Gravity four-story building section interpretation method and device

Abstract

The present invention discloses a method and device for interpreting a four-story gravity profile, belonging to the field of geological exploration technology. The present invention decomposes the Bouguer gravity anomaly into three layers of gravity anomalies, including the Moho surface gravity anomaly, the deep gravity anomaly, and the shallow gravity anomaly, and combines the ground elevation-geological profile established using gravity point elevations and geological maps to achieve a combined gravity-geological interpretation of structures at different depths. The present invention also provides an interpretation device for executing the four-story gravity profile interpretation method, with complete hardware and software supporting facilities to facilitate the promotion and use of the interpretation method. The present invention can be applied to gravity data processing and interpretation, and is particularly suitable for areas with different deep and shallow structural layers, so as to improve the ability of gravity exploration to solve complex geological problems.

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 building profile interpretation method and device. Background Art

[0002] Gravity exploration is a geophysical exploration method that uses gravimeters to collect gravity data and study underground geological structure, mineral and resource distribution through data processing and geological interpretation. In gravity exploration, gravity data acquisition provides the foundational data for processing and interpretation. Gravity data processing extracts gravity anomalies from the gravity data, revealing the geological targets under investigation. Geological interpretation, based on gravity and geological theories, integrates gravity anomalies with other exploration data to study underground geological structure, mineral 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 data: area data processing and interpretation, and profile data processing and interpretation. Among them, the existing methods for processing and interpreting gravity profile data are mainly to obtain gravity data along the profile through field data collection, or to obtain areal gravity data through field data collection, and then extract 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 undulation of the basin basement and the distribution of materials on it; 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 using the residual gravity anomaly curve for geological interpretation, and partially using 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 inability to intuitively reveal the geological relationship between deep and shallow structural layers, 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, which enables the gravity anomalies of geological bodies at different depths to be intuitively displayed and reasonably understood, thereby improving the ability of gravity exploration to solve complex geological problems;

[0005] Another object of the present invention is to provide an interpretation device for the gravity four-story profile interpretation method, which can intuitively reveal the geological relationship between deep and shallow structural layers compared with conventional gravity profile interpretation methods.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A gravity four-story building section interpretation method, the interpretation method comprising the following steps performed in sequence:

[0008] S1. Obtaining the Bouguer gravity anomaly from the gravity measurement profile

[0009] Collect gravity data along the gravity measurement profile to obtain the Bouguer gravity anomaly of the gravity measurement profile;

[0010] S2. Calculate the Moho gravity response and isostatic gravity anomaly using regional topographic elevation and Bouguer gravity anomaly

[0011] Collect elevation data and, based on the principle of static equilibrium of buoyancy, use the average density difference between the crust and mantle to calculate the depth of the Moho surface, and further calculate the gravity response of the Moho surface;

[0012] The equilibrium gravity anomaly is obtained by subtracting the Moho gravity response from the Bouguer gravity anomaly of the gravity measurement profile.

[0013] S3. Perform data processing to separate deep gravity anomalies from shallow gravity anomalies

[0014] Performing upward extension processing on the equilibrium gravity anomaly at at least two heights to obtain upward extension gravity anomalies at at least two heights;

[0015] Subtract the upward extension gravity anomaly from the equilibrium gravity anomaly to obtain the residual gravity anomaly corresponding to each extension height;

[0016] The residual gravity anomaly corresponding to each extension height is matched and analyzed with the ground structural data to obtain the shallow structural gravity anomaly;

[0017] The upward extension of the gravity anomaly corresponding to the shallow structural gravity anomaly is taken as the deep gravity anomaly;

[0018] S4. Draw a gravity four-story cross-section

[0019] Three gravity anomaly profiles are drawn in layers, including shallow gravity anomaly profile, deep gravity anomaly profile and Moho gravity response profile. They are arranged in three layers (upper, middle and lower) to obtain a three-story gravity profile.

[0020] Above the gravity three-story section, a gravity four-story section is formed after drawing an elevation-geological section based on the elevations of the gravity measurement section points and the strata, stratum boundaries, and fracture positions passed by the gravity measurement section read from the geological map.

[0021] S5. Conduct comprehensive geological interpretation of the four-story section

[0022] The gravity anomaly profiles of different layers in the gravity four-story profile are used to interpret the geological structures at different depths, thus realizing the comprehensive geological interpretation of the gravity four-story profile.

