A method for prospecting copper polymetallic ore target areas based on aeromagnetic data

Abstract

The present invention provides a method for prospecting a copper polymetallic ore target area based on aeromagnetic data, and relates to the technical field of mineral resource prospecting. The method performs variable-angle polarization on the acquired aeromagnetic data to obtain aeromagnetic ΔT anomalies under vertical magnetization; the aeromagnetic ΔT anomalies after polarization are extended upward to obtain regional anomalies and remove them, and obtain aeromagnetic local anomalies; the aeromagnetic data is subjected to depth-weighted three-dimensional magnetic susceptibility structure inversion, and the optimal solution of the objective function is solved to obtain the three-dimensional distribution structure of the crustal magnetic susceptibility; the aeromagnetic ΔT anomalies after polarization are subjected to depth inversion based on power spectrum analysis to obtain the Curie point depth of the study area; the three-dimensional fracture information of the three-dimensional magnetic susceptibility structure is extracted to obtain the three-dimensional fracture distribution in the crust; and the above information is comprehensively analyzed to establish the optimization principle of the favorable area of ​​copper polymetallic ore. The present invention provides support for the exploration and development of copper polymetallic ore based on high-precision aeromagnetic data and comprehensive multiple physical property parameters.

Description

Technical Field

[0001] The invention relates to the technical field of mineral resource exploration, and in particular to a method for exploring a copper polymetallic ore target area based on aeromagnetic data. Background Art

[0002] As energy and resource security has become a national strategy, the country's "14th Five-Year Plan" clearly states that it will "implement a new round of strategic actions to break through mineral exploration." Copper polymetallic ore is one of my country's scarce minerals, with a foreign dependence rate of up to 78%. Its exploration is of great significance to the country's science and technology, economy, military and national defense. However, the commonly used geophysical exploration methods currently include magnetotelluric, high-density electrical, gravity and drilling methods. There are many limitations in the large-scale survey of copper polymetallic ore:

[0003] 1. Magnetotelluric method and high-density electrical method: Affected by factors such as collection method and terrain, these methods can often only be used for local exploration, and the construction period is long, which is not suitable for large-scale preliminary survey work.

[0004] 2. Gravity survey method: including ground gravity measurement and aerial gravity measurement. Although ground gravity measurement can be used for high-precision measurement, it is also affected by the terrain and has low efficiency, so it cannot be applied to large-scale surveys. Although aerial gravity survey can overcome the influence of terrain, its resolution is low and its exploration effect on copper polymetallic ores is not good, which is not as good as the aeromagnetic survey method.

[0005] 3. Drilling method: The drilling method can directly measure the material properties of underground rocks and mineralized rock bodies with high precision, but the drilling cost is extremely high and it is not suitable for large-scale exploration work.

[0006] In view of the above limitations, the existing geophysical exploration methods are difficult to play an effective role in the early large-scale copper polymetallic ore survey. These methods have many limitations in the large-scale and early exploration stage, such as long construction period, sparse data sampling, high cost, terrain influence, etc. Therefore, there is an urgent need for a technical method that is economical and efficient and suitable for the optimization of large-scale copper polymetallic ore target areas. Summary of the invention

[0007] In view of this, in order to solve the problems of long construction period, sparse data sampling, high cost and terrain influence in the existing commonly used geophysical exploration methods, the purpose of the present invention is to propose a method for exploring copper polymetallic mineral target areas based on aeromagnetic data. Taking aeromagnetic data as the main data, by integrating multi-source information such as local anomaly distribution, magnetic susceptibility structure, Curie surface fluctuation and three-dimensional distribution of faults, it can economically and efficiently implement the optimization of large-scale copper polymetallic mineral target areas, and provide technical support for the exploration of copper polymetallic minerals.

[0008] Based on the above objectives, in a first aspect, the present invention provides a method for prospecting a copper polymetallic ore target area based on aeromagnetic data, the method comprising the following steps:

[0009] The acquired aeromagnetic data are polarized by changing the inclination angle, and the aeromagnetic anomaly with oblique magnetization is converted into the aeromagnetic ΔT anomaly under vertical magnetization.

[0010] The aeromagnetic ΔT anomaly after polarization is extended upward to obtain the regional anomaly, and the regional anomaly is removed from the aeromagnetic ΔT anomaly after polarization to obtain the aeromagnetic local anomaly;

[0011] The depth-weighted three-dimensional magnetic susceptibility structure inversion is performed on the aeromagnetic data, and the nonlinear conjugate gradient method is used to solve the optimal solution of the objective function to obtain the three-dimensional distribution structure of the crustal magnetic susceptibility.

[0012] Based on power spectrum analysis, the depth inversion of the aeromagnetic ΔT anomaly after polarization was performed to obtain the Curie point depth of the study area.

