CN116124870A - Correction method for hafnium isotope determination of laser micro-area cassiterite sample - Google Patents

Correction method for hafnium isotope determination of laser micro-area cassiterite sample Download PDF

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CN116124870A
CN116124870A CN202211638798.3A CN202211638798A CN116124870A CN 116124870 A CN116124870 A CN 116124870A CN 202211638798 A CN202211638798 A CN 202211638798A CN 116124870 A CN116124870 A CN 116124870A
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cassiterite
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杨岳衡
杨明
吴石头
黄超
谢烈文
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Institute of Geology and Geophysics of CAS
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    • G—PHYSICS
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    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/62—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode
    • G01N27/626—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating the ionisation of gases, e.g. aerosols; by investigating electric discharges, e.g. emission of cathode using heat to ionise a gas
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    • G01—MEASURING; TESTING
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Abstract

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

Description

Correction method for hafnium isotope determination of laser micro-area cassiterite sample
Technical Field
The invention relates to the technical field of isotope geochemistry hafnium isotopes, in particular to a correction method for measuring a hafnium isotope of a laser micro-area cassiterite sample.
Background
Cassiterite (SnO) 2 ) Belonging to the rutile mineral family, the oxide-type uranium-containing mineral of tetragonal system is not only the main ore mineral in various tin polymetallic ore deposits, but also a common accessory mineral, which is associated with a tungsten ore deposit related to granite, a lithium beryllium niobium tantalum ore related to pegmatite and a volcanic origin block sulfide ore deposit.
Early determinations concerning the age of tin deposits in ore formation were obtained mainly by measuring the crystallization age of granite associated with tin (e.g., zircon uranium-lead, mica argon-argon, whole rock rubidium-strontium, etc.), or by means of isotopic age data of gangue minerals, etc. Because of the different test mineral objects and test methods selected by different researchers, the resulting ore ages of the same deposit sometimes vary greatly, resulting in different insights into the cause of the deposit.
The sealing temperature of the cassiterite is high, the crystallization age of the cassiterite can directly represent the ore formation age, and the cassiterite is the most effective means for directly obtaining the formation time of the cassiterite. Because cassiterite has a relatively high uranium/lead ratio and a low lead content, it is an ideal target for uranium-lead isotope dating. In order to better limit the age of formation of tin ore deposits, a deep understanding of its geological origin is required. And its formation age is an important factor. Accurate acquisition of cassiterite age is a precondition for studying the mineralisation background, in comparison to known geological events.
Apart from the age of tin ore, the source of tin ore is another very important parameter in its isotopic geochemistry. The cassiterite contains a certain amount of hafnium (100-600 micrograms/gram) and is a potential object for measuring the hafnium isotope, so that a new means is provided for the isotope geochemical tracing of a source region of a stannic ore mineral substance, and a new knowledge and thinking are provided for the research of the chronology and the source region of the stannic ore.
Currently, the instrument for measuring hafnium isotopes is a multi-receiving plasma mass spectrometer. Since cassiterite is a solid, granular mineral, the entire cassiterite particle must be dissolved with acid at high temperatures,and then removing impurities and interfering elements through a chemical separation technology to obtain a pure hafnium solution, and finally testing the cassiterite hafnium isotope. The process yields whole cassiterite particles (particles about 10 -3 Gram), the accuracy of the obtained hafnium isotope is very high, generally less than 0.001%, for example 0.282190 + -0.000010 can be obtained for the hafnium stannate isotope, which is the most accurate method at present.
The above chemical method, because of the need to dissolve the cassiterite particles, gives an average value of the hafnium isotope of the cassiterite sample, whereas in practice, because the geological process of the growth of cassiterite is very complex, such as may undergo alteration, and in addition, a large amount of inclusions or co-or accompanies high hafnium minerals (such as zircon, columbite, etc.) with the cassiterite, the cassiterite may not have the same hafnium isotope on a large scale. If the hafnium stannate isotope is obtained only by a chemical method, the measured average value of the hafnium isotope cannot truly reflect the real hafnium isotope of the stannate in a micro-area scale (about 100 microns), so the chemical method is only suitable for carrying out the measurement of the hafnium isotope by using a simple and uniform stannate sample in the growth process, such as the calibration and calibration work of a standard substance of the hafnium stannate isotope. In addition, the greatest difficulty in the current chemical process is that cassiterite is difficult to dissolve, 20-30 mg of cassiterite needs to be dissolved at high temperature and high pressure for thirty days, which is the root cause of no chemical process for carrying out the hafnium isotope of cassiterite.
In recent twenty years, with the rapid development of technology, a laser micro-area hafnium isotope method (zircon and the like) has been widely applied, and becomes an important means for discussing the earth evolution and various geological action processes. Compared with a chemical method, the laser micro-area method has the obvious advantages of simple and convenient sample preparation, quick analysis, higher spatial resolution and the like, and simultaneously avoids complicated chemical experiments. Therefore, the development of the laser micro-region hafnium isotope technology is rapid, and the research on the geochemistry application of the hafnium isotope is greatly promoted.
However, laser microcellular hafnium isotope technology is mainly focused on minerals with high hafnium content (more than 1000 micrograms/gram) such as zircon, and the content of cassiterite is usually 100-600 micrograms/gram, and no related literature has yet reported in detail about cassiterite hafnium at presentIsotope work. Whether the laser micro-area zircon hafnium isotope determination method is suitable for cassiterite, whether matrix effect exists between zircon and cassiterite, and homoisobaric @ 176 Lu and 176 yb can interfere with 176 Hf) how to calculate the disturbance correction is not discussed or studied in detail.
In addition, the laser micro-area method is a relative analysis technology, and the minerals of the same class are not separated from each other and serve as standard substances for laser micro-area analysis. According to the research and understanding of the technical field of the inventor, no laser micro-area standard substance of the cassiterite hafnium isotope exists at present, so that the laser micro-area cassiterite hafnium isotope technology can truly enter the practical application stage only by fundamentally solving the technical problems.
Disclosure of Invention
The invention provides a correction method for measuring hafnium isotopes of a laser micro-region cassiterite sample, which aims to solve at least one of the technical problems and other potential technical problems.
The invention provides a correction method for measuring hafnium isotopes of a cassiterite sample in a laser micro-area, which comprises the following steps:
and arranging the granular first cassiterite standard substance into a first row, arranging the granular second cassiterite standard substance into a second row and arranging the granular cassiterite samples into a third row, respectively embedding the first cassiterite standard substance and the granular second cassiterite standard substance into the same epoxy resin, so as to prepare sample targets with the diameters of 1 inch to 2 inches, and placing the sample targets into a sample cavity of a laser ablation pool.
