Gravity four-storey building profile interpretation method and device

Abstract

The invention discloses a gravity four-storey building profile interpretation method and device, and belongs to the technical field of geological exploration. According to the method, the Bouguer gravity anomaly is decomposed into three layers of gravity anomalies including the mourhue surface gravity anomaly, the deep layer gravity anomaly and the shallow layer gravity anomaly, and the gravity-geology combined interpretation of different depth structures is realized by combining and utilizing the ground elevation-geological section established by the gravity point elevation and the geological map; the invention further provides an interpretation device for executing the gravity four-storey building profile interpretation method, software and hardware supporting facilities are perfect, and the interpretation method is convenient to popularize and use. The method can be applied to gravity data processing and interpretation, and is particularly suitable for regions with different development depths of structural layers, so that the capacity of gravity exploration for solving complex geological problems is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of geological exploration, and relates to a gravity data processing and interpretation method, in particular to a gravity four-story section interpretation method and device. Background Art

[0002] Gravity exploration is a geophysical exploration method that uses a gravimeter to collect gravity data and studies underground geological structures, minerals and resource distribution through data processing and geological interpretation. In gravity exploration, gravity data collection provides basic data for processing and interpretation. Gravity data processing extracts gravity anomalies of the geological target under study from gravity data. Geological interpretation is based on gravity theory and geological theory, and uses gravity anomalies and other exploration data to study underground geological structures, minerals and resource distribution. Therefore, geological interpretation of gravity data is one of the most important tasks in gravity exploration. There are two main methods for processing and interpretation of gravity exploration: area data processing and interpretation and profile data processing and interpretation. Among them, the gravity profile data processing and interpretation method in the prior art mainly obtains gravity data along the profile through field data collection, or obtains area gravity data through field data collection, and then extracts gravity data along a certain profile; after obtaining the profile gravity data, the regional gravity field is generally removed to obtain the residual gravity anomaly that reflects the basin basement undulation and the material distribution thereon; then, according to the gravity field theory and geological theory, the residual gravity anomaly is geologically analyzed and interpreted to obtain an understanding of the geology and mineral resource distribution of the study area.

[0003] The gravity profile interpretation in the existing technology all uses a gravity anomaly curve for geological interpretation, mainly uses the residual gravity anomaly curve for geological interpretation, and partially uses the Bouguer gravity anomaly curve for geological interpretation. It is difficult to carry out targeted and comprehensive interpretation of geological information from deep to shallow depths, resulting in the inability to fully explore the geological information contained in the gravity anomaly, and the geological relationship between deep and shallow structural layers cannot be intuitively revealed, which restricts the ability of gravity data to solve complex geological problems. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a gravity four-story profile interpretation method, so that the gravity anomalies of geological bodies at different depths can be intuitively displayed and reasonably understood, and the ability of gravity exploration to solve complex geological problems can be improved; Another object of the present invention is to provide an interpretation device for the gravity four-story profile interpretation method, which, compared with the conventional gravity profile interpretation method, can intuitively reveal the geological relationship between deep and shallow structural layers.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: A gravity four-story section interpretation method, the interpretation method comprising the following steps performed in sequence: S1. Obtaining the Bouguer gravity anomaly of the gravity measurement profile Collect gravity data along the gravity measurement profile to obtain the Bouguer gravity anomaly of the gravity measurement profile; S2. Calculation of Moho gravity response and isostatic gravity anomaly using regional terrain elevation and Bouguer gravity anomaly Collect elevation data, and according to the principle of static equilibrium of buoyancy, use the average density difference between the crust and the mantle to calculate the depth of the Moho surface, and further calculate the gravity response of the Moho surface; The equilibrium gravity anomaly is obtained by subtracting the Moho gravity response from the Bouguer gravity anomaly of the gravity measurement profile. S3. Perform data processing to separate deep gravity anomalies from shallow gravity anomalies Performing upward extension processing on the isostatic gravity anomaly at at least two heights respectively, to obtain upward extension gravity anomalies at at least two heights; Subtract each upward extension gravity anomaly from the equilibrium gravity anomaly to obtain the residual gravity anomaly corresponding to each extension height; The residual gravity anomaly corresponding to each extended height is matched and analyzed with the ground structural data to obtain the shallow structural gravity anomaly; The upward extension of the gravity anomaly corresponding to the shallow structural gravity anomaly is taken as the deep gravity anomaly; S4. Draw the gravity four-story section Three gravity anomaly profiles are drawn in layers, including shallow gravity anomaly profile, deep gravity anomaly profile and Moho gravity response profile, and arranged in layers of upper, middle and lower layers to obtain a gravity three-story profile; Above the gravity three-story section, a gravity four-story section is formed after drawing an elevation-geology section according to the elevation of the gravity measurement section measurement point and the strata and strata boundary positions and fracture positions passed by the gravity measurement section read from the geological map; S5. Conduct comprehensive geological interpretation of the four-story section The gravity anomaly profiles of different layers in the gravity four-story profile are used to explain the geological structures at different depths, thus realizing the comprehensive geological interpretation of the gravity four-story profile.

