Three-dimensional positioning method for concealed copper-gold mine target area based on integrated geophysical data fusion

Abstract

The present application relates to the field of quantum magnetic field measurement, disclose a kind of concealed copper gold mine target area three-dimensional positioning method based on integrated geophysical data fusion, comprising the following steps: combined with geological topographic background layout integrated geophysical survey line;Adopt controllable source audio magnetotelluric method and collect, obtain anti-interference geoelectric field response data using quantum magnetometer based on diamond NV color center technology;At the same point, using equivalent inverse magnetic flux transient electromagnetic method receives secondary field data on zero magnetic flux plane;The one-dimensional inversion result of the above two types of data is preprocessed, and the initial model constraint is constructed by splicing and fusing in depth domain, and high-precision two-dimensional resistivity profile is obtained by joint inversion;Based on the profile boundary, construct three-dimensional apparent resistivity data volume, and solve the target area shape parameters.The present application overcomes the problem of data multiple solutions by multi-source hardware and algorithm fusion, and accurately outputs the three-dimensional spatial positioning and geometric shape quantitative index of deep concealed target area.

Description

Technical Field

[0001] This invention relates to the field of quantum magnetic field measurement technology, specifically a three-dimensional localization method for concealed copper-gold ore target areas based on the fusion of comprehensive geophysical data. Background Technology

[0002] With the increasing exploration of shallow mineral resources, geological prospecting work is gradually shifting towards deep, concealed deposits. Concealed sulfide copper-gold ore bodies or water-filled cavities typically exhibit low resistivity anomalies compared to the surrounding rocks. Therefore, electromagnetic methods have become the primary detection means for delineating anomaly boundaries and locating target areas. Currently, in field operations, controlled-source audio-frequency magnetotellurics and transient electromagnetic methods are commonly used for detection.

[0003] Existing controlled-source audio-frequency magnetotelluric methods rely heavily on traditional induction rods to receive electromagnetic signals. These receivers operate based on the law of electromagnetic induction and are susceptible to interference from surface high-voltage lines and stray currents in complex mining environments, causing low-frequency data distortion and reducing the accuracy of deep target detection. Furthermore, conventional transient electromagnetic methods, when detecting shallow to medium-depth strata, generate a strong primary field induced electromotive force when the transmitting coil is switched off. This phenomenon directly masks the weak secondary field signals generated by the geological body, creating a detection blind zone.

[0004] Besides traditional induction magnets, other high-precision magnetic measurement devices have been attempted in existing technologies, but all have significant limitations: While superconducting quantum interference devices (SQIs) possess extremely high detection sensitivity, they require cryogenic cooling using liquid helium or liquid nitrogen, resulting in large size and extremely high maintenance costs, making them impractical for large-area continuous wiring data acquisition in complex field terrain; fluxgate magnetometers, although small in size and suitable for extremely low-frequency measurements, have a high noise floor and poor high-frequency response, failing to meet the resolution requirements of audio-frequency magnetotellurics for weak high-frequency signals; traditional optically pumped magnetometers have measurement blind zones (dead zones) and are easily affected by temperature drift, leading to baseline drift in mining environments with strong electromagnetic background noise. Therefore, finding a magnetic field sensor that can operate stably in ambient temperature field environments, cover the audio frequency range (kilohertz to hertz), and is immune to strong electromagnetic noise has become a key bottleneck for accurate positioning of deep, concealed mining targets.

[0005] In the inversion processing stage after acquiring observational data, conventional methods often use single electromagnetic data for one-dimensional or two-dimensional inversion. Due to the inherent ambiguity of geophysical inversion, observational data from a single method often fails to provide sufficient constraints, leading to deviations between the inverted resistivity profile and the actual geological conditions. Current data processing workflows typically fail to effectively stitch and fuse time-domain and frequency-domain data in the depth domain, lacking a mechanism to constrain deep inversion using shallow high-resolution results. These technical deficiencies, caused by hardware reception interference and the superposition of ambiguities in single algorithms, make it difficult for existing methods to construct accurate three-dimensional electrical data volumes. Consequently, the calculation of spatial boundaries, top and bottom burial depths, and volumetric morphological parameters of deep concealed target areas is inaccurate, failing to meet the three-dimensional positioning accuracy requirements of deep physical drilling projects. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a three-dimensional localization method for concealed copper-gold deposit target areas based on the fusion of comprehensive geophysical data. This method solves the technical problems of difficulty in extracting weak signals from deep deposits under strong background electromagnetic noise, as well as the high ambiguity of single electromagnetic methods and the difficulty in accurate spatial localization using conventional two-dimensional interpretation.

