A quantitative method for paleotemperature and paleoprecipitation recovery

Abstract

The application discloses a kind of palaeotemperature and palaeoprecipitation quantitative recovery method, first determine the modern relative species of " the palynological taxa of the depth of the recovery simulation " and its annual mean temperature and annual mean precipitation, second determine the relative abundance of various palynological taxa and its annual mean temperature proportion and annual mean precipitation proportion;On the basis of determining the annual precipitation of various palynological taxa and its proportion product, by weighted cumulative summation, determine the palaeotemperature, palaeoprecipitation at the depth of the recovery simulation, finally repeat the above steps, quantitative recovery palaeotemperature and palaeoprecipitation at different depths in the purpose layer.The application solves the problems of " relying on experience, narrow application, unreliable results " for the existing palaeotemperature and palaeoprecipitation qualitative and quantitative recovery method;The application can also be used to other climate parameters difficult to obtain, single data stratum to carry out palaeotemperature, palaeoprecipitation quantitative recovery, greatly improve the reliability of quantitative recovery palaeotemperature and palaeoprecipitation data.

Description

Technical Field

[0001] This invention belongs to the field of geological resources and geological engineering technology, and specifically relates to a method for quantitatively reconstructing paleotemperature and paleoprecipitation. Background Technology

[0002] Paleotemperature and paleoprecipitation influence the erosion, transport, and deposition processes of sedimentary particles on the Earth's surface, ultimately recording them as distinct sedimentary features in various sedimentary systems; they are two of the most important paleoclimate parameters. Paleotemperature and paleoprecipitation reconstruction not only provides a better understanding of climate evolution but also helps clarify the sedimentary environments of geological history; they are crucial components of sedimentological research.

[0003] Existing methods for reconstructing paleotemperature and paleoprecipitation mainly fall into two categories: qualitative and quantitative. (1) Qualitative reconstruction of paleotemperature and paleoprecipitation primarily uses methods such as carbon isotopes, pollen assemblages, climate-sensitive sediments (e.g., mudstone chroma), and the content and size of carbon fragments in sediments to qualitatively reconstruct the relative magnitude (high or low) of paleotemperature and paleoprecipitation. (2) Quantitative reconstruction of paleotemperature and paleoprecipitation primarily uses methods such as pollen data (e.g., species) and paleoclimate substitution indicators (e.g., lipid compounds GDGTs) to quantitatively reconstruct the absolute magnitude (high or low paleotemperature and paleoprecipitation) of paleotemperature and paleoprecipitation. Qualitative reconstruction methods for paleotemperature and paleoprecipitation can only reconstruct the relative changes in paleotemperature and paleoprecipitation; they suffer from drawbacks such as strong subjectivity, reliance on experience-based judgment, and unreliable results. Most quantitative methods for paleotemperature and paleoprecipitation reconstruction rely on the coexistence factor method to identify the climatic requirements of various plant groups, failing to consider the relative abundance differences of pollinia. Furthermore, obtaining geochemical parameters is difficult and the applicable conditions are stringent (GDGTs, a type of lipid compound, are not present in all strata). These methods suffer from drawbacks such as stringent applicable conditions and biased results due to the lack of consideration for the relative abundance of pollinia species. Therefore, there is an urgent need to develop a novel quantitative method for paleotemperature and paleoprecipitation reconstruction that overcomes these shortcomings and offers advantages such as easy data acquisition, strong applicability, and reliable reconstruction results. Summary of the Invention

[0004] This invention is proposed to solve the problem that existing technologies cannot easily and efficiently reconstruct the paleotemperature and paleoprecipitation of a target layer quantitatively. Its purpose is to provide a method for quantitatively reconstructing paleotemperature and paleoprecipitation.

