Sediment dating calibration method and system

Abstract

SOLUTION: The invention discloses a sediment dating correction method and system, and relates to the technical field of sediment age measurement. According to the method, the isotope characteristic of 210 Pb is utilized, the sediment horizon before 210 Pb is balanced is used as a modern substance (namely the modern sediment horizon), and the AMS14C dating data of the modern sediment horizon and the AMS14C dating data of the sediment to be measured obtained by adopting an AMS14C dating method are subjected to interpolation to obtain a corrected value of old carbon, so that all pieces of 14C dating data are corrected, and the age framework of the sediment to be measured is obtained (S100-S108).EFFECT: When a method is applied to the age correction of the 14C dating of the sediment lacking the perforated worms, the age of the sediment lacking the perforated worms can be accurately deduced, and the reliability and the accuracy of the 14C dating of the sediment are improved; in addition, the method is simple and easy to implement, extra equipment and complex experimental operation are not needed, and the cost and implementation difficulty of sediment age measurement are reduced.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the technical field of sediment dating, and in particular to a method and system for calibrating sediment dating. [Background technology]

[0002] Accurate dating data is the basis and core for reconstructing past human activities, climate, and environmental changes, and is essential for the analysis of sedimentary 14 C dating is the detection of radioactive carbon isotopes in sediments. 14 It is a method widely used in geology and archaeology to determine the age of a sample by measuring its C content. However, the C content of present-day sediments is 14 Although C dating relies primarily on the presence of foraminifera, in some specific environments, such as mountain lakes, glaciers, and desert areas, dating sediments lacking foraminifera requires the use of complete carbon samples. 14 C was used, and the dating results were too old due to the contamination of "old carbon." 14 Accurate age calibration cannot be performed using C dating. Summary of the Invention [Problem to be solved by the invention]

[0003] To solve the above problems existing in the prior art, the present invention provides a method and system for calibrating sediment dating. [Means for solving the problem]

[0004] To achieve the above objectives, the present invention provides the following solutions:

[0005] 1. A method for calibrating sediment dating, comprising: AMS 14 Using the C dating method, AMS of each layer of the measured sediment was performed. 14 Obtaining C dating data and Located in the shallow surface layer of the measured sediment 210By testing and analyzing Pb isotopes, it is possible to determine the 210 To achieve a balance of Pb decay, Depends on the depth of the deposits 210 Taking advantage of the equilibrium of Pb attenuation, the shallow surface layer of the measured sediments was considered to be the modern sedimentary horizon, and the AMS of the shallow surface layer of the measured sediments was used. 14 Measuring C dating data and AMS of the shallow surface layer of the measured sediment 14 C dating data and AMS 14 AMS of shallow surface layers of the measured sediments obtained by C dating 14 Obtaining a calibration value for "old carbon" by interpolating C dating data, AMS of other strata than the shallow surface layer of the measured sediments 14 The "old carbon" calibration value was subtracted from the C dating data, and the calibrated AMS for each layer of the measured sediment was calculated. 14 C to obtain the calendar year value, AMS after calibration of two adjacent layers in the measured sediment 14 determining a deposition rate based on the C calendar year value and the depth value between two adjacent layers; AMS of the deposit between two adjacent layers based on the deposition rate 14 Determining the calendar year value of C; AMS of deposits other than the two adjacent layers based on the deposition rate 14 Determining the calendar year value of C; AMS after calibration for each layer of the measured deposit 14 C calendar year value, AMS of the deposit between two adjacent layers 14 C calendar year values ​​and AMS of sediments other than the two adjacent layers 14 This involves constructing a dating framework based on the C calendar year value and completing the dating of the measured sediments.

[0006] Optionally, AMS 14 Using the C dating method, AMS of each layer of the measured sediment was performed. 14 Specifically, obtaining C dating data involves: obtaining a sediment sample from each layer of the sediment to be measured, and converting acid-insoluble organic carbon in the sediment sample into graphite; The graphite is gasified, and carbon atoms in the gasified graphite are separated through an accelerator. Faraday cups are used at various positions in the accelerator orbit to receive the separated carbon atoms. 12 C. 13 C and 14 containing C; Based on the carbon atoms received after separation 14 C / 12 C value or 14 C / 13 Determine the C value, 14 C measurement and AMS for each layer of the measured deposit 14 and obtaining C dating data.

