A method for finding tungsten ore under iron

Abstract

This invention relates to the field of geophysical exploration technology for mineral resources, and particularly to a method for finding tungsten deposits beneath iron ore. The method involves collecting Bouguer gravity anomaly data of the study area, identifying low-density anomalies, the distribution range of concealed granite bodies, and the protruding parts at the top of the rock masses through three-dimensional density inversion; conducting high-precision magnetic surveys within this range and performing polarization processing on the data; and delineating favorable magnetic target areas and high / weak magnetic transition zones according to the principle of finding non-magnetic areas with weak magnetic fields in the iron-under-iron tungsten mineralization model. Then, within the favorable magnetic target areas, resistivity inversion is performed on audio-frequency magnetotelluric sounding data to identify deep high-resistivity bodies and mid-level low-resistivity zones, generating scheelite enrichment layers and ore-controlling depths; finally, three-dimensional spatial overlay is performed to generate priority drilling locations, and the locations are corrected and interpreted using core logging data and laboratory analysis results. This invention effectively improves the targeting of concealed scheelite borehole location determination and increases the efficiency of scheelite prospecting.

Description

Technical Field

[0001] This invention relates to the field of geophysical exploration technology for mineral resources, and in particular to a method for finding tungsten deposits in iron ore deposits, which is used for locating target areas and determining drilling locations for concealed scheelite deposits. Background Technology

[0002] In the field of geophysical exploration technology for mineral resources, existing schemes for exploring concealed scheelite deposits typically rely on a comprehensive interpretation of geological mapping, geochemical anomalies, and exploration engineering data. In conventional scenarios, these schemes are usually used to delineate prospecting target areas or metallogenic prospective areas. However, within sedimentary caprock-concealed granite structural zones, surface mineralization clues are discontinuous, and the spatial correspondences between concealed rock masses, magnetic anomalies, and electrical anomalies are complex. This can easily lead to limitations such as inconsistent anomaly interpretation objects, unclear target area boundaries, and insufficient borehole depth constraints.

[0003] Existing methods often rely on granite contact zones, fracture structures, alteration assemblages, or single physical anomalies for analysis. In magnetic exploration, the principle of "finding non-magnetic areas with weak magnetic fields" refers to a prospecting approach where, when the target ore body itself is non-magnetic or has extremely weak magnetic properties, the spatial location of the target ore body is indirectly indicated by identifying magnetic anomalies generated by magnetic markers that have a fixed symbiotic or coupled relationship with it in space. When there is a spatial coupling relationship between an upper ferruginous layer and an underlying scheelite ore body, magnetic anomalies are usually interpreted as the magnetic body itself. The lack of stable connections between low-density anomalies formed by gravity interpretation, high-magnetic anomaly zones formed by magnetic interpretation, and low-resistivity anomaly zones formed by electromagnetic interpretation can easily lead to unclear correspondences between different geophysical interpretations in terms of spatial location and depth.

[0004] For the joint processing of Bouguer gravity anomaly data, magnetic survey data, and audio-frequency magnetotelluric sounding data, existing technologies still suffer from insufficient coordination between geophysical anomaly layering interpretation, three-dimensional spatial overlay, and borehole location generation. Therefore, it is necessary to address the issue of how to generate priority borehole locations through a continuous geophysical interpretation chain, focusing on low-density anomalies, magnetic anomaly zones, and resistivity anomaly zones in concealed scheelite exploration areas. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a method for prospecting for tungsten deposits under iron ore, comprising: S100: Receive Bouguer gravity anomaly data of the study area, perform three-dimensional density inversion and low-density anomaly identification, and generate the low-density anomaly boundary, the distribution range of the concealed granite body and the protruding part of the top of the rock body. S200. Receive high-precision magnetic survey data within the distribution range of the concealed granite body, perform polarization processing, and interpret the high magnetic anomaly area as the upper iron layer and the underlying scheelite body according to the spatial coupling relationship between the upper iron layer and the underlying scheelite body in the iron-under-tungsten mineralization model. Mark the relatively weak magnetic anomaly zone located below the high magnetic anomaly area as the underlying scheelite occurrence indicator zone, thereby generating a favorable magnetic target area and a high magnetic / weak magnetic transition zone. S300: Receive audio magnetotelluric sounding data in the magnetic method favorable target area, perform resistivity inversion, identify the deep high resistivity body corresponding to the top protrusion of the rock mass and the middle low resistivity zone corresponding to the interlayer fracture zone, and generate scheelite enrichment layer and ore-controlling depth. S400. Perform spatial overlay analysis of the low-density anomaly boundary, the high magnetic / weak magnetic transition zone and the central low resistivity zone in a three-dimensional coordinate system, and filter the spatial units located above the top protrusion of the rock mass in the intersection area of ​​the three to generate priority drilling positions. S500. Based on the core logging data and analysis results received from the priority drilling sites, the interpretation positions of the low-density anomaly boundary, the high magnetic / weak magnetic transition zone, and the central low-resistivity zone are corrected.

[0006] Furthermore, the Bouguer gravity anomaly data is obtained from gravity observation data through terrain correction, intermediate layer correction, and Bouguer correction; before the three-dimensional density inversion, the Bouguer gravity anomaly data is subjected to upward extension, horizontal derivative processing, and vertical derivative processing to generate local gravity anomalies for identifying the low-density anomaly body.

[0007] Furthermore, the protruding part at the top of the rock mass is identified based on the top surface burial depth, top undulation amplitude, closed boundary, and contact relationship with the sedimentary cover layer of the low-density anomaly; the protruding part at the top of the rock mass serves as a pore location screening constraint in the spatial overlay analysis.

[0008] Furthermore, the high-precision magnetic measurement data includes geomagnetic gradient data and diurnal variation observation data; the polarization processing includes performing diurnal variation correction, normal field correction and polarization parameter conversion on the geomagnetic gradient data to generate polarization magnetic anomalies.

[0009] Furthermore, the highly magnetic anomaly zone and the relatively weak magnetic anomaly zone are delineated based on the polarization magnetic anomaly; the highly magnetic anomaly zone is interpreted as a magnetite-rich layer or a pyrrhotite-rich layer; the relatively weak magnetic anomaly zone is located below the highly magnetic anomaly zone and has a spatial correspondence with the protruding part at the top of the rock mass.

[0010] Furthermore, an audio-frequency magnetotelluric sounding profile is deployed along the vertical strike of the ore body within the favorable target area of ​​the magnetic method to collect natural field signals in the 0.01-10000Hz frequency band; the natural field signals are denoised, statically corrected, and impedance estimated to generate impedance data; the impedance data are then subjected to two-dimensional or three-dimensional resistivity inversion to generate a resistivity structure model.

[0011] Furthermore, the deep high-resistivity body and the middle low-resistivity zone are identified based on the resistivity structure model; the deep high-resistivity body corresponds to the projection range of the top protrusion of the rock mass on the audio-frequency magnetotelluric sounding profile; the middle low-resistivity zone is located above the deep high-resistivity body, and the ore-controlling depth is generated based on the top and bottom plate depths of the middle low-resistivity zone.

[0012] Furthermore, the spatial overlay analysis includes: unifying the boundary of the low-density anomaly, the protruding part at the top of the rock mass, the high magnetic / weak magnetic transition zone, and the low resistivity zone in the middle to the same three-dimensional coordinate system, generating the intersection region of the three through grid overlay or isosurface intersection, and forming a candidate set of borehole locations according to the spatial distance between the intersection region of the three and the protruding part at the top of the rock mass.

[0013] Furthermore, the preferred drilling location includes borehole coordinates, borehole direction, dip angle, designed borehole depth, and target stratum to be traversed; the designed borehole depth is set to penetrate the scheelite-rich stratum and enter the top surface of the concealed granite body.

[0014] Furthermore, when the spatial overlay analysis does not generate the intersection region of the three, a record without intersection of the three is generated; based on the pairwise overlapping anomalous regions in the low-density anomaly boundary, the high magnetic / weak magnetic transition zone, and the central low-resistivity zone, a candidate aperture downgrade record is generated.

[0015] The key innovations of this invention include: (1) Within the distribution range of the concealed granite body, the high-precision magnetic survey data is processed by polarization, and according to the spatial coupling relationship between the upper iron layer and the underlying scheelite in the iron-under-tungsten mineralization model, the high magnetic anomaly area is interpreted as the upper iron layer, and the relatively weak magnetic anomaly zone below it is marked as the underlying scheelite occurrence indicator zone, thus generating a favorable target area for magnetic methods and a high magnetic / weak magnetic transition zone.

[0016] (2) Using the low-density anomaly boundary formed by Bouguer gravity anomaly data, the distribution range of concealed granite bodies and the protruding part at the top of the rock body as the preceding spatial constraints, audio magnetotelluric sounding data are received in the favorable target area of ​​the magnetic method and resistivity inversion is performed to identify the deep high resistivity body and the middle low resistivity zone, and generate the scheelite enrichment layer and ore-controlling depth.

[0017] (3) The boundary of the low-density anomaly, the high magnetic / weak magnetic transition zone and the middle low resistivity zone are unified into a three-dimensional coordinate system for spatial superposition analysis. Spatial units located above the top protrusion of the rock mass in the intersection area of ​​the three are selected to generate priority drilling positions. The relevant interpretation positions are corrected based on the core logging data and test analysis results.

[0018] The following are its main beneficial effects: (1) To address the issue that existing magnetic anomalies are typically interpreted only as magnetic bodies themselves, this paper proposes a layered interpretation of high magnetic anomaly zones and relatively weak magnetic anomaly zones under the constraint of the iron-based tungsten mineralization model. This allows the magnetic interpretation results to form a spatial correspondence record between the upper iron layer and the underlying scheelite occurrence indicator zone, providing a clear geophysical object for subsequent magnetic target area delineation. This layered interpretation rule is essentially a specific technical implementation of the principle of "finding non-magnetic ore bodies with weak magnetic fields," expanding the magnetic exploration technology, which is traditionally used only to find magnetic ore bodies, to a new functional dimension of indirectly indicating non-magnetic scheelite ore bodies.

[0019] (2) To address the problem of insufficient connection between the interpretation results of gravity, magnetic and electromagnetic methods, the magnetic interpretation range is limited by the boundary of the low-density anomaly and the protruding part at the top of the rock mass, and the audio-frequency magnetotelluric sounding range is limited by the favorable target area of ​​the magnetic method, so that different geophysical results are continuously transmitted according to spatial range and depth layer, forming an interpretation chain from the concealed granite body to the scheelite enrichment layer.