[0005] This invention is achieved through the following technical solution: A method for quantitatively reconstructing paleotemperature and paleoprecipitation using paleontological data, the method comprising: S1. Obtain palynological data from the paleontological data at the target well's intended restoration depth, and determine the palynological species at the intended restoration depth based on the palynological data; compare the palynological species at the intended restoration depth with the fossil palynological species in the fossil palynological paleotemperature and paleoprecipitation quantitative database to determine the current relatives of the palynological species at the intended restoration depth, and use the annual average temperature and annual average precipitation of the current relatives as the annual average temperature of the corresponding palynological species. ) and average annual rainfall ( ); The formula for calculating the average annual temperature is: In the formula: The average annual temperature for the i-th pollen species is expressed in °C. The lowest annual temperature for the current relatives of the i-th pollen species is given in °C. The highest annual temperature of the current relatives of the i-th pollen species is expressed in °C. The formula for calculating the average annual rainfall is: In the formula: denoted as the average annual rainfall for the i-th pollen species, in mm; The minimum annual rainfall for the current relatives of the i-th pollen species is given in mm. The maximum annual rainfall for the current relatives of the i-th pollen species is expressed in mm. S2. Based on the pollen data at the target well's intended recovery depth, determine the relative abundance of various pollen species at the target well's intended recovery depth. This relative abundance is the annual average temperature percentage of the pollen species. ) and the proportion of average annual rainfall ( ); The relative abundance of the pollen species is the proportion of each pollen species at the target well's intended recovery depth to the total number of pollen species at that depth. The proportion of the average annual temperature ( ) and the proportion of average annual rainfall ( The formula for calculating ) is: In the formula: The percentage of the annual average temperature for the i-th pollen species is dimensionless. denoted as the percentage of average annual rainfall for the i-th pollen species, dimensionless; n represents the total number of pollen species at the target well's intended recovery depth; and i represents the i-th pollen species. S3. Based on the average annual temperature of pollen species ( ) and the proportion of average annual temperature ( The product of ) and the average annual rainfall of pollinator species ( ) and the proportion of average annual rainfall ( The product of these values ​​is used to determine the paleotemperature T and paleoprecipitation P at the depth to be restored in the target well by weighted summation. The formula for calculating the paleotemperature T is: In the formula: T is the paleotemperature at the depth to be reconstructed in the target well, in °C; The average annual temperature for the i-th pollen species is expressed in °C. The percentage of the annual average temperature for the i-th pollen species is dimensionless. The formula for calculating the paleo-rainfall P is: In the formula: P is the paleoprecipitation at the depth to be restored in the target well, in mm; denoted as the average annual rainfall for the i-th pollen species, in mm; The percentage of annual rainfall for the i-th pollen species is dimensionless. S4. Repeat steps S1 to S3 to determine the paleotemperature and paleoprecipitation at different depths of the target well, and determine the evolution law and transition surface of paleotemperature and paleoprecipitation in the target well.

[0006] The beneficial effects of this invention are: This invention provides a method for quantitatively reconstructing paleotemperature and paleoprecipitation, which is easy to obtain data, has strong applicability, and provides reliable reconstruction results; Data acquisition is easy: This invention uses pollen data to quantitatively reconstruct paleotemperature and paleoprecipitation. Pollen is abundant in quantity and variety in strata and is widely distributed in terrestrial and lake sediments around the world, providing a rich source of samples for research. Moreover, the outer wall properties of pollen are stable, allowing it to be preserved in soil for millions of years. At the same time, pollen data can be acquired through methods such as strata borehole sampling and lake sediment sampling, which are relatively mature and easy to operate.

[0007] The method has strong applicability: This invention uses pollen data to quantitatively reconstruct paleotemperature and paleoprecipitation. Pollen has advantages such as wide spatial distribution, continuous preservation in strata, and clear climatic significance, and can be widely applied to paleoenvironmental studies at different spatiotemporal scales. It can also effectively extract information such as vegetation, temperature, and precipitation. In the process of calculating paleotemperature and paleoprecipitation, the annual average temperature and annual average precipitation of related species are accurately mapped to the survival environment parameters of pollen, making the calculation process simple and clear, and the method has strong applicability.

[0008] "Reliable restoration results": This invention uses pollen data to quantitatively restore paleotemperature and paleoprecipitation, and also considers and solves the impact of the relative abundance differences of pollen species on the data, and introduces the solution of the proportion of fossil pollen species in annual average temperature and annual average precipitation.

