Magnetic anomaly modeling method for intersection point type uranium deposit

Abstract

The invention relates to the field of magnetic anomaly analysis of uranium deposits, in particular to a magnetic anomaly modeling method of an intersection point type uranium deposit, which comprises the following steps of: S1, measuring magnetic characteristic parameters of a rock core by using magnetic measurement equipment; and S2, calculating a single finite-length inclined thin plate magnetic anomaly body model, and calculating overall magnetic anomaly. Reasonable construction is carried out through hydrothermal uranium vein intersection type uranium ore magnetic anomalies, various modeling structures such as deep and front parts, rich ore and lean ore are formed, and different types of ore body earth surface magnetic anomalies are obtained based on the obtained features. Ground magnetic survey can be assisted to more accurately divide the uranium ore deposit tectonic zone, and the rich ore zone in a real region is more accurately judged in combination with a magnetic survey result and a forward modeling model.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic anomaly analysis of uranium deposits, and in particular to a magnetic anomaly modeling method for intersection-type uranium deposits. Background Art

[0002] The interpretation of magnetic anomalies in vein uranium deposits is strongly influenced by the metamorphism of igneous rocks.

[0003] At present, the magnetic anomaly forward modeling technology is very mature for rock masses with typical structural indices, but it generally still requires the input of parameters such as magnetic declination, magnetic inclination and magnetic susceptibility to solve normal magnetic anomalies. The new model requires the input of magnetic parameters of various rock samples such as diabase or gabbro veins, silicified fault zones, uranium veins, etc., including magnetic declination, magnetic inclination and magnetic susceptibility or residual magnetization and magnetic susceptibility. Therefore, more deep core data measurements are required to accurately construct the magnetic anomaly characteristics of uranium deposits.

[0004] Since geophysical interpretation has a large degree of ambiguity, when considering the actual complex geological conditions, such as the irregularity of plate bodies, the magnetic inhomogeneity of rock veins, and the complex structure of silicified fault zones and uranium veins, the simulation results can better constrain the measured results, reduce the geophysical ambiguity to a great extent, and give a reasonable geological interpretation, but cannot achieve complete data matching. Summary of the invention

[0005] The purpose of the present invention is to solve the problem that there is a lack of suitable models in the background technology to analyze the magnetic anomaly of intersection-type uranium deposits, and to propose a magnetic anomaly modeling method for intersection-type uranium deposits.

[0006] The technical solution of the present invention is a method for modeling magnetic anomaly of intersection-type uranium deposits, comprising the following steps:

[0007] S1. Use magnetic measurement equipment to measure the magnetic characteristic parameters of the core;

[0008] S2. Calculate the magnetic anomaly model of a single finite-length inclined thin plate and calculate the overall magnetic anomaly.

[0009] Preferably, it also includes S3, constructing a combination of multiple inclined structural models according to the actual situation of the intersection-type uranium deposit.

[0010] Preferably, it also includes S4, forming different types of intersection-type uranium deposit mineralization patterns based on the above-constructed model, making a good comparison with the ground magnetic survey anomaly, analyzing the demagnetization characteristics of the diabase magnetic anomaly belt, and further identifying the intersection-type uranium ore belt.

[0011] Preferably, in S1, the parameters include the volume magnetic susceptibility κ of the rock sample, the magnetic anisotropy parameters, i.e., the magnetic anisotropy characteristic values ​​K1, K2 and K3, and the mass magnetic susceptibility χ, as well as the residual magnetization intensity of the standard sample, and its corresponding magnetic declination and inclination parameters.

[0012] Preferably, the rock samples include more than four categories: surrounding rock granite, diabase, altered diabase and ore-bearing rock; the volume magnetic susceptibility κ is measured using an SM30 magnetic susceptibility meter, the magnetic anisotropy parameters are measured using a Bartington MS2 multifunctional magnetic susceptibility meter, and the residual magnetization intensity of the standard sample and its corresponding magnetic declination and inclination parameters are measured using a Minispin magnetometer.