[0013] Extract 3D fracture information from the 3D magnetic susceptibility structure to obtain the 3D fracture distribution in the crust;

[0014] By comprehensively analyzing information on local aeromagnetic anomalies, three-dimensional magnetic susceptibility structure, Curie point depth and three-dimensional fault distribution, the optimization principles for favorable areas for copper-polymetallic deposits are established, and the optimization standards and plans for favorable areas for copper-polymetallic deposits based on aeromagnetic data are obtained.

[0015] As a further solution of the present invention, when the acquired aeromagnetic data are subjected to variable inclination polarization, the large-scale study area is divided into multiple secondary zones, the geomagnetic inclination of each secondary zone is polarized, and the polarization results of each sub-zone are fused and spliced ​​to form the aeromagnetic ΔT anomaly after polarization of the study area.

[0016] As a further solution of the present invention, when the oblique magnetization aeromagnetic anomaly is converted into the aeromagnetic ΔT anomaly under vertical magnetization, the polarization conversion relationship of the aeromagnetic ΔT anomaly is obtained by using the spectrum differential theorem:

[0017]

[0018] Where L0, M0, N0 are the direction cosines of the unit vector of the Earth's magnetic field, u and v are the frequencies in the x and y directions respectively; FT[] represents Fourier transform; It is the aeromagnetic anomaly after polarization, that is: the aeromagnetic ΔT anomaly after polarization; the geomagnetic field inclination angles corresponding to different positions are different, and the direction cosines L0, M0, and N0 of the geomagnetic field unit vector are different; the direction cosine area average value of the geomagnetic field unit vector of each secondary zone is substituted into the polarization conversion formula, and the aeromagnetic ΔT anomaly after polarization of each secondary zone is calculated, and the aeromagnetic ΔT anomaly after polarization of the entire area is obtained by splicing.

[0019] As a further solution of the present invention, when obtaining the local aeromagnetic anomaly, the frequency domain is extended upward to calculate the regional anomaly caused by deep geological factors. The calculation formula of the local aeromagnetic anomaly is:

[0020]

[0021] Where, ΔT res To obtain the local aeromagnetic anomaly, ΔT ⊥up It is the aeromagnetic anomaly extended upward;

[0022]

[0023] Where h is the upward extension height, u and v are the frequencies in the x and y axis directions respectively; FT[] represents Fourier transform; x, y, z0 are the position coordinates of the measuring point.

[0024] As a further solution of the present invention, when performing depth-weighted three-dimensional magnetic susceptibility structure inversion on aeromagnetic data, the objective function of the three-dimensional depth-weighted inversion of magnetic anomalies is:

[0025]

[0026] Among them, d is the observed data; m is the model space; G is the sensitivity matrix; Fitting functionals to the data; is the model stabilization functional, W d and W m are the weight matrices for data and model, respectively;

[0027] In the actual inversion process, the data weighting function W d Set as a constant diagonal matrix, Z is the depth weighted matrix, and the expression of the depth weighted matrix Z is:

[0028]

[0029] Among them, Z j represents the depth of the jth grid, β is a positive number related to the magnetic field decay rate, and is selected as 3 in three-dimensional magnetic field inversion.

[0030] As a further solution of the present invention, a nonlinear conjugate gradient method is used to solve the optimal solution of the objective function. When the three-dimensional distribution structure of the crustal magnetic susceptibility is obtained, the conjugate gradient method is used to write a MATLAB language program to solve the objective function of the three-dimensional depth weighted inversion of the magnetic anomaly to obtain a high-precision three-dimensional distribution structure of the crustal magnetic susceptibility.

[0031] As a further solution of the present invention, when obtaining the Curie point depth of the study area, a power spectrum analysis method based on a self-similar or fractal model is used to perform depth inversion on the aeromagnetic anomaly. For a magnetic layer that extends infinitely in the horizontal direction, the radial power spectrum of the total magnetic field anomaly generated is expressed as:

[0032]

[0033] Among them, P ΔT (|k|) and P M (|k|) are the radial average amplitude spectra of the total magnetic anomaly and magnetization intensity, respectively; |k| is the wave number of the circular frequency; Z t and Z b are the upper and lower interfaces of the magnetic layer respectively; B is a constant factor related to the direction of the magnetic field intensity and the direction of the geomagnetic field.

[0034] As a further solution of the present invention, based on the self-similar or fractal model to invert the Curie point depth, the crustal magnetization intensity presents fractal characteristics, namely:

[0035]

[0036] Among them, β is the fractal index;

[0037] According to the radial power spectrum of the total magnetic field anomaly and the fractal characteristics of the crustal magnetization intensity, the fitting formulas of the center depth and the upper interface depth are obtained:

[0038] ln[|k| β-2 ×P ΔT (|k|)]=B1-|k|·Z t

[0039] ln[|k| β ×P ΔT (|k|)]=B2-|k|·Z0

[0040] Among them, B1 and B2 are constants, Z0 is the depth of the center of the magnetic layer, and Z is obtained by three-dimensional fitting using the least squares method. t and Z0; depth Z of the inner surface b The calculation formula is:

[0041] Z b =2·Z0-Z t .