[0006] As a first limitation of the invention's gravity four-story profile interpretation method, in step S1, the method for obtaining the Bouguer gravity anomaly of the gravity measurement profile includes any one of the following two methods, the two methods including: The first method is to set up a gravity measurement profile vertically through the main structure in the study area, carry out field collection of gravity data, obtain the coordinates, elevation and gravity values ​​of the measuring points, and obtain the Bouguer gravity anomaly of the gravity measurement profile through gravity anomaly calculation; The second method is to deploy a gravity network in the study area, collect gravity data and calculate the Bouguer gravity anomaly, and then interpolate from the gravity plane data to obtain the Bouguer gravity anomaly of the gravity measurement profile.

[0007] As a second limitation of the invention's gravity four-story building profile interpretation method, in step S2, the range of the elevation data is a plane distance corresponding to a geographic longitude of not less than 1.5° extending from the boundary of the study area; The Moho surface depth is calculated by obtaining the average ground elevation within 1° of longitude and latitude with each elevation point as the center, and then calculating the Moho surface depth according to the buoyancy static equilibrium principle based on the average density difference between the crust and the mantle; The calculation of the Moho gravity response is to obtain the Moho gravity response by gravity forward calculation based on the burial depth of the Moho and the average density difference between the crust and the mantle; The gravity forward calculation includes a square cylinder model gravity calculation or a curved surface model gravity calculation.

[0008] As a third limitation of the gravity four-story profile interpretation method of the invention, in step S3, the matching analysis of the residual gravity anomaly corresponding to each extension height with the ground structure data includes: matching analysis of the residual gravity anomaly corresponding to each extension height with the ground structure data, and taking the residual gravity anomaly of a certain extension height with better matching as the shallow structure gravity anomaly; The matching analysis includes evaluating the matching of the location of the local high gravity anomaly with the location of the structure in the geological map, the width and amplitude of the local gravity anomaly with the width and amplitude of the structure in the geological map, etc.

[0009] As a fourth limitation to the invention's gravity four-story section interpretation method, in step S4, The horizontal axes of the three gravity anomaly profiles are the same, which are the distances from each measuring point of the gravity measurement profile to the first measuring point, or the horizontal coordinates or vertical coordinates of the gravity measuring points; the vertical axis is the gravity anomaly value; The drawing of the elevation-geological profile diagram includes: drawing a measuring point elevation curve with the horizontal axis of the three gravity anomaly profile diagrams as the horizontal axis and the gravity measuring point elevation as the vertical axis; The strata, strata boundary positions and fault positions that the gravity measurement profile passes through are read from the geological map, and the strata boundaries, strata symbols and fault boundaries are marked below the elevation curve of the measuring point to form an elevation-geological profile.

[0010] As the fifth limitation of the invention's four-story gravity profile interpretation method, in step S6, the geological structures at different depths are interpreted using the gravity anomaly profiles of different layers in the four-story gravity profile, including interpreting shallow structures using the fourth-layer elevation-geological profile and the third-layer shallow gravity anomaly profile; interpreting deep structures using the second-layer deep gravity anomaly profile; and interpreting Moho surface undulations using the first-layer Moho surface gravity response profile.

[0011] The present invention also provides an interpretation device for the gravity four-story profile interpretation method, the interpretation device comprises a Bouguer gravity anomaly acquisition module, a Moho gravity response and equilibrium gravity anomaly calculation module, a deep gravity anomaly and shallow gravity anomaly separation module, a gravity four-story profile drawing module, a comprehensive geological interpretation module and a central control module, wherein: The Bouguer gravity anomaly acquisition module is used to collect gravity data and obtain the Bouguer gravity anomaly of the gravity measurement section; The calculation module of the Moho gravity response and the equilibrium gravity anomaly is used to collect elevation data within the plane distance range corresponding to the expansion from the boundary of the study area, calculate the Moho gravity response; subtract the Moho gravity response from the Bouguer gravity anomaly of the gravity measurement profile to calculate the equilibrium gravity anomaly; The deep gravity anomaly and shallow gravity anomaly separation module is used to select the residual gravity anomaly corresponding to each extension height obtained based on the balanced gravity anomaly to obtain the shallow structural gravity anomaly; the upward extension gravity anomaly of the extension height corresponding to the shallow structural gravity anomaly is used as the deep gravity anomaly; The drawing module of the gravity four-story profile is used to draw the shallow gravity anomaly profile, the deep gravity anomaly profile and the Moho surface gravity response profile according to the upper, middle and lower layers. Figure 3 After obtaining the gravity anomaly profile, the elevation-geology profile is drawn by combining the gravity measurement point elevation and the geological map to form the gravity four-story profile. The comprehensive geological interpretation module is used to interpret geological structures at different depths using gravity anomaly profiles of different layers in the gravity four-story profile, thereby realizing comprehensive geological interpretation of the gravity four-story profile; The central control module is equipped with a control software module for controlling the Bouguer gravity anomaly acquisition module, the Moho gravity response and equilibrium gravity anomaly calculation module, the deep gravity anomaly and shallow gravity anomaly separation module, the gravity four-story profile drawing module and the signal flow and data processing in the comprehensive geological interpretation module.

