Method for testing luminescence sensitivity of sediment sample

Abstract

The invention discloses a method for testing the luminescence sensitivity of a sediment sample. The method comprises the following steps: sequentially carrying out target mineral purification, irradiation excitation test and data analysis on the sediment sample to obtain a result of the luminescence sensitivity of the sediment sample. According to the method, the problems of non-uniform pre-processing flow, non-standard test flow, unclear data processing method and the like in the prior art are effectively solved. According to the technical system constructed by the invention, the accuracy rate of luminescent sensitivity material source tracing is improved to 7% or above, the analysis efficiency is improved by 1.2 times compared with that of a traditional method, and the technology is promoted to be converted from theoretical research to actual geological application.

Description

Technical Field

[0001] The present invention relates to the field of luminescence technology, and in particular to a method for testing the luminescence sensitivity of a sediment sample. Background Art

[0002] During sediment transport, deposition, and burial, the luminescence sensitivity of mineral particles, in addition to the influence of the parent rock, is further altered by irradiation and solarization. For example, quartz's luminescence sensitivity is primarily controlled by the distribution of electron traps within its crystal structure, as well as by the transport and burial processes. This response mechanism is exemplified in loess-paleosol sequences, where quartz sensitivity exhibits a high plateau in paleosol layers and a lower plateau in loess layers, reflecting, to some extent, the sensitivity's response to paleoclimatic changes. Vertical sequences of luminescence sensitivity can complement traditional climate indices (such as grain size and magnetic susceptibility) to construct multi-parameter constrained paleoclimate models.

[0003] As an inherent property of minerals, luminescence sensitivity has a range and frequency distribution that are controlled by multiple factors, including parent rock type, diagenesis, and subsequent transformations, forming a source-specific "sensitivity fingerprint." Differences in luminescence sensitivity among quartz from different source regions are directly related to the radioactive element content (such as U and Th) in the parent rock and the crystal growth environment, providing direct evidence for the study of source-sink processes in sedimentary systems.

[0004] Within the framework of Earth system science, luminescence sensitivity research is deeply integrated with numerical simulation and machine learning. By constructing sensitivity-climate response models (such as Monte Carlo models), paleoenvironmental evolution over geological history can be inverted. Combined with CT scanning technology, three-dimensional coupled analysis of sensitivity distribution and sediment microstructure is possible. These technological advances have not only improved the accuracy of luminescence dating but also promoted its transformation from a single dating tool to a multi-dimensional environmental analysis indicator.

[0005] Currently, luminescence sensitivity testing faces the following key technical bottlenecks:

[0006] First, pre-treatment processes are not standardized. Significant differences exist between laboratories in sample pre-treatment and instrument testing, resulting in low comparability of test data for similar samples. This severely restricts the integrated analysis of research results from multiple regions and deposition systems.

[0007] Second, the testing process is not standardized. Existing methods lack a parameter adaptation mechanism based on the properties of the parent rock and its sedimentary history, which are key factors affecting quartz luminescence sensitivity. Improper parameter settings often lead to distortion of the sensitivity signal, making it difficult to accurately reflect differences in provenance characteristics.

[0008] Third, the data processing methods are unclear. In the quantitative analysis of sensitivity data, there is a lack of standardized signal component separation, noise filtering, and multi-factor coupling analysis methods, which limits the key breakthrough of this technology from qualitative description to quantitative judgment.

[0009] The above problems have resulted in the failure to fully utilize the application effectiveness of luminescence sensitivity in source tracing. There is an urgent need to establish systematic testing specifications and analysis methods to promote the practical application of this technology in fields such as source-sink system research. Summary of the Invention

[0010] In response to the above-mentioned technical problems and the shortcomings in the field, the present invention provides a method for testing the luminescence sensitivity of sediment samples, comprising subjecting the sediment samples to target mineral purification, irradiation excitation testing, and data analysis to obtain the luminescence sensitivity results of the sediment samples.