[0007] Optionally, in the shallow surface layer of the measured sediment 210 By testing and analyzing Pb isotopes, it is possible to determine the 210 Specifically, achieving balance in Pb decay involves: Taking a certain weight of the sediment to be measured, crushing it, and passing it through a 100 mesh sieve to obtain a sample powder; Put the sample powder into a sample tube, seal it, and leave it for a certain number of days. Using an ORTEC high-purity germanium well-type probe, a sample tube containing sample powder is probed for radioisotope measurement. 210 Analyzing the law of Pb decay exponentially with increasing depth according to the law of radioactive decay, 210 The change in Pb values ​​with sediment depth was observed until the change was relatively stable. 210 and achieving a balance of Pb decay.

[0008] Optionally, an AMS of the deposition between two adjacent layers based on said deposition rate by interpolation. 14 Determine the C calendar year value.

[0009] Optionally, by extrapolation, AMS of deposits other than two adjacent layers based on said deposition rates.14 Determine the C calendar year value.

[0010] Furthermore, the present invention also provides a sediment dating calibration system for use in carrying out the sediment dating calibration method provided above, said system comprising: AMS 14 Using the C dating method, AMS of each layer of the measured sediment was performed. 14 a first dating module used to obtain C dating data; Located in the shallow surface layer of the measured sediment 210 By testing and analyzing Pb isotopes, it is possible to determine the distribution of Pb depending on the depth of the sediment. 210 a balance determination module used to obtain the balance of Pb decay; Depends on the depth of the deposits 210 Taking advantage of the equilibrium of Pb attenuation, the shallow surface layer of the measured sediments was considered to be the modern sedimentary horizon, and the AMS of the shallow surface layer of the measured sediments was used. 14 a second dating module used to measure the C dating data; AMS of the shallow surface layer of the measured sediment 14 C dating data and AMS 14 AMS of shallow surface layers of the measured sediments obtained by C dating 14 a calibration value determination module used to obtain an "old carbon" calibration value by interpolating the C dating data; AMS of other strata than the shallow surface layer of the measured sediments 14 The "old carbon" calibration value was subtracted from the C dating data, and the calibrated AMS for each layer of the measured sediment was calculated. 14 a calibration module for the dating data used to obtain C calendar years; AMS after calibration of two adjacent layers in the measured sediment 14 a sedimentation rate determination module used to determine a sedimentation rate based on the C calendar year value and the depth value between two adjacent layers; AMS of the deposit between two adjacent layers based on the deposition rate 14 a third dating module used to determine the C calendar year value; AMS of deposits other than the two adjacent layers based on the deposition rate 14 a quaternary dating module used to determine the C calendar year value; AMS after calibration for each layer of the measured deposit 14 C calendar year value, AMS of the deposit between two adjacent layers 14 C calendar year values ​​and AMS of sediments other than the two adjacent layers 14 and a date frame construction module that constructs a date frame according to the C calendar year value and is used to complete the dating of the measured sediments. [Effects of the Invention]

[0011] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects. 1. The sediment dating calibration method provided by the present invention was applied to the dating of sediments lacking foraminifera. 14 When applied to the calibration of C dating, it can fill the gaps in the conventional technology. 2. The present invention is based on the total carbon content of sediments. 14 C dating data and 210 By analyzing Pb isotope data, we can accurately estimate the age of sediments lacking foraminifera and determine the sedimentary 14 This can improve the reliability and accuracy of C dating. 3. The present invention is simple and easy to implement, does not require additional equipment or complicated laboratory procedures, and reduces the cost and difficulty of sediment dating. [Brief explanation of the drawings]

[0012] In order to more clearly describe the embodiments of the present invention or the technical solutions in the prior art, the drawings necessary to be used in the embodiments will be briefly described below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those skilled in the art can further obtain other drawings based on these drawings without any creative efforts.