[0020] (3) To address the problem of unclear target area boundaries and borehole depth constraints, the boundary of low-density anomalies, the high magnetic / weak magnetic transition zone and the middle low resistivity zone are spatially superimposed in a three-dimensional coordinate system, and the top protrusion of the rock mass is introduced as a borehole selection constraint, so that the priority drilling locations simultaneously include rock mass background, magnetic anomaly stratification indicators and resistivity stratification information; the interpretation location is corrected by core logging data and chemical analysis results, so that subsequent geophysical interpretation retains drilling verification records.

[0021] (4) Under the combined effect of the above-mentioned continuous geophysical interpretation link and the quantitative hole generation method of three-dimensional spatial superposition analysis, the hit rate of priority drilling holes is effectively improved, thereby significantly improving the exploration efficiency of scheelite. Attached Figure Description

[0022] Figure 1 A flowchart illustrating a method for prospecting for tungsten deposits under iron ore, provided as an embodiment of this application; Figure 2 This is a structural block diagram of a method for finding tungsten deposits under iron ore, provided as an embodiment of this application. Detailed Implementation

[0023] Example 1: Refer to Figure 1This is a flowchart illustrating a method for prospecting for tungsten ore beneath iron ore, provided by an embodiment of the present invention. The process may include at least steps S100-S500: S100: Receive Bouguer gravity anomaly data of the study area, perform three-dimensional density inversion and low-density anomaly identification, and generate the low-density anomaly boundary, the distribution range of the concealed granite body and the protruding part of the top of the rock body. S200. Receive high-precision magnetic survey data within the distribution range of the concealed granite body, perform polarization processing, and interpret the high magnetic anomaly area as the upper iron layer and the underlying scheelite body according to the spatial coupling relationship between the upper iron layer and the underlying scheelite body in the iron-under-tungsten mineralization model. Mark the relatively weak magnetic anomaly zone located below the high magnetic anomaly area as the underlying scheelite occurrence indicator zone, thereby generating a favorable magnetic target area and a high magnetic / weak magnetic transition zone. S300: Receive audio magnetotelluric sounding data in the magnetic method favorable target area, perform resistivity inversion, identify the deep high resistivity body corresponding to the top protrusion of the rock mass and the middle low resistivity zone corresponding to the interlayer fracture zone, and generate scheelite enrichment layer and ore-controlling depth. S400. Perform spatial overlay analysis of the low-density anomaly boundary, the high magnetic / weak magnetic transition zone and the central low resistivity zone in a three-dimensional coordinate system, and filter the spatial units located above the top protrusion of the rock mass in the intersection area of ​​the three to generate priority drilling positions. S500. Based on the core logging data and analysis results received from the priority drilling sites, the interpretation positions of the low-density anomaly boundary, the high magnetic / weak magnetic transition zone, and the central low-resistivity zone are corrected.

[0024] S100: Receive Bouguer gravity anomaly data of the study area, perform three-dimensional density inversion and low-density anomaly identification, and generate the low-density anomaly boundary, the distribution range of concealed granite bodies, and the protruding parts at the top of the rock mass.

[0025] In this embodiment, S100 is executed by the gravity inversion module. The gravity inversion module receives gravity observation data, gravity measurement point coordinates, elevation data, and topographic data for the study area, and receives Bouguer gravity anomaly data formed from the gravity observation data through topographic correction, intermediate layer correction, and Bouguer correction. The gravity measurement point coordinates include the plane coordinates and elevation fields of each gravity measurement point, and the Bouguer gravity anomaly data includes the measurement point number, gravity anomaly value, correction type identifier, and data quality status. After receiving the complete measurement point record, the gravity inversion module spatially registers the Bouguer gravity anomaly data with the gravity measurement point coordinates, so that each gravity anomaly value corresponds to a fixed spatial location within the study area.

[0026] Specifically, the terrain correction is used to correct for differences in gravity observations caused by topographic undulations around the measuring point; the intermediate layer correction is used to correct for the influence of rock layer quality between the measuring point and the reference surface; and the Bouguer correction is used to form Bouguer gravity anomaly data under a unified reference. After completing the above corrections, the gravity inversion module performs upward extrapolation, horizontal derivative processing, and vertical derivative processing on the Bouguer gravity anomaly data to generate local gravity anomalies for identifying the low-density anomaly body. Upward extrapolation is used to separate regional gravity anomalies from local gravity anomalies, horizontal derivative processing is used to extract the lateral boundaries of the anomaly body, and vertical derivative processing is used to highlight anomaly changes in the shallow to mid-depth region. The local gravity anomalies formed by the above processing, together with the original Bouguer gravity anomalies, serve as input for three-dimensional density inversion.

[0027] In one implementation, the three-dimensional density inversion uses a three-dimensional grid of the study area as the computational unit, assigning density parameters and spatial coordinates to each grid unit. The gravity inversion module constructs a subsurface density structure model based on the local gravity anomaly, gravity measurement point coordinates, and initial density parameters, and iteratively solves the density of the grid units during the inversion process to obtain the density distribution at different depths within the study area. The low-density anomaly refers to an anomaly in the subsurface density structure model whose density value is lower than the background density of the surrounding rock and exhibits a continuous spatial distribution. The boundary of the low-density anomaly is jointly represented by the outer envelope surface, top surface burial depth, and bottom boundary burial depth of the low-density grid unit. The distribution range of the concealed granite body is jointly interpreted by the boundary of the low-density anomaly and the stratigraphic, structural, and lithological information in the existing geological mapping data of the study area.

[0028] The protruding parts at the top of the rock mass are identified based on the top surface burial depth, top undulation amplitude, closed boundary, and contact relationship with the sedimentary cover layer of the low-density anomaly. Specifically, the gravity inversion module extracts multiple top surface burial depth points along the top surface of the low-density anomaly, marking areas with shallower top surface burial depths relative to the surrounding top surfaces and forming closed or semi-closed shapes on the plane as protruding parts at the top of the rock mass. When there is a contact relationship between the protruding parts at the top of the rock mass and the sedimentary cover layer, this part is recorded as a mineralization-favorable rock mass target. The protruding parts at the top of the rock mass serve as pore location screening constraints in subsequent spatial overlay analysis and participate in the screening of three-dimensional intersection regions together with the subsequent high magnetic / weak magnetic transition zone and the central low resistivity zone.

[0029] S100 is initiated after the regional gravity exploration data is entered into the database in the study area. In one implementation, the regional gravity exploration uses a scale of 1:50,000 or 1:25,000 to set up measurement points, with a spacing of 200-500m between the gravity measurement points. In another implementation, the spacing between measurement points is adjusted according to the area and topographic relief of the study area, and the adjusted spacing is recorded in the acquisition configuration field of the gravity measurement point coordinates. When the Bouguer gravity anomaly data has missing measurement points, duplicate coordinates, or missing outliers, the gravity inversion module writes the corresponding measurement points into the data quality status field and retains the original observation records. When the missing measurement point is located near the boundary of a low-density anomaly, the gravity inversion module generates a re-sampling record and retains the boundary of the previous low-density anomaly before backfilling the re-sampling record. The low-density anomaly boundary, the distribution range of the concealed granite body, and the protruding part at the top of the rock mass formed by S100 are encapsulated as a gravity interpretation result record. The gravity interpretation result record includes the anomaly number, boundary coordinates, top surface burial depth, coordinates of the protruding part at the top of the rock mass, and interpretation version number. The distribution range of the concealed granite body serves as the spatial range for S200 to receive high-precision magnetic survey data, and the protruding part at the top of the rock mass serves as the spatial counterpart of S300 and S400.

[0030] S200. Receive high-precision magnetic survey data within the distribution range of the concealed granite body, perform polarization processing, and interpret the high magnetic anomaly zone as the upper iron layer and the underlying scheelite body according to the spatial coupling relationship between the upper iron layer and the underlying scheelite body in the iron-under-tungsten mineralization model. Mark the relatively weak magnetic anomaly zone located below the high magnetic anomaly zone as the underlying scheelite occurrence indicator zone, thereby generating a favorable magnetic target area and a high magnetic / weak magnetic transition zone.

[0031] In this embodiment, S200 is executed by the magnetic anomaly interpretation module. This module receives the distribution range of the concealed granite body, the boundary of the low-density anomaly, and the protruding parts at the top of the rock mass generated in S100, and receives high-precision magnetic survey data within the distribution range of the concealed granite body. The high-precision magnetic survey data includes geomagnetic gradient data and diurnal variation observation data. The geomagnetic gradient data includes the magnetic survey point number, survey line number, magnetic field observation value, survey point coordinates, and measurement time. The diurnal variation observation data includes the diurnal variation reference station number, diurnal variation time series, and diurnal variation correction value. The magnetic anomaly interpretation module spatially matches the magnetic survey point coordinates with the distribution range of the concealed granite body formed in S100. Magnetic survey point records located outside the distribution range of the concealed granite body are not included in the magnetic method's favorable target area delineation calculation and are retained as external control records.

[0032] Specifically, the magnetic anomaly interpretation module first applies diurnal variation correction and normal field correction to the geomagnetic gradient data to generate corrected magnetic anomaly data. The diurnal variation correction subtracts geomagnetic variations within the same measurement time period from the diurnal variation observation data, while the normal field correction subtracts the regional background magnetic field from the geomagnetic normal field parameters of the study area. After completing the above corrections, the magnetic anomaly interpretation module performs polarization processing on the corrected magnetic anomaly data according to polarization parameters to generate polarized magnetic anomalies. These polarization parameters include the geomagnetic dip and geomagnetic declination of the study area. The polarized magnetic anomalies are used to align the magnetic anomaly center with the spatial location of the magnetic body; subsequent high-magnetic-anomaly areas and relatively weak-magnetic-anomaly zones are delineated based on these polarized magnetic anomalies.

[0033] In this embodiment, the iron-based tungsten mineralization model refers to a mineralization interpretation model in which there is a spatial coupling relationship between the upper iron layer and the underlying scheelite ore body. In this model, the high magnetic anomaly zone is not interpreted as the magnetic response of the scheelite mineral itself, but as the geophysical response of the upper iron layer.

[0034] In this invention, the iron-based tungsten mineralization model is specifically embodied in the prospecting approach of "finding non-magnetic deposits using weak magnetic fields": the upper iron layer with obvious magnetism is used as a magnetic marker layer, and the anomalous zone below it, whose magnetic anomaly is relatively weak but whose spatial location corresponds to the protruding part at the top of the rock mass, is used as an indirect indicator of the occurrence of non-magnetic scheelite ore bodies. Through the quantitative identification of the above-mentioned spatial coupling relationship, the goal of indirectly finding scheelite ore using magnetic data is achieved.