[0042] As a further solution of the present invention, three-dimensional fracture information is extracted from the three-dimensional magnetic susceptibility structure, and the plane distribution and three-dimensional extension of the structural boundary and the fracture at different depths are characterized. When extracting the three-dimensional fracture, the boundary position is identified and the anisotropy is calculated through the three-dimensional statistical invariant intensity parameter; wherein the covariance matrix of the three-dimensional second-order spectral moment of the three-dimensional magnetic susceptibility structure is:

[0043]

[0044] Among them, C is the covariance matrix, K x , K y , K z is the partial derivative of magnetic susceptibility with respect to the x, y, and z directions, i = 1, 2, ... M α ,j=1,2,…N α ,k=1,2,…l α ;

[0045] m 200 ,m 020 ,m 002 ,m 110 m 101 ,m 011 are the six elements of the three-dimensional second-order spectral moment;

[0046] L α 、M α 、N α is the size of the three-dimensional sliding window;

[0047] Perform eigenvalue decomposition on the covariance matrix C to obtain the diagonal matrix A;

[0048]

[0049] Use the elements a1, a2, and a3 in the diagonal matrix A to construct the local strength 3 M2, identify the boundary location.

[0050] As a further aspect of the present invention, local strength 3 The M2 data volume is used as input, and the three elements b1, b2, and b3 of the diagonal matrix obtained by calculating the covariance matrix of the three-dimensional second-order spectral moment and the diagonal matrix A characterize the three-dimensional boundary coefficients of the fracture as follows:

[0051]

[0052] in is the local intensity 3 The divergence of the M2 data, It is used to take The inverse sign of .

[0053] In another aspect of the present invention, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, any one of the above methods for exploring a copper polymetallic mineral target area based on aeromagnetic data according to the present invention is executed.

[0054] In another aspect of the present invention, a computer-readable storage medium is provided, storing computer program instructions, which, when executed, implement any of the above methods for exploring a copper-polymetallic mineral target area based on aeromagnetic data according to the present invention.

[0055] Compared with the prior art, the method for prospecting copper polymetallic ore target areas based on aeromagnetic data proposed in the present invention has the following beneficial effects:

[0056] 1. High-precision data processing and conversion are achieved through aeromagnetic anomaly polarization and aeromagnetic local anomaly extraction. When aeromagnetic anomaly polarization is performed, the oblique magnetization aeromagnetic anomaly is converted into aeromagnetic ΔT anomaly with vertical magnetization by changing the inclination angle, which improves the accuracy and resolution of the anomaly data. When extracting aeromagnetic local anomalies, the upward continuation method is used to effectively extract local anomalies from the overall anomalies, and locate the target area more accurately.

[0057] 2. Through the inversion of three-dimensional magnetic susceptibility structure and Curie point depth inversion, the geological structure is deeply analyzed. When the three-dimensional magnetic susceptibility structure is inverted, the underground three-dimensional magnetic susceptibility structure is obtained through depth-weighted inversion, revealing the possible geological structure and magnetic characteristics of copper polymetallic mines. When the Curie point depth is inverted, the power spectrum analysis based on the self-similar or fractal model is used to infer the underground Curie point depth, which provides key parameters for deep mineral deposit exploration.

[0058] 3. Through the extraction of three-dimensional fracture information, the fracture and mineralization information analysis is realized. When extracting three-dimensional fracture information, the three-dimensional fracture distribution in the crust is extracted through the second-order spectral moment method, which helps to identify possible mineralization zones and mineral deposit control factors.

[0059] 4. Comprehensive analysis and optimization criteria were achieved through the establishment of optimization criteria. Based on the information of local aeromagnetic anomalies, magnetic susceptibility structure, fault distribution and Curie point depth, optimization criteria for favorable areas of copper polymetallic deposits were formulated to provide guidance for subsequent geological exploration and resource development.

[0060] In summary, the copper polymetallic ore target area exploration method based on aeromagnetic data of the present invention not only improves the accuracy and efficiency of exploration, but also can effectively reduce exploration risks, and provide comprehensive and reliable scientific support and guidance for mineral resource exploration and development. It has broad application prospects in resource exploration and development, especially in the discovery and evaluation of mineral resources in complex geological environments.