[0013] Preferably, the local geomagnetic field strength is calculated based on the sampling point using the international geomagnetic reference field model, the induced magnetization intensity is obtained based on the magnetic susceptibility product, and the vector sum of the induced magnetization intensity and the residual magnetization intensity is further obtained to obtain the total magnetization intensity M and magnetization inclination i of the four major types of rocks. s .

[0014] Preferably, in S2, the various parameters in the single finite length inclined thin plate magnetic anomaly body model are described as follows: h is the depth of the thin plate top from the ground, 2L is the thin plate length, 2l is the thin plate depth, 2b is the thin plate thickness, the thin plate magnetization intensity is M, and the magnetization inclination angle is i s , the thin plate inclination angle is β; the calculation of the overall magnetic anomaly includes the following steps:

[0015] S21. Calculate the vertical magnetic anomaly component Za based on the magnetized parallelepiped. The specific formula is as follows:

[0016]

[0017]

[0018] S22, through Fourier transform, Z a Convert to S z :

[0019]

[0020] S23. Calculate T i The Fourier transform of S T :

[0021]

[0022] in,

[0023] qt0=2π[i(L0u+M0v)+N0(u 2 +v 2 ) 12 ]

[0024] where L0, M0, and N0 are the direction cosines of the magnetization M,

[0025] Finally, the overall magnetic anomaly T is calculated by inverse Fourier transform:

[0026]

[0027] Compared with the prior art, the present invention has the following beneficial technical effects:

[0028] 1. By constructing a three-dimensional magnetic anomaly model of intersection-type uranium deposits of hydrothermal uranium veins, we have overcome the difficulties of complex extraction of magnetic characteristics of various lithologies, unclear magnetic characteristics of rich and poor ore zones, and different mineralization depths. We have realized the construction of magnetic anomaly characteristics of intersection-type uranium deposits from magnetic exploration, and finally we can model magnetic anomaly bodies under different conditions and perform comprehensive magnetic anomaly calculation and mapping.

[0029] 2. The constructed model breaks the conventional magnetic exploration method of general single rock modeling, but is targeted based on the magnetic anomaly modeling of intersection-type uranium deposits in South China vein-type uranium deposits. It can model intersection-type uranium deposits of different depths and different mineralization levels, and calculate the magnetic anomaly state, which more realistically reflects the ground magnetic anomaly characteristics of intersection-type uranium deposits. Combined with the ground measured magnetic anomaly, it can more clearly analyze the mineralization location area of ​​uranium deposits, which has certain practical significance for the deep prospecting of uranium deposits in South China. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic diagram of a finite length plate-like body;

[0031] Figure 2 This is a magnetic anomaly structure diagram of the diabase vein (10m) plus the silicified fault zone (10m) cutting through 100m;

[0032] Figure 3 This is a magnetic anomaly structure diagram that completely cuts through the diabase vein (10m) and the silicified fault zone (4m);

[0033] Figure 4 It is a combined magnetic anomaly structure diagram of irregular diabase veins and silicified fault zones;

[0034] Figure 5 Schematic diagram highlighting the impact of remanent magnetization intensity in combination with measured magnetic parameters for integrated magnetic anomaly modeling type. DETAILED DESCRIPTION

[0035] Embodiment 1, as Figure 1 As shown, a magnetic anomaly modeling method for an intersection-type uranium deposit proposed in the present invention comprises the following steps:

[0036] S1. Use magnetic measurement equipment to measure the magnetic characteristic parameters of the core;

[0037] S2. Calculate the magnetic anomaly model of a single finite-length inclined thin plate and calculate the overall magnetic anomaly. The magnetic anomaly model of the inclined thin plate is as follows: Figure 1 shown.

[0038] Embodiment 2, the present invention proposes a method for magnetic anomaly modeling of intersection-type uranium deposits. Compared with embodiment 1, this embodiment further adds S3 and S4.