[0013] [Figure 1] 1 is a flow chart of a sediment dating calibration method provided by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] The technical solutions in the embodiments of the present invention will now be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts will fall within the scope of protection of the present invention.

[0015] This invention allows us to accurately estimate the age of sediments lacking foraminifera and to 14 The present invention aims to provide a dating calibration method and system suitable for sediments lacking foraminifera, which can improve the reliability and accuracy of C dating and reduce the cost and difficulty of sediment dating because it does not require additional equipment or complicated experimental procedures.

[0016] In order to make the above objects, features and advantages of the present invention more apparent and comprehensible, the present invention will be described in more detail below with reference to the drawings and detailed description of the invention.

[0017] This invention utilizes the TRIZ "substitution" principle to analyze the total carbon sample of the sediment and 210 By analyzing the isotope content of Pb, traditional sediments relying on foraminifera 14 This method replaces the C dating method. This innovative alternative solves the problem that sediments lacking foraminifera cannot be accurately dated using traditional methods. At the same time, the present invention also incorporates the "interpolation" principle, establishes a relationship model between isotope content and age, and uses the interpolation calculation method to achieve accurate age calibration of the measured sediments.

[0018] As shown in FIG. 1, the sediment dating method provided by the present invention includes: Step 100: AMS 14 AMS of each layer of the sediment measured using C dating 14 Obtain C dating data. In practical applications, AMS for total carbon in the column deposit 14 C dating experiments were carried out and AMS was used to measure each layer of the sediment. 14 C dating data can be obtained, specifically, The acid-insoluble organic carbon in the sediment sample is first converted into graphite, and then the graphite is gasified and passed through an accelerator, which removes impurity particles, strips electrons, and accelerates positrons. 12 C. 13 C. 14 The carbon atoms of C are separated, and finally, Faraday cups are used at different points in the accelerator orbit to receive the carbon atoms, and then 14 To measure C 14 C / 12 C value or 14 C / 13 Calculate the C value and AMS 14 The goal is to obtain C dating data.

[0019] Step 101: In the shallow surface layer of the sediment to be measured 210 By testing and analyzing Pb isotopes, it is possible to determine the 210 Obtain a balance of Pb decay. In practical applications, the shallow surface layer of the sediment core was investigated through experiments. 210 Pb isotope testing and analysis were carried out to determine the Pb content depending on the depth of the sediment. 210 To obtain the balance of Pb attenuation, the experiment is carried out in accordance with the national standard of the People's Republic of China "Determination of Radionuclides in Marine Sediments - Gamma-ray Energy Spectroscopy (GB / T 30738-2014)". Specifically, A certain weight (e.g., 10 g) of dried sediment is crushed and passed through a 100-mesh sieve to remove the plant rhizomes. The sample is then placed in a sample tube, sealed, and left for a certain number of days (e.g., 20 days). Radioisotope measurements are then performed using an ORTEC high-purity germanium well-type probe (GWL-120-15N). The measurement time for each sample is usually 1 to 3 days, resulting in a total of 100 samples. 210 The Pb specific activity is 46.5 keV ( 210 Pb) and the background 210The specific activity of Pb is 351 keV ( 214 Pb, 226 The excess is calculated from the peak area at the Ra (atomic energy) 210 The specific activity of Pb is 210 Specific activity and background of Pb 210 This is the difference in the specific radioactivity of Pb. 210 We analyze the law of Pb decay, which follows the law of radioactive decay, and the following: 210 Pb is a uranium-based decay nuclide with a half-life of 22.3 a and is commonly used in sediment dating. 210 The intensity of Pb nuclides decays to about 1% of their initial value after about 7 half-lives, making it difficult to accurately detect them with instruments. 210 The upper limit for Pb dating is about 150 a. Total uranium-based decay nuclides in the sediments 210 Pb is composed of two parts, one part accumulated in sediments 226 Due to the natural collapse of Ra 210 Pb-derived and compensated 210 Pb, and the other part was precipitated 210 Pb-derived excess 210 Pb or 210 Pb ex It is called. 226 Ra and 210 Pb is both 238 It belongs to the U decay series nuclide, 226 Ra and 210 Pb can be considered as a pair of mother and child. 226 Ra and 210 Assuming there is no other input or output to Pb, the decay of these two nuclides reaches equilibrium at a certain depth, and then excess 210 The Pb values ​​show a relatively stable change, and the part above this depth can be identified as having the properties of modern sediments.