[0007] To achieve the above objectives, the present invention provides a three-dimensional localization method for concealed copper-gold deposit target areas based on integrated geophysical data fusion, comprising the following steps: An initial geological-geophysical model was established based on the geological background of the exploration area, and multiple integrated geophysical exploration lines were laid out in combination with topography and known information. Data was collected along each of the aforementioned integrated geophysical exploration lines using the controlled-source audio-frequency magnetotelluric method. In the electromagnetic field signal receiving stage, a quantum magnetometer based on diamond NV color center technology was used to measure the magnetic field and obtain the magnetotelluric field response data at each frequency point. On each of the aforementioned integrated object detection lines, the transient electromagnetic method is used to collect secondary field data at the same point; the transient electromagnetic method is the equivalent reverse magnetic flux transient electromagnetic method. During measurement, the receiving coil is placed on the primary field zero magnetic flux plane to eliminate interference from the primary field induced electromotive force and receive the secondary field data. The collected magnetotelluric response data and secondary field data are preprocessed and inverted to obtain one-dimensional inversion results of the controlled-source audio-frequency magnetotelluric method and the transient electromagnetic method, respectively. The one-dimensional inversion results and the one-dimensional inversion results of the transient electromagnetic method are stitched and fused in the depth domain to establish two-dimensional constraints as the initial model. Two-dimensional resistivity profiles corresponding to each of the comprehensive geophysical detection lines are obtained through joint inversion. Based on the obtained two-dimensional resistivity profiles, the high and low resistivity anomaly boundaries of the concealed copper-gold ore target area are extracted, and a three-dimensional apparent resistivity data volume is constructed to realize the three-dimensional positioning and morphological parameter calculation of the concealed copper-gold ore target area.

[0008] Furthermore, the use of a quantum magnetometer based on diamond NV center technology for magnetic field measurement specifically includes: utilizing the electron spin magnetic resonance characteristics of nitrogen-vacancy defects in diamond, and achieving absolute measurement of weak electromagnetic signals through photodetector magnetic resonance technology. The quantum magnetometer is then used as a quantum magnetic field strength meter or a quantum geomagnetic field strength meter to obtain high-precision quantum magnetic field and quantum geomagnetic measurement data. In addition, the quantum magnetometer is compatible with quantum biomagnetic measurement and biomagnetic measurement applications, and can be used as a quantum biomagnetic field strength meter for signal pickup. Traditional induction magnets are prone to signal attenuation due to the superposition of ionized interference signals in urban-rural fringe areas or areas with dense high-voltage power lines. This invention utilizes the extremely high sensitivity of quantum energy level transitions to magnetic fields to effectively overcome the attenuation and distortion of deep signals in conventional exploration.

[0009] Furthermore, the data acquisition along each of the aforementioned integrated geophysical survey lines using the controlled-source audio-frequency magnetotelluric method specifically includes: deploying powered transmitters and receivers such that the distance between the transmitters is less than one-third of the transmitter-receiver distance; employing multiple superposition techniques for data acquisition, with the measurement frequency range set from 7680 Hz to 1.2 Hz, and real-time evaluation of the standard deviation of signal amplitude and phase to eliminate interfering data. In this data acquisition step, as a specific implementation method for quality monitoring, the system can also use the Carnia apparent resistivity mean square relative error for auxiliary monitoring, the calculation formula of which is as follows: In the formula, For the first The mean square relative error of apparent resistivity at each measuring point; To check the total number of observed frequency points; For the first The original observed apparent resistivity value at the measuring point; For the first The apparent resistivity value was checked and observed at each measuring point.

[0010] Furthermore, the secondary field data acquisition at the same point using the equivalent reverse flux transient electromagnetic method specifically includes: placing the transceiver antenna horizontally, maintaining a set distance between the transceiver antenna and the main instrument to avoid high-frequency electromagnetic interference, performing data superposition at least 200 times, and using repeated observations to calculate the average relative error of the total observation channel for data quality monitoring. The formula for calculating the average relative error is as follows: In the formula, This represents the total average relative error across all observation channels. For the first Point 1 Original observation data; For the first Point 1 Check the observation data; for and The average value; The number of tracks included in the statistics.

[0011] Furthermore, the preprocessing of the collected magnetotelluric response data and the secondary field data specifically includes: removing flying point data affected by strong electromagnetic interference; addressing the static offset phenomenon caused by local electrical inhomogeneities near the Earth's surface; setting a reference resistivity based on known geological specimen properties; performing static correction by shifting the apparent resistivity curve upwards or downwards; and supplementing this with topographic correction and field source correction.

[0012] Furthermore, obtaining the two-dimensional resistivity profile corresponding to each of the aforementioned integrated geophysical survey lines through joint inversion specifically includes: using a two-dimensional smooth model with topography, based on the aforementioned two-dimensional constraints, performing two-dimensional joint constraint inversion by fitting the apparent resistivity and phase curves through inversion, and outputting the two-dimensional resistivity profile.

[0013] Furthermore, constructing the three-dimensional apparent resistivity data volume specifically includes: mapping the two-dimensional resistivity profiles corresponding to multiple adjacent integrated geophysical detection lines to a three-dimensional spatial coordinate system; and using an interpolation algorithm to perform gridding processing on the data between the profiles to generate a continuous three-dimensional apparent resistivity data volume, so as to characterize the overall electrical distribution characteristics of the underground space medium.