[0009] The absolute magnitude trends of paleotemperature and paleoprecipitation quantitatively reconstructed by this invention are consistent with the relative magnitude trends of paleotemperature and paleoprecipitation qualitatively reconstructed, thus ensuring the accuracy of the reconstructed paleotemperature and paleoprecipitation. Attached Figure Description

[0010] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a line graph showing the quantitative reconstruction results of paleotemperature and paleoprecipitation in the 1058-1902 m depth range of well BZ19-2-7 in Embodiment 1 of the present invention. Figure 3 This is a line graph showing the quantitative reconstruction results of paleotemperature and paleoprecipitation in the 1042-1831 m depth range of well BZ19-2-4 in Example 1 of this invention; Figure 4 This is a line graph showing the quantitative reconstruction results of paleotemperature and paleoprecipitation in the 1335-2261 m depth range of well BZ8-4S-1D in Embodiment 1 of the present invention. Figure 5 This is a comparison chart of paleotemperature and paleoprecipitation of wells BZ19-2-7, BZ19-2-4 and BZ8-4S-1D in Embodiment 1 of the present invention (the early paleotemperature is higher and the paleoprecipitation is larger, while the late paleotemperature is lower and the paleoprecipitation is smaller, and a paleoclimate transition surface appears between them).

[0011] For those skilled in the art, other related figures can be obtained from the above figures without any creative effort. Detailed Implementation

[0012] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0013] Example 1 like Figure 1 As shown, a method for quantitatively reconstructing paleotemperature and paleoprecipitation using paleontological data includes the following steps: S1. Based on the pollen species identification reports from wells BZ8-4S-1D (2120 m), BZ19-2-4 (1350 m), and BZ19-2-7 (1795 m), these reports were compared with the fossil pollen species in Appendix 1 to determine the modern related species corresponding to all pollen from these wells. , The calculation formulas are used to calculate the annual average temperature ( ), average annual rainfall ( The results are detailed in Table 1: Table 1: ( ) and average annual rainfall ( Calculation results S2. Pollen species identification report based on well BZ19-2-7, according to the proportion of average annual temperature ( ) and the proportion of average annual rainfall ( The calculation formula determines the abundance of different pollen species at a depth of 1795 m in well BZ19-2-7. This abundance is the percentage of the annual average temperature of that pollen. ) and the proportion of average annual rainfall ( The results are detailed in Table 2: Table 2: Annual average temperature percentage of fossil pollen species at a depth of 1795m in Well BZ19-2-7 ( ) and the proportion of average annual rainfall ( Calculation results Based on the pollen species identification report from well BZ19-2-4, and according to the proportion of annual average temperature ( ) and the proportion of average annual rainfall ( The calculation formula determines the abundance of different pollen species at a depth of 1350m in well BZ19-2-4. This abundance is the percentage of the annual average temperature of that pollen. ) and the proportion of average annual rainfall ( The results are detailed in Table 3: Table 3: Annual average temperature distribution of fossil pollen species at a depth of 1350 m in Well BZ19-2-4 ( ) and the proportion of average annual rainfall ( Calculation results Based on the pollen species identification report from well BZ8-4S-1D, according to the proportion of annual average temperature ( ) and the proportion of average annual rainfall ( The calculation formula determines the abundance of different pollen species at a depth of 2120 m in well BZ8-4S-1D. This abundance is the percentage of the annual average temperature of that pollen. ) and the proportion of average annual rainfall ( The results are detailed in Table 4: Table 4: Annual average temperature distribution of fossil pollen species at a depth of 2120 m in Well BZ8-4S-1D ( ) and the proportion of average annual rainfall ( Calculation results S3. The paleotemperature parameters corresponding to all pollen at a depth of 1795 m in well BZ19-2-7 are weighted and summed. Based on the paleotemperature calculation formula, the paleotemperature at a depth of 1795 m is determined as follows: The paleotemperature parameters corresponding to all pollen at a depth of 1350 m in well BZ19-2-4 were weighted and summed. Based on the paleotemperature calculation formula, the paleotemperature at a depth of 1350 m was determined as follows: The paleotemperature parameters corresponding to all pollen at a depth of 2120 m in well BZ8-4S-1D were weighted and summed. Based on the paleotemperature calculation formula, the paleotemperature at a depth of 2120 m was determined as follows: S4. The paleoprecipitation parameters corresponding to all pollen at a depth of 1795 m in well BZ19-2-7 are weighted and summed. Based on the paleoprecipitation calculation formula, the paleoprecipitation at a depth of 1795 m is determined as follows: The paleoprecipitation parameters corresponding to all pollen at a depth of 1350 m in well BZ19-2-4 were weighted and summed. Based on the paleoprecipitation calculation formula, the paleoprecipitation at a depth of 1350 m was determined as follows: The paleoprecipitation parameters corresponding to all pollen at a depth of 2120 m in well BZ8-4S-1D were weighted and summed. Based on the paleoprecipitation calculation formula, the paleoprecipitation at a depth of 2120 m was determined as follows: In summary, the quantitative reconstruction results using this invention indicate that the paleotemperature at a depth of 1795 m in well BZ19-2-7 is 13.02 ℃ and the paleoprecipitation is 1222.86 mm. Figure 2 The paleotemperature at a depth of 1350 m in well BZ19-2-4 is 9.29 ℃ and the paleoprecipitation is 1183.75 mm. Figure 3 The paleotemperature at a depth of 2120 m in well BZ8-4S-1D is 11.26 ℃ and the paleoprecipitation is 1324.74 mm. Figure 4 ).