[0012] As a limitation of the above interpretation device, the drawing module of the gravity four-story profile includes a gravity three-story profile drawing module and an elevation-geology profile drawing module, wherein: The gravity three-story profile drawing module is used to draw three gravity anomaly profiles including a shallow gravity anomaly profile, a deep gravity anomaly profile and a Moho gravity response profile, and arrange them in layers according to the upper, middle and lower layers to obtain a gravity three-story profile; The elevation-geological profile drawing module is used to draw a measuring point elevation curve above the gravity three-story profile, with the horizontal axis of the above three gravity anomaly profiles as the horizontal axis and the gravity measuring point elevation as the vertical axis; read the strata and stratum boundary positions and fracture positions passed by the gravity measurement profile from the geological map, mark the stratum boundaries and stratum symbols, and fracture boundaries below the measuring point elevation curve to form an elevation-geological profile.

[0013] As another limitation of the above-mentioned interpretation device, the comprehensive geological interpretation module includes interpreting shallow structures with the fourth layer elevation-geological profile and the third layer shallow gravity anomaly profile; interpreting deep structures with the second layer deep gravity anomaly profile; and interpreting Moho surface undulations with the first layer Moho surface gravity response profile.

[0014] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art: ① The gravity four-story profile interpretation method proposed in the present invention decomposes the Bouguer gravity anomaly into three layers of gravity anomaly including Moho gravity anomaly, deep gravity anomaly and shallow gravity anomaly, and establishes ground elevation-geological profile in combination with gravity point elevation and geological map, so as to realize the joint interpretation of geological structures at different depths. The interpretation method can also comprehensively study the interaction and influence of each layer of structure, improve the geological understanding of each depth, and thus improve the ability of gravity exploration to solve complex geological problems; ② Compared with the gravity anomaly profile in the prior art, which draws a certain gravity anomaly curve (such as the Bouguer gravity anomaly curve or the residual gravity anomaly curve), the gravity four-story profile interpretation method proposed in the present invention draws three gravity anomaly curves representing three depth structures in step S4, namely, the gravity three-story profile diagram, which includes the Moho gravity response reflecting the change of the buried depth of the bottom of the crust, the deep gravity anomaly reflecting the ups and downs of the deep structure, and the shallow structure gravity anomaly reflecting the distribution of the shallow structure; drawing the gravity anomaly curve according to the three depths is conducive to comparing and analyzing the differences and interaction relationships of structures at different depths. This information is not significant on a single gravity anomaly curve, and the corresponding geological understanding is also difficult to obtain; The present invention uses the elevation of the gravity measurement point as the ground surface to draw the geological profile, and marks the stratum boundaries, stratum symbols, and fracture boundaries in the elevation-geological profile, which is well integrated with the above-mentioned gravity three-story profile, and can more intuitively see the information of geological structures at different depths; ④ The present invention provides an interpretation device for executing the gravity four-story profile interpretation method, with complete software and hardware supporting facilities, which is convenient for the promotion and use of the test method.

[0015] The gravity four-story profile interpretation method and device provided by the present invention can be applied to the processing and interpretation of gravity data in a research area, and is particularly suitable for areas with different depths and shallow structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] Figure 1 This is a flow chart of a gravity four-story section interpretation method in Example 1 of the present invention; Figure 2 This is a schematic diagram of a Bouguer gravity anomaly curve of a gravity measurement profile in Example 1 of the present invention; Figure 3 It is a schematic diagram of a gravity four-story section of a gravity measurement section in Example 1 of the present invention; Figure 4 A structural block diagram of an interpretation device for a gravity four-story profile interpretation method provided in Example 2 of the present invention; in the figure: 1-central control module, 2-Bouguer gravity anomaly acquisition module, 3-Moho surface gravity response and equilibrium gravity anomaly calculation module, 4-deep gravity anomaly and shallow gravity anomaly separation module, 5-gravity four-story profile drawing module, 6-comprehensive geological interpretation module. DETAILED DESCRIPTION

[0018] The present invention will be further described in detail below by means of specific embodiments in combination with the accompanying drawings. It should be understood that the described embodiments are preferred examples of the present invention and are only used to explain the present invention and do not limit the present invention.