[0014] Furthermore, the three-dimensional positioning and morphological parameter calculation of the concealed copper-gold ore target area specifically includes: delineating a low-resistivity closed area in three-dimensional space based on the high and low resistivity anomaly boundary as the inferred concealed copper-gold ore target area; calculating the maximum radius, top burial depth, and bottom burial depth of the concealed copper-gold ore target area; and estimating the total volume of the concealed copper-gold ore target area based on the three-dimensional spatial integral of the low-resistivity closed area.

[0015] Furthermore, the high-low resistivity anomaly boundary is the electrical difference interface between the target probe and its surrounding rock; the target probe is a concealed sulfide copper-gold ore body exhibiting low resistivity characteristics. As an extended application of the present invention, the target probe can also be a concealed salt mine water-filled cavity with the same low-resistivity physical response characteristics.

[0016] Furthermore, the deployment of multiple integrated geophysical exploration lines specifically includes: based on the regional geological structure, avoiding surface high-voltage power lines and obstacles, the integrated geophysical exploration lines are deployed in parallel, using a profile measurement method, with the measurement point spacing on each integrated geophysical exploration line set at 10 to 20 meters. This invention provides a three-dimensional positioning method for concealed copper-gold deposit target areas based on integrated geophysical data fusion. It has the following beneficial effects: 1. To address the technical challenge of extracting weak signals from deep locations under strong background electromagnetic noise, this invention innovatively employs a quantum magnetometer based on diamond NV centers for magnetic field measurement in controlled-source audio-frequency magnetotelluric detection. This approach leverages the extremely high sensitivity of quantum spin magnetic resonance to weak electromagnetic fields, effectively shielding against the superposition interference of surface high-voltage lines and stray currents, fundamentally improving the signal-to-noise ratio of deep response data in concealed target areas.

[0017] 2. To address the technical problems of multiple solutions in a single electromagnetic method and the difficulty in accurate spatial positioning using conventional two-dimensional interpretation, this invention integrates magnetotelluric and transient electromagnetic data at the same location for joint inversion constraints, and constructs a three-dimensional apparent resistivity data volume based on profile anomaly boundaries. This scheme eliminates equivalence bias in the inversion process, upgrading traditional qualitative inference to three-dimensional quantitative positioning of the spatial boundaries, burial depth, and geometric volume of concealed low-resistivity bodies.

[0018] 3. To address the problem of multiple solutions in a single electromagnetic method, this invention performs a two-dimensional joint constrained inversion by stitching together magnetotelluric and transient electromagnetic results in the depth domain and constructing a three-dimensional apparent resistivity data volume. This effectively reduces the equivalence bias of the inversion and achieves high-precision three-dimensional positioning of concealed mineral target areas. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a schematic diagram of the field survey line layout according to the present invention; Figure 3 This is a schematic diagram of the magnetotelluric data acquisition and quantum magnetometer receiving principle of the present invention; Figure 4 This is a schematic diagram illustrating the principle of the equivalent reverse flux transient electromagnetic method of the present invention; Figure 5 This is a two-dimensional joint inversion cross-section diagram of the present invention; Figure 6 This is a three-dimensional target area morphology localization diagram of the present invention.

[0020] It should be noted that in the various figures of this invention, solid arrows mainly represent the sequential execution order of method steps, physical connections of entities, or main current transmission paths; dashed arrows mainly represent magnetic field action paths, spatial signal radiation, data feedback directions, or auxiliary logical connections. Detailed Implementation

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see the appendix Figure 1 - Appendix Figure 6 This invention provides a three-dimensional localization method for concealed copper-gold deposit target areas based on integrated geophysical data fusion, comprising the following steps: An initial geological-geophysical model was established based on the geological background of the exploration area, and multiple integrated geophysical exploration lines were laid out in combination with topography and known information. Data was collected along each of the aforementioned integrated geophysical exploration lines using the controlled-source audio-frequency magnetotelluric method. In the electromagnetic field signal receiving stage, a quantum magnetometer based on diamond NV color center technology was used to measure the magnetic field and obtain the magnetotelluric field response data at each frequency point. On each of the aforementioned integrated object detection lines, the transient electromagnetic method is used to collect secondary field data at the same point; the transient electromagnetic method is the equivalent reverse magnetic flux transient electromagnetic method. During measurement, the receiving coil is placed on the primary field zero magnetic flux plane to eliminate interference from the primary field induced electromotive force and receive the secondary field data. The collected magnetotelluric response data and secondary field data are preprocessed and inverted to obtain one-dimensional inversion results of the controlled-source audio-frequency magnetotelluric method and the transient electromagnetic method, respectively. The one-dimensional inversion results and the one-dimensional inversion results of the transient electromagnetic method are stitched and fused in the depth domain to establish two-dimensional constraints as the initial model. Two-dimensional resistivity profiles corresponding to each of the comprehensive geophysical detection lines are obtained through joint inversion. Based on the obtained two-dimensional resistivity profiles, the high and low resistivity anomaly boundaries of the concealed copper-gold ore target area are extracted, and a three-dimensional apparent resistivity data volume is constructed to realize the three-dimensional positioning and morphological parameter calculation of the concealed copper-gold ore target area.