[0061] These and other aspects of the present application will be more concise and understandable in the following description of the embodiments. It should be understood that the above general description and the following detailed description are only exemplary and explanatory and cannot limit the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0063] In the figure:

[0064] Figure 1 The present invention is a flowchart of a method for exploring a copper polymetallic mineral target area based on aeromagnetic data according to an embodiment of the present invention. DETAILED DESCRIPTION

[0065] Below, the present application is further described in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0066] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0067] The commonly used geophysical exploration methods for copper polymetallic ores include magnetotelluric method, high-density electrical method, gravity method and drilling method. Magnetotelluric and high-density electrical methods are often mainly local explorations due to the influence of acquisition methods and terrain, and the construction period is long; the regional geoelectric method has sparse data sampling and high cost, so magnetotelluric and high-density methods are not suitable for large-scale and large-scale copper polymetallic mine surveys in the early stage. Gravity exploration methods include ground gravity measurement and aerial gravity measurement methods. Although ground gravity can be measured with high precision, it is also affected by terrain and has low efficiency, and cannot be applied to the exploration of large-scale copper polymetallic ores. Aerogravity exploration technology can overcome the influence of terrain, but its resolution is low, and the exploration effect of copper polymetallic ores is not good, which is not as good as aeromagnetic measurement method. The drilling method can directly measure the material properties of underground rocks and mineralized rock bodies with high precision, but the drilling cost is very high and it is not suitable for large-scale development.

[0068] In view of this, the present invention proposes a method for exploring copper polymetallic mineral target areas based on aeromagnetic data. It is a comprehensive processing solution with aeromagnetic data as the main data, integrating multi-source information such as local anomaly distribution, magnetic susceptibility structure, Curie surface fluctuations and three-dimensional distribution of faults. Especially in the Sanjiang mineralization belt, the terrain conditions are complex, and the volcanic rocks and intermediate-acidic magmatic rocks related to copper polymetallic minerals have medium to high intensity magnetism. Through the technology proposed in the present invention, the optimization of large-scale copper polymetallic mineral target areas can be implemented economically and efficiently, providing good technical support for strategic breakthrough actions in prospecting.

[0069] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0070] The flowcharts shown in the accompanying drawings are only examples and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may also be decomposed, combined or partially merged, so the actual execution order may change according to actual conditions.

[0071] See also Figure 1 As shown, an embodiment of the present invention provides a method for prospecting a copper polymetallic ore target area based on aeromagnetic data, the method comprising the following steps:

[0072] Step S10, performing polarization on the acquired aeromagnetic data to convert the oblique magnetization aeromagnetic anomaly into the aeromagnetic ΔT anomaly under vertical magnetization;

[0073] Step S20, the aeromagnetic ΔT anomaly after polarization is extended upward to obtain a regional anomaly, and the regional anomaly is removed from the aeromagnetic ΔT anomaly after polarization to obtain aeromagnetic local anomaly;

[0074] Step S30, performing depth-weighted three-dimensional magnetic susceptibility structure inversion on the aeromagnetic data, using a nonlinear conjugate gradient method to find the optimal solution of the objective function, and obtaining the three-dimensional distribution structure of the crustal magnetic susceptibility;

[0075] Step S40, performing depth inversion of the aeromagnetic ΔT anomaly after polarization based on power spectrum analysis to obtain the Curie point depth of the study area;

[0076] Step S50, extracting three-dimensional fracture information from the three-dimensional magnetic susceptibility structure to obtain three-dimensional fracture distribution in the crust;

[0077] Step S60: Establish the optimization principle of favorable areas for copper polymetallic deposits by comprehensively analyzing the information of local aeromagnetic anomalies, three-dimensional magnetic susceptibility structure, Curie point depth and three-dimensional fault distribution, and obtain the optimization criteria and scheme for favorable areas for copper polymetallic deposits based on aeromagnetic data.

[0078] The method for exploring the target area of ​​copper polymetallic ore based on aeromagnetic data in the embodiment of the present invention adopts the steps of obtaining aeromagnetic ΔT anomaly under vertical magnetization; obtaining aeromagnetic local anomaly; obtaining the three-dimensional distribution structure of crustal magnetic susceptibility; obtaining Curie point depth; obtaining the distribution of fractures in the crust, and the optimization criteria for the favorable area of ​​copper polymetallic ore, etc., and obtains the optimization criteria and scheme for the favorable area of ​​copper polymetallic ore based on aeromagnetic data through comprehensive analysis of the distribution of aeromagnetic local anomaly, magnetic susceptibility structure, fracture distribution and Curie point depth. The present invention provides support for the exploration and development of copper polymetallic ore based on high-precision aeromagnetic data and comprehensive multiple physical property parameters.

[0079] In this embodiment, in step S10, the method of polarization by changing the inclination angle is adopted to improve the accuracy of polarization processing. When performing polarization by changing the inclination angle on the acquired aeromagnetic data, a large-scale study area is divided into multiple secondary zones, the geomagnetic inclination of each secondary zone is polarized, and the polarization results of each zone are fused and spliced ​​to form the aeromagnetic ΔT anomaly after polarization in the study area.