[0035] Specifically, the magnetic anomaly interpretation module delineates a high magnetic anomaly zone based on the polarization magnetic anomaly and interprets it as a magnetite-rich layer or a pyrrhotite-rich layer. Subsequently, it searches for anomaly zones below the high magnetic anomaly zone whose magnetic anomaly values ​​are relatively lower and spatially correspond to the protruding parts at the top of the rock mass, marking these as relatively weak magnetic anomaly zones. These relatively weak magnetic anomaly zones serve as indicators of underlying scheelite occurrence and, together with the high magnetic anomaly zone, form a high / weak magnetic transition zone.

[0036] In one implementation, the favorable magnetic target area is jointly defined by the high magnetic anomaly area, the relatively weak magnetic anomaly zone, the high / weak magnetic transition zone, and the protruding portion at the top of the rock mass output by S100. The magnetic anomaly interpretation module extracts the boundaries of the high magnetic anomaly area and the relatively weak magnetic anomaly zone in the plane and records the vertical positional relationship between the high magnetic anomaly area and the relatively weak magnetic anomaly zone in the profile direction. When the relatively weak magnetic anomaly zone is spatially located below the high magnetic anomaly area and its projection range overlaps with the protruding portion at the top of the rock mass, the magnetic anomaly interpretation module writes this area into the favorable magnetic target area record. When the high magnetic anomaly area exists but the relatively weak magnetic anomaly zone is discontinuous, the magnetic anomaly interpretation module generates a discontinuous weak magnetic tape record and writes this area into the candidate verification record, which is not used as the main deployment range for subsequent audio-frequency magnetotelluric sounding profiles.

[0037] S200 is initiated after the distribution range of the concealed granite body output by S100 is interpreted and verified. In one embodiment, a 1:10000 scale high-precision geomagnetic gradient measurement is carried out within the distribution range of the concealed granite body, with a magnetic measurement point spacing of 50-100m and a measurement line spacing of 200-500m. In another embodiment, the measurement lines are densified according to the planar distribution direction of the protruding part at the top of the rock mass, and the densified measurement line number is written into the measurement line field of the high-precision magnetic measurement data. When the high-precision magnetic measurement data has missing diurnal variation observations, measurement point coordinates exceeding the distribution range of the concealed granite body, or missing polarization parameters, the magnetic anomaly interpretation module writes the corresponding record into the magnetic data quality status field. When polarization parameters are missing, the magnetic anomaly interpretation module retains the magnetic anomaly data after diurnal variation correction and normal field correction, and generates a polarization parameter supplementary record.

[0038] The magnetic target area record output by S200 includes the magnetic target area number, the boundary of the high magnetic anomaly zone, the boundary of the relatively weak magnetic anomaly zone, the boundary of the high magnetic / weak magnetic transition zone, the corresponding rock mass top protrusion number, and the magnetic interpretation version number. The magnetic target area serves as the deployment range for the audio-frequency magnetotelluric sounding profile in S300; the high magnetic / weak magnetic transition zone serves as the input object for spatial overlay analysis in the three-dimensional coordinate system in S400; the spatial correspondence between the relatively weak magnetic anomaly zone and the rock mass top protrusion is used in subsequent borehole location selection.

[0039] This step concretizes the principle of "finding non-magnetic ore by weak magnetic field" into a hierarchical interpretation rule of high magnetic anomaly area and relatively weak magnetic anomaly zone. That is, the upper iron layer is used as a magnetic marker, and the non-magnetic scheelite body is indirectly located by identifying the relatively weak magnetic anomaly zone below it.

[0040] In one specific embodiment: S200 is executed by the magnetic anomaly interpretation module; the magnetic anomaly interpretation module receives the distribution range of the concealed granite body, the boundary of the low-density anomaly body, and the protruding part at the top of the rock body generated by S100, and receives high-precision magnetic measurement data within the distribution range of the concealed granite body.

[0041] The high-precision magnetic measurement data includes geomagnetic gradient data and diurnal variation observation data; the geomagnetic gradient data includes magnetic measurement point number, survey line number, magnetic field observation value, measurement point coordinates and measurement time; the diurnal variation observation data includes diurnal variation reference station number, diurnal variation time series and diurnal variation correction value.

[0042] The magnetic anomaly interpretation module first spatially matches the planar coordinates of each magnetic measuring point with the distribution range of the concealed granite body output by S100. Only when the coordinates of the magnetic measuring point fall within the planar projection boundary of the distribution range of the concealed granite body will all the recorded fields of the magnetic measuring point be included in the subsequent magnetic method favorable target area delineation calculation link. Magnetic measuring point records that fall outside the distribution range of the concealed granite body do not participate in the target area delineation. Their original observation data, survey line number, and coordinate fields are separately encapsulated as external comparison records, which are used to compare the spatial distribution characteristics of external magnetic interference bodies during subsequent interpretation and verification.

[0043] After spatial matching is completed, the magnetic anomaly interpretation module extracts magnetic field observations from the geomagnetic gradient data for each valid measuring point within the distribution range of the concealed granite body, using its magnetic measuring point number as the primary key. Simultaneously, based on the measurement time field of the measuring point, the diurnal variation correction value at the same moment is retrieved from the diurnal variation observation data. The geomagnetic normal field value corresponding to the coordinates of the measuring point was read from the geomagnetic normal field parameters of the study area. .

[0044] Based on this, to eliminate the influence of time-domain geomagnetic variations on the observation data and to remove the regional background magnetic field, the magnetic anomaly interpretation module performs diurnal variation correction and normal field correction for each valid measuring point. Its processing logic is as follows: taking the same measuring line direction as the order, it calculates the difference between the observed magnetic field value and the diurnal variation correction value and the normal field value for each measuring point, generating corrected magnetic anomaly data. .

[0045] The practical problem addressed in this step is that the geomagnetic gradient data contains time-varying external magnetic field disturbances (diurnal variations) and regional gradients caused by the background geomagnetic field of the study area. If these are not removed, the subsequent delineation of highly magnetic anomaly areas and relatively weak magnetic anomaly zones will lose spatial resolution due to the superposition of diurnal noise and the background field, resulting in blurred boundaries of highly magnetic anomaly areas and the spatial correspondence between relatively weak magnetic anomaly zones and the protruding parts at the top of the rock mass being obscured by the background field gradient. Formula ① describes the above correction calculation:

[0046] in, The corrected magnetic anomaly data represents the residual magnetic anomaly caused by the magnetic inhomogeneity of the underground medium after removing diurnal disturbances and the background of the normal geomagnetic field. It is the output conclusion value of formula ①. : Survey line number index, with a value of positive integer, derived from the survey line number field in the geomagnetic gradient data, identifying the sequence number of the survey line in the high-precision magnetic survey data; : Measurement point number index, with a value of positive integer, derived from the magnetic measurement point number field in the geomagnetic gradient data, identifying the sequence number of measurement points within the same measurement line; : No. The first survey line The magnetic field observation values ​​at each measuring point are directly extracted from the magnetic field observation value field in the geomagnetic gradient data, representing the raw readings of the total magnetic field strength at that measuring point. :and The diurnal variation correction value at the same measurement time is obtained by interpolating the diurnal variation correction value field in the diurnal variation observation data according to the measurement time, and is used to subtract the external disturbance component of the geomagnetic field at that time. : No. The first survey line The geomagnetic normal field value at each measuring point is read from the geomagnetic normal field parameter table of the study area based on the plane coordinates of that measuring point, and is used to subtract the theoretical values ​​of the Earth's core main magnetic field and the regional background magnetic field at that location.

[0047] Formula ① As the first intermediate output inside S200, it will be directly called by the polarization process in Formula ②.

[0048] The magnetic anomaly interpretation module obtains corrected magnetic anomaly data from all valid measuring points in the entire measurement area. Subsequently, a polarization process was initiated, the goal of which is to eliminate the asymmetric distortion caused by the tilting magnetization of the geomagnetic field on the magnetic anomaly morphology, so that the magnetic anomaly center is aligned with the actual spatial position of the underground magnetic body.

[0049] To achieve this goal, the magnetic anomaly interpretation module uses the two-dimensional spatial frequency domain as its computational domain. A fast Fourier transform is performed to transform the magnetic anomaly from the spatial domain to the wavenumber domain. In the wavenumber domain, the anomaly is multiplied by a polarization transfer function constructed from the geomagnetic dip and declination of the study area. Then, an inverse Fourier transform is performed to return the anomaly to the spatial domain, generating the polarization magnetic anomaly. .

[0050] The polarization transfer function The magnetic anomaly interpretation module interprets the magnetic dip angle of the study area. and magnetic declination The calculated amplitude and phase modulation factors, in the wavenumber domain, are used to compensate for the offset effect of the magnetic anomaly source under oblique magnetization conditions. Equation ② describes the complete calculation of the pole-changing treatment:

[0051] in, : Polarization magnetic anomaly is the output conclusion value of formula ②, which represents the magnetic anomaly data field after correction by the polarization transfer function, and after the magnetic anomaly center is relatively aligned with the actual spatial position of the underground magnetic body. The two-dimensional fast Fourier transform operator transforms the corrected magnetic anomaly data in the spatial domain to the wavenumber domain, outputting a complex spectrum. The two-dimensional inverse fast Fourier transform operator transforms the complex spectrum modulated by the polarization transfer function in the wavenumber domain back to the spatial domain. Its definition is the same as in formula ①, and it is used as in formula ②. The input object is directly provided by the output of formula ①; : Polarization transfer function, determined by the geomagnetic dip angle of the study area (in degrees) and magnetic declination (Dimension: degrees) Constructed in the wavenumber domain, acting on each Frequency components are used to eliminate abnormal center horizontal offset caused by magnetization direction tilt; : Spatial frequency index along the survey line in the wavenumber domain, with a value that is a non-zero integer; : Spatial frequency index in the wavenumber domain perpendicular to the survey line direction, with a value that is a non-zero integer; The Fourier spectrum of the corrected magnetic anomaly data is a complex intermediate variable, output by formula ①. Obtained by Fourier transform, in the wavenumber domain, and Perform point-by-point multiplication.

[0052] Formula ② output This serves as the foundational data field delineating the high magnetic anomaly region and the relatively weak magnetic anomaly zone in Formula ③.