[0023] In the specific implementation process, the preliminary geodetic preparation and geological model construction work in the above process are carried out first.

[0024] Based on geological data from boreholes and mines in the target area, the distribution patterns and structural characteristics of stratigraphic lithology are extracted to establish an initial geological-geophysical model. This model clearly defines the interface of electrical differences between the target probe and its surrounding rocks, and uniformly defines concealed sulfide copper-gold orebodies or water-bearing salt cavities as low-resistivity anomalies with significant differences from the surrounding rocks.

[0025] Based on the established initial geological-geophysical model and the site's topographic features, multiple integrated geophysical survey lines were laid out in parallel. The principle for laying these lines was to ensure they intersect perpendicularly or at a large angle with the inferred structural orientation of the concealed target body. To minimize near-source electromagnetic interference, the survey lines were strictly avoided from surface high-voltage power lines, transformers, and large metal structures. A profiling method was used, with physical measurement points sequentially laid out and marked along the survey lines according to pre-set point spacing. In this embodiment, the measurement point spacing along each integrated geophysical survey line was specifically set to 10 to 20 meters to balance detection resolution and construction efficiency.

[0026] Geodetic work employs real-time dynamic carrier phase differential technology to obtain the three-dimensional spatial coordinates of the measurement points. The measurement coordinate system is set as the national standard geodetic coordinate system, and a standard elevation datum is used. During the measurement process, instrument accuracy is calibrated at known control points to ensure stable communication between the base station and the rover station, and that the number of effectively received satellite signals meets the accuracy requirements for fixed solution calculations.

[0027] To ensure the quality of geodetic data across the region, this embodiment employs a re-measurement and verification mechanism using the same instrument at different times for quality control. The accuracy of the three-dimensional spatial coordinate acquisition is measured by calculating the mean square errors of the longitudinal and transverse coordinates of physical measurement points, the mean square errors of the planar positions, and the mean square errors of the elevations. The calculation methods for the mean square errors of each accuracy evaluation are as follows: Mean error of the ordinate of the measuring point: Mean error of the x-coordinate of the measuring point: The mean square error of the plane position of the measuring point: Mean error of elevation of measuring point: In the above formula, The vertical axis error; The x-axis error; This refers to the positional error of a point in the plane. This refers to the elevation error; For the first The difference between the observed ordinate values ​​and the known theoretical coordinate values ​​of each checkpoint; For the first The difference between the observed x-coordinate values ​​and the known theoretical coordinate values ​​of each checkpoint; For the first The difference between the observed elevation value and the known theoretical elevation value of each checkpoint; This represents the total number of checkpoints participating in the statistical analysis.

[0028] In practice, all error values ​​must be controlled within the threshold range allowed by the exploration specifications. Through the above-mentioned rigorous error verification and quality control, the authenticity and validity of the acquired coordinate system data are ensured, thereby providing a high-precision spatial location benchmark for subsequent magnetotelluric inversion and three-dimensional anomaly boundary characterization.

[0029] In this embodiment of the invention, after completing the initial geodetic survey, magnetotelluric data acquisition based on quantum magnetic field measurement is carried out. When conventional controlled-source audio-frequency magnetotelluric methods receive weak electromagnetic signals from deep sources, the traditional induction magnets rely on the law of electromagnetic induction and are highly susceptible to severe interference from high-voltage lines on the surface of the survey area and stray currents underground, resulting in severe distortion and attenuation of low-frequency data.

[0030] To address the shortcomings of this technology, this invention abandons the conventional receiving coil in the electromagnetic field signal receiving stage and employs a quantum magnetometer based on diamond NV color center technology for magnetic field measurement. This detection system uses the nitrogen-vacancy defect structure in diamond as its underlying core and utilizes the electron spin magnetic resonance characteristics to perform highly sensitive absolute measurement of weak alternating magnetic fields in space.

[0031] To overcome the challenges of sensor selection in large-area, deep-depth geophysical exploration operations, this embodiment preferentially uses a quantum magnetometer based on diamond NV color center technology. Compared with other magnetic measurement technologies, this solution has the following irreplaceable advantages: First, the advantages of frequency band matching and noise immunity. In this embodiment, the measurement frequency of the controlled-source audio-frequency magnetotelluric method is set to 7680 Hz to 1.2 Hz. Traditional induction coils are susceptible to severe interference from 50 Hz power frequency and harmonics in this frequency band; while the NV color center quantum magnetometer utilizes the electron spin magnetic resonance characteristic to detect transitions by locking a specific microwave frequency. It is an absolute quantity measurement and does not rely on Faraday's law of electromagnetic induction. Therefore, it has a natural physical shielding effect against macroscopic low-frequency stray currents generated by high-voltage lines and large metal structures on the surface of the mining area.