[0080] Among them, when the oblique magnetization aeromagnetic anomaly is converted into the aeromagnetic ΔT anomaly under vertical magnetization, the polarization conversion relationship of the aeromagnetic ΔT anomaly is obtained by using the spectrum differential theorem:

[0081]

[0082] Where L0, M0, N0 are the direction cosines of the unit vector of the Earth's magnetic field, u and v are the frequencies in the x and y directions respectively; FT[] represents Fourier transform; is the aeromagnetic anomaly after polarization, that is, the aeromagnetic ΔT anomaly after polarization; the geomagnetic field inclination angles corresponding to different positions are different, and the direction cosines L0, M0, and N0 of the geomagnetic field unit vector are different; the direction cosine area average value of the geomagnetic field unit vector of each secondary zone is substituted into the polarization conversion formula (1), and the aeromagnetic ΔT anomaly after polarization of each secondary zone is calculated, and the aeromagnetic ΔT anomaly after polarization of the entire zone is obtained by splicing.

[0083] In this embodiment, in step S20, the method of removing the regional anomaly from the aeromagnetic ΔT anomaly after polarization is used to obtain the aeromagnetic local anomaly. When the aeromagnetic local anomaly is obtained, the frequency domain is extended upward to calculate the regional anomaly caused by deep geological factors. The calculation formula of the aeromagnetic local anomaly is:

[0084]

[0085] Where, ΔT res To obtain the local aeromagnetic anomaly, It is the aeromagnetic anomaly extended upward;

[0086]

[0087] Where h is the upward extension height, u and v are the frequencies in the x and y axis directions respectively; FT[] represents Fourier transform; x, y, z0 are the position coordinates of the measuring point.

[0088] The aeromagnetic local anomaly can be obtained by using formula (2) and formula (3). The aeromagnetic local anomaly can more clearly reflect the shallow geological structure, especially the magnetic igneous rock body, which is of great significance for the exploration of copper polymetallic deposits.

[0089] In this embodiment, in step S30, the three-dimensional physical structure of the aeromagnetic pole ΔT anomaly is inverted to obtain the magnetic susceptibility and depth information of the magnetic source body. When the depth-weighted three-dimensional magnetic susceptibility structure inversion is performed on the aeromagnetic data, the objective function of the three-dimensional depth-weighted inversion of the magnetic anomaly is:

[0090]

[0091] Among them, d is the observed data; m is the model space; G is the sensitivity matrix; Fitting functionals to the data; is the model stabilization functional, W d and W m are the weight matrices for data and model, respectively;

[0092] In the actual inversion process, the data weighting function W d Set as a constant diagonal matrix, Z is the depth weighted matrix, and the expression of the depth weighted matrix Z is:

[0093]

[0094] Among them, Z j represents the depth of the jth grid, β is a positive number related to the magnetic field decay rate, and is selected as 3 in three-dimensional magnetic field inversion.

[0095] Finally, the conjugate gradient method is used to write a MATLAB language program to solve the objective function (4) of the three-dimensional depth weighted inversion of magnetic anomalies and obtain a high-precision three-dimensional distribution structure of crustal magnetic susceptibility.

[0096] In this embodiment, in step S40, the Curie point is the Curie isotherm where magnetic minerals change from ferromagnetism to paramagnetism. It is a geophysical characteristic interface that reflects the thermal state of the lithosphere. Its burial depth is closely related to deep tectonic movement, magmatic activity and mineralization. Inverting its depth is of great significance to geotectonic research and mineral resource exploration. When obtaining the Curie point depth of the study area, a power spectrum analysis method based on a self-similar or fractal model is used to perform aeromagnetic anomaly depth inversion. For a magnetic layer that extends infinitely in the horizontal direction, the radial power spectrum of the generated total magnetic field anomaly is expressed as:

[0097]

[0098] Among them, P ΔT (|k|) and P M (|k|) are the radial average amplitude spectra of the total magnetic anomaly and magnetization intensity, respectively; |k| is the wave number of the circular frequency; Z t and Z b are the upper and lower interfaces of the magnetic layer respectively; B is a constant factor related to the direction of the magnetic field intensity and the direction of the geomagnetic field.

[0099] Based on the self-similar or fractal model to invert the Curie point depth, the crustal magnetization intensity shows fractal characteristics, namely:

[0100]

[0101] Among them, β is the fractal index;

[0102] According to the radial power spectrum of the total magnetic field anomaly and the fractal characteristics of the crustal magnetization intensity, the fitting formulas of the center depth and the upper interface depth are obtained:

[0103] ln[|k| β-2 ×P ΔT (|k|)]=B1-|k|·Z t (8)

[0104] ln[|k| β ×P ΔT (|k|)]=B2-|k|·Z0 (9)

[0105] Among them, B1 and B2 are constants, Z0 is the depth of the center of the magnetic layer, and Z is obtained by three-dimensional fitting using the least squares method. t and Z0; depth Z of the inner surface b The calculation formula is:

[0106] Z b =2·Z0-Z t (10).