[0053] The magnetic anomaly interpretation module outputs the polarization magnetic anomaly based on formula ②. Within the planar projection boundary of the distribution range of the concealed granite body, a sliding window statistical field is constructed point by point to quantify the magnetic anomaly amplitude of each point relative to the local background, and based on this, high magnetic anomaly areas and relatively weak magnetic anomaly zones are delineated respectively.

[0054] Specifically, for each measuring point Take a square sliding window centered on it. The window side length is The local mean of the polarization magnetic anomaly is calculated within a window based on the spacing between each measuring point. and local standard deviation This serves as a statistical description of the local background field at the measuring point.

[0055] The delineation rule for high magnetic anomaly regions is as follows: when the polarization magnetic anomaly value at the measuring point is greater than the local mean and the first multiple factor... When the sum of the local standard deviations is doubled, the measuring point is marked as a highly magnetic anomaly; the connected regions of all highly magnetic anomalies are clustered into highly magnetic anomaly regions by eight-neighbor clustering. The delineation rule for relatively weak magnetic anomaly zones is: in areas of high magnetic anomaly... Within the area of ​​the plane projection and its extended region below, the search polarization anomaly value is lower than the local mean and the second multiple factor. The measurement points with the difference of multiple local standard deviations are required to have spatial overlap with the planar projection of the protruding part at the top of the rock mass. That is, the coordinates of the low-value measurement points must fall inside the planar projection boundary of the protruding part at the top of the rock mass. The connected regions of low-value measurement points that meet all the above conditions are marked as relatively weak magnetic anomaly zones after eight-neighbor clustering. .

[0056] The practical problem addressed in this step is that high-value areas in magnetic polarization anomalies may be caused by multiple factors (upper iron layer, basic rock dikes, and surface magnetic interference bodies). Simply delineating high-value areas using absolute thresholds cannot distinguish their geological origins. As an indicator zone for the occurrence of underlying scheelite, the relatively weak magnetic anomaly zone must satisfy the vertical position constraint of "located below the high magnetic anomaly zone" and the spatial correlation constraint of "corresponding to the protruding part at the top of the rock mass". Formula ③ simultaneously achieves adaptive extraction of the boundary of the high magnetic anomaly zone and spatial correlation verification of the relatively weak magnetic anomaly zone through sliding window statistics and dual judgment conditions.

[0057] Formula ③ gives the definitions of the above statistics and decision sets:

[0058] in, : using measuring points The arithmetic mean of the polar magnetic anomalies within the square sliding window centered on the measurement point represents the level of local background magnetic anomalies around that measurement point. The standard deviation of the polarization magnetic anomaly within the same window represents the degree of dispersion of the local magnetic anomaly field around the measuring point. The total number of measurement points contained within the sliding window. ,in The window side length parameter (in terms of the number of measurement point spacings); Sliding window The survey line number index of any internal measuring point is a positive integer, subject to the window boundaries. Sliding window The measurement point index of any measurement point within the window is a positive integer and is limited by the window boundaries. : using measuring points Centered on, with side length as A square sliding window with spacing between each measuring point is used to limit the spatial range of measuring points participating in local statistics; Any measuring point within the window The polarization magnetic anomaly value at a given location is obtained by indexing the polarization magnetic anomaly data field output by formula ② according to coordinates. extract; : window A summation operator is used to accumulate the polarization magnetic anomaly values ​​of all measuring points within the window to calculate the total anomaly value within the window; The high magnetic anomaly region is one of the conclusions output by formula ③, determined by the polarization magnetic anomaly value being greater than the local mean plus... The set of spatially connected regions formed by eight-neighbor clustering of all measurement points up to double the standard deviation, including the planar coordinates and outlier fields of each measurement point; The multiplier factor used to delineate the high magnetic anomaly region is preset by the magnetic anomaly interpretation module based on the statistical characteristics of the magnetic susceptibility of known ferrous layers within the study area, and its value range is [value range missing]. ; The relative weak magnetic anomaly zone is the second conclusion value output by formula ③, which is determined by simultaneously satisfying the condition that the magnetic anomaly value of the polarization is less than the local mean. The set of spatially connected regions formed by clustering all measuring points under the three conditions of being double the standard deviation, located inside the plane projection of the high magnetic anomaly area, and located inside the plane projection of the top protrusion of the rock mass through eight-neighbor clustering. The relative weak magnetic anomaly zone delineation factor is preset by the magnetic anomaly interpretation module based on the magnetic anomaly response amplitude of the scheelite mineralization layers within the study area, and its value range is [value range missing]. ; The planar projection operator projects a set of coordinates or a region of space in three-dimensional space vertically onto a horizontal plane, and outputs a set of planar coordinates. The top protrusion of the rock mass is derived from the coordinate field of the top protrusion of the rock mass in the interpretation result record output by S100, which includes its planar projection boundary and top surface burial depth information.

[0059] The polarization magnetic anomaly output by formula ② Extracting window statistics required The local sampling value of the polarization magnetic anomaly is denoted as , and the plane projection boundary is extracted from the coordinates of the protruding part at the top of the rock mass output by S100 and denoted as . Together, these two form the input variables in formula ③. Formula ③ outputs... and This serves as the fundamental input for generating the high magnetic / weak magnetic transition zone in Formula ④.

[0060] After delineating the high magnetic anomaly region and the relatively weak magnetic anomaly zone, the magnetic anomaly interpretation module calculates the spatial transition relationship from the high magnetic anomaly region to the relatively weak magnetic anomaly zone point by point along each measurement line direction, generating a high magnetic / weak magnetic transition zone.

[0061] The high magnetic / weak magnetic transition zone is spatially characterized as a strip-shaped transition area between the lower edge of the high magnetic anomaly zone and the upper edge of the relatively weak magnetic anomaly zone. Its planar boundary is jointly defined by the inward buffer zone of the outer boundary of the high magnetic anomaly zone and the expansion buffer zone of the outer boundary of the relatively weak magnetic anomaly zone. Its vertical positional relationship is recorded as the high magnetic anomaly zone being located above the relatively weak magnetic anomaly zone.

[0062] The magnetic anomaly interpretation module extracts highly magnetic anomaly regions on a plane. Boundary polygons and relatively weak magnetic anomaly zones The boundary polygons are defined, and their vertical stacking relationship in the cross-sectional direction is recorded as a spatial topological pair.

[0063] Formula ④ uses distance transformation and the high / weak magnetic transition strength index. Quantitative calculations transform the spatial transition zone between the highly magnetic anomaly region and the relatively weak magnetic anomaly zone into a vector boundary object that can be directly invoked by subsequent S400 three-dimensional overlay analysis.

[0064] in, Measurement point To the boundary of the high magnetic anomaly region The shortest Euclidean distance is obtained by traversing all boundary points and taking the minimum distance. Measurement point To the boundary of the relatively weak magnetic anomaly zone The shortest Euclidean distance is obtained by traversing all boundary points and taking the minimum distance. Boundary of the high magnetic anomaly region The survey line number index of any boundary point is a positive integer, extracted from the coordinate record field in the boundary tracking result. Boundary of the high magnetic anomaly region The measurement point index of any boundary point is a positive integer, extracted from the coordinate record field in the boundary tracking result. High magnetic anomaly region The set of boundary points, determined by the magnetic anomaly interpretation module. The data obtained by performing eight-neighbor boundary tracing includes the planar coordinates and magnetic anomaly value fields of the boundary points; Relative weak magnetic anomaly zone The set of boundary points, composed of pairs The data obtained by performing the same boundary tracing includes the planar coordinates of the boundary points and the magnetic anomaly value fields. Measurement point With boundary points The Euclidean distance between them is calculated based on the plane coordinates of the measuring points; : All of the boundaries of the high magnetic anomaly region Operator that selects the minimum distance; : All of the boundaries of the relatively weak magnetic anomaly zone Operator that selects the minimum distance; : High magnetic / weak magnetic transition strength index, with a value range of ,Depend on and The ratio is defined as the intermediate conclusion value of formula ④, which is used to quantitatively characterize the transition position of the measuring point between the high magnetic anomaly region and the relatively weak magnetic anomaly zone. : The high magnetic / weak magnetic transition zone is the output conclusion value of formula ④. It is a set of spatial strip-shaped regions formed by clustering all measuring points that satisfy the transition intensity index within the threshold range and the vertical positional relationship that satisfies the condition of upper high and lower low. It includes the planar boundary coordinates and vertical topological relationship. The threshold value for the transition zone is preset by the magnetic anomaly interpretation module based on the spatial distribution width between the high magnetic anomaly zone and the relatively weak magnetic anomaly zone in the study area. The typical value is 0.35. The threshold value for the transition zone is preset by the magnetic anomaly interpretation module based on the spatial distribution width between the high magnetic anomaly zone and the relatively weak magnetic anomaly zone in the study area. The typical value is 0.65. High magnetic anomaly region at the measuring point The top surface depth coordinates (with the surface as the reference and downward as the positive) are obtained by spatial interpolation from the top surface burial depth field of the protruding part of the rock mass output by S100. The relative weak magnetic anomaly zone at the measuring point The top surface depth coordinates (positive with the surface as the reference) are obtained by spatial interpolation from the depth field of the boundary point of the relatively weak magnetic anomaly zone.

[0065] The high magnetic anomaly region output by formula ③ Extracting boundaries Let be the set of high magnetic boundary points, and let be the relatively weak magnetic anomaly zone output by formula ③. Extracting boundaries The weak magnetic boundary point set is denoted as the weak magnetic boundary point set, and together they form the distance transformation object input in formula ④; the depth field of the top surface of the protruding part of the rock mass output by S100 is interpolated to obtain the distance. The depth field of the relative weak magnetic anomaly zone is obtained by interpolation. Together, they form the vertical constraint condition in formula ④.

[0066] Formula ④ outputs the high magnetic / weak magnetic transition band The boundary coordinates and spatial topological relationships are written into the magnetically favorable target area record and used as input objects for spatial superposition analysis in the three-dimensional coordinate system of S400.

[0067] The magnetic anomaly interpretation module outputs the highly magnetic anomaly region using formula ③. Relative weak magnetic anomaly zone And the high magnetic / weak magnetic transition band output by formula ④ Based on this, the protruding portion at the top of the rock mass output by S100 Together they define the favorable target area for magnetic methods.