Performing laser micro-domain ablation with an excimer laser source and focused in parallel light onto the first cassiterite standard substance on the sample target at a first time to produce aerosol particles of the first cassiterite standard substance; the aerosol particles of the first cassiterite standard substance pass through an electric field and a magnetic field in the multi-receiving inductively coupled plasma mass spectrometer to realize angle and speed double focusing and reach an ion signal detection system, so that a first detection signal is obtained.
Performing laser micro-domain ablation with an excimer laser source and focused in parallel light onto the second cassiterite standard on the sample target at a second time to produce aerosol particles of the second cassiterite standard; the aerosol particles of the second cassiterite standard substance pass through an electric field and a magnetic field in the multi-receiving inductively coupled plasma mass spectrometer to realize angle and speed double focusing and reach an ion signal detection system, so that a second detection signal is obtained.
Laser micro-domain ablation of said cassiterite sample with an excimer laser source and focused in parallel light onto said sample target at a third time to produce aerosol particles of said cassiterite sample; the aerosol particles of the cassiterite sample pass through an electric field and a magnetic field in the multi-receiving inductively coupled plasma mass spectrometer to realize angle and speed double focusing and reach an ion signal detection system, so that a third detection signal is obtained.
Obtaining an initial hafnium isotope in the first cassiterite standard substance according to the first detection signal, obtaining an initial hafnium isotope in the second cassiterite standard substance according to the second detection signal, and obtaining an initial hafnium isotope in the cassiterite sample according to the third detection signal.
Correcting the initial hafnium isotope in the cassiterite sample by using the initial hafnium isotope in the first cassiterite standard substance and the initial hafnium isotope in the second cassiterite standard substance so as to obtain a correction result of initial hafnium isotope determination in the cassiterite sample.
According to an embodiment of the present disclosure, 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, Z is a natural number of 1 or more.
According to an embodiment of the present disclosure, when X and Y are even and Z is a multiple of 5, 2 of the first cassiterite standards are focused and laser micro-area ablated at a first time, 2 of the second cassiterite standards are focused and laser micro-area ablated at a second time, and 5 of the cassiterite samples are focused and laser micro-area ablated at a third time, and sequentially cycled until detection of all particles is completed.
According to an embodiment of the present disclosure, the ion signal detection system is a faraday cup; the magnetic field strength of the magnetic field can be adjusted to enable the primary ions to be in 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; wherein Yb is ytterbium, lu is lutetium, and 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, primary ions of the second cassiterite standard substance and are detected as the second detection signal at a second time, and primary ions of the cassiterite sample and are detected as the third detection signal at a third time.
According to an embodiment of the present disclosure, the obtaining the initial hafnium isotope in the first cassiterite standard substance according to the first detection signal includes performing a calculation according to the following formulas (1) to (4):
176 Yb measuring ＝ 172 Yb Measuring × ( 176 Yb/ 172 Yb) True sense × (M 176 /M 172 ) βYb (1)
176 Lu Measuring ＝ 175 Lu Measuring × ( 176 Lu/ 175 Lu) True sense × (M 176 /M 175 ) βLu (2)
176 Hf Measuring ＝ ( 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring ) - 176 Yb Measuring - 176 Lu Measuring (3)
[ 176 Hf/ 177 Hf] Measurement of ＝[ 176 Hf/ 177 Hf] Initial initiation + [ 176 Lu/ 177 Hf] Measurement of *(e λ176t -1) (4)
Wherein, the formula (1) is used for calculating 176 Yb Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (1) 176 Yb/ 172 Yb) True sense Is known from the first cassiterite standard substance 176 Yb/ 172 Theoretical true value of Yb, M 176 /M 172 Is that 176 Quality number of Yb 172 The ratio of the mass numbers of Yb, βYb a fractionation factor of Yb in the first cassiterite standard substance; 172 Yb measuring For detection in said first detection signal 172 And (3) measuring Yb.
Wherein equation (2) is used for calculation 176 Lu Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (1) 176 Lu/ 175 Lu) True sense Is known from the first cassiterite standard substance 176 Lu/ 175 Theoretical true value of Lu, M 176 /M 175 Is that 176 Mass number and Lu 175 The ratio of the mass numbers of Lu, βLu a Lu fractionation factor for the first cassiterite standard; 175 Lu measuring For detection in said first detection signal 175 Lu measurements.
Wherein, the formula (3) is calculated according to the results of the formula (1) and the formula (2) 176 Hf Measuring The method comprises the steps of carrying out a first treatment on the surface of the While 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring For detection in said first detection signal 176 Yb+ 176 Lu+ 176 Hf measurement.
Wherein, the formula (4) is obtained from the formulas (1) - (3) 176 Lu Measuring And 176 Hf measuring Then, combining the detected signals in the first detection signal 177 Measurement of Hf to obtain the initial hafnium isotope in the first cassiterite standard substance 176 Hf/ 177 Hf] Initial initiation The method comprises the steps of carrying out a first treatment on the surface of the Decay constant lambda in equation (4) 176 ＝1.867*10 -11 Is a known constant and t is the age time of the known first cassiterite standard.
According to an embodiment of the present disclosure, the obtaining the initial hafnium isotope in the second cassiterite standard substance according to the second detection signal includes performing a calculation according to the following formulas (5) to (8):
176 Yb measuring ＝ 172 Yb Measuring ×( 176 Yb/ 172 Yb) True sense ×(M 176 /M 172 ) βYb (5)
176 Lu Measuring ＝ 175 Lu Measuring ×( 176 Lu/ 175 Lu) True sense ×(M 176 /M 175 ) βLu (6)
176 Hf Measuring ＝( 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring )- 176 Yb Measuring - 176 Lu Measuring (7)
[ 176 Hf/ 177 Hf] Measurement of ＝[ 176 Hf/ 177 Hf] Initial initiation +[ 176 Lu/ 177 Hf] Measurement of *(e λ176t -1) (8)
Wherein equation (5) is used for calculation 176 Yb Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (5) 176 Yb/ 172 Yb) True sense Is known as such from the second cassiterite standard 176 Yb/ 172 Theoretical true value of Yb, M 176 /M 172 Is that 176 Quality number of Yb 172 The ratio of the mass numbers of Yb, βYb a fractionation factor of Yb in the second cassiterite standard substance; 172 Yb measuring For detection in said second detection signal 172 And (3) measuring Yb.
Wherein equation (6) is used for calculation 176 Lu Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (6) 176 Lu/ 175 Lu) True sense Is known as such from the second cassiterite standard 176 Lu/ 175 Theoretical true value of Lu, M 176 /M 175 Is that 176 Mass number and Lu 175 The ratio of the mass numbers of Lu, βLu a Lu fractionation factor for the second cassiterite standard; 175 Lu Measuring For detection in said second detection signal 175 Lu measurements.
Wherein, the formula (7) is calculated according to the results of the formula (5) and the formula (6) 176 Hf Measuring The method comprises the steps of carrying out a first treatment on the surface of the While 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring For detection in said second detection signal 176 Yb+ 176 Lu+ 176 Hf measurement.