[0039] S3. According to the actual situation of intersection-type uranium deposits, a variety of inclined structural model combinations are constructed, including (i) pure diabase vein model (poor ore); (ii) diabase vein shallow cutting through silicified fault zone model (poor ore); (iii) diabase vein full cutting through silicified fault zone model (poor ore); (iv) irregular diabase vein and silicified zone intersection model (poor ore); (v) diabase vein fault zone shallow mineralization model (rich ore); (vi) diabase vein fault zone deep mineralization model (rich ore), etc.

[0040] S4. Based on the above constructed model, different types of intersection-type uranium deposit mineralization patterns are formed, which are well compared with ground magnetic survey anomalies, and the demagnetization characteristics of the diabase magnetic anomaly belt are analyzed to further identify the intersection-type uranium ore belt.

[0041] Embodiment three, as Figure 2 As shown, the present invention proposes a magnetic anomaly modeling method for intersection-type uranium deposits. Compared with the first embodiment, this embodiment introduces S1 in detail.

[0042] In S1, the parameters include the volume susceptibility κ of the rock sample, the magnetic anisotropy parameters, i.e., the magnetic anisotropy characteristic values ​​K1, K2 and K3, and the mass susceptibility χ, as well as the residual magnetization intensity of the standard sample, and its corresponding magnetic declination, magnetic inclination and other parameters. The rock samples include more than four categories: surrounding granite, diabase, altered diabase and ore-bearing rock; the volume susceptibility κ is measured using the SM30 magnetic susceptibility meter, the magnetic anisotropy parameters are measured using the Bartington MS2 multifunctional magnetic susceptibility meter, and the residual magnetization intensity of the standard sample, and its corresponding magnetic declination, magnetic inclination and other parameters are measured using the Minispin magnetometer; the local geomagnetic field intensity is calculated based on the sampling point using the international geomagnetic reference field model, the induced magnetization intensity is obtained based on the magnetic susceptibility product, and the vector sum of the induced magnetization intensity and the residual magnetization intensity is further calculated to obtain the total magnetization intensity M and the magnetic inclination i of the four major types of rocks s .

[0043] Embodiment 4, a magnetic anomaly modeling method for intersection-type uranium deposits proposed by the present invention, compared with embodiment 3, this embodiment introduces S2 in detail.

[0044] In S2, the various parameters in the single finite length inclined thin plate magnetic anomaly model are described as follows: h is the depth of the thin plate top from the ground, 2L is the thin plate length, 2l is the thin plate depth, 2b is the thin plate thickness, the thin plate magnetization intensity is M, and the magnetization inclination angle is i s , the thin plate inclination angle is β; the calculation of the overall magnetic anomaly includes the following steps:

[0045] S21. Calculate the vertical magnetic anomaly component Za based on the magnetized parallelepiped. The specific formula is as follows:

[0046]

[0047]

[0048] S22, through Fourier transform, Z a Convert to S z :

[0049]

[0050] S23. Calculate T i The Fourier transform of S T :

[0051]

[0052] in,

[0053] qt0=2π[i(L0u+M0v)+N0(u 2 +v 2 ) 12 ]

[0054] where L0, M0, and N0 are the direction cosines of the magnetization M,

[0055] Finally, the overall magnetic anomaly T is calculated by inverse Fourier transform:

[0056]

[0057] After using the present invention:

[0058] Figure 2 The magnetic anomaly result map shows that a silicified fault zone is cut vertically in the middle of the NWW-SEE diabase vein, with a cutting depth of 100 meters from the surface to the underground. The direction of the diabase vein can be clearly identified. In addition, there is an obvious low magnetic anomaly value at the cutting position of the silicified fault zone, which is the demagnetization phenomenon of the intersection-type uranium vein. It is worth noting that although the cutting depth of the silicified zone fault zone is 100m, the characteristics of the deep diabase vein can still be identified through the high-low-high magnetic anomaly change trend.