[0032] Second, it overcomes the size and environmental limitations in deep penetration detection. Compared to superconducting magnetometers that require cryogenic cooling, the NV color center quantum magnetometer can operate stably at room temperature, and its sensor probe can be highly miniaturized, greatly reducing the difficulty of dense wiring in large-area, complex terrain mining areas.

[0033] Third, the complementary integration with transient electromagnetic methods. Addressing the potential 1 / f noise limitation of NV color center technology in deep penetration magnetotelluric exploration from extremely low frequencies (below 1 Hz) of natural sources, this invention does not employ a single magnetotelluric extremely low frequency bathymetry method. Instead, it controls the lower limit of the detection frequency band to 1.2 Hz and innovatively introduces the equivalent back flux transient electromagnetic method at the same location to collect secondary field data in the shallow to mid-depth region. By stitching and fusing the transient electromagnetic method with the controlled-source audio-frequency magnetotelluric method in the depth domain, it not only leverages the advantage of NV color centers in high signal-to-noise ratio detection in the audio band but also effectively compensates for deep-level constraints, avoiding the limitations of a single technology in deep-depth exploration.

[0034] Specifically, under the influence of a weak magnetotelluric field in the target area, the ground-state electron spin energy level of the diamond NV color center will undergo Zeeman splitting. The detection system initializes it with optical pumping using a laser of a specific wavelength, and simultaneously applies a swept-frequency microwave field to excite its electron spin to resonantly flip. The fluorescence intensity change caused by the energy level transition is captured by optically probed magnetic resonance technology, thereby accurately calculating the transient intensity of the magnetotelluric field at the test point.

[0035] This measurement mechanism, based on microscopic quantum state energy level transitions, physically isolates the interference of macroscopic free currents. As a high-precision quantum geomagnetic field strength meter, the quantum magnetometer is perfectly suited for quantum geomagnetic measurements in complex electromagnetic environments. Furthermore, this core detection technology is also compatible with quantum biomagnetic measurement applications, enabling it to be used as a quantum biomagnetic field strength meter for cross-domain pickup of extremely weak signals.

[0036] During field deployment of the survey line, the detection system transmits a frequency-converted alternating current to the target underground via the power supply electrodes at the transmitting end. By adjusting the transmit-receive distance between the transmitting electrode spacing (formed by the connection of the power supply electrodes) and the receiving area at the measurement point, the requirement that the transmit-receive distance length be less than one-third of the transmit-receive distance is strictly met. This spatial deployment constraint ensures that the signal observed at the receiving end satisfies the plane wave source assumption for far-field radiation, eliminating non-plane wave effects caused by the near-field and transition regions.

[0037] During actual data acquisition, the system employs a multiple-overlay technique, setting the measurement frequency range to 7680 Hz to 1.2 Hz. Within the preset frequency sweep range, signals are sent and received point by point. To ensure the reliability of the raw field data, the data acquisition platform synchronously and in real-time evaluates the standard deviation of the signal amplitude and phase at each frequency point, eliminating interference data that exceeds the error threshold.

[0038] To further quantify the observation quality of the system-wide inspection, this embodiment uses the Carnia apparent resistivity mean square relative error index for systematic data quality monitoring of the collected electromagnetic field response data. The formula for calculating this mean square relative error is as follows: In the above formula, Representing the The mean square relative error of apparent resistivity of Carnia at each physical measurement point; This represents the total number of observation frequency points at that measurement point that participated in the statistical analysis; Representing the The raw observed apparent resistivity values ​​were acquired by the system at each frequency point; This represents the apparent resistivity value obtained by retesting using the system at the same measurement point and frequency.

[0039] By performing the above calculations and evaluations on all quality inspection points in the entire region, when the mean square relative error of the obtained apparent resistivity is strictly controlled within the qualified threshold set by the exploration specifications, the data based on quantum magnetic field measurements is determined to be true and valid, thus providing basic data support with a high signal-to-noise ratio for the subsequent extraction of deep structural features of the hidden target area.

[0040] In this embodiment of the invention, after acquiring the magnetotelluric field response data, in order to compensate for the limitations of single frequency domain electromagnetic detection in the vertical resolution of shallow and middle strata, the system uses transient electromagnetic method to collect secondary field data at the same location on each of the aforementioned integrated geophysical detection lines.

[0041] In conventional transient electromagnetic systems, the strong primary field induced electromotive force generated at the moment the transmitting coil is turned off can severely mask the weak shallow secondary field signal, creating a detection blind zone. To address this issue, the transient electromagnetic method described in this embodiment specifically employs the equivalent anti-magnetic flux transient electromagnetic method, which receives a pure signal through the mutual cancellation of the magnetic fields in physical space.

[0042] In actual field operations, the system employs a dual-transmitting coil structure with parallel upper and lower sections. When transmitting the primary field, equal and opposite currents are applied to the two transmitting coils, creating a plane on the plane of symmetry between the two coils where the combined magnetic flux of the primary field is always zero. During measurement, the receiving coil is strictly positioned on this zero-flux plane of the primary field.