[0020] Step 102: Depending on the depth of the deposit 210 Taking advantage of the equilibrium of Pb attenuation, the shallow surface layer of the measured sediments was considered to be the modern sedimentary horizon, and the AMS of the shallow surface layer of the measured sediments was used. 14 Measure C dating data. Step 103: AMS of the shallow surface layer of the measured sediment 14 C dating data and AMS 14 AMS of shallow surface layers of the measured sediments obtained by C dating 14 Calibrated values ​​of "old carbon" are obtained by interpolating C dating data. Step 104: AMS of other horizons than the shallow surface layer of the measured sediment 14 The calibrated "old carbon" values ​​were subtracted from the C dating data, and the calibrated AMS for each layer of the measured sediment was used. 14 C Get the calendar year value.

[0021] Steps 102 to 104 are shallow surface deposits depending on the depth in step 101. 210 The equilibrium of Pb attenuation was used to determine the modern depositional horizon (0 cal BP) and its AMS 14 C dating data and AMS measurements in steps 100 and 102 14 C dating data to obtain a calibration value for "old carbon" and to perform AMS analysis of other strata. 14 The calibration value of the "old carbon" was subtracted from the C value to achieve calibration, and the calibrated AMS for each layer of the measured sediment was then calculated. 14 C Get the calendar year value.

[0022] Step 105: AMS after calibration of two adjacent layers in the measured deposit 14 Determine the deposition rate based on the C calendar year value and the value of the depth between two adjacent layers. Step 106: Based on the deposition rate, AMS of the deposit between two adjacent layers 14 Determine the C calendar year value, and then interpolate the corresponding AMS value for the part between the two horizons depending on the deposition rate. 14 Calculate the calendar year value. Step 107: Based on the deposition rate, AMS of the deposits other than the two adjacent layers is performed. 14 C calendar years were determined, and then extrapolated to all but two stratigraphic horizons to establish subsequent age frames, and the corresponding AMS 14 Calculate C calendar year values ​​and realize calendar year value interpolation and data augmentation. Step 108: AMS after calibration for each layer of the measured deposit 14 C calendar year value, AMS of the deposit between two adjacent layers 14 C calendar year values ​​and AMS of sediments other than the two adjacent layers 14 A dating framework is constructed based on the C calendar year value, and the dating of the measured sediments is completed.

[0023] Based on the above description, the present invention provides: 210 Based on the fact that Pb is widely present in the natural environment and has a half-life of 22.3 a, previously formed 210 According to the law of radioactive decay, Pb decays exponentially with increasing depth, reaching equilibrium at a certain depth, and deposition beyond that depth is thought to occur within 150 a. 14 Compared to the half-life of C dating and the error of several decades to several hundred years, 210 The sedimentary horizon before Pb equilibration can be considered as modern material and the age value is set as 0 Cal a BP. 14 The C measurement value is determined as the error value of "old carbon" and all 14 Calibrate the C dating data and establish a calendar year dating window.

[0024] Based on this, the present invention utilizes the TRIZ "substitution" principle to analyze the total carbon sample of the deposit and 210 By analyzing the isotope content of Pb, traditional sediments relying on foraminifera 14 This method replaces the C dating method. This alternative method solves the problem that traditional methods cannot accurately date sediments lacking foraminifera. At the same time, the present invention also incorporates the "interpolation" principle to establish a relationship model between isotope content and age, and uses the interpolation calculation method to achieve accurate age calibration of the measured sample.

[0025] The present invention also provides a sediment dating calibration system for use in implementing the sediment dating calibration method provided above, the system including a first dating module, an equilibrium determination module, a second dating module, a calibration value determination module, a dating data calibration module, a sedimentation rate determination module, a third dating module, a fourth dating module, and a date frame construction module.

