cassiterite standard substance and are detected as the second detection signal at a second time, and are primary ions of the cassiterite sample and are detected as the third detection signal at a third time.

5. The correction method of laser micro-tin ore sample Cm isotope determination according to claim 4, characterized in that, The initial hafnium isotope in the first cassiterite standard substance is obtained according to the first detection signal, including calculation according to the following formulas (1) to (4): wherein formula (1) is used to calculate ; the formula (1) in is a known theoretical true value, M 176 / M 172 is a ratio of a mass number of to a mass number of , is a Yb fractionation factor in the first cassiterite standard substance; is a measured value of in the first detection signal; wherein formula (2) is used to calculate ; the formula (2) in is the known theoretical true value, M 176 / M 175 is the mass number of and the mass number of , is the Lu fractionation factor in the first cassiterite standard substance; is the measured value of in the first detection signal; wherein the formula (3) is calculated from the results of the formula (1) and the formula (2) ; and is the measured value of the detected in the first detection signal; Formula (4) is obtained from formula (1) - formula (3). and Then, combined with the detected signal from the first detection signal The initial hafnium isotopes in the first cassiterite standard were obtained by measuring the values. The decay constant in formula (4) t is a known constant, and t is the known age of the first cassiterite standard.

6. The method for correction of laser microbeam tin stone sample Cm isotope measurement according to claim 4, characterized in that, The initial hafnium isotope in the second cassiterite standard substance is obtained according to the second detection signal, including calculation according to the following formulas (5) to (8): wherein formula (5) is used to calculate ; formula (5) is known in the second cassiterite standard material theoretical true value, is the mass number of Yb and the mass number of Sn, the mass number of Yb and the mass number of Sn, the Yb fractionation factor in the second cassiterite standard material; the measured value of Yb in the second detection signal the measured value; wherein formula (6) is used to calculate ; formula (6) in is a known theoretical true value, M 176 / M 175 is a ratio of a mass number of to a mass number of , is a Lu fractionation factor in the second cassiterite standard substance; is a measured value of in the second detection signal; wherein the formula (7) is calculated from the results of the formula (5) and the formula (6) ; and is the measured value of the second detection signal detected in the second detection signal; Formula (8) is obtained from formula (5) - formula (7). and Then, combined with the detected signal from the second detection signal The initial hafnium isotopes in the second cassiterite were obtained by measuring the values. The decay constant in formula (8) t is a known constant, and t is the known age of the second cassiterite standard.

7. The method for correction of laser microbeam tin stone sample Cm isotope measurement according to claim 4, characterized in that, The initial hafnium isotope in the cassiterite sample is obtained according to the third detection signal, including calculation according to the following formulas (9) to (12): wherein formula (9) is used to calculate ; the formula (9) in is a known theoretical true value, in the first cassiterite standard material or the second cassiterite standard material the mass number of the mass number of is the Yb fractionation factor in the first cassiterite standard material or the second cassiterite standard material; is the measured value of the third detection signal; wherein formula (10) is used to calculate ; formula (10) in is a known theoretical true value, M 176 / M 175 is a mass number of and a mass number of , is a Lu fractionation factor in the first cassiterite standard substance or the second cassiterite standard substance; is a measured value of the detected wherein the formula (11) is calculated from the results of the formula (9) and the formula (10) ; and is the measured value of the third detection signal detected in the third detection signal Formula (12) is obtained from formula (9) - formula (11). and Then, combined with the detected signal in the third detection signal The initial hafnium isotopes in the cassiterite sample were obtained by measuring the values. The decay constant in formula (12) is a known constant, and t is the known age of the cassiterite sample.

8. The method for correction of laser microbeam tin stone sample Cm isotope measurement according to any one of claims 1-3, characterized in that, The surface of the sample target is also subjected to polishing and cleaning treatment; the multi-receiving inductively coupled plasma mass spectrometer is Neptune Plus and is equipped with a Jet sample cone and an X intercept cone, and is assisted by 2-4 milliliter / minute high-purity nitrogen gas to improve the sensitivity of the multi-receiving inductively coupled plasma mass spectrometer; the parameters of the multi-receiving inductively coupled plasma mass spectrometer include: the output intensity of the laser beam is 100 millijoules, the laser energy density of the surface of the sample target is 5 joules / square centimeter, the laser beam spot size is 160 micrometers, and the laser ablation frequency is 6-8 hertz.

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