[0043] Through the aforementioned zero flux surface receiving mechanism, the receiving coil can effectively eliminate the coupling effect interference caused by the primary field turn-off delay, and directly receive the secondary field data induced by the underground concealed geological body. This acquisition method does not require a long turn-off time, significantly improving the morphological resolution capability for shallow to medium-depth concealed low-resistivity target areas.

[0044] During the survey line setup phase, operators kept the transceiver antenna horizontal and maintained a set safe distance between it and the main unit of the instrument to prevent high-frequency electromagnetic interference from the operation of the internal electronic components of the main unit on the weak secondary field signal. Simultaneously, to effectively suppress random noise in the field, the number of superpositions of the secondary field data at a single point was set to no less than 200.

[0045] To ensure the reliability and rigor of multi-source geophysical data acquisition across the entire line, this embodiment conducts a rigorous quality assessment of the secondary field data acquired using the equivalent back flux transient electromagnetic method. At the same physical measurement points in the field, repeated observations are used to obtain inspection data, and the average relative error of the total observation channels is used for overall data quality monitoring. The formula for calculating this average relative error is as follows: In the above formula, This represents the total average relative error of all transient electromagnetic observation channels; Representative at the At the first measuring point Raw observation data acquired in each time channel; Represents the same first At the first measuring point Inspection and observation data acquired at each time point; Represents the original observation data With the inspection and observation data The arithmetic mean; This represents the total number of valid channels participating in this statistical analysis.

[0046] In actual exploration, the data processing system calculates and verifies the average relative error of each measuring point in real time. Measuring points exceeding the specified error threshold are discarded and re-measured in their original locations. This quality control process ensures that the magnetotelluric response data and secondary field data ultimately imported into the preprocessing module meet the quality requirements for high-precision integrated inversion.

[0047] In this embodiment of the invention, after completing the acquisition and quality monitoring of multi-source geophysical data, the system preprocesses the acquired magnetotelluric field response data and the secondary field data, and obtains a two-dimensional resistivity profile in the survey area by multi-dimensional joint inversion to eliminate non-uniqueness.

[0048] The preprocessing stage first edits the original sequence recorded by the acquisition system to identify and remove distorted flying point data caused by occasional strong electromagnetic interference.

[0049] Because near-surface geological bodies often contain localized electrically inhomogeneous bodies, high-frequency bands are prone to electromagnetic field distortion, causing the apparent resistivity curve across the entire frequency band to shift in a logarithmic coordinate system—a phenomenon known as static offset. To address this static offset, the system sets a reference resistivity for the target stratum based on measured physical property parameters from known geological samples within the exploration area. Using this reference resistivity, the distorted apparent resistivity curve is shifted upwards or downwards to complete static correction. Subsequently, topographic correction and field source correction are performed using measured topographic elevation data from the exploration area to obtain electromagnetic field data reflecting the true underground electrical structure.

[0050] In the process of geophysical data inversion, the results of inversion using a single method often suffer from severe ambiguity. To address this, this embodiment constructs a two-dimensional joint constraint inversion mechanism based on the fusion of multi-source prior information.

[0051] The system extracts the pre-processed one-dimensional inversion results from the transient electromagnetic method and the controlled-source audio-frequency magnetotelluric method. Since the transient electromagnetic method has extremely high vertical resolution for shallow to mid-depth strata, while the controlled-source audio-frequency magnetotelluric method has a penetrating advantage in deep exploration, the system stitches and fuses the two one-dimensional inversion results in the depth domain to construct an initial model for the two-dimensional inversion. This initial model provides highly valuable prior constraints for subsequent iterations, effectively narrowing the inversion solution space.

[0052] After completing the initial model construction, the system employs a two-dimensional smoothed model inversion algorithm with terrain features to fit the preprocessed observed apparent resistivity and phase curves. The essence of this two-dimensional joint inversion process is to optimize a regularized objective function containing model smoothing constraints, minimizing the inversion objective function. The formula for calculating this inversion objective function is as follows: In the above formula, Represents the inversion objective function; This represents the preprocessed observation data vector, which includes the apparent resistivity and phase observations at each frequency point. Represents the forward response operator; This represents the parameter matrix of the underground grid model to be solved; This represents the initial model constructed by fusing magnetotelluric and transient electromagnetic data; The weighted variance matrix represents the data and is used to measure the reliability of each observation. The model smoothness constraint matrix is ​​used to ensure the continuity of electrical variations between adjacent grids; This represents the regularization parameter, used to balance the data fitting residuals with the smoothness of the model structure.

[0053] By continuously updating the model parameter matrix and performing forward modeling, the inversion algorithm achieves convergence of the fitting residuals between the calculated response and the actual observed data after multiple iterations. Finally, the inversion objective function is minimized to output a high-precision two-dimensional resistivity profile. This profile accurately reflects the electrical distribution characteristics of deep, concealed geological bodies and overcomes the problem of multiple solutions in conventional exploration data at the algorithmic level.