[0059] Figure 3 The results show that a silicified fault zone was cut vertically in the middle of the NWW-SEE-trending diabase vein, and the cutting depth was completely cut through, and the magnetic anomaly result map of the hydrothermal uranium vein with a depth of 100m was shown. The results show that the direction of the diabase vein can be clearly identified, but obvious demagnetization can be observed at the cutting position of the silicified fault zone. Because the magnetic parameters of the uranium vein are relatively close to those of the silicified zone, there is no high-low-high demagnetization enhancement phenomenon. However, when the uranium deposit appears on the surface of the fault tectonic zone or outcrops, the magnitude of this demagnetization will be significantly reduced.

[0060] Figure 4 The combination of irregular diabase and silicified fault zones constructed based on this method is shown. Figure 2 Similarly, a magnetic anomaly structure similar to the actual geological situation is formed. Figure 4 It can be seen that despite the influence of the irregular shape of the diabase vein, the deep structure of the diabase vein and the silicified fault zone can still be judged from the change trend of the demagnetization area for the intersection-type deposit structure.

[0061] Therefore, further combining with ground magnetic survey, analyzing the magnetic anomaly characteristics of the diabase tectonic area based on the ground magnetic survey anomaly map, and analyzing the special magnetic anomaly characteristics of the diabase demagnetization area, and closely combining with the inventive method, can help to effectively delineate the rich ore areas of the intersection-type uranium deposits.

[0062] Specific application example: Diabase veins with a certain width are widely distributed in South China, showing a near east-west distribution, mainly in the NWW-SEE direction, and silicified fault zones are distributed nearly vertically along the diabase veins. Uranium veins are mostly produced in a certain depth area where the diabase veins and silicified fault zones intersect. Here it is assumed that the apparent thickness of the diabase vein is 10m and the dip angle is 60°; the silicified fault zone cuts through the diabase vein vertically with a width of 4-10m; the uranium vein is set in two states, one is an outcrop deposit and the other is a deposit with a depth of 100m. The magnetic parameters of all rock bodies are given by the measured values ​​of local cores. Then, several intersection deposit types such as rich ore, poor ore, outcrop ore and deep mineralization are built, and the magnetic anomaly results of intersection-type uranium deposits are calculated according to the model parameters.

[0063] Other applications:

[0064] The data processing algorithm of the present invention is not limited to the abnormal modeling of deep prospecting of intersection-type uranium veins. Under certain circumstances, other types of uranium belts in South China can be modeled. For example, the silicified belt type uranium deposit is also one of the typical uranium mineralization types in Xiazhuang area of ​​South China. In the silicified belt mineralization in the granite area, the enrichment of uranium elements appears between the silicified belt and the granite surrounding rock. This hydrothermal reduction mineralization also has corresponding expressions in the iron oxide conversion. The magnetite formed by reduction is also reflected in the magnetic anomaly. The magnetic parameters of the vein can be measured, and then the silicified belt model provided by the present invention can be used for modeling and analysis.

[0065] On this basis, the data processing algorithm of the present invention is not limited to the anomaly modeling of deep uranium deposit prospecting. Under certain circumstances, magnetic anomaly modeling can be performed on other non-ferrous metal minerals and their occurrence in fault zones or structural zones and other types of rock bodies ( Figure 5 ). Generally, the non-ferrous metal mineral occurrence fault zone or structural zone can be modeled using a model of rock plate cutting through the surrounding rock, based on the rock magnetic results of the ore-bearing samples and the surrounding rock obtained by high-precision magnetic parameters. By using the structural model of the deep or front part, rich ore or poor ore provided by the present invention, the ground magnetic survey characteristics are forward analyzed. It is possible to effectively identify the possible rich ore areas based on the measured magnetic survey results.