[0026] The first dating module is AMS 14 AMS of each layer of the sediment measured using C dating 14 Used to obtain C dating data.

[0027] The equilibrium determination module is located in the shallow surface layer of the measured sediment. 210 By testing and analyzing Pb isotopes, it is possible to determine the distribution of Pb depending on the depth of the sediment. 210 Used to balance the decay of Pb.

[0028] The second dating module measures the depth of the deposits. 210 Taking advantage of the equilibrium of Pb attenuation, the shallow surface layer of the measured sediments was considered to be the modern sedimentary horizon, and the AMS of the shallow surface layer of the measured sediments was used. 14 Used to measure C dating data.

[0029] The calibration value determination module is based on the AMS of the shallow surface layer of the measured sediment. 14 C dating data and AMS 14 AMS of shallow surface layers of the measured sediments obtained by C dating 14 It is used to obtain a calibration value for "old carbon" by interpolating C dating data.

[0030] The calibration module for dating data is designed to calibrate the AMS data for stratigraphic horizons other than the shallow surface layer of the measured sediments. 14 The calibrated "old carbon" values ​​were subtracted from the C dating data, and the calibrated AMS for each layer of the measured sediment was used. 14 Used to obtain the C calendar year value.

[0031] The deposition rate determination module is based on the calibrated AMS of two adjacent layers in the measured deposit. 14 C is used to determine the deposition rate based on the calendar year value and the value of the depth between two adjacent layers.

[0032] The third dating module is based on the deposition rate and AMS of the sediments between two adjacent layers. 14 Used to determine the C calendar year value.

[0033] The fourth dating module is based on the deposition rate and AMS data for sediments other than the two adjacent layers. 14 Used to determine the C calendar year value.

[0034] The construction module for the age frame is the AMS after calibration for each layer of the measured sediment. 14 C calendar year value, AMS of the deposit between two adjacent layers 14 C calendar year values ​​and AMS of sediments other than the two adjacent layers 14 A dating window is constructed based on the C calendar year value and is used to complete the dating of the measured sediments.

[0035] Each embodiment in this specification is described step by step, and the main points described in each embodiment are the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. The systems disclosed in the embodiments correspond to the methods disclosed in the embodiments, so the explanation is relatively simple, and for related information, refer to the explanation of the method part.

[0036] In this specification, specific examples are used to explain the principles and embodiments of the present invention, and the description of the above examples is only used to understand the method and core idea of ​​the present invention, and at the same time, those skilled in the art can change the form and application scope for implementing the invention based on the idea of ​​the present invention. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. 1. A method for calibrating sediment dating, comprising: AMS １４ Using the C dating method, AMS was performed on each layer of the sediment being measured. １４ Obtaining C dating data; Located in the shallow surface layer of the measured sediment ２１０ By testing and analyzing Pb isotopes, it is possible to determine the ２１０ To obtain a balance of Pb decay, Depends on the depth of the deposits ２１０ Taking advantage of the equilibrium of Pb attenuation, the shallow surface layer of the measured sediment is considered to be the modern sedimentary horizon, and the AMS of the modern sedimentary horizon is used. １４ measuring C dating data; AMS of modern sedimentary horizons １４ C dating data and AMS １４ AMS of the measured sediments obtained by the C dating method １４ Obtaining a calibration value for "old carbon" by interpolating C dating data; AMS of strata other than the shallow surface layer of the measured sediment １４ The "old carbon" calibration value was subtracted from the C dating data, and the calibrated AMS for each layer of the measured sediment was calculated. １４ Obtaining a calendar year value of C; AMS after calibration of two adjacent layers in the measured deposit １４ determining a deposition rate based on the C calendar year value and the depth value between two adjacent layers; Based on the deposition rate, the AMS of the deposit between two adjacent layers is calculated. １４ determining a calendar year value of C; Based on the deposition rate, the AMS of the deposit other than the two adjacent layers １４ determining a calendar year value of C; AMS after calibration for each layer of the measured deposit １４ C calendar year value, AMS of the deposit between two adjacent layers １４ C calendar year values ​​and AMS of sediments other than the two adjacent layers １４ and constructing a time frame according to the C calendar year value and completing the dating of the sediment to be measured.