[0054] In this embodiment of the invention, after obtaining a two-dimensional resistivity profile in the test area that eliminates non-uniqueness, the system extracts the high and low resistivity anomaly boundaries of the concealed copper-gold ore target area based on the two-dimensional inversion results of multiple adjacent test lines, and then constructs a three-dimensional apparent resistivity data volume to realize the three-dimensional positioning and morphological parameter calculation of the target area.

[0055] The system first maps the two-dimensional resistivity profiles corresponding to multiple adjacent integrated geophysical detection lines to a three-dimensional spatial coordinate system. Since there are physical detection intervals between adjacent profiles, the system uses interpolation algorithms (such as Kriging interpolation or inverse distance weighted interpolation) to mesh the data between profiles. This process generates continuously distributed grid nodes in the three-dimensional spatial domain and assigns corresponding resistivity attribute values, thereby constructing a three-dimensional apparent resistivity data volume that fully reflects the overall electrical distribution characteristics of the underground spatial medium.

[0056] Based on the constructed three-dimensional apparent resistivity data volume, the system, combined with the regional geological and rock physical characteristics, tracks and extracts the electrical difference interface between the target probe and its surrounding rock, i.e., the high and low resistivity anomaly boundary. By setting a low resistivity threshold characterizing the target lithology, the system extracts and delineates closed low resistivity isosurfaces in the three-dimensional data volume, defining the closed low resistivity region in this three-dimensional space as the inferred concealed target area.

[0057] After completing the three-dimensional spatial delineation of the concealed target area, the system quantitatively calculates its spatial distribution characteristics and morphological parameters. The system directly extracts the minimum and maximum depth coordinates in the vertical direction from the three-dimensional spatial coordinate matrix of the low-resistivity closed area, and marks them as the top and bottom burial depths of the concealed target area, respectively; at the same time, it calculates the maximum geometric span of the closed boundary on the horizontal projection plane to obtain the maximum radius of the target area.

[0058] To estimate the total volume of the concealed target area, the system performs a three-dimensional spatial integration operation on the extracted low-resistivity closed region. The formula for calculating the total volume is as follows: In the above formula, The total calculated volume representing the concealed target region; The geometric boundary conditions represent the three-dimensional closed low-resistivity region defined by the high and low resistance anomaly boundaries. , , These represent the x-coordinate, y-coordinate, and depth coordinates in a three-dimensional Cartesian coordinate system, respectively.

[0059] In actual geophysical exploration, sulfide-buried copper-gold deposits and water-filled concealed salt caverns exhibit highly consistent physical equivalence in electromagnetic detection responses; that is, the relatively dense surrounding rocks both display extremely obvious low-resistivity and high-conductivity anomalies. To accurately verify the accuracy and feasibility of the integrated geophysical three-dimensional positioning method described in this invention, this embodiment uses a salt cavern concealed cavern exploration area as an equivalent physical verification field.

[0060] The data acquisition, fusion inversion, and 3D reconstruction methods provided by this invention were applied to the verification area. The final extracted 3D morphology of the target area showed obvious banded and ellipsoidal distribution patterns. Automatic calculations by the system determined that the top slab of this deep, concealed, low-resistivity target area was buried between 190 and 320 meters underground, with the bottom slab extending downwards. The calculated total volume of the target area was greater than 7.22 million cubic meters. These measured 3D calculation results highly matched the previously known detection data, fully demonstrating that this method can accurately output the 3D spatial positioning and quantitative geometric morphology indicators of deep, concealed target areas, providing reliable digital geological data for subsequent physical drilling and underground engineering development.

[0061] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A three-dimensional localization method for concealed copper-gold deposit target areas based on integrated geophysical data fusion, characterized in that, Includes the following steps: An initial geological-geophysical model was established based on the geological background of the exploration area, and multiple integrated geophysical exploration lines were laid out in combination with topography and known information. Data was collected along each of the aforementioned integrated geophysical exploration lines using the controlled-source audio-frequency magnetotelluric method. In the electromagnetic field signal receiving stage, a quantum magnetometer based on diamond NV color center technology was used to measure the magnetic field and obtain the magnetotelluric field response data at each frequency point. On each of the aforementioned integrated object detection lines, the transient electromagnetic method is used to collect secondary field data at the same point; the transient electromagnetic method is the equivalent reverse magnetic flux transient electromagnetic method. During measurement, the receiving coil is placed on the primary field zero magnetic flux plane to eliminate interference from the primary field induced electromotive force and receive the secondary field data. The collected magnetotelluric response data and secondary field data are preprocessed and inverted to obtain one-dimensional inversion results of the controlled-source audio-frequency magnetotelluric method and the transient electromagnetic method, respectively. The one-dimensional inversion results are spliced ​​and fused with the one-dimensional inversion results of the transient electromagnetic method in the depth domain to establish two-dimensional constraints as an initial model. Two-dimensional resistivity profiles corresponding to each of the comprehensive geophysical detection lines are obtained through joint inversion. Based on the obtained two-dimensional resistivity profiles, the high and low resistivity anomaly boundaries of the concealed copper-gold ore target area are extracted, and a three-dimensional apparent resistivity data volume is constructed to realize the three-dimensional positioning and morphological parameter calculation of the concealed copper-gold ore target area.