[0019] Example 1 A gravity four-story section interpretation method In a basin in Central Asia, before the Qinghai-Tibet Plateau was uplifted, the basin was in a process of subsidence, during which a set of salt rock strata developed in the Jurassic. After entering the Cenozoic Era, the Indian Plate and the Eurasian Plate collided and squeezed, and the basin was affected by the collision and compression. Due to the strong plasticity of the salt rock layer, the structural layer above the salt slipped and fractured along the rock layer, forming multiple rows of imbricate superimposed thrust belts. This phenomenon has been verified in ground geology and previous exploration research results, while the development of the subsalt structure is unclear. In order to strengthen geological research in this area, gravity exploration was carried out in the area, and some geological understandings were obtained, but a good understanding of the subsalt structure has not been achieved.

[0020] This embodiment takes the above-mentioned Central Asian basin study area as an example to provide a gravity four-story profile interpretation method, and its flow chart is as follows: Figure 1As shown, the interpretation method specifically includes the following steps performed in sequence: A gravity four-story section interpretation method, the interpretation method comprising the following steps performed in sequence: S1. Obtaining the Bouguer gravity anomaly of the gravity measurement profile Gravity data collection, obtaining the Bouguer gravity anomaly of the gravity measurement profile, specifically may include any one of the following two methods, the two methods include: the first method, arranging a gravity measurement profile vertically through the main structure in the study area, carrying out field gravity data collection, obtaining the coordinates, elevation and gravity values ​​of the measuring points, and obtaining the Bouguer gravity anomaly of the gravity measurement profile through gravity anomaly calculation; The second method is to deploy a gravity network within a certain range of the study area. After collecting gravity data and calculating the Bouguer gravity anomaly, the Bouguer gravity anomaly of the gravity measurement profile is interpolated from the gravity plane data.

[0021] The first method is selected in this embodiment, specifically: based on the terrain characteristics that the overall trend of the shallow structure in the study area is nearly north-south, an area gravity survey network is laid out in the gravity exploration design, and the survey line direction is east-west; Gravity data were collected in the field using gravity instruments and measuring equipment to obtain the coordinates, elevations and gravity values ​​of the gravity measuring points. The Bouguer gravity anomaly at different measuring points was obtained through gravity anomaly calculation. The Bouguer gravity anomaly curve of the gravity measurement profile was obtained by drawing with drawing software. Figure 2 Schematic diagram of the Bouguer gravity anomaly curve of a certain gravity measurement profile.

[0022] from Figure 2 It can be seen that the Bouguer gravity anomaly of the gravity measurement section has two major characteristics. First, the gravity value has a characteristic of decreasing significantly from left to right. Combined with existing research results, it can be seen that this feature is a reflection of the gradual deepening of the Moho surface from left to right in this area; second, multiple gravity highs and lows are arranged alternately on the gravity measurement section. Combined with ground geological data, it can be seen that this is a reflection of the imbricate thrust superposition of the suprasalt strata. However, the subsalt structural characteristics are not obvious and cannot be reasonably explained.

[0023] S2. Calculation of Moho gravity response and isostatic gravity anomaly using regional terrain elevation and Bouguer gravity anomaly In order to eliminate the influence of the gravity effect of the Moho surface, the elevation data of the study area and its surrounding areas were collected from public data sources. The elevation data range was extended by 300 km from the boundary of the study area, meeting the requirement that the plane distance corresponding to 1.5° geographic longitude (166.7 km) from the boundary of the study area should not be less than that. Then, the average ground elevation within 1° longitude and latitude was calculated with each calculation point as the center, that is, the smoothed ground elevation, and then the average crustal density of 2.67 g / cm was selected. 3 The average density of the mantle is 3.27 g / cm3 Average density difference -0.60g / cm 3 , according to the principle of crustal mass equilibrium, calculate the depth of Moho surface; The gravity calculation formula of the square cylinder model is used, based on the Moho surface burial depth and the density difference between the average density of the crust and the mantle -0.60g / cm 3 , calculate the Moho gravity response, and draw the Moho gravity response curve of the gravity measurement section. The Moho gravity response curve of a gravity measurement section is as follows: Figure 3 The first layer is shown in cross section; The equilibrium gravity anomaly is obtained by subtracting the Moho gravity response from the Bouguer gravity anomaly of the gravity measurement profile.