[0107] In this embodiment, in step S50, by performing three-dimensional boundary extraction on the three-dimensional magnetic susceptibility structure obtained by inversion of aeromagnetic data, the planar distribution and three-dimensional extension of the structural boundary and the fracture at different depths can be effectively characterized. The three-dimensional fracture extraction method is a new method developed based on the three-dimensional second-order spectral moment and its statistical invariant. By performing three-dimensional fracture information extraction on the three-dimensional magnetic susceptibility structure, the planar distribution and three-dimensional extension of the structural boundary and the fracture at different depths are characterized. When extracting three-dimensional fractures, the boundary position is identified and the anisotropy is calculated through the three-dimensional statistical invariant intensity parameter; wherein the covariance matrix of the three-dimensional second-order spectral moment of the three-dimensional magnetic susceptibility structure is:

[0108]

[0109] Among them, C is the covariance matrix, K x , K y , K z is the partial derivative of magnetic susceptibility with respect to the x, y, and z directions, i = 1, 2, ... M α ,j=1,2,…N α ,k=1,2,…l α ;

[0110] m 200 ,m 020 ,m 002 ,m 110 m 101 ,m 011 are the six elements of the three-dimensional second-order spectral moment;

[0111] L α 、M α 、n α is the size of the three-dimensional sliding window;

[0112] Perform eigenvalue decomposition on the covariance matrix C to obtain the diagonal matrix A;

[0113]

[0114] Use the elements a1, a2, and a3 in the diagonal matrix A to construct the local strength 3 M2, identify the boundary location.

[0115] The local strength 3 The M2 data volume is used as input. The three elements b1, b2, and b3 of the diagonal matrix are calculated by the covariance matrix of the three-dimensional second-order spectral moment and the diagonal matrix A through formula (11) and formula (12). The three-dimensional boundary coefficients of the fracture are:

[0116]

[0117] in is the local intensity 3 The divergence of the M2 data, It is used to take The inverse sign of .

[0118] Formula (13) identifies the three-dimensional boundaries in the data volume. The new three-dimensional fracture extraction method based on the three-dimensional second-order spectral moment can not only enhance the weak boundary recognition ability and improve the lateral resolution, but also this local surface element statistical calculation method can effectively suppress high-frequency noise. At the same time, unlike the traditional two-dimensional boundary recognition method that can only obtain the plane boundary distribution, this method can obtain the three-dimensional boundary distribution data volume, which can not only characterize the plane distribution characteristics of the fracture at different depths, but also characterize the extension morphology of the fracture from shallow to deep.

[0119] In this embodiment, in step S60, the optimization principle of favorable areas for copper polymetallic deposits is established by comprehensively analyzing the local aeromagnetic anomalies obtained in step S20, the three-dimensional magnetic susceptibility structure obtained by depth weighted inversion in step S30, the three-dimensional fault distribution obtained in step S40, and the Curie point depth information calculated in step S50. Generally, the local medium-strong magnetic anomalies of the aeromagnetic model, the medium-high magnetic susceptibility distribution area in the middle and upper crust, the deep and large fault distribution area, and the Curie point uplift area are favorable areas for copper polymetallic deposits. Among them, the local medium-strong magnetic anomalies and deep and large fault distribution of the aeromagnetic model are the first-level control factors, the medium-high magnetic susceptibility distribution area in the middle and upper crust is the second-level control factor, and the Curie point uplift area is the third-level control factor. By ranking the importance of these control factors and combining them with geological, geochemical and other data for comprehensive analysis, the target areas of copper polymetallic deposits controlled by magma and structure can be optimized.

[0120] The method for prospecting copper polymetallic ore target areas based on aeromagnetic data of the present invention realizes high-precision data processing and conversion through aeromagnetic anomaly polarization and aeromagnetic local anomaly extraction. When aeromagnetic anomaly polarization is performed, the obliquely magnetized aeromagnetic anomaly is converted into a vertically magnetized aeromagnetic ΔT anomaly by changing the inclination angle of the pole, thereby improving the accuracy and resolution of the anomaly data. When extracting aeromagnetic local anomalies, the upward continuation method is used to effectively extract local anomalies from the overall anomalies, and the target area is located more accurately. Through three-dimensional magnetic susceptibility structure inversion and Curie point depth inversion, in-depth analysis of geological structure is achieved. When inverting the three-dimensional magnetic susceptibility structure, the underground three-dimensional magnetic susceptibility structure is obtained through depth weighted inversion, revealing the possible geological structure and magnetic characteristics of the copper polymetallic ore. When inverting the Curie point depth, the underground Curie point depth is inferred based on the power spectrum analysis of the self-similar or fractal model, which provides a key parameter for deep mineral deposit exploration. By extracting three-dimensional fracture information, fracture and mineralization information analysis is achieved. When extracting three-dimensional fracture information, the second-order spectral moment method is used to extract the three-dimensional fracture distribution in the crust, which helps to identify possible mineralized zones and deposit control factors. Through the establishment of optimization criteria, comprehensive analysis and optimization criteria are achieved. Based on the information of local aeromagnetic anomalies, magnetic susceptibility structure, fracture distribution and Curie point depth, optimization criteria for favorable areas of copper polymetallic deposits are formulated to provide guidance for subsequent geological exploration and resource development.