[0014] S5. Repeat steps S1 to S4 to quantitatively recover the paleotemperature and paleoprecipitation of three wells (BZ19-2-7, 1058-1902 m depth; BZ19-2-4, 1042-1831 m depth; and BZ8-4S-1D, 1335-2261 m depth) in the lower section of the Minghuazhen Formation during the Late Miocene in the Bohai Bay Basin.

[0015] The paleotemperature and paleoprecipitation data reconstructed according to this invention exhibit a clear numerical transition surface. Below the interface, paleotemperature and paleoprecipitation are relatively high, while above the interface, they are relatively low (this interface is defined as the "paleoclimate transition surface"). Figures 2-5 ).

[0016] Specifically, according to the calculation results of this invention, the average paleotemperature values ​​below the paleoclimate transition surfaces of wells BZ19-2-7, BZ19-2-4, and BZ8-4S-1D (depth ranges of 1553-1899 m for well BZ19-2-7, 1452-1831 m for well BZ19-2-4, and 1755.5-2260.9 m for well BZ8-4S-1D) are 10.17 ℃, 11.39 ℃, and 9.81 ℃, respectively, and the average paleoprecipitation values ​​are 1171.62 mm, 1288.89 mm, and 1205.55 mm, respectively. Figures 2-4 Above the interface (depth ranges of 1052.75-1553 m in well BZ19-2-7, 1041-1452 m in well BZ19-2-4, and 1337-1755.5 m in well BZ8-4S-1D), the average paleotemperature values ​​were 8.71 ℃, 8.76 ℃, and 8.84 ℃, respectively, and the average paleoprecipitation values ​​were 1068.05 mm, 1122.17 mm, and 1110.81 mm, respectively. Figures 2-4 ).

[0017] This indicates that the lower segment of the Minghuazhen Formation in the Late Miocene of the Bohai Bay Basin's Bozhong Depression developed a paleoclimate transition surface characterized by a change in paleotemperature from low to high and paleoprecipitation from low to high from bottom to top. Figure 5 This result is also confirmed by existing qualitative and quantitative methods for reconstructing paleotemperature and paleoprecipitation. Based on existing qualitative methods for paleotemperature and paleoprecipitation, wells BZ19-2-7, BZ19-2-4, and BZ8-4S-1D show relatively rich concentrations of cold- and drought-loving pollen above the paleoclimate transition surface, indicating a relatively dry and cold climate. Conversely, wells below the interface show relatively rich concentrations of heat- and moisture-loving pollen, indicating a relatively hot and humid climate. Figures 2-4 The qualitative restoration results are similar to the paleotemperature and paleoprecipitation trends reflected in the quantitative calculation results of this invention.

[0018] Based on existing qualitative reconstruction methods for paleotemperature and paleoprecipitation (based on Mg / Ca and CaO / Al2O3 indices), wells BZ19-2-7, BZ19-2-4, and BZ8-4S-1D exhibit relatively lower paleotemperatures and palativities above the paleoclimate transition surface, while below the surface, paleotemperatures and palativities are relatively higher. Figures 2-4 The quantitative restoration results are consistent with the paleotemperature and paleoprecipitation trends reflected in the quantitative calculation results of this invention.