[0024] S3. Perform data processing to separate deep gravity anomalies from shallow gravity anomalies S31. In order to study the deep structural characteristics of the subsalt layer, the isostatic gravity anomaly was extended upward at multiple heights of 2km, 3km, 5km, 7km, 10km, and 15km to obtain the upward extended gravity anomaly at the corresponding heights; S32. Subtract each upward extension gravity anomaly from the equilibrium gravity anomaly to obtain the residual gravity anomaly corresponding to each extension height; S33. The residual gravity anomalies of the extended heights in all directions were compared with the ground structure and existing research results. After comparison, it was found that the residual gravity anomalies extended upward by 7 km had good matching with the ground structure and existing research results in terms of the location of the local gravity anomaly high and the location of the structure in the geological map, the width and amplitude of the local gravity anomaly and the width and amplitude of the structure in the geological map, which can basically reflect the characteristics of the geological structure above the salt. After comprehensive consideration, the residual gravity anomaly extended upward by 7 km was selected as the shallow structural gravity anomaly; S34. The upward extension of the gravity anomaly corresponding to the shallow structural gravity anomaly is taken as the deep gravity anomaly.

[0025] S4. Draw the gravity four-story section S41. Draw the gravity anomaly profile according to the upper, middle and lower layers, where the lower layer is the Moho gravity response profile, the second layer is the deep gravity anomaly profile, and the third layer is the shallow gravity anomaly profile, thus obtaining the gravity three-story profile; The horizontal axis of the gravity three-story section diagram is the distance, which is the distance from each measuring point to the first measuring point on the gravity measurement section, or the horizontal coordinate or vertical coordinate of the gravity measuring point; the vertical axis is the gravity anomaly value of the measuring point, which is the corresponding gravity anomaly value of the gravity measuring point; in this embodiment, the horizontal axis is the horizontal coordinate of each measuring point on the gravity measurement section diagram; The existing commonly used gravity anomaly profiles draw a certain gravity anomaly curve, such as the Bouguer gravity anomaly curve or the residual gravity anomaly curve. At this time, it is impossible to intuitively compare and analyze the differences and interactions between structures at different depths; the present invention draws three gravity anomaly curves representing structures at three depths, including a Moho gravity response profile reflecting the changes in the depth of the bottom of the crust, a deep gravity anomaly profile reflecting the ups and downs of the subsalt structure, and a shallow structure gravity anomaly profile reflecting the distribution of the structure above the salt. In this step of the present invention, the gravity anomaly curves are drawn according to three depths, which is conducive to comparing and analyzing the differences and interactions between structures at different depths.

[0026] S42. In order to make full use of ground geological data to carry out gravity interpretation, a measuring point elevation curve is drawn above the gravity three-story profile according to the elevation of the measuring point of the gravity measurement profile; the horizontal axis of the measuring point elevation curve is the horizontal coordinate of the measuring point, which has the same value as the three-story gravity anomaly profile, and the vertical axis is the elevation of the gravity measuring point; Then the gravity measurement section position is plotted on the geological map, and the strata and strata boundary positions passed by the gravity measurement section are read, and then the strata boundaries and strata symbols are marked below the elevation curve of the measuring point to form an elevation-geological section map; Finally, a gravity four-story building section is formed. The schematic diagram of the gravity four-story building section is as follows: Figure 3 shown.

[0027] S5. Conduct comprehensive geological interpretation of gravity four-story profiles The geological structures at different depths are explained by the gravity anomaly profiles of different layers in the four-story gravity profile. Specifically, the shallow structures are explained by the fourth-layer elevation-geological profile and the third-layer shallow gravity anomaly profile; the deep structures are explained by the second-layer deep gravity anomaly profile; and the Moho surface undulations are explained by the first-layer Moho surface gravity response profile. Furthermore, the interaction and influence of structures at different depths are comprehensively studied to improve the understanding of geological structures at each depth and realize the comprehensive geological interpretation of the four-story gravity profile.