[0121] The copper polymetallic ore target area exploration method based on aeromagnetic data of the present invention not only improves the accuracy and efficiency of exploration, but also can effectively reduce exploration risks, and provide comprehensive and reliable scientific support and guidance for mineral resource exploration and development. It has broad application prospects in resource exploration and development, especially in the discovery and evaluation of mineral resources in complex geological environments.

[0122] According to a second aspect of an embodiment of the present invention, a computer device is provided, including a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the method of any one of the above embodiments is implemented.

[0123] The computer device includes a processor and a memory, and may also include an input system and an output system. The processor, memory, input system and output system may be connected via a bus or other means, and the input system may receive input digital or character information, and generate signal input related to the migration of the method for prospecting copper polymetallic ore target areas based on aeromagnetic data. The output system may include display devices such as a display screen.

[0124] As a non-volatile computer-readable storage medium, the memory can be used to store non-volatile software programs, non-volatile computer executable programs and modules, such as the program instructions / modules corresponding to the method for prospecting copper polymetallic ore target areas based on aeromagnetic data in the embodiment of the present application. The memory may include a program storage area and a data storage area, wherein the program storage area may store an operating system and an application required for at least one function; the data storage area may store data created by the use of the method for prospecting copper polymetallic ore target areas based on aeromagnetic data, etc. In addition, the memory may include a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device, a flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory may optionally include a memory remotely arranged relative to the processor, and these remote memories may be connected to the local module via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0125] The processor may be a central processing unit (CPU), a controller, a microcontroller, a microprocessor, or other data processing chip in some embodiments. The processor is generally used to control the overall operation of the computer device. In this embodiment, the processor is used to run the program code stored in the memory or process data. The processors of the multiple computer devices of the computer device of this embodiment execute various functional applications and data processing of the server by running the non-volatile software programs, instructions and modules stored in the memory, that is, to implement the steps of the method for exploring the copper polymetallic ore target area based on aeromagnetic data in the above method embodiment.

[0126] It should be understood that, to the extent that they do not conflict with each other, all the embodiments, features and advantages described above for the method for prospecting a copper-polymetallic mineral target area based on aeromagnetic data according to the present invention are also applicable to the method and storage medium for prospecting a copper-polymetallic mineral target area based on aeromagnetic data according to the present invention.

[0127] It will also be appreciated by those skilled in the art that various exemplary logic blocks, modules, circuits and algorithm steps described in conjunction with the disclosure herein can be implemented as electronic hardware, computer software or a combination of the two. In order to clearly illustrate this interchangeability of hardware and software, a general description has been given to the functions of various schematic components, blocks, modules, circuits and steps. Whether this function is implemented as software or implemented as hardware depends on specific applications and the design constraints imposed on the entire system. Those skilled in the art can implement the function in various ways for each specific application, but this implementation decision should not be interpreted as causing a departure from the disclosed scope of the embodiments of the present invention.

[0128] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0129] It should be understood that, as used herein, the singular form "a" or "an" is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations of one or more of the items listed in association. The serial numbers of the embodiments disclosed in the above embodiments of the present invention are for description only and do not represent the advantages and disadvantages of the embodiments.

[0130] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the embodiments of the present invention as above, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for prospecting copper polymetallic ore target areas based on aeromagnetic data, characterized in that: The following steps are involved: The acquired aeromagnetic data is polarized by changing the inclination angle, and the oblique magnetization aeromagnetic anomaly is converted into aeromagnetic data under vertical magnetization. abnormal; Aeromagnetic after polarization The anomaly is extended upward to obtain the regional anomaly, and the regional anomaly is obtained from the aeromagnetic Remove the anomaly and obtain the aeromagnetic local anomaly; The depth-weighted three-dimensional magnetic susceptibility structure inversion is performed on the aeromagnetic data, and the nonlinear conjugate gradient method is used to solve the optimal solution of the objective function to obtain the three-dimensional distribution structure of the crustal magnetic susceptibility. Aeromagnetic analysis of polarization based on power spectrum The anomaly is subjected to depth inversion to obtain the Curie point depth of the study area; Extract 3D fracture information from the 3D magnetic susceptibility structure to obtain the 3D fracture distribution in the crust; By comprehensively analyzing information on local aeromagnetic anomalies, three-dimensional distribution structure of crustal magnetic susceptibility, Curie point depth and three-dimensional fault distribution, the optimization principles for favorable areas for copper-polymetallic deposits are established, and the optimization standards and plans for favorable areas for copper-polymetallic deposits based on aeromagnetic data are obtained.

2. The method for prospecting copper polymetallic ore target area based on aeromagnetic data according to claim 1, characterized in that: When the acquired aeromagnetic data are polarized by varying the inclination angle, the large-scale study area is divided into multiple secondary zones, the geomagnetic inclination of each secondary zone is polarized, and the polarization results of each zone are fused and spliced ​​to form the aeromagnetic data of the study area after polarization. abnormal.