[0019] This invention's quantitative method considers the impact of variations in the relative abundance of pollen species on the reconstruction of paleotemperature and paleoprecipitation data, enabling a more accurate and objective assessment of paleotemperature and paleoprecipitation at different depths in the target well. Compared to existing technologies that only provide qualitative analysis and fail to quantitatively reconstruct paleotemperature and paleoprecipitation, this invention's quantitative calculation of pollen species data avoids the drawbacks of qualitative methods, such as strong subjectivity, reliance on experience, inaccurate results, and difficulty in comparison and integration with other quantitative data. Furthermore, compared to existing technologies that only quantitatively reconstruct paleotemperature and paleoprecipitation, this invention's quantitative calculation of pollen species to reconstruct paleotemperature and paleoprecipitation considers the relative abundance differences of pollen groups, and the selected pollen data is easy to obtain and widely available. Simultaneously, pollen has advantages such as wide spatial distribution, continuous preservation in strata, and clear climatic significance, making it widely applicable to paleoenvironmental studies at different spatiotemporal scales, and effectively extracting information on vegetation, temperature, and precipitation.

[0020] This invention not only comprehensively considers the influence of the relative abundance differences of pollen species data at the sites to be restored, but also accurately and objectively restores paleotemperature and paleoprecipitation at different depths. Furthermore, it can quantitatively calculate and evaluate the restored paleotemperature and paleoprecipitation at different depths, providing a novel, simple, and efficient method for the restoration of paleotemperature and paleoprecipitation.

[0021] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for quantitatively reconstructing paleotemperature and paleoprecipitation, characterized in that: Includes the following steps: S1. Obtain pollen data at the depth to be restored in the specified target well, and determine the species of pollen at the depth to be restored in the target well based on the pollen data; compare the species of pollen at the depth to be restored with the species of fossil pollen in the fossil pollen paleotemperature and paleoprecipitation quantitative database, determine the current relatives of the species of pollen at the depth to be restored in the target well, and use the average annual temperature and average annual precipitation of the current relatives as the average annual temperature and average annual precipitation of the corresponding pollen species; S2. Based on the pollen data at the target well's intended recovery depth, determine the relative abundance of various pollen species at the target well's intended recovery depth. This relative abundance is the percentage of pollen species by average annual temperature and average annual rainfall. S3. Determine the paleotemperature and paleoprecipitation at the depth to be restored in the target well based on the product of the annual average temperature and the percentage of annual average temperature of pollen species and the product of the annual average precipitation and the percentage of annual average precipitation of pollen species. S4. Repeat steps S1 to S3 to determine the paleotemperature and paleoprecipitation at different depths of the target well, and determine the evolution law and transition surface of paleotemperature and paleoprecipitation in the target well.

2. The method for quantitative reconstruction of paleotemperature and paleoprecipitation according to claim 1, characterized in that: The formula for calculating the average annual temperature is: In the formula: The average annual temperature for the i-th pollen species is expressed in °C. The lowest annual temperature for the current relatives of the i-th pollen species is given in °C. The highest annual temperature for the current relatives of the i-th pollen species is given in °C.

3. The method for quantitative reconstruction of paleotemperature and paleoprecipitation according to claim 1, characterized in that: The formula for calculating the average annual rainfall is: In the formula: denoted as the average annual rainfall for the i-th pollen species, in mm; The minimum annual rainfall for the current relatives of the i-th pollen species is given in mm. The maximum annual rainfall for the current relatives of the i-th pollen species is expressed in mm.

4. The method for quantitative reconstruction of paleotemperature and paleoprecipitation according to claim 1, characterized in that: The formulas for calculating the proportion of average annual temperature and the proportion of average annual rainfall are as follows: In the formula: The percentage of the annual average temperature for the i-th pollen species is dimensionless. denoted as the percentage of average annual rainfall for the i-th pollen species, dimensionless; n represents the total number of pollen species at the target well's intended recovery depth; and i represents the i-th pollen species.

5. The method for quantitative reconstruction of paleotemperature and paleoprecipitation according to claim 1, characterized in that: The formula for calculating the paleotemperature T is: In the formula: T is the paleotemperature at the depth to be reconstructed in the target well, in °C; The average annual temperature for the i-th pollen species is expressed in °C. denoted as the annual average temperature percentage of the i-th pollen species, dimensionless.

6. The method for quantitative reconstruction of paleotemperature and paleoprecipitation according to claim 1, characterized in that: The formula for calculating the paleo-rainfall P is: In the formula: P is the paleoprecipitation at the depth to be restored in the target well, in mm; denoted as the average annual rainfall for the i-th pollen species, in mm; denoted as the percentage of average annual rainfall for the i-th pollen species, dimensionless.

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