[0028] Combined with this embodiment Figure 3 For example, the specific explanation is as follows: Figure 3 The third shallow gravity anomaly profile can identify the existence of 6 gravity highs within the profile range. The 4 gravity highs west of the horizontal coordinate 450000 have larger amplitudes, which corresponds well to Figure 3The anticlinal structure reflected by the Tertiary E1 stratum and the Upper Cretaceous K2 stratum on the elevation-geological profile of the fourth layer; the two gravity highs to the east of the horizontal coordinate 450000 show the characteristics of the gravity high amplitude gradually decreasing from west to east. They are not exposed on the elevation-geological profile of the fourth layer, reflecting the characteristics of the increasing buried depth of the structure they reflect. It can be seen that the information reflected by the shallow gravity anomaly profile of the third layer is consistent with that reflected by the elevation-geological profile of the fourth layer. In the second layer of deep gravity anomaly profile, the whole to the west of the horizontal coordinate 450000 presents a gravity high, including two gravity highs, which is consistent with the uplift zone inferred by previous researchers; the gravity low is presented to the east of the horizontal coordinate 450000, which is consistent with the depression zone inferred by previous researchers. In the first layer of Moho gravity response profile, the overall gravity value shows a trend of gradually decreasing from west to east, reflecting that the eastern part of this profile is closer to the Indian plate than the western part, and the depth of the Moho surface deepens from west to east. The above are the independent interpretation results of three sets of structural layers at deep and shallow depths. Comprehensive analysis of the three-layer gravity profiles reveals that there are large differences in the structures on the east and west sides, with the horizontal coordinate of 450,000 as the boundary. On the first-layer Moho gravity response profile, this position is roughly the inflection point of the Moho gravity response curve. The gravity curve on the west is relatively gentle, and the gravity curve on the east decreases faster toward the east; on the second-layer deep gravity anomaly profile, the whole area to the west of this position is a high gravity area, and the area to the east is a low gravity area, reflecting that this position is the boundary between the western uplift area and the eastern depression area, which is different from the conventional gravity anomaly profile (such as Figure 2 ) is difficult to find on the surface; on the shallow gravity anomaly profile of the third layer, the four gravity high amplitudes on the west side of the coordinate are large, and the two gravity high amplitudes on the east side are small, reflecting that the thrust and superposition of the supra-salt structural layer above the deep structural uplift area in the west is intense, while the thrust and superposition of the supra-salt structural layer in the deep structural depression area in the east is weak. This phenomenon is also confirmed by the ground elevation in the fourth layer elevation-geological profile and the widespread development of Quaternary strata on the ground.

[0029] From the above analysis, it can be seen that the gravity four-story profile interpretation method can reveal richer geological information than the traditional gravity anomaly profile interpretation method, study the geological structure characteristics at different depths, and reveal the mutual connection and influence of structures at different depths, which has great advantages for geological research in complex structural areas.

[0030] Embodiment 2 An interpretation device for a gravity four-story section interpretation method This embodiment provides an interpretation device for a gravity four-story section interpretation method. The block diagram of the interpretation device is as follows: Figure 4 As shown, it includes six modules: Bouguer gravity anomaly acquisition module 2, Moho gravity response and equilibrium gravity anomaly calculation module 3, deep gravity anomaly and shallow gravity anomaly separation module 4, gravity four-story profile drawing module 5, comprehensive geological interpretation module 6 and central control module 1, as follows: (1) The Bouguer gravity anomaly acquisition module 2 is used to collect gravity data and obtain the Bouguer gravity anomaly of the gravity measurement profile; (2) Module 3 for calculating the Moho gravity response and isostatic gravity anomaly is used to collect elevation data and calculate the Moho gravity response; The equilibrium gravity anomaly is calculated by subtracting the Moho gravity response from the Bouguer gravity anomaly of the gravity measurement profile; (3) The deep gravity anomaly and shallow gravity anomaly separation module 4 is used to select the residual gravity anomalies corresponding to each extension height obtained based on the equilibrium gravity anomaly to obtain the shallow structural gravity anomaly; the upward extension gravity anomaly of the extension height corresponding to the shallow structural gravity anomaly is used as the deep gravity anomaly; (4) Module 5 for drawing the gravity four-story profile is used to draw the shallow gravity anomaly profile, deep gravity anomaly profile and Moho gravity response profile according to the upper, middle and lower layers. Figure 3 After obtaining the gravity anomaly profile, the elevation-geology profile is drawn by combining the gravity measurement point elevation and the geological map to form the gravity four-story profile. The drawing module 5 of the gravity four-story profile includes a gravity three-story profile drawing module and an elevation-geology profile drawing module, wherein: The gravity three-story profile drawing module is used to draw three types of gravity anomaly profiles, including shallow gravity anomaly profile, deep gravity anomaly profile and Moho gravity response profile, in layers. The three layers are arranged in upper, middle and lower layers to obtain the gravity three-story profile. The elevation-geological profile drawing module is used to draw the measuring point elevation curve above the gravity three-story profile, with the horizontal axis of the above three gravity anomaly profiles as the horizontal axis and the gravity measuring point elevation as the vertical axis; read the strata and strata boundary positions and fracture positions passed by the gravity measurement profile from the geological map, mark the strata boundaries and strata symbols, and fracture boundaries below the measuring point elevation curve, and form an elevation-geological profile; (5) Comprehensive geological interpretation module 6 is used to interpret geological structures at different depths using gravity anomaly profiles of different layers in the gravity four-story profile, thereby realizing comprehensive geological interpretation of the gravity four-story profile; Specifically, it includes using the fourth layer elevation-geological profile and the third layer shallow gravity anomaly profile to explain shallow structures; using the second layer deep gravity anomaly profile to explain deep structures; and using the first layer Moho gravity response profile to explain Moho surface undulations.