Wherein, the formula (8) is obtained from the formula (5) -the formula (7) 176 Lu Measuring And 176 Hf measuring Then, combining the detected signals in the second detection signal 177 Measurement of Hf to obtain the initial hafnium isotope in the second cassiterite standard substance 176 Hf/ 177 Hf] Initial initiation The method comprises the steps of carrying out a first treatment on the surface of the Decay constant lambda in equation (8) 176 ＝1.867*10 -11 Is a known constant and t is the age time of the second cassiterite standard substance.
According to an embodiment of the present disclosure, the obtaining the initial hafnium isotope in the cassiterite sample from the third detection signal includes performing a calculation according to the following formulas (9) to (12):
176 Yb measuring ＝ 172 Yb Measuring ×( 176 Yb/ 172 Yb) True sense ×(M 176 /M 172 ) βYb (9)
176 Lu Measuring ＝ 175 Lu Measuring ×( 176 Lu/ 175 Lu) True sense ×(M 176 /M 175 ) βLu (10)
176 Hf Measuring ＝( 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring )- 176 Yb Measuring - 176 Lu Measuring (11)
[ 176 Hf/ 177 Hf] Measurement of ＝[ 176 Hf/ 177 Hf] Initial initiation +[ 176 Lu/ 177 Hf] Measurement of *(e λ176t -1) (12)
Wherein equation (9) is used for calculation 176 Yb Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (9) 176 Yb/ 172 Yb) True sense Is known as the first cassiterite standard substance or the second cassiterite standard substance 176 Yb/ 172 Theoretical true value of Yb, M 176 /M 172 Is that 176 Quality number of Yb 172 The ratio of the mass numbers of Yb, βYb a Yb fractionation factor for the first cassiterite standard or the second cassiterite standard; 172 Yb Measuring For detection in the third detection signal 172 And (3) measuring Yb.
Wherein equation (10) is used for calculation 176 Lu Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (10) 176 Lu/ 175 Lu) True sense Is known as the first cassiterite standard substance or the second cassiterite standard substance 176 Lu/ 175 Theoretical true value of Lu, M 176 /M 175 Is that 176 Mass number and Lu 175 The ratio of the mass numbers of Lu, βLu a Lu fractionation factor in the first cassiterite standard or the second cassiterite standard; 175 Lu measuring For detection in the third detection signal 175 Lu measurements.
Wherein, the formula (11) is calculated according to the results of the formula (9) and the formula (10) 176 Hf Measuring The method comprises the steps of carrying out a first treatment on the surface of the While 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring For detection in the third detection signal 176 Yb+ 176 Lu+ 176 Hf measurement.
Wherein the formula (12) is obtained from the formulas (9) - (11) 176 Lu Measuring And 176 Hf measuring Then, the third detection signal is combined 177 Measurement of Hf to obtain the initial hafnium isotope in the cassiterite sample 176 Hf/ 177 Hf] Initial initiation The method comprises the steps of carrying out a first treatment on the surface of the Decay constant lambda in equation (12) 176 ＝1.867*10 -11 Is a known constant and t is the known age time of the cassiterite sample.
According to an embodiment of the present disclosure, the correcting the initial hafnium isotope in the cassiterite sample using the initial hafnium isotope in the first cassiterite standard and the initial hafnium isotope in the second cassiterite standard to obtain a corrected result of initial hafnium isotope determination in the cassiterite sample includes: performing linear fitting on the initial hafnium isotope in the first cassiterite standard substance obtained through multiple measurements to obtain a first correction coefficient K1; performing linear fitting on the initial hafnium isotope in the second cassiterite standard substance 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 average value by the initial hafnium isotope in the cassiterite sample to obtain a correction result of initial hafnium isotope determination in the cassiterite sample.
According to embodiments of the present disclosure, the surface of the sample target is also subjected to polishing and cleaning treatments; the multi-receiving inductively coupled plasma mass spectrometer is Neptune Plus and is provided with a Jet sample cone and an X-intercept cone, and high-purity nitrogen of 2-4 ml/min is assisted to improve the sensitivity of the multi-receiving inductively coupled plasma mass spectrometer; 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.
According to an embodiment of the disclosure, the first cassiterite standard substance is a cassiterite main standard substance Rond-A with a known initial hafnium isotope ratio, and the second cassiterite standard substance is a cassiterite monitoring standard substance BB#7 with a known initial hafnium isotope ratio; the initial hafnium isotope ratio of the main cassiterite standard substance Rond-A is 0.28217 +/-0.00003; the initial hafnium isotope ratio of the cassiterite monitoring standard substance BB#7 is 0.28189 +/-0.00003.
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For a clearer description of the technical solutions of the present invention, the drawings that are needed in the description of the embodiments will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a comparison of the results of a hafnium isotope assay with the results of a solution method for a laser micro-area cassiterite sample of the present invention, the sample being Rond-A.
FIG. 2 is a comparison of the results of a hafnium isotope determination of a laser micro-area cassiterite sample with the results of a solution method according to an embodiment of the present invention, and the sample is BB #7.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments, but not all embodiments of the present invention, and all other embodiments obtained by those skilled in the art without any inventive effort based on the embodiments of the present invention are included in the scope of protection of the present invention.
Various exemplary embodiments of the present invention provide a correction method for measuring hafnium isotopes in a laser micro-area cassiterite sample, which includes steps of step S100, step S102, step S104, step S106, step S108, step S110, and the like, and is described below.
In step S100, a first cassiterite standard substance in a particle form is arranged in a first row, a second cassiterite standard substance in a particle form is arranged in a second row, and a third row of cassiterite samples are arranged in a particle form, which are respectively embedded in the same epoxy resin, so as to prepare sample targets with diameters of 1 inch to 2 inches (wherein 1 inch is 2.54 cm, which can be a wafer placed in a sample cavity, which is called a target), and the sample targets are placed in a sample cavity of a laser ablation cell.
For example, the sample surface may be polished, cleaned (e.g., for sample surface leveling, cleaning for sample removal of potential contamination), and then placed in the laser ablation cell sample cavity for more accurate measurement. The particles of the cassiterite sample and cassiterite standard are very small, about 100-200 microns, and small particles of these cassiterite samples of unknown age can be aligned in one row and small particles of the cassiterite standard (first cassiterite standard, second cassiterite standard) aligned in another row, all embedded on a sample target of, for example, 1 inch. Then, during testing, a laser beam spot of about 100 or 120 microns may be used to ablate and sample, for example, multiple samples or standard particles may be tested separately using an automated test sequence.