[0011] The specific technical solutions are as follows:

[0012] A method for testing the luminescence sensitivity of a sediment sample comprises the following steps:

[0013] (1) Purify the target minerals from the sediment sample and prepare crystalline mineral samples;

[0014] (2) Irradiation excitation test of crystal mineral samples, including the following steps:

[0015] (2-1) The crystal mineral sample is excited at the excitation temperature to clear the original luminescence signal;

[0016] (2-2) irradiating the crystal mineral sample after clearing the original luminescence signal in step (2-1) with a β dose, giving the crystal mineral sample an artificial dose (regeneration dose);

[0017] (2-3) performing thermoluminescence excitation on the crystalline mineral sample treated in step (2-2), wherein the temperature conditions for the thermoluminescence excitation include programmed temperature increase from room temperature to a thermoluminescence excitation endpoint temperature;

[0018] (2-4) performing optically stimulated luminescence excitation on the crystal mineral sample treated in step (2-3) at an excitation temperature;

[0019] (3) Data analysis to obtain the luminescence sensitivity results of sediment samples, including:

[0020] The integral of the thermoluminescence excitation counts in step (2-3) is calculated as follows:

[0021]

[0022] Where: both \(x\) and \(k\) represent the counting temperature; \(f(*)\) represents the thermoluminescence excitation count value corresponding one-to-one with the counting temperature, which is directly measured; \(\Delta T\) represents the counting temperature interval; \(T_1\) and \(T_2\) respectively represent the lower limit and upper limit of the thermoluminescence excitation count integration temperature, where \(T_1 \lt 110^{\circ}C \lt T_2 \leq\) the thermoluminescence excitation end temperature;

[0023] Calculate the optically stimulated luminescence excitation count in step (2 - 4) according to the following formula:

[0024]

[0025] Where: \(f(y)\) represents the optically stimulated luminescence excitation count in step (2 - 4); \(i = 1, 2, \ldots, a\), representing the labels of the first \(a\) data points recorded during the optically stimulated luminescence excitation process; \(b\) represents the total number of data points recorded during the optically stimulated luminescence excitation process; \(j = b - m + 1, b - m + 2, \ldots, b\), representing the labels of the last \(m\) data points recorded during the optically stimulated luminescence excitation process; \(a \lt j\); \(y\) i 、\(y\) j respectively represent the optically stimulated luminescence excitation count values corresponding to the data point labels \(i\) and \(j\), which are directly measured;

[0026] Perform normalization calculation on the integral of the thermoluminescence excitation count in step (2 - 3) and the optically stimulated luminescence excitation count in step (2 - 4) to obtain the thermoluminescence sensitivity and optically stimulated luminescence sensitivity of the sediment sample.

[0027] During the process of calculating the optically stimulated luminescence excitation count in step (2 - 4) of the method for testing the luminescence sensitivity of sediment samples in the present invention, the background value calculated by the optically stimulated luminescence excitation count values of the last \(m\) data points recorded through the optically stimulated luminescence excitation process is deducted, making the calculation of the optically stimulated luminescence sensitivity more accurate.

[0028] In step (1), the target mineral can be quartz mineral, feldspar mineral, etc.

[0029] In step (1), the purification of the target mineral from the sediment sample preferably includes the steps of:

[0030] (1 - 1) Ultrasonically oscillate and clean the sediment sample to fully disperse the sample;

[0031] (1 - 2) Add hydrogen peroxide and hydrochloric acid to the sample obtained in step (1 - 1) to fully remove organic matter and carbonate minerals, then wash to neutrality, and screen to obtain mineral particles with the target particle size;

[0032] (1 - 3) Sort the mineral particles obtained in step (1 - 2) with a heavy liquid to purify the target mineral.

[0033] In step (1 - 1), the ultrasonic oscillation time is preferably 10 - 15 minutes.