[0031] (6) The central control module 1 is equipped with a control software module for controlling the signal flow and data processing in the Bouguer gravity anomaly acquisition module 2, the Moho gravity response and equilibrium gravity anomaly calculation module 3, the deep gravity anomaly and shallow gravity anomaly separation module 4, the gravity four-story profile drawing module 5 and the comprehensive geological interpretation module 6.

[0032] The above description is only an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A gravity four-story section interpretation method, characterized in that: The interpretation method comprises the following steps which are performed in sequence: S1. Bouguer gravity anomaly of gravity measurement profile obtained through gravity data acquisition Collect gravity data along the gravity measurement profile to obtain the Bouguer gravity anomaly of the gravity measurement profile; S2. Calculation of Moho gravity response and isostatic gravity anomaly using regional terrain elevation and Bouguer gravity anomaly Collect elevation data, and according to the principle of static equilibrium of buoyancy, use the average density difference between the crust and the mantle to calculate the depth of the Moho surface, and further calculate the gravity response of the Moho surface; The equilibrium gravity anomaly is obtained by subtracting the Moho gravity response from the Bouguer gravity anomaly of the gravity measurement profile. S3. Perform data processing to separate deep gravity anomalies from shallow gravity anomalies Performing upward extension processing on the isostatic gravity anomaly at at least two heights respectively, to obtain upward extension gravity anomalies at at least two heights; Subtract each upward extension gravity anomaly from the equilibrium gravity anomaly to obtain the residual gravity anomaly corresponding to each extension height; The residual gravity anomaly corresponding to each extended height is matched and analyzed with the ground structural data to obtain the shallow structural gravity anomaly; The upward extension of the gravity anomaly corresponding to the shallow structural gravity anomaly is taken as the deep gravity anomaly; S4. Draw the gravity four-story section Three gravity anomaly profiles are drawn in layers, including shallow gravity anomaly profile, deep gravity anomaly profile and Moho gravity response profile, and arranged in layers of upper, middle and lower layers to obtain a gravity three-story profile; Above the gravity three-story section, a gravity four-story section is formed after drawing an elevation-geology section according to the elevation of the gravity measurement section measurement point and the strata and strata boundary positions and fracture positions passed by the gravity measurement section read from the geological map; S5. Conduct comprehensive geological interpretation of the four-story section The gravity anomaly profiles of different layers in the gravity four-story profile are used to explain the geological structures at different depths, thus realizing the comprehensive geological interpretation of the gravity four-story profile.

2. The gravity four-story section interpretation method according to claim 1 is characterized in that: In step S1, the method for obtaining the Bouguer gravity anomaly of the gravity profile includes any one of the following two methods, wherein the two methods include: The first method is to set up a gravity measurement profile vertically through the main structure in the study area, carry out field collection of gravity data, obtain the coordinates, elevation and gravity values ​​of the measuring points, and obtain the Bouguer gravity anomaly of the gravity measurement profile through gravity anomaly calculation; The second method is to set up a gravity network in the study area, collect gravity data and calculate the Bouguer gravity anomaly, and then interpolate from the gravity plane data to obtain the Bouguer gravity anomaly of the gravity profile.

3. The gravity four-story section interpretation method according to claim 1 is characterized in that: In step S2, the Moho surface burial depth is calculated by obtaining the average ground elevation within 1° of longitude and latitude with each elevation point as the center, and then calculating the Moho surface burial depth according to the buoyancy static equilibrium principle based on the average density difference between the crust and the mantle; The calculation of the Moho gravity response is to obtain the Moho gravity response by gravity forward calculation based on the burial depth of the Moho and the average density difference between the crust and the mantle; The gravity forward calculation includes a square cylinder model gravity calculation or a curved surface model gravity calculation.