2. AMS １４ Using the C dating method, AMS was performed on each layer of the sediment being measured. １４ Specifically, obtaining C dating data involves: obtaining a sediment sample from each layer of the sediment to be measured, and converting acid-insoluble organic carbon in the sediment sample into graphite; The graphite is gasified, and carbon atoms in the gasified graphite are separated through an accelerator. Faraday cups are used at various positions in the accelerator orbit to receive the separated carbon atoms. １２ C. １３ C and １４ containing C; Based on the carbon atoms received after separation １４ C / １２ C value or １４ C / １３ Determine the C value, １４ C measurement was realized, and AMS of each layer of the measured deposit was performed. １４ and acquiring C dating data.

3. Located in the shallow surface layer of the measured sediment ２１０ By testing and analyzing Pb isotopes, it is possible to determine the ２１０ To achieve a balanced decay of Pb, specifically: Taking a certain weight of the sediment to be measured, crushing it, and passing it through a 100 mesh sieve to obtain a sample powder; Put the sample powder into a sample tube, seal it, and leave it for a certain number of days. An ORTEC high-purity germanium well-type probe was used to probe the sample tube containing the sample powder for radioisotope measurement. ２１０ Analyzing the law of Pb decay exponentially with increasing depth according to the law of radioactive decay, ２１０ The change in Pb value with the depth of the deposits will be relatively stable until the change in Pb value becomes relatively stable. ２１０ and obtaining a balance of Pb decay.

4. Based on the deposition rate by interpolation, AMS of the deposit between two adjacent layers is calculated. １４ 2. The method of claim 1 for calibrating sediment dating, further comprising determining a C calendar year value.

5. By extrapolation, based on the deposition rate, the AMS of the deposit other than the two adjacent layers １４ 2. The method of claim 1 for calibrating sediment dating, further comprising determining a C calendar year value.

6. A sediment dating calibration system, said system being used to implement the sediment dating calibration method according to any one of claims 1 to 5, said system comprising: AMS １４ Using the C dating method, AMS was performed on each layer of the sediment being measured. １４ a first dating module used to obtain C dating data; Located in the shallow surface layer of the measured sediment ２１０ By testing and analyzing Pb isotopes, it is possible to determine the difference depending on the depth of the deposits. ２１０ a balance determination module used to obtain the balance of the Pb decay; Depends on the depth of the deposits ２１０ Taking advantage of the equilibrium of Pb attenuation, the shallow surface layer of the measured sediment was considered to be the modern sedimentary horizon, and the AMS of the shallow surface layer of the measured sediment was used. １４ a second dating module used to measure the C dating data; and AMS of the shallow surface layer of the measured sediment １４ C dating data and AMS １４ AMS of the shallow surface layer of the measured sediment obtained by the C dating method １４ a calibration value determination module used to obtain an "old carbon" calibration value by interpolating the C dating data; AMS of strata other than the shallow surface layer of the measured sediment １４ The "old carbon" calibration value was subtracted from the C dating data, and the calibrated AMS for each layer of the measured sediment was calculated. １４ a dating data calibration module used to obtain C calendar year values; AMS after calibration of two adjacent layers in the measured deposit １４ a deposition rate determination module used to determine a deposition rate based on the C calendar year value and the depth value between two adjacent layers; Based on the deposition rate, the AMS of the deposit between two adjacent layers is calculated. １４ a third dating module used to determine the C calendar year value; Based on the deposition rate, the AMS of the deposit other than the two adjacent layers １４ a quaternary dating module used to determine the C calendar year value; AMS after calibration for each layer of the measured deposit １４ C calendar year value, AMS of the deposit between two adjacent layers １４ C calendar year values ​​and AMS of sediments other than the two adjacent layers １４ and a date frame construction module that constructs a date frame according to the C calendar year value and is used to complete the dating of the measured sediment.

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