[0034] In step (1-2), the mass concentration of hydrogen peroxide is preferably 30%, and the mass concentration of hydrochloric acid is preferably 10%. Hydrogen peroxide and hydrochloric acid are preferably added in multiple times until the reaction is fully achieved.

[0035] In step (1-2), the target particle size is 90 to 125 μm or 180 to 250 μm.

[0036] In step (1-3), the heavy liquid is preferably a lithium polytungstate solution or a sodium polytungstate solution.

[0037] In step (1), the preparation can be carried out using conventional techniques in the art. For example, after obtaining the purified target mineral, the target mineral can be adhered to a test piece with silicone oil, and the mass of the target mineral sample can be weighed in milligrams with an accuracy of one decimal place.

[0038] The excitation temperature in step (2-1) and step (2-4) is preferably 60°C or 125°C.

[0039] In some preferred embodiments, in step (2-1), the photoluminescence excitation time is 40 seconds.

[0040] In some preferred embodiments, in step (2-2), the β dose irradiation time is 100 seconds.

[0041] In some preferred embodiments, the thermoluminescence excitation endpoint temperature in step (2-3) is 220°C.

[0042] The heating rate of the programmed temperature in step (2-3) is preferably 2 to 5°C / s.

[0043] In some preferred embodiments, in step (2-4), the photoluminescence excitation time is 40 seconds.

[0044] In some preferred examples, the sediment sample luminescence sensitivity test method has T1 of 60°C, T2 of 120°C, and ΔT of 1°C, which can cover the thermoluminescence peak signal of crystalline mineral samples at 110°C.

[0045] In the sediment sample luminescence sensitivity test method, the value of a is related to the excitation power of the device.

[0046] In some preferred examples, in the sediment sample luminescence sensitivity test method, the value of a is the number of data points within 1 second before the luminescence excitation process.

[0047] In some preferred examples, in the sediment sample luminescence sensitivity test method, the value of a is 5 to 20, such as 8.

[0048] In some preferred examples, in the sediment sample luminescence sensitivity test method, b is 250 and m is 50.

[0049] In some preferred examples, in the sediment sample luminescence sensitivity test method, the normalization includes artificial dose normalization and mass normalization.

[0050] The method for testing the luminescence sensitivity of sediment samples provided by the present invention, through target mineral purification, irradiation excitation testing, and data analysis, effectively solves the problems of inconsistent pre-treatment processes, non-standardized testing processes, and unclear data processing methods in the prior art, and can achieve the following beneficial effects:

[0051] By establishing a standard pre-treatment and purification process, the standard deviation of test data from different laboratories was reduced from 15% to 8%, and data comparability was improved by 7%, providing a basis for multi-regional data integration.

[0052] By simplifying the testing process, the measurement error of luminescence sensitivity was reduced from 12% to 6%, significantly improving the accuracy of identifying provenance characteristics in complex sedimentary environments, while effectively shortening the testing time by more than 20%.

[0053] The calculation method of luminescence sensitivity test data was standardized, and the contribution of the 110°C peak signal of the crystal mineral regeneration dose was successfully quantified, providing key technical support for the establishment of a provenance identification model.

[0054] The overall technical advantage of the present invention lies in that the technical system constructed by the present invention increases the accuracy of luminescence-sensitive source tracing to more than 7%, and the analysis efficiency is 1.2 times higher than that of traditional methods, promoting the transformation of this technology from theoretical research to practical geological applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 This is a graph showing the trend of luminescence sensitivity of quartz in the loess sample cross section in Example 1 as a function of depth.

[0056] Figure 2 This is the luminescence sensitivity distribution diagram of river sediment feldspar in Example 2. DETAILED DESCRIPTION

[0057] The present invention will be further described below in conjunction with the accompanying drawings and specific examples. It should be understood that these examples are intended to illustrate the present invention and are not intended to limit the scope of the invention. The operating methods in the following examples where no specific conditions are specified are generally performed under conventional conditions or as recommended by the manufacturer.