[0023] As a first limitation of the invention's four-story gravity 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:

[0024] The first method is to lay out a gravity measurement profile vertically through the main structure in the study area, carry out field gravity data collection, obtain the coordinates, elevation and gravity values ​​of the measuring points, and calculate the gravity anomaly to obtain the Bouguer gravity anomaly of the gravity measurement profile;

[0025] 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.

[0026] 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 extending from the boundary of the study area by no less than 1.5° of geographic longitude;

[0027] The Moho depth is calculated by taking the average ground elevation within 1° of longitude and latitude with each elevation point as the center, and then calculating the Moho depth based on the average density difference between the crust and the mantle according to the principle of static equilibrium of buoyancy.

[0028] The Moho gravity response is calculated by forward gravity modeling based on the depth of the Moho and the average density difference between the crust and the mantle to obtain the Moho gravity response.

[0029] The gravity forward calculation includes a square cylinder model gravity calculation or a curved surface model gravity calculation.

[0030] As a third limitation of the four-story gravity profile interpretation method of the present invention, in step S3, matching and analyzing the residual gravity anomalies corresponding to each extension height with the ground structure data includes: matching and analyzing the residual gravity anomalies corresponding to each extension height with the ground structure data, and using the residual gravity anomaly of a certain extension height with better matching as the shallow structure gravity anomaly;

[0031] The matching analysis includes evaluating the matching between the location of the local high gravity anomaly and the location of the structure in the geological map, and the width and amplitude of the local gravity anomaly and the width and amplitude of the structure in the geological map.

[0032] As a fourth limitation of the invention's gravity four-story section interpretation method, in step S4,

[0033] The horizontal axis of the three gravity anomaly profiles is 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 measuring point; the vertical axis is the gravity anomaly value;

[0034] The drawing of the elevation-geological profile includes: drawing a measuring point elevation curve with the horizontal axis of the three gravity anomaly profiles as the horizontal axis and the elevation of the gravity measuring point as the vertical axis;

[0035] The strata, stratum boundary positions and fault positions passed by the gravity measurement profile are read from the geological map, and the stratum boundaries, stratum symbols and fault boundaries are marked below the elevation curve of the measuring point to form an elevation-geological profile.

[0036] As a fifth limitation of the invented gravity four-story profile interpretation method, in step S6, the gravity anomaly profiles of different layers in the gravity four-story profile are used to interpret geological structures at different depths, including using the fourth layer elevation-geological profile and the third layer shallow gravity anomaly profile to interpret shallow structures; using the second layer deep gravity anomaly profile to interpret deep structures; and using the first layer Moho gravity response profile to interpret Moho surface undulations.

[0037] The present invention also provides an interpretation device for the gravity four-story profile interpretation method, which includes a Bouguer gravity anomaly acquisition module, a Moho surface 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:

[0038] The Bouguer gravity anomaly acquisition module is used to collect gravity data and obtain the Bouguer gravity anomaly of the gravity measurement profile;

[0039] The calculation module for the Moho gravity response and the equilibrium gravity anomaly is used to collect elevation data within a plane distance range corresponding to the expansion of the study area boundary, calculate the Moho gravity response; and calculate the equilibrium gravity anomaly by subtracting the Moho gravity response from the Bouguer gravity anomaly of the gravity measurement profile.

[0040] The deep gravity anomaly and shallow gravity anomaly separation module 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;

[0041] The drawing module of the gravity four-story profile is used to draw the shallow gravity anomaly profile, deep gravity anomaly profile and 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.

[0042] 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 achieving comprehensive geological interpretation of the gravity four-story profile;

[0043] The central control module is equipped with a control software module for controlling the signal flow and data processing in the Bouguer gravity anomaly acquisition module, the Moho surface 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 comprehensive geological interpretation module.

[0044] As a limitation of the above interpretation device, the module for drawing the gravity four-story profile includes a module for drawing the gravity three-story profile and a module for drawing the elevation-geology profile, wherein:

[0045] 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 of upper, middle and lower layers to obtain a gravity three-story profile.

[0046] 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.

[0047] 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.

[0048] Due to the adoption of the above technical solution, the present invention has the following technical advancements compared with the prior art:

[0049] ① The four-story gravity profile interpretation method proposed in this invention decomposes the Bouguer gravity anomaly into three layers of gravity anomalies, including the Moho gravity anomaly, the deep gravity anomaly, and the shallow gravity anomaly. It then establishes a ground elevation-geological profile based on the gravity point elevation and geological map, thereby achieving a joint interpretation of geological structures at different depths. This interpretation method can also comprehensively study the interactions and influences of each layer of structure, improve geological understanding at each depth, and thus enhance the ability of gravity exploration to solve complex geological problems.