For example, the cassiterite standard in the present disclosure may be cassiterite whose hafnium isotope is known in advance (e.g., may be measured in advance by a solution method in order to know its true value). It will be appreciated that the cassiterite standard acts as a standard (standard) to facilitate correction and revision of the measurement results of the cassiterite sample to obtain more accurate results. Because the cassiterite standard substance and the cassiterite sample are manufactured in the same sample target and put into the sample cavity of the laser ablation cell, the detection environments are identical, and the detection environments can be used as cross references. Even if the test equipment or the test environment changes, the environments of the test equipment and the test environment change at the same time, so that the measured results change synchronously and can be used as references. For example, even if there is a slight change in the instrument (e.g., a multi-receiving plasma mass spectrometer) conditions, the conditions of the standard substance and the unknown sample are similar, the unknown sample can be corrected by the standard substance, and the test results are more accurate.
According to an embodiment of the disclosure, the first cassiterite standard substance is a cassiterite main standard substance Rond-A with a known initial hafnium isotope ratio, and the second cassiterite standard substance is a cassiterite monitoring standard substance BB#7 with a known initial hafnium isotope ratio; the initial hafnium isotope ratio of the main cassiterite standard substance Rond-A is 0.28217 +/-0.00003; the initial hafnium isotope ratio of the cassiterite monitoring standard substance BB#7 is 0.28189 +/-0.00003 respectively.
It will be appreciated that the two standards have the benefit of effectively monitoring the condition of the instrument, determining whether the measured results are reliable and valid, the hafnium isotope ratios of the main and monitoring standards are known (e.g. can be determined in advance by chemical means), and if their laser micro-zone in-situ results agree with known values within an error range, the instrument condition is considered to be normal, and the measurement results for unknown cassiterite samples are also reliable and reliable. Otherwise, the instrument needs to be debugged, and instrument parameters are optimized until the in-situ result of the laser micro-region of the standard substance is consistent with the known value within the error range.
Therefore, two cassiterite standard substances (a first cassiterite standard substance and a second cassiterite standard substance) are adopted in the present disclosure, and can be used as a main standard substance and a monitoring standard substance respectively, so as to effectively monitor the state of an instrument, and judge whether the measured result is reliable and effective, thereby preventing deviation or inaccuracy of the result generated by relying on only one standard substance.
According to an embodiment of the present disclosure, 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, Z is a natural number of 1 or more.
For example, X, Y, Z can be a natural number in the range of 2 to 100. Through the measurement of a plurality of groups, multiunit, can make measuring result, it is more accurate to look at in a comprehensive way.
According to an embodiment of the present disclosure, when X and Y are even and Z is a multiple of 5, 2 of the first cassiterite standards are focused and laser micro-area ablated at a first time, 2 of the second cassiterite standards are focused and laser micro-area ablated at a second time, and 5 of the cassiterite samples are focused and laser micro-area ablated at a third time, and sequentially cycled until detection of all particles is completed.
For example, as shown in Table 1, in which the first cassiterite standard substance is Rond-A (Rond-A is employed as shown in FIG. 1), as the main standard substance; the second cassiterite standard substance was BB#7 (BB#7 was used as shown in FIG. 2), and was used as a monitoring standard substance. Each cassiterite standard substance is respectively measured according to a group of every two or every two cassiterite standard substances; the cassiterite samples are measured in groups of 5 or 5 samples, so that the measurement efficiency of the cassiterite samples is considered under the condition of saving standard substances.
For example, referring to table 1, at a first time 2 of the first cassiterite standards were focused and laser micro-area ablated, at a second time 2 of the second cassiterite standards were focused and laser micro-area ablated, at a third time 5 of the cassiterite samples were focused and laser micro-area ablated, and so on, until all of the first cassiterite standards (e.g., rond-a 01 … … Rond-a 06), the second cassiterite standards (e.g., bb#701 01 … … bb#706), and the cassiterite samples (e.g., sample 01 … … sample 15) were measured.
Table 1 test sequence of standard substance and actual sample in laser micro-zone cassiterite sample hafnium isotope determination
Figure BDA0004007671870000091
Figure BDA0004007671870000101
In step S102, laser micro-area ablation is performed at a first time with an excimer laser source and focused in parallel light onto the first cassiterite standard substance on the sample target so as to generate aerosol particles of the first cassiterite standard substance; the aerosol particles of the first cassiterite standard substance pass through an electric field and a magnetic field in the multi-receiving inductively coupled plasma mass spectrometer to realize angle and speed double focusing and reach an ion signal detection system, so that a first detection signal is obtained.
According to embodiments of the present disclosure, the surface of the sample target is also subjected to polishing and cleaning treatments; the multi-receiving inductively coupled plasma mass spectrometer is Neptune Plus and is provided with a Jet sample cone and an X-intercept cone, and high-purity nitrogen of 2-4 ml/min is assisted to improve the sensitivity of the multi-receiving inductively coupled plasma mass spectrometer; 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.
For example, parameters of a laser micro-area multi-receive inductively coupled plasma mass spectrometer include: the laser is excimer laser focused in parallel, the output intensity of the laser beam is 100 millijoules, the laser energy density indicated by the cassiterite sample is 4 joules/square centimeter, the laser beam spot size is 100-120 micrometers, and the laser ablation frequency is 6-8 hertz; the acceleration voltage of the Neptune Plus of the multi-receiving plasma mass spectrometer is-10 KV, the measurement group number is 200, the single-point analysis precision is 0.0008%, the total single-point analysis time is about 60 seconds, and the mass resolution of the multi-receiving plasma mass spectrometer is about 400.
According to an embodiment of the present disclosure, the ion signal detection system is a faraday cup; the magnetic field strength of the magnetic field can be adjusted to enable the primary ions to be in 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; wherein Yb is ytterbium, lu is lutetium, and Hf is hafnium; wherein the primary ion is a primary ion of the first cassiterite standard substance at a first time and is detected as the first detection signal.
For example, at a first time t1, the first cassiterite standard substance is first subjected to laser micro-domain ablation, aerosol particles (containing primary ions) of the first cassiterite standard substance can be obtained, and then the aerosol particles reach the ion signal detection system through an electric field and a magnetic field in the multi-receiving inductively coupled plasma mass spectrometer, wherein 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 sequentially passes through the electric field and the magnetic field to reach the ion signal detection system, so that a detection result is obtained, and the detection result can be used as a first detection signal of the first cassiterite standard substance.
In step S104, laser micro-domain ablation is performed at a second time with an excimer laser source and focused in parallel light onto the second cassiterite standard substance on the sample target, so as to generate aerosol particles of the second cassiterite standard substance; the aerosol particles of the second cassiterite standard substance pass through an electric field and a magnetic field in the multi-receiving inductively coupled plasma mass spectrometer to realize angle and speed double focusing and reach an ion signal detection system, so that a second detection signal is obtained.