[0068] The logic for determining a favorable target area using magnetic methods is as follows: In the plane, the target area must simultaneously include the effective boundary of the high magnetic anomaly zone, the effective boundary of the relatively weak magnetic anomaly zone, and the boundary of the high magnetic / weak magnetic transition zone between the two, and the three must be spatially continuous; in the vertical direction, there must be a record of the vertical positional relationship between the high magnetic anomaly zone and the relatively weak magnetic anomaly zone within the area covered by the target area, and the planar projection range of the relatively weak magnetic anomaly zone overlaps with the planar projection range of the protruding part at the top of the rock mass.

[0069] When all the above conditions are met, the magnetic anomaly interpretation module records the vertical relationship between the planar boundary polygon of the region, the high magnetic anomaly area, and the relatively weak magnetic anomaly zone, as well as the corresponding rock mass top protrusion number, and encapsulates it into a magnetically favorable target area record; when the high magnetic anomaly area exists but the relatively weak magnetic anomaly zone is discontinuous, i.e., in formula ③... After eight-neighbor clustering, multiple disconnected blocks are formed, and the area of ​​any block is less than the preset minimum target area threshold. At this time, the magnetic anomaly interpretation module does not include the area in the main deployment scope, but generates a weak magnetic tape discontinuity record and writes it into the candidate verification record. The record contains the boundary coordinates of the discontinuous block, the discontinuity type identifier and the corresponding rock mass top protrusion number, which serves as the alternative location for subsequent audio magnetotelluric sounding profile verification.

[0070] Formula ⑤ describes the three-dimensional spatial determination rule for the favorable target area in magnetic methods. This rule directly uses the output results of Formulas ③ and ④ to form the logical determination condition:

[0071] in, : The favorable target area for magnetic method is the output conclusion value of formula ⑤, which includes the coordinates of all measurement points in the target area that meet all the judgment conditions and their corresponding abnormal attribute fields, and serves as the deployment range of the audio-frequency magnetotelluric sounding profile in S300. : Union operator, used for set operations, indicates that the measurement point belongs to any one of the three: high magnetic anomaly region, relatively weak magnetic anomaly zone, or high magnetic / weak magnetic transition zone; : Spatial continuity determination function, the input is the boundary polygon of the high magnetic anomaly zone, the relatively weak magnetic anomaly zone and the high magnetic / weak magnetic transition zone, and the output is a Boolean value True or False. True indicates that the three form a continuous transition in space and there is no break zone exceeding the preset gap threshold. The function calculates the overlap area ratio. The input consists of two polygons: the plane projection of the relative weak magnetic anomaly zone and the plane projection of the protruding part at the top of the rock mass. The result is obtained by dividing the intersection area of ​​the two polygons by the projected area of ​​the relative weak magnetic anomaly zone. The minimum overlap area ratio threshold is preset by the magnetic anomaly interpretation module based on the spatial statistical relationship between the top protrusion of the rock mass in the study area and the known scheelite mineralization layer. The typical value is 0.3.

[0072] The high magnetic anomaly region output by formula ③ and relatively weak magnetic anomaly zone And the high magnetic / weak magnetic transition band output by formula ④ Together they constitute the spatial continuity determination function The input object; the protruding part at the top of the rock mass output by S100. Extracting planar projection As a benchmark for calculating the overlap area ratio.

[0073] Formula ⑤ outputs the magnetic field favorable target area It is written into the magnetically favorable target area record and serves as the deployment range for the S300 audio-frequency magnetotelluric sounding profile.

[0074] The magnetic anomaly interpretation module generates a favorable target area for magnetic methods. At the same time, the integrity and legality of the high-precision magnetic measurement data are checked item by item, and the check results are written into the magnetic data quality status field.

[0075] When the high-precision magnetic measurement data has issues such as missing diurnal variation observations, measurement point coordinates exceeding the distribution range of the concealed granite body, or missing polarization parameters, the magnetic anomaly interpretation module generates corresponding anomaly records based on the error type. Specifically, missing diurnal variation observations refer to a measurement point where the measurement time within the valid time window of the diurnal variation observation data does not have a corresponding diurnal variation correction value. In this case, the corrected magnetic anomaly data for that measurement point... Not calculated, in formula ① Items marked as missing; measuring point coordinates exceeding the distribution range of concealed granite bodies refer to measuring point plane coordinates falling outside the plane projection boundary of the concealed granite body distribution range output by S100. In this case, all records of the measuring point are not included in the target area delineation calculation of formulas ③ to ⑤, and are only retained as external control records; missing polarization parameters refer to incomplete geomagnetic dip or geomagnetic declination parameters of the study area. In this case, the polarization transfer function in formula ② Unable to construct; the magnetic anomaly interpretation module retains the magnetic anomaly data after diurnal variation correction and normal field correction. The polarization process will be delayed until the polarization parameters are completed and then re-executed.

[0076] Formula ⑥ defines the comprehensive score for data quality status. The generation logic is used to perform a binary judgment on the data validity of each measurement point. This scoring result is used in the statistics of the effective measurement point coverage in the magnetic favorable target area record:

[0077] in, The overall data quality score is 0 or 1, and is the output conclusion value of formula ⑥. It is 1 when all four checks are passed (data is valid) and 0 when any one check is failed (data is invalid). : No. Item inspection at measuring point The pass / fail indicator can be either 0 or 1, where 1 indicates that the check has passed and 0 indicates that it has failed. : Check item index, with values ​​of 1, 2, 3, 4, corresponding to the completeness check of diurnal variation observation, spatial attribution check of measuring points, completeness check of polarization parameters, and rationality check of magnetic field observation amplitude, respectively; : Multiplication operator, multiplies the four check flags from m=1 to 4, and the result is 1 only when all four flags are 1; : Indicator function, takes the value 1 when the condition within the curly braces is true, and takes the value 0 when the condition is false; Its definition is the same as in formula ①, and in formula ⑥ This is used to check if the daily variation correction value exists; The distribution range of the concealed granite body is derived from the interpretation results record output by S100, including its planar projection boundary. In formula ⑥ This is used to determine whether the coordinates of a measuring point fall within its interior; The geomagnetic dip angle of the study area is derived from the polarization parameter, as shown in formula ⑥. This is used to check the completeness of the data entry; The geomagnetic declination of the study area is derived from the polarization parameter, as shown in formula ⑥. Zhongyu Both are used to check the integrity of polarization parameters; Its definition is the same as in formula ①, and in formula ⑥ Take its absolute value and Comparison is used for reasonableness checks; The maximum reasonable amplitude threshold of the magnetic field observation value is determined by the reasonable range of the normal field amplitude in the study area and is used to eliminate outliers caused by instrument failure or strong interference.

[0078] Planar projection extracted from the distribution range of the concealed granite body The spatial boundary is denoted by the geomagnetic dip angle in the polarization parameters. and magnetic declination The entry status is recorded as a parameter integrity identifier, which is determined by the magnetic field observation value in the geomagnetic gradient data. The extracted amplitude is recorded as the input for the rationality check, and the four together form the check conditions in formula ⑥.

[0079] Formula ⑥ output It is written into the magnetic data quality status field and bound to the target area number and interpretation version number in each magnetic favorable target area record, for use in subsequent data verification to trace the validity of the source data.

[0080] After completing all the above processing steps, the magnetic anomaly interpretation module will determine the magnetically favorable target area. High magnetic anomaly region Relative weak magnetic anomaly zone and high magnetic / weak magnetic transition zone The boundary coordinates, spatial topological relationships, and corresponding rock mass top protrusion numbers and magnetic interpretation version numbers are encapsulated as a magnetic favorable target area record.

[0081] The fields recorded for the favorable magnetic target area include the magnetic target area number, the boundary coordinate sequence of the high magnetic anomaly zone, the boundary coordinate sequence of the relatively weak magnetic anomaly zone, the boundary coordinate sequence of the high magnetic / weak magnetic transition zone, the corresponding rock mass top protrusion number, and the magnetic interpretation version number; wherein, the magnetic target area number is a unique primary key for each target area record, automatically assigned by the magnetic anomaly interpretation module according to the generation order; the boundary coordinate sequence of the high magnetic anomaly zone is obtained from formula ③. The boundary tracking results output includes several ordered coordinate pairs; the boundary coordinate sequence of the relative weak magnetic anomaly zone is given by formula ③. The boundary tracking results are output; the boundary coordinate sequence of the high magnetic / weak magnetic transition zone is given by formula ④. The clustering results are output; the corresponding rock mass top protrusion number is directly referenced from the rock mass top protrusion number field in the interpretation result record output by S100; the magnetic interpretation version number is associated with the interpretation version number in the gravity interpretation result record output by S100, and is used to backtrack the geophysical interpretation version during subsequent S500 drilling feedback correction.

[0082] The magnetically favorable target area record is output to S300, serving as the spatial range for the deployment of the audio-frequency magnetotelluric sounding profile in S300; simultaneously, the high magnetic / weak magnetic transition zone... The boundary coordinates and spatial topological relationships are output to S400 as independent spatial objects, serving as input objects for spatial overlay analysis in the three-dimensional coordinate system of S400; the relative weak magnetic anomaly zone With the protruding part at the top of the rock mass The spatial correspondence (including the coordinates of the overlapping areas in the plane and the records of the upper and lower layers) is stored separately as a spatial correspondence index table, which is called in the subsequent S400 hole location screening to constrain the vertical order of the borehole crossing the layers.

[0083] Technical benefits of this section: By strictly limiting the spatial reception range of high-precision magnetic survey data to the interior of the concealed granite body, and based on the iron-under-tungsten mineralization model, the S200 interprets the polarization magnetic anomaly as a vertical coupling between a high magnetic anomaly zone and a relatively weak magnetic anomaly zone below. This transforms the magnetic interpretation results from identifying a single magnetic body into a layered spatial object with clear mineralization indications, consisting of an upper iron layer and an underlying scheelite occurrence indication zone. This layered interpretation rule provides a causal constraint-type input that differs from conventional parallel stacking schemes for subsequent audio-frequency magnetotelluric sounding profile deployment and three-dimensional intersection well location screening.

[0084] S300. Receive audio magnetotelluric sounding data within the favorable target area of ​​the magnetic method, perform resistivity inversion, identify the deep high-resistivity body corresponding to the top protrusion of the rock mass and the middle low-resistivity zone corresponding to the interlayer fracture zone, and generate scheelite enrichment layers and ore-controlling depths.

[0085] In this embodiment, S300 is executed by the audio-visual magnetotelluric (AMT) inversion module. This module receives the favorable magnetic target area and the high / weak magnetic transition zone generated in S200, and the protruding portion at the top of the rock mass generated in S100. The AMT sounding data includes sounding point coordinates, sounding profile number, natural field signal, measurement time, sounding point azimuth, and data quality status. The natural field signal includes electric field and magnetic field components. The AMT inversion module configures the sounding profile according to the boundary of the favorable magnetic target area and the strike of the ore body, and correlates the profile direction with the strike of the high / weak magnetic transition zone in S200.