2. The method for three-dimensional localization of concealed copper-gold deposit target areas based on integrated geophysical data fusion according to claim 1, characterized in that, The specific methods for magnetic field measurement using a quantum magnetometer based on diamond NV color center technology include: By utilizing the electron spin magnetic resonance characteristics of nitrogen-vacancy defects in diamond, the absolute measurement of weak electromagnetic signals can be achieved through optically detected magnetic resonance technology. The quantum magnetometer can be used as a quantum magnetic field strength meter or a quantum geomagnetic field strength meter to obtain high-precision quantum magnetic field measurement and quantum geomagnetic measurement data.

3. The method for three-dimensional localization of concealed copper-gold deposit target areas based on integrated geophysical data fusion according to claim 1, characterized in that, Data acquisition along each of the aforementioned integrated geophysical survey lines using the controlled-source audio-frequency magnetotelluric method specifically includes: The transmitter and receiver are configured with power supply so that the distance between the transmitters is less than one-third of the transmission distance. Data acquisition was performed using a multi-overlay technique, with the measurement frequency range set from 7680 Hz to 1.2 Hz. The standard deviation of signal amplitude and phase was evaluated in real time to eliminate interference data.

4. The method for three-dimensional localization of concealed copper-gold deposit target areas based on integrated geophysical data fusion according to claim 1, characterized in that, The acquisition of secondary field data at the same point using the equivalent reverse flux transient electromagnetic method specifically includes: Place the transceiver antenna horizontally, maintaining a set distance between it and the main instrument to avoid high-frequency electromagnetic interference. The data should be superimposed at least 200 times, and repeated observations should be used to calculate the average relative error of the total observation channels for data quality monitoring.

5. The method for three-dimensional localization of concealed copper-gold deposit target areas based on integrated geophysical data fusion according to claim 1, characterized in that, The preprocessing of the collected magnetotelluric response data and the secondary field data specifically includes: To remove flying point data affected by strong electromagnetic interference, and to address the static offset phenomenon caused by local electrical inhomogeneities near the Earth's surface, a reference resistivity is set based on known geological specimen properties. Static correction is performed by shifting the apparent resistivity curve upwards or downwards, supplemented by topographic correction and field source correction.

6. The method for three-dimensional localization of concealed copper-gold deposit target areas based on integrated geophysical data fusion according to claim 1, characterized in that, The specific steps for obtaining the two-dimensional resistivity profiles corresponding to each of the aforementioned integrated geophysical lines through joint inversion include: A two-dimensional smooth model with terrain is adopted. Based on the two-dimensional constraints, two-dimensional joint constraint inversion is performed by inverting and fitting the apparent resistivity and phase curves to output the two-dimensional resistivity profile.

7. The method for three-dimensional localization of concealed copper-gold deposit target areas based on integrated geophysical data fusion according to claim 1, characterized in that, Constructing a three-dimensional apparent resistivity data volume specifically includes: The two-dimensional resistivity profiles corresponding to multiple adjacent composite detection lines are mapped to a three-dimensional spatial coordinate system; Interpolation algorithms are used to mesh the data between profiles to generate a continuous three-dimensional apparent resistivity data volume, which characterizes the overall electrical distribution characteristics of the underground space medium.

8. The method for three-dimensional localization of concealed copper-gold deposit target areas based on integrated geophysical data fusion according to claim 1, characterized in that, The specific steps for achieving three-dimensional localization and morphological parameter calculation of the concealed copper-gold ore target area include: The low-resistivity closed region in three-dimensional space is delineated based on the high and low resistivity anomaly boundary as the inferred target area of ​​the concealed copper-gold deposit. The maximum radius, top burial depth, and bottom burial depth of the concealed copper-gold ore target area are calculated, and the total volume of the concealed copper-gold ore target area is estimated based on the three-dimensional spatial integral of the low-resistivity closed region.

9. The method for three-dimensional localization of concealed copper-gold deposit target areas based on integrated geophysical data fusion according to claim 8, characterized in that, The high and low resistivity anomaly boundary is the electrical difference interface between the target probe and its surrounding rock; the target probe is a concealed sulfide copper-gold ore body exhibiting low resistivity characteristics.

10. The method for three-dimensional localization of concealed copper-gold deposit target areas based on integrated geophysical data fusion according to claim 1, characterized in that, The deployment of multiple integrated geophysical survey lines specifically includes: Based on the regional geological structure, and avoiding surface high-voltage power lines and obstacles, the comprehensive object detection lines are laid out in parallel, using a profile measurement method, with the measurement point spacing on each comprehensive object detection line set at 10 to 20 meters.

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