4. The gravity four-story section interpretation method according to claim 1 is characterized in that: In step S3, matching the residual gravity anomaly corresponding to each extended height with the ground structure data includes: matching and analyzing the residual gravity anomaly corresponding to each extended height with the ground structure data to obtain indicators including the location of the local high gravity anomaly, the width and amplitude of the gravity anomaly, and obtaining the shallow structure gravity anomaly.

5. The gravity four-story section interpretation method according to claim 1 is characterized in that: In step S4, the horizontal axes of the three gravity anomaly profiles are the same, which is the distance from each measuring point of the gravity measurement profile to the first measuring point, or the horizontal coordinate or vertical coordinate of the gravity measurement point; the vertical axis is the gravity anomaly value; The drawing of the elevation-geological profile diagram includes: drawing a measuring point elevation curve with the horizontal axis of the above three gravity anomaly profile diagrams as the horizontal axis and the gravity measuring point elevation as the vertical axis; The strata, strata boundary positions and fault positions that the gravity profile passes through are read from the geological map, and the strata boundaries, strata symbols and fault boundaries are marked below the elevation curve of the measuring point to form an elevation-geological profile.

6. The gravity four-story section interpretation method according to any one of claims 1 to 5, characterized in that: In step S6, the geological structures at different depths are explained by using the gravity anomaly profiles of different layers in the gravity four-story profile, including explaining the shallow structure by using the fourth-layer elevation-geological profile and the third-layer shallow gravity anomaly profile; Interpretation of deep structures using second-layer deep gravity anomaly profiles; The first Moho gravity response profile is used to explain the Moho surface fluctuation.

7. The interpretation device of the gravity four-story section interpretation method according to any one of claims 1 to 6, characterized in that: It includes the module for acquiring Bouguer gravity anomaly, the module for calculating Moho gravity response and equilibrium gravity anomaly, the module for separating deep gravity anomaly and shallow gravity anomaly, the module for drawing gravity four-story profile, the module for comprehensive geological interpretation and the central control module. The Bouguer gravity anomaly acquisition module is used to collect gravity data and obtain the Bouguer gravity anomaly of the gravity measurement section; The calculation module of the Moho gravity response and the equilibrium gravity anomaly is used to collect elevation data and calculate the Moho gravity response; the equilibrium gravity anomaly is calculated by subtracting the Moho gravity response from the Bouguer gravity anomaly of the gravity measurement profile; The deep gravity anomaly and shallow gravity anomaly separation module is used to select the residual gravity anomaly corresponding to each extension height obtained based on the balanced gravity anomaly to obtain the shallow structural gravity anomaly; the upward extension gravity anomaly of the extension height corresponding to the shallow structural gravity anomaly is used as the deep gravity anomaly; The drawing module of the gravity four-story building profile is used to draw three gravity anomaly profiles, namely, shallow gravity anomaly profile, deep gravity anomaly profile and Moho gravity response profile, according to the upper, middle and lower layers, and then draw the elevation-geological profile in combination with the gravity measurement point elevation and the geological map to form the gravity four-story building profile; The comprehensive geological interpretation module is used to interpret geological structures at different depths using gravity anomaly profiles of different layers in the gravity four-story profile, thereby realizing comprehensive geological interpretation of the gravity four-story profile; The central control module is equipped with a control software module for controlling the Bouguer gravity anomaly acquisition module, the Moho gravity response and equilibrium gravity anomaly calculation module, the deep gravity anomaly and shallow gravity anomaly separation module, the gravity four-story profile drawing module and the signal flow and data processing in the comprehensive geological interpretation module.

8. The interpretation device according to claim 7, characterized in that The drawing module of the gravity four-story profile includes a gravity three-story profile drawing module and an elevation-geology profile drawing module, wherein: The gravity three-story profile drawing module is used to draw three gravity anomaly profiles including a shallow gravity anomaly profile, a deep gravity anomaly profile and a Moho gravity response profile, and arrange them in layers according to the upper, middle and lower layers to obtain a gravity three-story profile; The elevation-geological profile drawing module is used to draw a measuring point elevation curve above the gravity three-story profile, with the horizontal axis of the above three gravity anomaly profiles as the horizontal axis and the gravity measuring point elevation as the vertical axis; read the strata and stratum boundary positions and fracture positions passed by the gravity measurement profile from the geological map, mark the stratum boundaries and stratum symbols, and fracture boundaries below the measuring point elevation curve to form an elevation-geological profile.

9. The interpretation device according to claim 7, characterized in that The comprehensive geological interpretation module includes interpreting shallow structures with the fourth layer elevation-geological profile and the third layer shallow gravity anomaly profile; Interpretation of deep structures using second-layer deep gravity anomaly profiles; The first Moho gravity response profile is used to explain the Moho surface fluctuation.

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