According to an embodiment of the present disclosure, the magnetic field strength of the magnetic field can be adjusted such that in 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 passes through an electric field and a magnetic field to reach the ion signal detection system; wherein Yb is ytterbium, lu is lutetium, and Hf is hafnium; wherein the primary ion is a primary ion of the second cassiterite standard substance at a second time and is detected as the second detection signal.
For example, at a second time t2, the second cassiterite standard substance is then subjected to laser micro-scale ablation to obtain aerosol particles (containing primary ions) of the second cassiterite standard substance, and then passed through the electric and magnetic fields in a multi-receive inductively coupled plasma mass spectrometer to the ion signal detection system, where the magnetic field may direct one of 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 passes through the electric field and the magnetic field to reach the ion signal detection system, so that a detection result is obtained, and the detection result can be used as a second detection signal of a second cassiterite standard substance.
In step S106, laser micro-domain ablation is performed on the cassiterite sample focused on the sample target in parallel light using an excimer laser source at a third time to generate aerosol particles of the cassiterite sample; the aerosol particles of the cassiterite sample pass through an electric field and a magnetic field in the multi-receiving inductively coupled plasma mass spectrometer to realize angle and speed double focusing and reach an ion signal detection system, so that a third detection signal is obtained.
According to an embodiment of the present disclosure, the magnetic field strength of the magnetic field can be adjusted such that in 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 passes through an electric field and a magnetic field to reach the ion signal detection system; wherein Yb is ytterbium, lu is lutetium, and Hf is hafnium; wherein the primary ion is a primary ion of the cassiterite sample at a third time and is detected as the third detection signal.
For example, at a third time t3, the cassiterite-like quality is then subjected to laser micro-scale ablation to obtain aerosol particles of the cassiterite sample (containing primary ions) and then passed through the electric and magnetic fields in a multi-receive inductively coupled plasma mass spectrometer to the ion signal detection system, where the magnetic field directs one of 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 passes through the electric field and the magnetic field to reach the ion signal detection system, so that a detection result is obtained, and the detection result can be used as a third detection signal of the cassiterite sample.
In step S108, the initial hafnium isotope (which is typically a ratio) in the first cassiterite standard substance is obtained from the first detection signal, the initial hafnium isotope (which is typically a ratio) in the second cassiterite standard substance is obtained from the second detection signal, and the initial hafnium isotope (which is typically a ratio) in the cassiterite sample is obtained from the third detection signal.
According to an embodiment of the present disclosure, the obtaining the initial hafnium isotope in the first cassiterite standard substance according to the first detection signal includes performing a calculation according to the following formulas (1) to (4):
176 Yb measuring ＝ 172 Yb Measuring × ( 176 Yb/ 172 Yb) True sense × (M 176 /M 172 ) βYb (1)
176 Lu Measuring ＝ 175 Lu Measuring × ( 176 Lu/ 175 Lu) True sense × (M 176 /M 175 ) βLu (2)
176 Hf Measuring ＝ ( 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring ) - 176 Yb Measuring - 176 Lu Measuring (3)
[ 176 Hf/ 177 Hf] Measurement of ＝[ 176 Hf/ 177 Hf] Initial initiation + [ 176 Lu/ 177 Hf] Measurement of *(e λ176t -1) (4)
Wherein, the formula (1) is used for calculating 176 Yb Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (1) 176 Yb/ 172 Yb) True sense Is known from the first cassiterite standard substance 176 Yb/ 172 Theoretical true value of Yb, M 176 /M 172 Is that 176 Quality number of Yb 172 The ratio of the mass numbers of Yb, βYb a fractionation factor of Yb in the first cassiterite standard substance; 172 Yb measuring For detection in said first detection signal 172 And (3) measuring Yb. It will be appreciated that the fractionation factor generally represents the deviation of the measured value from the theoretical value.
Wherein equation (2) is used for calculation 176 Lu Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (1) 176 Lu/ 175 Lu) True sense Is known from the first cassiterite standard substance 176 Lu/ 175 Theoretical true value of Lu, M 176 /M 175 Is that 176 Mass number and Lu 175 The ratio of the mass numbers of Lu, βLu a Lu fractionation factor for the first cassiterite standard; 175 Lu measuring For detection in said first detection signal 175 Lu measurements.
Wherein, the formula (3) is calculated according to the results of the formula (1) and the formula (2) 176 Hf Measuring The method comprises the steps of carrying out a first treatment on the surface of the While 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring For detection in said first detection signal 176 Yb+ 176 Lu+ 176 Hf measurement.
It will be appreciated that the number of components, 176 Yb， 176 lu as 176 The homoisobaric interference of Hf, when the first detection signal is obtained, is 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring The measured value, which is an overall measured value, i.e 176 Yb， 176 Lu， 176 Hf was not measured separately. Therefore, it is necessary to eliminate 176 Yb， 176 Lu pair 176 The homoisobaric interference of Hf. Accordingly, equations (1) and (2) are utilized in the present disclosure to obtain 176 Yb Measuring And 176 Lu measuring Then, the formula (3) is reused to obtain 176 Hf in order to eliminate homoisobaric interference.
Wherein, the formula (4) is obtained from the formulas (1) - (3) 176 Lu Measuring And 176 Hf measuring Then, combining the detected signals in the first detection signal 177 Measurement of Hf to obtain the initial hafnium isotope in the first cassiterite standard substance 176 Hf/ 177 Hf] Initial initiation The method comprises the steps of carrying out a first treatment on the surface of the Decay constant lambda in equation (4) 176 ＝1.867*10 -11 Is a known constant and t is the age time of the known first cassiterite standard.
According to an embodiment of the present disclosure, the obtaining the initial hafnium isotope in the second cassiterite standard substance according to the second detection signal includes performing a calculation according to the following formulas (5) to (8):
176 Yb measuring ＝ 172 Yb Measuring × ( 176 Yb/ 172 Yb) True sense × (M 176 /M 172 ) βYb (5)
176 Lu Measuring ＝ 175 Lu Measuring × ( 176 Lu/ 175 Lu) True sense × (M 176 /M 175 ) βLu (6)
176 Hf Measuring ＝ ( 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring ) - 176 Yb Measuring - 176 Lu Measuring (7)
[ 176 Hf/ 177 Hf] Measurement of ＝[ 176 Hf/ 177 Hf] Initial initiation + [ 176 Lu/ 177 Hf] Measurement of *(e λ176t -1) (8)
Wherein equation (5) is used for calculation 176 Yb Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (5) 176 Yb/ 172 Yb) True sense Is known as such from the second cassiterite standard 176 Yb/ 172 Theoretical true value of Yb, M 176 /M 172 Is that 176 Quality number of Yb 172 The ratio of the mass numbers of Yb, βYb a fractionation factor of Yb in the second cassiterite standard substance; 172 Yb measuring For detection in said second detection signal 172 And (3) measuring Yb.