[0050] ② Compared with the prior art gravity anomaly profile that plots a single gravity anomaly curve (such as the Bouguer gravity anomaly curve or the residual gravity anomaly curve), the four-story gravity profile interpretation method proposed in the present invention plots three gravity anomaly curves representing structures at three depths in step S4—a three-story gravity profile. These curves include the Moho gravity response reflecting the depth variation of the crustal bottom, 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. Plotting the gravity anomaly curves at three depths facilitates comparative analysis of the differences and interactions between structures at different depths. This information is not significant on a single gravity anomaly curve, and the corresponding geological understanding is difficult to obtain.

[0051] The present invention uses the elevation of gravity measurement points as the ground surface to draw geological profiles, 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, making it possible to more intuitively see the information of geological structures at different depths;

[0052] 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 facilitates the promotion and use of the test method.

[0053] 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 study area, and is particularly suitable for areas with different deep and shallow structural layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0055] Figure 1 This is a flow chart of a gravity four-story building section interpretation method in Example 1 of the present invention;

[0056] 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;

[0057] Figure 3 This is a schematic diagram of a gravity four-story cross-section of a gravity measurement section in Example 1 of the present invention;

[0058] Figure 4 This is 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

[0059] The present invention will be further described in detail below by means of specific embodiments in conjunction with the accompanying drawings. It should be understood that the embodiments described are preferred examples of the present invention and are only used to explain the present invention and are not intended to limit the present invention.

[0060] Example 1 A gravity four-story building section interpretation method

[0061] Prior to the uplift of the Qinghai-Tibet Plateau, a basin in Central Asia was undergoing subsidence, with a salt rock formation developing within the Jurassic. During the Cenozoic, the Indian and Eurasian plates collided and compressed, impacting the basin and causing deformation. Due to the high plasticity of the salt rock, the supra-salt tectonic layers slipped and fractured along the rock strata, forming multiple rows of imbricate thrust belts. This phenomenon has been verified both in surface geology and previous exploration studies, but the extent of the subsalt structures remained unclear. To strengthen geological research in this area, gravity exploration has been conducted, yielding some geological insights, but a better understanding of the subsalt structures has remained elusive.

[0062] 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 1 As shown, the interpretation method specifically includes the following steps performed in sequence:

[0063] A gravity four-story building section interpretation method, the interpretation method comprising the following steps performed in sequence:

[0064] S1. Obtaining the Bouguer gravity anomaly from the gravity measurement profile

[0065] Gravity data collection to obtain the Bouguer gravity anomaly of the gravity measurement profile may specifically include any one of the following two methods: the first method is to arrange a gravity measurement profile vertically through the main structure in the study area, conduct field gravity data collection, obtain the coordinates, elevations and gravity values ​​of the measuring points, and calculate the gravity anomaly to obtain the Bouguer gravity anomaly of the gravity measurement profile;

[0066] 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 obtained by interpolation from the gravity plane data.

[0067] This embodiment uses the first method, specifically: based on the topographical characteristics of the shallow structure in the study area, which is generally in a north-south direction, an area gravity survey network is laid out in the gravity exploration design, with the survey line direction being east-west;

[0068] 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 plotting with drawing software. Figure 2 Schematic diagram of the Bouguer gravity anomaly curve of a certain gravity measurement profile.

[0069] from Figure 2 As can be seen from the figure, the Bouguer gravity anomaly on this gravity profile has two major characteristics. First, the gravity value decreases significantly from left to right. Combined with existing research results, this characteristic reflects the gradual deepening of the Moho surface from left to right in this area. Second, the gravity profile is interspersed with multiple gravity highs and lows. Combined with ground geological data, this reflects the imbrication of thrusts in the suprasalt strata. However, the subsalt structural characteristics are not obvious and cannot be reasonably explained.

[0070] S2. Calculate the Moho gravity response and isostatic gravity anomaly using regional topographic elevation and Bouguer gravity anomaly

[0071] To eliminate the influence of the gravity effect of the Moho surface, 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 to meet the requirement that the plane distance corresponding to 1.5° of geographic longitude (166.7 km) from the boundary of the study area should be no less than 1.5°. Then, the average ground elevation within 1° of longitude and latitude was calculated with each calculation point as the center, that is, the smoothed ground elevation. Then, the average crustal density of 2.67 g / cm was selected. 3 and the average density of the mantle is 3.27 g / cm 3 The average density difference is -0.60g / cm 3 , according to the principle of crustal mass equilibrium, calculate the depth of the Moho surface;

[0072] The gravity calculation formula of the square cylinder model is used, based on the Moho surface 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;

[0073] The equilibrium gravity anomaly is obtained by subtracting the Moho gravity response from the Bouguer gravity anomaly of the gravity measurement profile.