[0058] Example 1:

[0059] Quartz sensitivity test of 10 loess profile sediment samples, the specific steps are as follows:

[0060] Quartz mineral purification:

[0061] Step 1: Shake and clean: Take 100-150 g of the original sample and ultrasonically shake it for 10 minutes to fully disperse the sample.

[0062] Step 2: Add 30% hydrogen peroxide in small amounts to the sample treated in Step 1 repeatedly to remove organic matter from the sample until the reaction is complete. This process lasts for approximately 24 hours. After allowing the sample to stand and discarding the upper liquid, add 10% hydrochloric acid in small amounts repeatedly to fully remove carbonate minerals from the sample until the reaction is complete.

[0063] Step 3: The sample processed in step 2 was sieved with 170-mesh and 115-mesh standard sieves to separate mineral particles with a particle size of 90 to 125 μm.

[0064] Step 4: After drying the sample treated in step 3, use a 3 and 2.62g / cm 3 The lithium polytungstate solution is sorted to remove heavy minerals and feldspar minerals, and then washed and dried before testing.

[0065] Step 5: After obtaining the sample processed in step 4, use silicone oil to stick the crystal minerals on the test piece, and weigh the mass of the quartz mineral particles on 20 test pieces respectively.

[0066] Radiation stimulation test:

[0067] Step 1: Heating to 125℃ and blue light excitation for 40 seconds to remove the natural dose remaining in the quartz mineral particles.

[0068] Step 2: Irradiate with an artificial dose of Sr-90 radioactive source for 100 seconds.

[0069] Step 3: Thermoluminescence excitation test, including programmed temperature increase from room temperature to the thermoluminescence excitation end point temperature of 220°C at a heating rate of 2°C / s.

[0070] Step 4: OSL excitation test: blue light excitation for 40 seconds at 125°C.

[0071] Data Analysis:

[0072] Step 1: Calculate the integral of the thermoluminescence counts of the sample from 60°C to 120°C (the counting temperature interval is 1°C) according to the following thermoluminescence excitation count calculation formula:

[0073]

[0074] Where: x and k both represent the counting temperature; f(*) represents the thermoluminescence excitation count corresponding to the counting temperature, which is obtained by direct measurement.

[0075] Step 2: Calculate the optically stimulated luminescence counts according to the following optically stimulated luminescence excitation count calculation formula:

[0076]

[0077] Where: f(y) represents the photoluminescence excitation count; i = 1, 2, ..., a, represents the labels of the first a data points recorded during the photoluminescence excitation process; j represents the labels of the last 50 data points recorded during the photoluminescence excitation process; a is the number of data points within the first 1 second of the photoluminescence excitation process, specifically 8; y i 、y j They represent the optically stimulated luminescence excitation count values corresponding to data point labels i and j, respectively, which are obtained by direct measurement.

[0078] Step 3: Normalize the calculated integral of thermoluminescence excitation counts and optically stimulated luminescence excitation counts by regeneration dose and mass respectively to obtain the thermoluminescence and optically stimulated luminescence sensitivity of the sample, and obtain the trend diagram of the thermoluminescence and optically stimulated luminescence sensitivity of quartz in the sample with depth, as shown in the figure: Figure 1 shown.

[0079] Example 2:

[0080] The feldspar sensitivity test of river sediment samples is carried out in the following steps:

[0081] Feldspar mineral purification:

[0082] Step 1: Shake and clean: Take 100-150 g of the original sample and ultrasonically shake it for 10 minutes to fully disperse the sample.

[0083] Step 2: Add 30% hydrogen peroxide in small amounts to the sample treated in Step 1 repeatedly to remove organic matter from the sample until the reaction is complete. This process lasts for approximately 24 hours. After allowing the sample to stand and discarding the upper liquid, add 10% hydrochloric acid in small amounts repeatedly to fully remove carbonate minerals from the sample until the reaction is complete.