Wherein equation (6) is used for calculation 176 Lu Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (6) 176 Lu/ 175 Lu) True sense Is known as such from the second cassiterite standard 176 Lu/ 175 Theoretical true value of Lu, M 176 /M 175 Is that 176 Mass number and Lu 175 The ratio of the mass numbers of Lu, βLu a Lu fractionation factor for the second cassiterite standard; 175 Lu measuring For detection in said second detection signal 175 Lu measurements.
Wherein, the formula (7) is calculated according to the results of the formula (5) and the formula (6) 176 Hf Measuring The method comprises the steps of carrying out a first treatment on the surface of the While 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring For detection in said second detection signal 176 Yb+ 176 Lu+ 176 Hf measurement.
It will be appreciated that the number of components, 176 Yb， 176 lu as 176 The homoisobaric interference of Hf, when the second detection signal is obtained, is 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring The measured value, which is an overall measured value, i.e 176 Yb， 176 Lu， 176 Hf was not measured separately. Therefore, it is necessary to eliminate 176 Yb， 176 Lu pair 176 The homoisobaric interference of Hf. Accordingly, equations (5) and (6) are utilized in the present disclosure to obtain 176 Yb Measuring And 176 Lu measuring Then, the formula (7) is utilized again to obtain 176 Hf in order to eliminate homoisobaric interference.
Wherein, the formula (8) is obtained from the formula (5) -the formula (7) 176 Lu Measuring And 176 Hf measuring Then, combining the detected signals in the second detection signal 177 Measurement of Hf to obtain the initial hafnium isotope in the second cassiterite standard substance 176 Hf/ 177 Hf] Initial initiation The method comprises the steps of carrying out a first treatment on the surface of the Decay constant lambda in equation (8) 176 ＝1.867*10 -11 Is a known constant and t is the age time of the second cassiterite standard substance.
According to an embodiment of the present disclosure, the obtaining the initial hafnium isotope in the cassiterite sample from the third detection signal includes performing a calculation according to the following formulas (9) to (12):
176 Yb measuring ＝ 172 Yb Measuring × ( 176 Yb/ 172 Yb) True sense × (M 176 /M 172 ) βYb (9)
176 Lu Measuring ＝ 175 Lu Measuring × ( 176 Lu/ 175 Lu) True sense × (M 176 /M 175 ) βLu (10)
176 Hf Measuring ＝ ( 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring ) - 176 Yb Measuring - 176 Lu Measuring (11)
[ 176 Hf/ 177 Hf] Measurement of ＝[ 176 Hf/ 177 Hf] Initial initiation + [ 176 Lu/ 177 Hf] Measurement of *(e λ176t -1) (12)
Wherein equation (9) is used for calculation 176 Yb Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (9) 176 Yb/ 172 Yb) True sense Is known as the first cassiterite standard substance or the second cassiterite standard substance 176 Yb/ 172 Theoretical values of Yb (for simplicity, the first cassiterite standard or the second cassiterite standard may be known in the present disclosure 176 Yb/ 172 Yb theoretical true value as cassiterite sample 176 Yb/ 172 Theoretical true value of Yb), M 176 /M 172 Is that 176 Quality number of Yb 172 The ratio of the mass numbers of Yb, βYb as the Yb fractionation factor in the first cassiterite standard substance or the second cassiterite standard substance (for simplicity, the Yb fractionation factor in the first cassiterite standard substance or the second cassiterite standard substance may be used as the Yb fractionation factor of a cassiterite sample in the present disclosure); 172 Yb Measuring For detection in the third detection signal 172 And (3) measuring Yb.
Wherein equation (10) is used for calculation 176 Lu Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (10) 176 Lu/ 175 Lu) True sense Is known as the first cassiterite standard substance or the second cassiterite standard substance 176 Lu/ 175 A Lu theoretical true value (for simplicity, the first cassiterite standard or the second cassiterite standard may be known in the present disclosure 176 Lu/ 175 Theoretical true value of Lu as cassiterite sample 176 Lu/ 175 Lu theoretical true value), M 176 /M 175 Is that 176 Mass number and Lu 175 The ratio of the mass numbers of Lu, βLu a Lu fractionation factor in the first cassiterite standard substance or the second cassiterite standard substance (for simplicity, the Lu fractionation factor in the first cassiterite standard substance or the second cassiterite standard substance may be used as the Lu fractionation factor of a cassiterite sample in the present disclosure); 175 Lu measuring For detection in the third detection signal 175 Lu measurements.
Wherein, the formula (11) is calculated according to the results of the formula (9) and the formula (10) 176 Hf Measuring The method comprises the steps of carrying out a first treatment on the surface of the While 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring For detection in the third detection signal 176 Yb+ 176 Lu+ 176 Hf measurement.
It will be appreciated that the number of components, 176 Yb， 176 lu as 176 The homoisobaric interference of Hf, when the third detection signal is obtained, is 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring The measured value, which is an overall measured value, i.e 176 Yb， 176 Lu， 176 Hf was not measured separately. Therefore, it is necessary to eliminate 176 Yb， 176 Lu pair 176 The homoisobaric interference of Hf. Accordingly, equations (9) and (10) are utilized in the present disclosure to obtain 176 Yb Measuring And 176 Lu measuring Then, the formula (11) is reused to obtain 176 Hf in order to eliminate homoisobaric interference.
Wherein the formula (12) is obtained from the formulas (9) - (11) 176 Lu Measuring And 176 Hf measuring Then, the third detection signal is combined 177 Measurement of Hf to obtain the initial hafnium isotope in the cassiterite sample 176 Hf/ 177 Hf] Initial initiation The method comprises the steps of carrying out a first treatment on the surface of the Decay constant lambda in equation (12) 176 ＝1.867*10 -11 Is a known constant and t is the known age time of the cassiterite sample.
In step S110, the initial hafnium isotope in the cassiterite sample is corrected by using the initial hafnium isotope in the first cassiterite standard substance and the initial hafnium isotope in the second cassiterite standard substance, so as to obtain a correction result of initial hafnium isotope measurement in the cassiterite sample.
According to an embodiment of the present disclosure, the correcting the initial hafnium isotope in the cassiterite sample using the initial hafnium isotope in the first cassiterite standard and the initial hafnium isotope in the second cassiterite standard to obtain a corrected result of initial hafnium isotope determination in the cassiterite sample includes: performing linear fitting on the initial hafnium isotope in the first cassiterite standard substance obtained through multiple measurements to obtain a first correction coefficient K1; performing linear fitting on the initial hafnium isotope in the second cassiterite standard substance 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 average value by the initial hafnium isotope in the cassiterite sample to obtain a correction result of initial hafnium isotope determination in the cassiterite sample.
It will be appreciated that by averaging the first correction factor K1 with the second correction factor K2, such a result is more accurate, and that by multiplying the initial hafnium isotope in the cassiterite sample by the average value, the result of the initial hafnium isotope determination in the cassiterite sample is more accurate, and errors in the result due to correction by only relying on a single standard substance are prevented.