[0086] Specifically, an audio-frequency magnetotelluric (AFM) sounding profile is deployed along the strike perpendicular to the ore body within the favorable target area for magnetic methods, acquiring natural field signals in the 0.01-10000 Hz frequency band. The AFM inversion module performs denoising, static correction, and impedance estimation on the natural field signals to generate impedance data. The denoising includes removing abrupt jumps, eliminating time windows affected by strong interference periods, and retaining stable frequency records. The static correction includes correcting static displacement based on the apparent resistivity changes of adjacent measuring points within the same sounding profile. The impedance estimation calculates the impedance tensor for each frequency point based on the electric and magnetic field components, generating impedance data records. The impedance data records include frequency points, measuring point coordinates, impedance components, apparent resistivity, and a phase field.

[0087] The audio-magnetic inversion module performs two-dimensional or three-dimensional resistivity inversion on the impedance data to generate a resistivity structure model. The resistivity structure model includes the spatial coordinates of the profile or three-dimensional grid cells, resistivity values, inversion depth, and model quality status. The deep high-resistivity body is identified through continuous grid cells located deep within the resistivity structure model that have relatively higher resistivity compared to the surrounding rock. The central low-resistivity zone is identified through continuous grid cells located above the deep high-resistivity body, distributed in a banded or layered pattern, and with relatively lower resistivity. When the projection range of the top protrusion of the rock mass generated by S100 on the audio-magnetic sounding profile corresponds to the deep high-resistivity body, the audio-magnetic inversion module interprets it as the response of a concealed granite body in its electrical structure. When the central low-resistivity zone is located above the deep high-resistivity body and corresponds to an interlayer fracture zone, the audio-magnetic inversion module records it as a low-resistivity fracture zone layer.

[0088] In one embodiment, the scheelite-enriched stratum is generated by the spatial correspondence between the central low-resistivity zone and the high / weak magnetic transition zone. Specifically, the audio-frequency magnetotelluric inversion module projects the high / weak magnetic transition zone output by S200 onto the audio-frequency magnetotelluric sounding profile and overlays it with the top and bottom plate depths of the central low-resistivity zone. When the central low-resistivity zone is located below the high magnetic anomaly zone, within the spatial range indicated by the relative weak magnetic anomaly zone, and corresponds to the deep high-resistivity body below it, this stratum is recorded as a scheelite-enriched stratum. The ore-controlling depth is generated based on the top and bottom plate depths of the central low-resistivity zone and its distance from the top surface of the concealed granite body; the ore-controlling depth record includes the stratum number, profile number, top plate depth, bottom plate depth, and target crossing depth fields.

[0089] S300 is activated after S200 generates a favorable magnetic target area. When multiple high-magnetic / weak-magnetic transition zones exist within the favorable magnetic target area, the audio-frequency magnetotelluric (AMT) inversion module deploys multiple AMT sounding profiles according to the spatial correspondence between each high-magnetic / weak-magnetic transition zone and the protruding part at the top of the rock mass. In one embodiment, a single sounding profile passes through the protruding part at the top of the rock mass, the relatively weak magnetic anomaly zone, and the center of the favorable magnetic target area. In another embodiment, parallel profiles are deployed along both sides of the high-magnetic / weak-magnetic transition zone, and the inversion results of the parallel profiles are incorporated into the same resistivity structure model. When the natural field signal has continuous frequency point missing, abnormal grounding status of the measuring point, or static displacement amplitude exceeding the configuration range, the AMT inversion module writes the measuring point into the AMT data quality anomaly record and retains usable frequency points on the same sounding profile for inversion. When a profile cannot form a continuous central low-resistivity band, the AMT inversion module outputs that the low-resistivity band is not continuously recorded and marks the profile as a profile to be verified.

[0090] The scheelite enrichment layers and ore-controlling depths output by S300, along with the low-density anomaly boundaries from S100 and the high / weak magnetic transition zones from S200, serve as inputs for the S400 spatial overlay analysis. The scheelite enrichment layer records include the corresponding magnetically favorable target area number, sounding profile number, central low-resistivity zone boundary, deep high-resistivity body boundary, and ore-controlling depth. The central low-resistivity zone boundary is converted into a spatial object in a three-dimensional coordinate system and participates in raster overlay or isosurface intersection in S400.

[0091] S400. Perform spatial overlay analysis of the low-density anomaly boundary, the high magnetic / weak magnetic transition zone and the central low-resistivity zone in a three-dimensional coordinate system, and filter the spatial units located above the protruding part at the top of the rock mass in the intersection area of ​​the three to generate priority drilling positions.

[0092] In this embodiment, S400 is executed by the spatial overlay module. The spatial overlay module receives the low-density anomaly boundary and the protruding portion at the top of the rock mass generated in S100, the high-magnetic / weak-magnetic transition zone generated in S200, and the central low-resistivity zone and ore-controlling depth generated in S300. The spatial overlay module first unifies the coordinates of the aforementioned spatial objects, transforming the low-density anomaly boundary, the protruding portion at the top of the rock mass, the high-magnetic / weak-magnetic transition zone, and the central low-resistivity zone to the same three-dimensional coordinate system. The three-dimensional coordinate system includes planar coordinates and elevation or depth coordinates; the depth coordinates are consistent with the reference surface used for gravity inversion, resistivity inversion, and drilling design.

[0093] Specifically, the boundary of the low-density anomaly is represented by a three-dimensional isosurface or a three-dimensional grid; the high magnetic / weak magnetic transition zone is represented by a planar boundary and a vertical projection range; and the central low-resistivity zone is represented by the top plate depth, bottom plate depth, and planar boundary in the resistivity structure model. After spatial registration of the above objects, the spatial overlay module generates the intersection region of the three through grid overlay or isosurface intersection. Grid overlay refers to dividing the three-dimensional coordinate system into multiple spatial units and recording whether each spatial unit falls within the low-density anomaly boundary, the high magnetic / weak magnetic transition zone, or the central low-resistivity zone; spatial units that simultaneously satisfy the above three spatial conditions are written into the intersection region. Isosurface intersection refers to geometrically intersecting the low-density anomaly boundary, the outer envelope of the high magnetic / weak magnetic transition zone, and the outer envelope of the central low-resistivity zone to form the boundary of the three-dimensional intersection region.

[0094] The protruding portion at the top of the rock mass serves as a borehole location selection constraint in the spatial overlay analysis. After generating the intersection region of the three elements, the spatial overlay module calculates the spatial distance between each spatial unit in the intersection region and the protruding portion at the top of the rock mass. Spatial units located above the protruding portion and overlapping or adjacent to it in planar projection are added to the borehole location candidate set. The borehole location candidate set includes a candidate borehole number, an intersection region number, spatial unit coordinates, a corresponding low-density anomaly number, a corresponding high-magnetic / weak-magnetic transition zone number, a corresponding central low-resistivity zone number, and a spatial distance field. Based on the correspondence between the borehole location candidate set and the ore-controlling depth, the spatial overlay module generates priority drilling locations.

[0095] In one embodiment, the preferred drilling location includes borehole coordinates, borehole orientation, dip angle, designed borehole depth, and target stratum to be traversed. The borehole coordinates are obtained by projecting the target spatial unit from the candidate borehole location set onto the surface; the borehole orientation is configured according to the strike of the ore body and the direction of the sounding profile, adopting a direction perpendicular to the strike of the ore body or at a large angle to the strike of the ore body; the dip angle is calculated based on the depth of the target spatial unit, the topographic elevation, and the drilling conditions; the designed borehole depth is set to penetrate the scheelite-rich stratum and enter the top surface of the concealed granite body. The target stratum to be traversed includes the spatial location corresponding to the relatively weak magnetic anomaly zone, the depth of the top and bottom plates of the central low-resistivity zone, and the depth of the top surface of the concealed granite body.

[0096] S400 is initiated after S300 generates the scheelite enrichment layer and ore-controlling depth. When the same favorable magnetic target area corresponds to multiple central low-resistivity zones, the spatial overlay module performs spatial overlay analysis on the boundaries of each central low-resistivity zone and the low-density anomaly, as well as the high-magnetic / weak-magnetic transition zone, and generates the intersection region of the three. When the spatial overlay analysis does not generate the intersection region of the three, the spatial overlay module generates a record with no intersection. The record with no intersection includes the low-density anomaly number, the high-magnetic / weak-magnetic transition zone number, the central low-resistivity zone number, and the spatial non-overlap type. In this case, the spatial overlay module generates a candidate borehole downgrade record based on the pairwise overlapping anomaly regions among the low-density anomaly boundary, the high-magnetic / weak-magnetic transition zone, and the central low-resistivity zone. The candidate borehole downgrade record does not replace the priority drilling borehole and serves as the input record for subsequent survey line densification or interpretation verification.

[0097] The priority drilling locations output by S400 serve as a spatial index for S500 to receive core logging data and laboratory analysis results. The priority drilling location record includes the borehole coordinates, borehole orientation, dip angle, designed borehole depth, target stratum, the corresponding intersection region number, and the borehole location version number. This version number is linked to the low-density anomaly boundary interpretation version, the magnetic interpretation version, and the resistivity structure model version; subsequently, when receiving core logging data and laboratory analysis results, S500 uses this borehole location version number to trace back the corresponding geophysical interpretation results.

[0098] S500. Based on the core logging data and analysis results received from the priority drilling sites, the interpretation positions of the low-density anomaly boundary, the high magnetic / weak magnetic transition zone, and the central low-resistivity zone are corrected.

[0099] In this embodiment, S500 is executed by the drilling feedback correction module. This module receives the priority drilling locations generated by S400 and the core logging data and analytical results generated during the drilling process. The core logging data includes borehole number, borehole coordinates, borehole orientation, dip angle, actual borehole depth, lithological stratification, fracture zone location, mineralized strata, and depth of the top surface of the rock mass. The analytical results include sample number, sampling depth, sample length, and WO3 content. The drilling feedback correction module binds the core logging data and analytical results to the priority drilling location record based on the borehole number and retrieves the geophysical interpretation results generated by S100, S200, S300, and S400 under that borehole location version number.