3. The method for prospecting copper polymetallic ore target area based on aeromagnetic data according to claim 2, characterized in that: Converting oblique magnetization aeromagnetic anomalies into perpendicular magnetization aeromagnetic anomalies When abnormal, the aeromagnetic The abnormal polarization conversion relationship is: ， in, , , is the direction cosine of the unit vector of the Earth's magnetic field, , They are , Frequency in the axial direction; represents Fourier transform; The aeromagnetic anomaly after polarization is Anomaly; different locations correspond to different geomagnetic field inclinations, and the direction cosines of the geomagnetic field unit vector , , Different; Substitute the direction cosine area average value of the geomagnetic field unit vector of each secondary zone into the polarization conversion formula to calculate the polarized aeromagnetic value of each secondary zone. Abnormal, splicing to obtain the aeromagnetic after polarization of the entire area abnormal.

4. The method for prospecting copper polymetallic ore target area based on aeromagnetic data according to claim 3, characterized in that: When the local aeromagnetic anomaly is obtained, the frequency domain is extended upward to calculate the regional anomaly caused by deep geological factors. The calculation formula of the local aeromagnetic anomaly is: ， in, To obtain the local aeromagnetic anomaly, It is the aeromagnetic anomaly extended upward; ， in, is the upward extension height, , They are , Frequency in the axial direction; represents Fourier transform; , , is the position coordinate of the measuring point.

5. The method for prospecting copper polymetallic ore target area based on aeromagnetic data according to claim 4, characterized in that: When performing depth-weighted three-dimensional magnetic susceptibility structure inversion on aeromagnetic data, the objective function of the three-dimensional depth-weighted inversion of magnetic anomalies is: ， in, is the observation data; is the model space; is the sensitivity matrix; Fitting functionals to the data; is the model stabilizing functional, and are the weight matrices for data and model, respectively; In the actual inversion process, the data weighting function Assume it to be a constant diagonal matrix, is the depth weighting matrix, the depth weighting matrix The expression is: ， in, Representative The depth of the grid, It is a positive number related to the magnetic field decay rate and is selected as 3 in three-dimensional magnetic field inversion.

6. The method for prospecting copper polymetallic ore target area based on aeromagnetic data according to claim 5, characterized in that: When obtaining the Curie point depth of the study area, the power spectrum analysis method based on the self-similar or fractal model is used to perform depth inversion of the aeromagnetic anomaly. For the magnetic layer that extends infinitely in the horizontal direction, the radial power spectrum of the total magnetic field anomaly is expressed as: ， in, and are the radial average amplitude spectra of the total magnetic anomaly and magnetization intensity, respectively; is the wave number of the circular frequency; and They are the upper and lower interfaces of the magnetic layer respectively; is a constant factor related to the direction of magnetic field strength and the direction of the geomagnetic field.

7. The method for prospecting copper polymetallic ore target area based on aeromagnetic data according to claim 6, characterized in that: Based on the self-similar or fractal model to invert the Curie point depth, the crustal magnetization intensity shows fractal characteristics, namely: ， in, is the fractal index; According to the radial power spectrum of the total magnetic field anomaly and the fractal characteristics of the crustal magnetization intensity, the fitting formulas of the center depth and the upper interface depth are obtained: ， ， in, and are constants, is the depth of the center point of the magnetic layer; and the least squares method is used to fit the three-dimensional and ; Curie depth The calculation formula is: 。 8. The method for prospecting copper polymetallic ore target area based on aeromagnetic data according to claim 7, characterized in that: By extracting three-dimensional fracture information from the three-dimensional magnetic susceptibility structure, the planar distribution and three-dimensional extension of the structural boundary and fracture at different depths are characterized. When extracting three-dimensional fractures, the boundary position is identified and the anisotropy is calculated through the three-dimensional statistical invariant intensity parameter; among them, the covariance matrix of the three-dimensional second-order spectral moment of the three-dimensional magnetic susceptibility structure is: ， in, C is the covariance matrix, , , is the magnetic susceptibility , The partial derivative of the direction, , , ; , , , , are the six elements of the three-dimensional second-order spectral moment; is the size of the three-dimensional sliding window; Covariance matrix C Perform eigenvalue decomposition to obtain a diagonal matrix A; ， Using the elements in the diagonal matrix A Build local strength 3 M 2 , identify the boundary location.

9. The method for prospecting copper polymetallic ore target area based on aeromagnetic data according to claim 8, characterized in that: Local Strength 3 M 2 The data volume is taken as input, and the three elements of the diagonal matrix obtained by calculating the covariance matrix of the three-dimensional second-order spectral moment and the diagonal matrix A are , the three-dimensional boundary coefficient describing the fracture is: ， in 3 M 2 is the local intensity 3 M 2 The divergence of the data, -sgn( 3 M 2 ) is used to obtain 3 M 2 The inverse sign of .

Images