From the above description of embodiments, it will be clear to a person skilled in the art that the present invention can also be implemented in other structures, and that the features of the present invention are not limited to the preferred embodiments described above. Any changes or modifications which may be easily contemplated by those skilled in the art are intended to be included within the scope of the present invention.

Claims (10)

1. A calibration method for hafnium isotope determination of a laser micro-area cassiterite sample, comprising:
arranging a first granular cassiterite standard substance into a first row, arranging a second granular cassiterite standard substance into a second row and arranging granular cassiterite samples into a third row, respectively embedding the first and second granular cassiterite standard substances and the third row into the same epoxy resin, so as to prepare sample targets with diameters of 1-2 inches, and placing the sample targets into a sample cavity of a laser ablation pool;
Performing laser micro-domain ablation with an excimer laser source and focused in parallel light onto the first cassiterite standard substance on the sample target at a first time to produce aerosol particles of the first cassiterite standard substance; the aerosol particles of the first cassiterite standard substance pass through an electric field and a magnetic field in the multi-receiving inductively coupled plasma mass spectrometer to realize angle and speed double focusing and reach an ion signal detection system, so that a first detection signal is obtained;
performing laser micro-domain ablation with an excimer laser source and focused in parallel light onto the second cassiterite standard on the sample target at a second time to produce aerosol particles of the second cassiterite standard; the aerosol particles of the second cassiterite standard substance pass through an electric field and a magnetic field in the 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;
laser micro-domain ablation of said cassiterite sample with an excimer laser source and focused in parallel light onto said sample target at a third time to produce aerosol particles of said cassiterite sample; the aerosol particles of the cassiterite sample pass through an electric field and a magnetic field in the multi-receiving inductively coupled plasma mass spectrometer to realize angle and speed double focusing and reach an ion signal detection system, so that a third detection signal is obtained;
Obtaining an initial hafnium isotope in the first cassiterite standard substance according to the first detection signal, obtaining an initial hafnium isotope in the second cassiterite standard substance according to the second detection signal, and obtaining an initial hafnium isotope in the cassiterite sample according to the third detection signal; and
correcting the initial hafnium isotope in the cassiterite sample by using the initial hafnium isotope in the first cassiterite standard substance and the initial hafnium isotope in the second cassiterite standard substance so as to obtain a correction result of initial hafnium isotope determination in the cassiterite sample.
2. The correction method for hafnium isotope determination of a laser micro-area cassiterite sample according to claim 1, wherein 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, Z is a natural number of 1 or more.
3. The method of calibrating a hafnium isotope measurement of a laser micro-segment cassiterite sample according to claim 2, wherein when X and Y are even and Z is a multiple of 5, 2 of the first cassiterite standard substances are focused and laser micro-segment ablated at a first time, 2 of the second cassiterite standard substances are focused and laser micro-segment ablated at a second time, and 5 of the cassiterite samples are focused and laser micro-segment ablated at a third time, and sequentially cycled until detection of all particles is completed.
4. A calibration method for hafnium isotope determination of a laser micro-area cassiterite sample according to any one of claims 1-3, wherein the ion signal detection system is a faraday cup; the magnetic field strength of the magnetic field can be adjusted to enable the primary ions to be in 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; wherein Yb is ytterbium, lu is lutetium, and 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, primary ions of the second cassiterite standard substance and are detected as the second detection signal at a second time, and primary ions of the cassiterite sample and are detected as the third detection signal at a third time.
5. The method for calibrating a hafnium isotope measurement of a laser micro-area cassiterite sample according to claim 4, wherein obtaining the initial hafnium isotope in the first cassiterite standard substance based on the first detection signal comprises performing a calculation according to the following formulas (1) to (4):
176 Yb measuring ＝ 172 Yb Measuring × ( 176 Yb/ 172 Yb) True sense × (M 176 /M 172 ) βYb (1)
176 Lu Measuring ＝ 175 Lu Measuring × ( 176 Lu/ 175 Lu) True sense × (M 176 /M 175 ) βLu (2)
176 Hf Measuring ＝ ( 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring ) - 176 Yb Measuring - 176 Lu Measuring (3)
[ 176 Hf/ 177 Hf] Measurement of ＝[ 176 Hf/ 177 Hf] Initial initiation + [ 176 Lu/ 177 Hf] Measurement of *(e λ176t -1) (4)
Wherein, the formula (1) is used for calculating 176 Yb Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (1) 176 Yb/ 172 Yb) True sense Is known from the first cassiterite standard substance 176 Yb/ 172 Theoretical true value of Yb, M 176 /M 172 Is that 176 Quality number of Yb 172 The ratio of the mass numbers of Yb, βYb a fractionation factor of Yb in the first cassiterite standard substance; 172 Yb measuring For detection in said first detection signal 172 A Yb measurement;
wherein equation (2) is used for calculation 176 Lu Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (1) 176 Lu/ 175 Lu) True sense Is known from the first cassiterite standard substance 176 Lu/ 175 Theoretical true value of Lu, M 176 /M 175 Is that 176 Mass number and Lu 175 The ratio of the mass numbers of Lu, βLu a Lu fractionation factor for the first cassiterite standard; 175 Lu measuring For detection in said first detection signal 175 A Lu measurement;
wherein, the formula (3) is calculated according to the results of the formula (1) and the formula (2) 176 Hf Measuring The method comprises the steps of carrying out a first treatment on the surface of the While 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring For detection in said first detection signal 176 Yb+ 176 Lu+ 176 A Hf measurement;
wherein, the formula (4) is obtained from the formulas (1) - (3) 176 Lu Measuring And 176 Hf measuring Then, combining the detected signals in the first detection signal 177 Measurement of Hf to obtain the initial hafnium isotope in the first cassiterite standard substance 176 Hf/ 177 Hf] Initial initiation The method comprises the steps of carrying out a first treatment on the surface of the Decay constant lambda in equation (4) 176 ＝1.867*10 -11 Is a known constant and t is the age time of the known first cassiterite standard.