[0100] Specifically, the drilling feedback correction module first performs depth registration between the actual exposed strata in the core logging data and the target traversed strata recorded by S400. During the depth registration process, the borehole depth is converted into a spatial position in a three-dimensional coordinate system according to the borehole elevation, borehole orientation, dip angle, and inclination records. Subsequently, the drilling feedback correction module compares the actual exposed scheelite mineralization strata with the scheelite enrichment strata generated by S300, compares the actual exposed rock mass top surface depth with the top protrusion and low-density anomaly boundary generated by S100, and compares the actual exposed fracture zone location with the central low-resistivity zone generated by S300. The above comparisons form an actual stratum deviation record, which includes scheelite mineralization stratum deviation, rock mass top surface depth deviation, fracture zone location deviation, and borehole version number.

[0101] The laboratory analysis results are used to correlate with the mineralized strata in the core logging data. The drilling feedback correction module writes the WO3 content into the corresponding mineralized strata record according to the sample number and sampling depth. When the depth of the mineralized strata in the laboratory analysis results is inconsistent with that in the core logging data, the drilling feedback correction module generates a sample depth verification record and retains the original depth field of the core logging data. For boreholes where the actual exposed scheelite mineralization strata deviate from the S300 scheelite enrichment strata, the drilling feedback correction module writes the deviation direction and distance into the geophysical interpretation model correction record. For boreholes where the actual exposed rock mass top surface depth deviates from the top surface of the S100 low-density anomaly, the drilling feedback correction module records the top surface burial depth of the corresponding area within the boundary of the low-density anomaly as the object to be corrected.

[0102] When correcting the interpretation positions of the low-density anomaly boundary, the high-magnetic / weak-magnetic transition zone, and the central low-resistivity zone, the drilling feedback correction module establishes three types of correction records. The first type of correction record corresponds to the low-density anomaly boundary and records the difference between the measured depth of the rock mass top surface and the gravity-inverted top surface burial depth, returning this difference to the gravity interpretation result record. The second type of correction record corresponds to the high-magnetic / weak-magnetic transition zone and records the positional differences of the actual scheelite mineralization layer relative to the relatively weak magnetic anomaly zone in both planar and depth directions, returning this difference to the magnetic interpretation result record. The third type of correction record corresponds to the central low-resistivity zone and records the difference between the actual fracture zone position and the top and bottom plate depths of the central low-resistivity zone in the resistivity structure model, returning this difference to the audio-frequency magnetotelluric inversion result record. These three types of correction records together form the corrected geophysical interpretation model.

[0103] S500 is activated after core logging and analysis results are generated during drilling. When core logging data arrives before analysis results, the drilling feedback correction module first generates a drilling verification record and marks the analysis status as pending backfilling. After the analysis results arrive, the drilling feedback correction module supplements the WO3 content field based on the sample number and sampling depth. When drilling deviates from the borehole direction, dip angle, or designed depth output by S400, the drilling feedback correction module records the actual borehole trace in the borehole deviation field and performs three-dimensional coordinate transformation based on the actual borehole trace. When drilling does not encounter scheelite mineralization, the drilling feedback correction module generates a record of no mineralization encountered and retains the original interpretation positions of the low-density anomaly boundary, high / weak magnetic transition zone, and central low-resistivity zone, respectively, for correction after subsequent densification of survey lines or review of candidate borehole downgrade records.

[0104] In one implementation, the corrected geophysical interpretation model generated by S500 includes a low-density anomaly boundary correction version, a high-magnetic / weak-magnetic transition zone correction version, and a central low-resistivity zone correction version. Each version records the borehole number, core logging data version, and laboratory analysis result version for which correction was performed. The corrected geophysical interpretation model is returned to the interpretation records corresponding to S100, S200, and S300, serving as input for gravity inversion boundary verification, magnetic favorable target area verification, and audio-frequency magnetotelluric sounding profile densification in subsequent rounds. The subsequent survey line deployment suggestions output by S500 include the low-density anomaly boundary segments that need verification, the high-magnetic / weak-magnetic transition zone segments that need re-surveying, the locations of audio-frequency magnetotelluric sounding profiles that need densification, and the corresponding borehole version numbers. This output, together with the priority drilling site records generated by S400, constitutes the data basis for the next round of geophysical interpretation and drilling verification in the study area.

[0105] Example 2: Figure 2 A structural block diagram of a method for prospecting for tungsten ore under iron ore, according to an embodiment of the present invention, is shown. Figure 2 As shown, the structure may include: The gravity inversion module 01 is used to receive Bouguer gravity anomaly data from the study area, perform three-dimensional density inversion and low-density anomaly identification, and generate low-density anomaly boundaries, the distribution range of concealed granite bodies, and the protruding parts at the top of the rock mass. Specifically, the gravity inversion module receives Bouguer gravity anomaly data formed from gravity exploration in the study area, and receives the coordinates, elevation data, and topographic data of the gravity measurement points corresponding to the Bouguer gravity anomaly data. Before entering the gravity inversion module, the Bouguer gravity anomaly data is formed from gravity observation data through topographic correction, intermediate layer correction, and Bouguer correction. The gravity inversion module spatially registers the coordinates of each gravity measurement point with the corresponding Bouguer gravity anomaly value to form a gravity anomaly record. The gravity inversion module performs upward extension, horizontal derivative processing, and vertical derivative processing on the gravity anomaly record to form local gravity anomalies for low-density anomaly identification. The gravity inversion module constructs a subsurface density structure model based on the local gravity anomalies, and extracts values ​​with density values ​​lower than the background density of the surrounding rock from the subsurface density structure model. Anomalous bodies with continuous spatial distribution form low-density anomalies. The gravity inversion module generates the boundary of the low-density anomaly based on its outer envelope, top surface depth, and spatial extension, and interprets this boundary with geological mapping data to form the distribution range of concealed granite bodies. The gravity inversion module extracts the top surface depth variation along the top surface of the low-density anomaly, recording the parts with shallower top surface depths relative to the surrounding top surfaces and forming closed or semi-closed shapes as the top protrusions of the rock mass. When the input gravity measurement point coordinates are missing, Bouguer gravity anomaly values ​​are missing, or measurement point coordinates are duplicated, the gravity inversion module writes the data quality status and retains the corresponding gravity observation data. The gravity inversion module transmits the low-density anomaly boundary, the distribution range of the concealed granite body, and the top protrusions of the rock mass to the magnetic anomaly interpretation module. The distribution range of the concealed granite body serves as the spatial range for the magnetic anomaly interpretation module to receive high-precision magnetic measurement data, and the top protrusions of the rock mass serve as the spatial objects called by the subsequent audio-visual magnetotelluric inversion module and spatial overlay module.

[0106] The magnetic anomaly interpretation module 02, connected to the gravity inversion module, is used to receive high-precision magnetic survey data based on the distribution range of the concealed granite body, perform polarization processing, and interpret the high magnetic anomaly area as the upper iron layer and the underlying scheelite body according to the spatial coupling relationship between the upper iron layer and the underlying scheelite body in the iron-under-tungsten mineralization model. The relatively weak magnetic anomaly zone located below the high magnetic anomaly area is marked as the underlying scheelite occurrence indicator zone, generating a favorable magnetic target area and a high / weak magnetic transition zone. Specifically, the magnetic anomaly interpretation module receives the distribution range of the concealed granite body and the top of the rock mass from the gravity inversion module. The system receives high-precision magnetic survey data located within the distribution range of the concealed granite body at the protruding portion. This high-precision magnetic survey data includes geomagnetic gradient data, diurnal variation observation data, magnetic survey point coordinates, and survey line numbers. The magnetic anomaly interpretation module spatially matches the magnetic survey point coordinates with the distribution range of the concealed granite body, and records magnetic survey points outside the distribution range of the concealed granite body are written into an external reference record. The magnetic anomaly interpretation module performs diurnal variation correction and normal field correction on the geomagnetic gradient data to form corrected magnetic anomaly data, and interprets the corrected magnetic anomaly data based on the polarization parameters. A polarization process is performed to form a polarized magnetic anomaly. The magnetic anomaly interpretation module delineates a high-magnetic-anomaly zone based on this polarization magnetic anomaly and interprets it as an upper iron layer, including a magnetite-rich layer or a pyrrhotite-rich layer, according to the iron-under-tungsten mineralization model. The module then searches for anomaly zones below the high-magnetic-anomaly zone that have relatively lower magnetic anomaly values ​​and spatial correspondence with the protruding parts at the top of the rock mass, marking these zones as relatively weak magnetic anomaly zones. The module records these relatively weak magnetic anomaly zones as underlying scheelite deposits. The system stores the indicator band and generates a high magnetic / weak magnetic transition band based on the spatial adjacency relationship between the high magnetic anomaly area and the relatively weak magnetic anomaly band. When the polarization parameter is missing, the diurnal variation observation data is missing, or the relatively weak magnetic anomaly band is discontinuous, the magnetic anomaly interpretation module writes the corresponding data quality status or weak magnetic tape discontinuity record. The magnetic anomaly interpretation module transfers the magnetic favorable target area to the audio magnetotelluric inversion module as the receiving range of the audio magnetotelluric bathymetry data, and transfers the high magnetic / weak magnetic transition band to the spatial overlay module as the input object for spatial overlay analysis in the three-dimensional coordinate system.

[0107] The audio-visual magnetotelluric inversion module 03, connected to the magnetic anomaly interpretation module, is used to receive audio-visual magnetotelluric sounding data based on the favorable magnetic target area, perform resistivity inversion, identify the deep high-resistivity body corresponding to the top protrusion of the rock mass and the middle low-resistivity zone corresponding to the interlayer fracture zone, and generate the scheelite enrichment layer and ore-controlling depth. Specifically, the audio-visual magnetotelluric inversion module receives the favorable magnetic target area and high / weak magnetic transition zone from the magnetic anomaly interpretation module, and receives the top protrusion of the rock mass from the gravity inversion module; the audio-visual magnetotelluric inversion module... Audio magnetotelluric (AMT) sounding data is received within the favorable target area for magnetic methods. This AMT sounding data includes sounding point coordinates, sounding profile number, natural field signal, sounding point azimuth, and data quality status. The AMT inversion module receives the natural field signal along the sounding profile perpendicular to the ore body strike, performs denoising, static correction, and impedance estimation on the natural field signal, generating impedance data. The AMT inversion module then performs two-dimensional or three-dimensional resistivity inversion on the impedance data, generating a resistivity structure model. The AMT inversion module then performs resistivity structure... The model identifies deep high-resistivity bodies and spatially correlates them with the projection range of the top protrusion of the rock mass on the sounding profile. The audio-visual magnetotelluric inversion module identifies a mid-level low-resistivity zone, distributed in a banded or layered pattern, above the deep high-resistivity body and interprets it in relation to the interlayer fracture zone. The audio-visual magnetotelluric inversion module then positions the mid-level low-resistivity zone with the high / weak magnetic transition zone in a three-dimensional coordinate system, forming a scheelite enrichment layer. Based on the top and bottom depths of the mid-level low-resistivity zone and its relationship with the deep high-resistivity body... The spatial relationship of the resistivity body generates the ore-controlling depth. When there are missing continuous frequency points in the natural field signal, the coordinates of the sounding point do not match the favorable target area of ​​the magnetic method, or the resistivity inversion result does not form a continuous central low-resistivity band, the audio-magnetic inversion module writes the data quality status or the low-resistivity band is not continuously recorded. The audio-magnetic inversion module transmits the central low-resistivity band, the scheelite enrichment layer, and the ore-controlling depth to the spatial overlay module. The central low-resistivity band is used as the input object for the calculation of the three-dimensional intersection region, and the ore-controlling depth is used as the design hole depth reference object when generating the priority drilling position.