[0084] Step 3: The sample processed in step 2 is sieved with 80-mesh and 60-mesh standard sieves to separate mineral particles with a particle size of 180 to 250 μm.

[0085] Step 4: After drying the sample treated in step 3, use a 3 The lithium tungstate solution is sorted to remove heavy minerals and quartz minerals, and then washed and dried before testing.

[0086] Step 5: After obtaining the sample processed in step 4, use silicone oil to stick the crystalline minerals on the test piece, and weigh the mass of the feldspar mineral particles on 60 test pieces respectively.

[0087] Radiation stimulation test:

[0088] Step 1: Heating to 60℃ and infrared light excitation for 40 seconds to remove the remaining natural dose in the feldspar mineral particles.

[0089] Step 2: Irradiate with an artificial dose of Sr-90 radioactive source for 100 seconds.

[0090] Step 3: Thermoluminescence excitation test, including programmed temperature increase from room temperature to the thermoluminescence excitation end point temperature of 220°C at a heating rate of 2°C / s.

[0091] Step 4: OSL excitation test: infrared light excitation for 40 seconds at 60°C.

[0092] Data Analysis:

[0093] Step 1: Calculate the integral of the thermoluminescence counts of the sample from 60°C to 120°C (the counting temperature interval is 1°C) according to the following thermoluminescence excitation count calculation formula:

[0094]

[0095] Where: x and k both represent the counting temperature; f(*) represents the thermoluminescence excitation count corresponding to the counting temperature, which is obtained by direct measurement.

[0096] Step 2: Calculate the photoluminescence counts according to the photoluminescence excitation count calculation formula.

[0097]

[0098] Where: f(y) represents the photoluminescence excitation count; i = 1, 2, …, a, represents the labels of the first a data points recorded during the photoluminescence excitation process; j represents the labels of the last 50 data points recorded during the photoluminescence excitation process; a is the number of data points within the first 1 second of the photoluminescence excitation process, specifically 20; y i 、y j They represent the optically stimulated luminescence excitation count values corresponding to data point labels i and j, respectively, which are obtained by direct measurement.

[0099] Step 3: Normalize the calculated integral of thermoluminescence excitation counts and optically stimulated luminescence excitation counts by regeneration dose and mass respectively to obtain the thermoluminescence and optically stimulated luminescence sensitivity of the sample. The horizontal axis is the optically stimulated luminescence sensitivity, and the vertical axis is the distribution diagram of the thermoluminescence sensitivity, as shown in the figure below: Figure 2 As shown, from Figure 2 It can be seen that the river sediment samples in this example mainly come from two different potential provenance areas.

[0100] It can be seen that the vertical variation of luminescence sensitivity and provenance tracing studies have broken through the limitations of traditional luminescence dating, which only focuses on the "time dimension", and established a three-dimensional research system of "time-environment-provenance". In the field of paleoclimate, it provides a new approach to solving difficult problems such as regional calibration bias of deep-sea oxygen isotope curves and fine dating of climate cycles on the Loess Plateau. In provenance research, it plays an irreplaceable role in solving key problems such as estimating the flux of terrigenous debris into the sea and reconstructing the migration of ancient river channels. With the popularization of single-particle sensitivity analysis technology and the development of automated testing platforms, this technology is expected to open up broader application space in fields such as global change research and geological disaster warning.