6. The method for calibrating a hafnium isotope measurement of a laser micro-area cassiterite sample according to claim 4, wherein obtaining the initial hafnium isotope in the second cassiterite standard substance based on the second detection signal comprises performing calculations according to the following formulas (5) to (8):
176 Yb Measuring ＝ 172 Yb Measuring × ( 176 Yb/ 172 Yb) True sense × (M 176 /M 172 ) βYb (5)
176 Lu Measuring ＝ 175 Lu Measuring × ( 176 Lu/ 175 Lu) True sense × (M 176 /M 175 ) βLu (6)
176 Hf Measuring ＝ ( 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring ) - 176 Yb Measuring - 176 Lu Measuring (7)
[ 176 Hf/ 177 Hf] Measurement of ＝[ 176 Hf/ 177 Hf] Initial initiation + [ 176 Lu/ 177 Hf] Measurement of *(e λ176t -1) (8)
Wherein equation (5) is used for calculation 176 Yb Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (5) 176 Yb/ 172 Yb) True sense Is known as such from the second cassiterite standard 176 Yb/ 172 Theoretical true value of Yb, M 176 /M 172 Is that 176 Quality number of Yb 172 The ratio of the mass numbers of Yb, βYb is saidThe Yb fractionation factor in the second cassiterite standard; 172 Yb measuring For detection in said second detection signal 172 A Yb measurement;
wherein equation (6) is used for calculation 176 Lu Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (6) 176 Lu/ 175 Lu) True sense Is known as such from the second cassiterite standard 176 Lu/ 175 Theoretical true value of Lu, M 176 /M 175 Is that 176 Mass number and Lu 175 The ratio of the mass numbers of Lu, βLu a Lu fractionation factor for the second cassiterite standard; 175 Lu measuring For detection in said second detection signal 175 A Lu measurement;
wherein, the formula (7) is calculated according to the results of the formula (5) and the formula (6) 176 Hf Measuring The method comprises the steps of carrying out a first treatment on the surface of the While 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring For detection in said second detection signal 176 Yb+ 176 Lu+ 176 A Hf measurement;
wherein, the formula (8) is obtained from the formula (5) -the formula (7) 176 Lu Measuring And 176 Hf measuring Then, combining the detected signals in the second detection signal 177 Measurement of Hf to obtain the initial hafnium isotope in the second cassiterite standard substance 176 Hf/ 177 Hf] Initial initiation The method comprises the steps of carrying out a first treatment on the surface of the Decay constant lambda in equation (8) 176 ＝1.867*10 -11 Is a known constant and t is the age time of the second cassiterite standard substance.
7. The method of calibrating a hafnium isotope measurement of a laser micro-area cassiterite sample according to claim 4, wherein obtaining an initial hafnium isotope in the cassiterite sample based on the third detection signal comprises performing a calculation according to the following formulas (9) to (12):
176 Yb measuring ＝ 172 Yb Measuring × ( 176 Yb/ 172 Yb) True sense × (M 176 /M 172 ) βYb (9)
176 Lu Measuring ＝ 175 Lu Measuring × ( 176 Lu/ 175 Lu) True sense × (M 176 /M 175 ) βLu (10)
176 Hf Measuring ＝ ( 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring ) - 176 Yb Measuring - 176 Lu Measuring (11)
[ 176 Hf/ 177 Hf] Measurement of ＝[ 176 Hf/ 177 Hf] Initial initiation + [ 176 Lu/ 177 Hf] Measurement of *(e λ176t -1) (12)
Wherein equation (9) is used for calculation 176 Yb Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (9) 176 Yb/ 172 Yb) True sense Is known as the first cassiterite standard substance or the second cassiterite standard substance 176 Yb/ 172 Theoretical true value of Yb, M 176 /M 172 Is that 176 Quality number of Yb 172 The ratio of the mass numbers of Yb, βYb a Yb fractionation factor for the first cassiterite standard or the second cassiterite standard; 172 Yb measuring For detection in the third detection signal 172 A Yb measurement;
wherein equation (10) is used for calculation 176 Lu Measuring The method comprises the steps of carrying out a first treatment on the surface of the In the formula (10) 176 Lu/ 175 Lu) True sense Is known as the first cassiterite standard substance or the second cassiterite standard substance 176 Lu/ 175 Theoretical true value of Lu, M 176 /M 175 Is that 176 Mass number and Lu 175 The ratio of the mass numbers of Lu, βLu a Lu fractionation factor in the first cassiterite standard or the second cassiterite standard; 175 Lu Measuring For detection in the third detection signal 175 A Lu measurement;
wherein, the formula (11) is calculated according to the results of the formula (9) and the formula (10) 176 Hf Measuring The method comprises the steps of carrying out a first treatment on the surface of the While 176 Yb Measuring + 176 Lu Measuring + 176 Hf Measuring For detection in the third detection signal 176 Yb+ 176 Lu+ 176 A Hf measurement;
wherein the formula (12) is obtained from the formulas (9) - (11) 176 Lu Measuring And 176 Hf measuring Then, the third detection signal is combined 177 Measurement of Hf to obtain the initial hafnium isotope in the cassiterite sample 176 Hf/ 177 Hf] Initial initiation The method comprises the steps of carrying out a first treatment on the surface of the Decay constant lambda in equation (12) 176 ＝1.867*10 -11 Is a known constant and t is the known age time of the cassiterite sample.
8. A correction method for hafnium isotope determination of a laser micro-area cassiterite sample according to any one of claims 1-3, wherein said correcting initial hafnium isotope in said cassiterite sample with initial hafnium isotope in said first cassiterite standard substance and initial hafnium isotope in said second cassiterite standard substance to obtain correction result of initial hafnium isotope determination in said cassiterite sample comprises:
performing linear fitting on the initial hafnium isotope in the first cassiterite standard substance obtained through multiple measurements to obtain a first correction coefficient K1; performing linear fitting on the initial hafnium isotope in the second cassiterite standard substance 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 average value by the initial hafnium isotope in the cassiterite sample to obtain a correction result of initial hafnium isotope determination in the cassiterite sample.
9. A calibration method for hafnium isotope determination of a laser micro-area cassiterite sample according to any one of claims 1-3, characterized in that the surface of the sample target is further subjected to polishing and cleaning treatments; the multi-receiving inductively coupled plasma mass spectrometer is Neptune Plus and is provided with a Jet sample cone and an X-intercept cone, and high-purity nitrogen of 2-4 ml/min is assisted to improve the sensitivity of the multi-receiving inductively coupled plasma mass spectrometer; 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.
10. A correction method for hafnium isotope determination of a laser micro-area cassiterite sample according to any one of claims 1-3, wherein the first cassiterite standard substance is a main cassiterite standard substance Rond-a with a known initial hafnium isotope ratio, and the second cassiterite standard substance is a monitoring cassiterite standard substance bb#7 with a known initial hafnium isotope ratio; the initial hafnium isotope ratio of the main cassiterite standard substance Rond-A is 0.28217 +/-0.00003; the initial hafnium isotope ratio of the cassiterite monitoring standard substance BB#7 is 0.28189 +/-0.00003.
CN202211638798.3A 2022-12-20 2022-12-20 Correction method for hafnium isotope determination of laser micro-area cassiterite sample Pending CN116124870A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118243772A (en) * 2024-03-22 2024-06-25 中国地质大学（武汉） Rapid analysis method for main trace elements in geological sample

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN118243772A (en) * 2024-03-22 2024-06-25 中国地质大学（武汉） Rapid analysis method for main trace elements in geological sample

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