[0074] S3. Perform data processing to separate deep gravity anomalies from shallow gravity anomalies

[0075] S31. To study the structural characteristics of the deep subsalt layer, the isostatic gravity anomaly was extended upwards at various altitudes, such as 2km, 3km, 5km, 7km, 10km, and 15km, to obtain the upward extended gravity anomalies at the corresponding altitudes.

[0076] S32. Subtract each upward extension gravity anomaly from the equilibrium gravity anomaly to obtain the residual gravity anomaly corresponding to each extension height;

[0077] S33. The residual gravity anomalies at all extension heights were compared with the surface structure and existing research results. The comparison revealed that the residual gravity anomaly extending upward 7 km matched well with the surface structure and existing research results in terms of the location of the local high gravity anomaly and the location of the structure in the geological map, as well as the width and amplitude of the local gravity anomaly and the width and amplitude of the structure in the geological map. This indicates that the residual gravity anomaly extending upward 7 km can basically reflect the characteristics of the supra-salt geological structure. Based on comprehensive considerations, the residual gravity anomaly extending upward 7 km was selected as the shallow structural gravity anomaly.

[0078] S34. The upward extension of the gravity anomaly corresponding to the shallow structural gravity anomaly is used as the deep gravity anomaly.

[0079] S4. Draw a gravity four-story cross-section

[0080] S41. Draw a gravity anomaly profile according to the upper, middle, and lower layers. 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, resulting in a three-layer gravity profile.

[0081] The horizontal axis of the gravity three-story cross-section is the distance, which is the distance from each measuring point to the first measuring point on the gravity measurement cross-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 cross-section;

[0082] Existing commonly used gravity anomaly profiles plot a single gravity anomaly curve, such as the Bouguer gravity anomaly curve or the residual gravity anomaly curve, which makes it difficult to intuitively compare and analyze the differences and interactions between structures at different depths. The present invention plots three gravity anomaly curves representing structures at three depths: a Moho gravity response profile reflecting variations in crustal depth, a deep gravity anomaly profile reflecting the fluctuations of subsalt structures, and a shallow structural gravity anomaly profile reflecting the distribution of structures above the salt. Plotting gravity anomaly curves at three depths facilitates comparative analysis of the differences and interactions between structures at different depths.

[0083] S42. To fully utilize ground geological data for gravity interpretation, a measuring point elevation curve is drawn above the three-story gravity profile based on the elevations of the measuring points in the gravity measurement profile. The horizontal axis of the measuring point elevation curve represents the abscissa of the measuring point, which has the same value as the three-story gravity anomaly profile, and the vertical axis represents the elevation of the gravity measuring point.

[0084] Then the gravity measurement section position is plotted on the geological map, and the strata and stratum boundary positions passed by the gravity measurement section are read. The stratum boundaries and stratum symbols are then marked below the elevation curve of the measuring point to form an elevation-geological section map.

[0085] Finally, the cross section of the gravity four-story building is formed. The cross section diagram of the gravity four-story building is as follows: Figure 3 shown.

[0086] S5. Conduct comprehensive geological interpretation of the gravity four-story section

[0087] The gravity anomaly profiles of different layers in the four-story gravity profile are used to interpret the geological structures at different depths. Specifically, the shallow structures are interpreted using the fourth-layer elevation-geological profile and the third-layer shallow gravity anomaly profile; the deep structures are interpreted using the second-layer deep gravity anomaly profile; and the Moho surface undulations are interpreted using the first-layer Moho surface gravity response profile. Furthermore, a comprehensive study is conducted on the interactions and influences of structures at different depths to improve the understanding of geological structures at each depth and achieve a comprehensive geological interpretation of the four-story gravity profile.