[0108] Spatial overlay module 04, connected to the audio-visual magnetotelluric inversion module, is used to perform spatial overlay analysis in a three-dimensional coordinate system based on the low-density anomaly boundary, the high magnetic / weak magnetic transition zone, and the central low-resistivity zone. It filters spatial units located above the protruding portion at the top of the rock mass within the intersection region of these three elements to generate priority drilling locations. Specifically, the spatial overlay module receives the low-density anomaly boundary and the protruding portion at the top of the rock mass from the gravity inversion module, the high magnetic / weak magnetic transition zone from the magnetic anomaly interpretation module, and the audio-visual magnetotelluric inversion module. The geomagnetic inversion module identifies the central low-resistivity zone, scheelite enrichment layer, and ore-controlling depth. The spatial overlay module unifies the low-density anomaly boundary, the top protrusion of the rock mass, the high / weak magnetic transition zone, and the central low-resistivity zone into the same three-dimensional coordinate system. The spatial overlay module expresses the low-density anomaly boundary as a three-dimensional boundary object, the high / weak magnetic transition zone as a spatial object with planar boundaries and depth ranges, and the central low-resistivity zone as a spatial object with top plate depth, bottom plate depth, and planar boundaries. The block performs spatial overlay analysis on the aforementioned spatial objects through raster overlay or isosurface intersection, generating an intersection region that simultaneously falls within the boundary of the low-density anomaly, the high magnetic / weak magnetic transition zone, and the central low-resistivity zone. The spatial overlay module calculates the spatial distance between the spatial cells within the intersection region and the top protrusion of the rock mass, and filters the spatial cells located above the top protrusion of the rock mass to form a candidate set of borehole locations. Based on the candidate set of borehole locations and the ore-controlling depth, the spatial overlay module generates priority drilling locations, which include boreholes... The system includes the borehole coordinates, borehole orientation, dip angle, designed borehole depth, and target traversal strata. When the spatial overlay analysis does not generate an intersection region among these three parameters, the spatial overlay module generates a record without intersection and generates a candidate borehole downgrade record based on the pairwise overlapping anomaly regions in the low-density anomaly boundary, the high magnetic / weak magnetic transition zone, and the central low-resistivity zone. The spatial overlay module transmits the preferred drilling borehole to the drilling feedback correction module and establishes an association between the preferred drilling borehole and the corresponding low-density anomaly boundary, high magnetic / weak magnetic transition zone, central low-resistivity zone, and borehole version number.

[0109] The drilling feedback correction module 05, connected to the spatial overlay module, is used to correct the interpretation positions of the low-density anomaly boundary, the high magnetic / weak magnetic transition zone, and the central low-resistivity zone based on the core logging data and laboratory analysis results received from the priority drilling locations. Specifically, the drilling feedback correction module receives priority drilling locations from the spatial overlay module, and receives core logging data and laboratory analysis results generated during the drilling process. The core logging data includes borehole number, borehole coordinates, borehole orientation, dip angle, actual borehole depth, lithological stratification, fracture zone location, mineralized strata, and the depth of the top surface of the rock mass. The laboratory analysis results include sample number, sampling depth, sample length, and tungsten trioxide content. Based on the borehole number and borehole version number, the drilling feedback correction module binds the core logging data and the laboratory analysis results to the priority drilling locations, and calls up the low-density anomaly boundary, high-magnetic / weak-magnetic transition zone, and central low-resistivity zone associated with the priority drilling locations. The drilling feedback correction module compares the actual exposed depth of the top surface of the rock mass with the top surface burial depth in the low-density anomaly boundary, and compares the actual exposed scheelite mineralization strata with the spatial location of the high-magnetic / weak-magnetic transition zone. A comparison is performed, comparing the actual exposed fracture zone location with the top and bottom depths of the central low-resistivity zone to form an actual stratigraphic deviation record. The drilling feedback correction module generates correction records for the low-density anomaly boundary, the high-magnetic / weak-magnetic transition zone, and the central low-resistivity zone based on the actual stratigraphic deviation record, and returns these correction records to the corresponding gravity inversion module, magnetic anomaly interpretation module, and audio-visual magnetotelluric inversion module. When core logging data arrives before the analysis results, the drilling feedback correction module generates a record to be backfilled, and supplements the tungsten trioxide content according to the sample number and sampling depth after the analysis results arrive. When drilling does not encounter scheelite mineralization, the drilling feedback correction module generates a drilling no-mineralization record, and retains the original interpretation locations of the low-density anomaly boundary, the high-magnetic / weak-magnetic transition zone, and the central low-resistivity zone for subsequent survey line deployment and candidate well site downgrading record reading.

Claims

1. A method for prospecting for tungsten ore beneath iron ore, characterized in that, include: S100: Receive Bouguer gravity anomaly data of the study area, perform three-dimensional density inversion and low-density anomaly identification, and generate the low-density anomaly boundary, the distribution range of the concealed granite body and the protruding part of the top of the rock body. S200. Receive high-precision magnetic survey data within the distribution range of the concealed granite body, perform polarization processing, and interpret the high magnetic anomaly area as the upper iron layer and the underlying scheelite body according to the spatial coupling relationship between the upper iron layer and the underlying scheelite body in the iron-under-tungsten mineralization model. Mark the relatively weak magnetic anomaly zone located below the high magnetic anomaly area as the underlying scheelite occurrence indicator zone, thereby generating a favorable magnetic target area and a high magnetic / weak magnetic transition zone. S300: Receive audio magnetotelluric sounding data in the magnetic method favorable target area, perform resistivity inversion, identify the deep high resistivity body corresponding to the top protrusion of the rock mass and the middle low resistivity zone corresponding to the interlayer fracture zone, and generate scheelite enrichment layer and ore-controlling depth. S400. Perform spatial overlay analysis of the low-density anomaly boundary, the high magnetic / weak magnetic transition zone and the central low resistivity zone in a three-dimensional coordinate system, and filter the spatial units located above the top protrusion of the rock mass in the intersection area of ​​the three to generate priority drilling positions. S500. Based on the core logging data and analysis results received from the priority drilling sites, the interpretation positions of the low-density anomaly boundary, the high magnetic / weak magnetic transition zone, and the central low-resistivity zone are corrected.

2. The method according to claim 1, characterized in that, The Bouguer gravity anomaly data is obtained from gravity observation data through terrain correction, intermediate layer correction, and Bouguer correction. Before the three-dimensional density inversion, the Bouguer gravity anomaly data is subjected to upward extension, horizontal derivative processing, and vertical derivative processing to generate local gravity anomalies for identifying the low-density anomaly.

3. The method according to claim 1, characterized in that, The protruding part at the top of the rock mass is identified based on the top surface burial depth, top undulation amplitude, closed boundary, and contact relationship with the sedimentary cover layer of the low-density anomaly; the protruding part at the top of the rock mass serves as a pore location screening constraint in the spatial overlay analysis.

4. The method according to claim 1, characterized in that, The high-precision magnetic measurement data includes geomagnetic gradient data and diurnal variation observation data; the polarization processing includes diurnal variation correction, normal field correction and polarization parameter conversion of the geomagnetic gradient data to generate polarization magnetic anomalies.

5. The method according to claim 4, characterized in that, The highly magnetic anomaly zone and the relatively weak magnetic anomaly zone are delineated based on the polarization magnetic anomaly; the highly magnetic anomaly zone is interpreted as a magnetite-rich layer or a pyrrhotite-rich layer; the relatively weak magnetic anomaly zone is located below the highly magnetic anomaly zone and has a spatial correspondence with the protruding part at the top of the rock mass.

6. The method according to claim 1, characterized in that, Within the favorable target area for magnetic methods, an audio-frequency magnetotelluric sounding profile is deployed along the strike perpendicular to the ore body to collect natural field signals in the 0.01-10000Hz frequency band. The natural field signals are then denoised, statically corrected, and impedance estimated to generate impedance data. Two-dimensional or three-dimensional resistivity inversion is performed on the impedance data to generate a resistivity structure model.

7. The method according to claim 6, characterized in that, The deep high-resistivity body and the middle low-resistivity zone are identified based on the resistivity structure model; the deep high-resistivity body corresponds to the projection range of the top protrusion of the rock mass on the audio magnetotelluric sounding profile; the middle low-resistivity zone is located above the deep high-resistivity body, and the ore-controlling depth is generated based on the top and bottom plate depths of the middle low-resistivity zone.

8. The method according to claim 1, characterized in that, The spatial overlay analysis includes: unifying the boundary of the low-density anomaly, the protruding part at the top of the rock mass, the high magnetic / weak magnetic transition zone, and the low resistivity zone in the middle into the same three-dimensional coordinate system; generating the intersection region of the three through grid overlay or isosurface intersection; and forming a candidate set of borehole locations based on the spatial distance between the intersection region of the three and the protruding part at the top of the rock mass.

9. The method according to claim 1, characterized in that, The preferred drilling locations include borehole coordinates, borehole orientation, dip angle, designed borehole depth, and target strata to be penetrated; the designed borehole depth is set to penetrate the scheelite-rich strata and enter the top surface of the concealed granite body.

10. The method according to claim 1, characterized in that, When the spatial overlay analysis does not generate the intersection region of the three, a record without intersection of the three is generated; based on the pairwise superimposed anomalous regions in the low-density anomaly boundary, the high magnetic / weak magnetic transition zone and the central low-resistivity zone, a candidate aperture downgrade record is generated.

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