[0101] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for testing the luminescence sensitivity of a sediment sample, characterized in that: Including the steps: (1) Purify the target minerals from the sediment sample and prepare a crystal mineral sample by making a specimen. (2) Irradiation excitation test on the crystal mineral sample, including the steps: (2-1) Optically stimulated luminescence (OSL) excitation of the crystal mineral sample at the excitation temperature to clear the original luminescence signal. (2-2) Irradiate the crystal mineral sample after clearing the original luminescence signal in step (2-1) with a β dose to give an artificial dose to the crystal mineral sample. (2-3) Conduct thermoluminescence (TL) excitation on the crystal mineral sample processed in step (2-2). The temperature conditions for TL excitation include a programmed temperature increase from room temperature to the TL excitation end temperature. (2-4) Conduct OSL excitation on the crystal mineral sample processed in step (2-3) at the excitation temperature. (3) Obtain the luminescence sensitivity results of the sediment sample through data analysis, including: Calculate the integral of the TL excitation counts in step (2-3) according to the following formula: Where: x and k both represent the counting temperature; f(*) represents the TL excitation counts corresponding one-to-one with the counting temperature, which is directly measured; ΔT represents the counting temperature interval; T1 and T2 respectively represent the lower limit and upper limit of the integral temperature of the TL excitation counts, T1 < 110 °C < T2 ≤ the TL excitation end temperature. Calculate the OSL excitation counts in step (2-4) according to the following formula: Where: f(y) represents the photoluminescence excitation count in steps (2-4); i = 1, 2, ..., a, represents the labels of the first a data points recorded during the photoluminescence excitation process; b represents the total number of data points recorded during the photoluminescence excitation process; j = b-m+1, b-m+2, ..., b, represents the labels of the last m data points recorded during the photoluminescence excitation process; a <j;y i 、y j They represent the optically stimulated luminescence count values corresponding to data point labels i and j, respectively, which are obtained by direct measurement; Normalize the integral of the TL excitation counts in step (2-3) and the OSL excitation counts in step (2-4) obtained, to get the TL sensitivity and OSL sensitivity of the sediment sample.

2. The method for testing the luminescence sensitivity of sediment samples according to claim 1, characterized in that: In step (1): The target mineral is quartz mineral or feldspar mineral. The purification of the target minerals from the sediment sample includes the steps: (1-1) Ultrasonically oscillate and clean the sediment sample to fully disperse the sample. (1-2) Add hydrogen peroxide and hydrochloric acid to the sample obtained in step (1-1) to fully remove organic matter and carbonate minerals, then wash to neutral and screen to obtain mineral particles with the target particle size. (1-3) Sort the mineral particles obtained in step (1-2) with a heavy liquid to purify the target mineral.

3. The method for testing the luminescence sensitivity of sediment samples according to claim 2, wherein: In step (1-1), the ultrasonic oscillation time is 10 - 15 minutes. In step (1-2), the mass concentration of hydrogen peroxide is 30%, the mass concentration of hydrochloric acid is 10%, and hydrogen peroxide and hydrochloric acid are added in multiple times. In step (1-2), the target particle size is 90 - 125 μm or 180 - 250 μm. In step (1-3), the heavy liquid is a lithium metatungstate solution or a sodium metatungstate solution.

4. The method for testing the luminescence sensitivity of sediment samples according to claim 1, wherein: The excitation temperature in steps (2-1) and (2-4) is 60 °C or 125 °C.

5. The method for testing the luminescence sensitivity of sediment samples according to claim 1, wherein: The TL excitation end temperature in step (2-3) is 220 °C.

6. The method for testing the luminescence sensitivity of sediment samples according to claim 1, wherein: The heating rate of the programmed temperature increase in step (2-3) is 2 - 5 °C / s.

7. The method for testing the luminescence sensitivity of sediment samples according to claim 1, wherein: T1 is 60 °C, T2 is 120 °C, and ΔT is 1 °C.

8. The method for testing the luminescence sensitivity of sediment samples according to claim 1, wherein: The value of a is the number of data points within the first 1 second during the OSL excitation process.

9. The method for testing the luminescence sensitivity of sediment samples according to claim 1, wherein: The value of a is 5 - 20, b is 250, and m is 50.

10. The method for testing the luminescence sensitivity of sediment samples according to claim 1, characterized in that: The normalization includes artificial dose normalization and mass normalization.

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