[0066] In summary, the present invention overcomes the problems of complex extraction of magnetic characteristics of various lithologies, unclear magnetic characteristics of rich and poor ore zones, and different mineralization depths by constructing a three-dimensional magnetic anomaly modeling model of intersection-type uranium deposits of hydrothermal uranium veins, and realizes the construction of magnetic anomaly characteristics of intersection-type uranium deposits from magnetic exploration, and finally can model magnetic anomaly bodies under different conditions, and perform comprehensive magnetic anomaly calculation and mapping. The constructed model breaks the conventional magnetic exploration method for general single rock modeling, but is targeted based on the magnetic anomaly modeling of intersection-type uranium deposits of vein-type uranium deposits in South China, and can model intersection-type uranium deposits of different depths and different mineralization degrees, and calculate the magnetic anomaly state, which more truly reflects the ground magnetic anomaly characteristics of intersection-type uranium deposits. Combined with the ground measured magnetic anomaly, the mineralization location area of ​​uranium deposits can be analyzed more clearly, which has certain practical significance for the deep prospecting of uranium deposits in South China.

[0067] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto, and various changes can be made within the knowledge scope of technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A magnetic anomaly modeling method for intersection-type uranium deposits, characterized in that: The following steps are involved: S1. Use magnetic measurement equipment to measure the magnetic characteristic parameters of the core; S2. Calculate the magnetic anomaly model of a single finite-length inclined thin plate and calculate the overall magnetic anomaly.

2. The magnetic anomaly modeling method for intersection-type uranium deposits according to claim 1, characterized in that: It also includes S3, which constructs a combination of various inclined structural models based on the actual conditions of intersection-type uranium deposits.

3. The magnetic anomaly modeling method for intersection-type uranium deposits according to claim 1, characterized in that: It also includes S4, which forms different types of intersection-type uranium deposit mineralization patterns based on the above-mentioned model, compares well with ground magnetic survey anomalies, analyzes the demagnetization characteristics of the diabase magnetic anomaly belt, and further identifies the intersection-type uranium ore belt.

4. The magnetic anomaly modeling method for intersection-type uranium deposits according to claim 1, characterized in that: In S1, the parameters include the volume magnetic susceptibility κ of the rock sample, the magnetic anisotropy parameters, namely the magnetic anisotropy characteristic values ​​K1, K2 and K3, and the mass magnetic susceptibility χ, as well as the residual magnetization intensity of the standard sample, and its corresponding magnetic declination and inclination parameters.

5. The magnetic anomaly modeling method for intersection-type uranium deposits according to claim 4, characterized in that: The rock samples include more than four categories: surrounding rock granite, diabase, altered diabase and ore-bearing rock; the volume magnetic susceptibility κ is measured using an SM30 magnetic susceptibility meter, the magnetic anisotropy parameters are measured using a Bartington MS2 multi-functional magnetic susceptibility meter, and the Minispin magnetometer is used to measure the residual magnetization intensity of the standard sample and its corresponding magnetic declination and inclination parameters.

6. The magnetic anomaly modeling method for intersection-type uranium deposits according to claim 4, characterized in that: Based on the sampling points, the local geomagnetic field strength is calculated using the international geomagnetic reference field model, and the induced magnetization intensity is obtained based on the magnetic susceptibility product. The vector sum of the induced magnetization intensity and the residual magnetization intensity is further calculated to obtain the total magnetization intensity M and magnetization inclination i of the four major types of rocks. s .

7. The magnetic anomaly modeling method for intersection-type uranium deposits according to claim 6, characterized in that: In S2, the various parameters in the single finite length inclined thin plate magnetic anomaly model are described as follows: h is the depth of the thin plate top from the ground, 2L is the thin plate length, 2l is the thin plate depth, 2b is the thin plate thickness, the thin plate magnetization intensity is M, and the magnetization inclination angle is i s , the thin plate inclination angle is β; the calculation of the overall magnetic anomaly includes the following steps: S21. Calculate the vertical magnetic anomaly component Za based on the magnetized parallelepiped. The specific formula is as follows: S22, through Fourier transform, Z a Convert to S z : S23. Calculate T i The Fourier transform of S T : in, Among them, L0, M0, and N0 are the direction cosines of the magnetization intensity M. Finally, the overall magnetic anomaly T is calculated by inverse Fourier transform:

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