[0088] 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 amplitudes of the 4 gravity highs to the west of the horizontal coordinate 450000 are large, which corresponds well to the Figure 3The fourth layer's elevation-geological profile shows anticline structures reflected in the Tertiary E1 and Upper Cretaceous K2 formations. Two gravity highs east of the horizontal coordinate 450,000 show a gradually decreasing amplitude from west to east. These highs are not visible on the fourth layer's elevation-geological profile, indicating an increasing depth of the structures they represent. The shallow gravity anomaly profile of the third layer agrees with the fourth layer's elevation-geological profile. In the second layer's deep gravity anomaly profile, the area west of the horizontal coordinate 450,000 exhibits a gravity high, including two highs, consistent with previously inferred uplift zones. A gravity low appears east of the horizontal coordinate, consistent with previously inferred depression zones. In the first layer's Moho gravity response profile, gravity values ​​generally decrease from west to east, reflecting that the eastern portion of the profile is closer to the Indian Plate than the western portion, and the Moho depth deepens from west to east. The above are the independent interpretation results of three sets of structural layers at deep and shallow levels. 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 side is relatively flat, and the gravity curve on the east side decreases faster towards the east. On the second-layer deep gravity anomaly profile, the entire 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. This is different from the conventional gravity anomaly profile (such as Figure 2 ) is difficult to find; 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 and the widespread development of Quaternary strata on the ground in the fourth layer elevation-geological profile.

[0089] 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. It has great advantages for geological research in complex structural areas.

[0090] Example 2: An interpretation device for a gravity four-story building section interpretation method

[0091] This embodiment provides an interpretation device for a gravity four-story cross-section interpretation method. The block diagram of the interpretation device is as follows: Figure 4As 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. The details are as follows:

[0092] (1) Bouguer gravity anomaly acquisition module 2 is used to collect gravity data and obtain the Bouguer gravity anomaly of the gravity measurement profile;

[0093] (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;

[0094] The equilibrium gravity anomaly is calculated by subtracting the Moho gravity response from the Bouguer gravity anomaly of the gravity measurement profile;

[0095] (3) The deep-layer gravity anomaly and shallow-layer gravity anomaly separation module 4 is used to select the residual gravity anomalies corresponding to the extension heights obtained based on the equilibrium gravity anomaly to obtain the shallow-layer structural gravity anomaly; the upward extension gravity anomaly of the extension height corresponding to the shallow-layer structural gravity anomaly is used as the deep-layer gravity anomaly;

[0096] (4) The drawing module 5 of the gravity four-story profile is used to draw the shallow gravity anomaly profile, deep gravity anomaly profile and 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.

[0097] 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:

[0098] 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. The three-story gravity profile is arranged in layers of upper, middle and lower layers to obtain the three-story gravity profile.

[0099] 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 three gravity anomaly profiles as the horizontal axis and the gravity measuring point elevation as the vertical axis; the strata and stratum boundary positions and fracture positions passed by the gravity measurement profile are read from the geological map, and the stratum boundaries and stratum symbols and fracture boundaries are marked below the measuring point elevation curve to form an elevation-geological profile;

[0100] (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 achieving comprehensive geological interpretation of the gravity four-story profile;

[0101] Specifically, it includes using the fourth layer elevation-geological profile and the third layer shallow gravity anomaly profile to interpret shallow structures; using the second layer deep gravity anomaly profile to interpret deep structures; and using the first layer Moho gravity response profile to interpret Moho surface undulations.

[0102] (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 surface 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.

[0103] The above description is merely an optional embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A gravity four-story building section interpretation method, characterized in that: The interpretation method comprises the following steps, performed in sequence: S1. Bouguer gravity anomaly of the gravity 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. Calculate the Moho gravity response and isostatic gravity anomaly using regional topographic elevation and Bouguer gravity anomaly Collect elevation data and, based on the principle of static equilibrium of buoyancy, use the average density difference between the crust and 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 equilibrium gravity anomaly at at least two heights to obtain upward extension gravity anomalies at at least two heights; Subtract the 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 extension 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 a gravity four-story cross-section Three gravity anomaly profiles are drawn in layers, including shallow gravity anomaly profile, deep gravity anomaly profile and Moho gravity response profile. They are arranged in three layers (upper, middle and lower) to obtain a three-story gravity profile. Above the gravity three-story section, a gravity four-story section is formed after drawing an elevation-geological section based on the elevations of the gravity measurement section points and the strata, stratum boundaries, 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 interpret 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, 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: The first method is to lay out a gravity measurement profile vertically through the main structure in the study area, carry out field gravity data collection, obtain the coordinates, elevation and gravity values ​​of the measuring points, and calculate the gravity anomaly to obtain the Bouguer gravity anomaly of the gravity measurement profile; 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 profile.

3. The gravity four-story section interpretation method according to claim 1, characterized in that: In step S2, the Moho surface depth is calculated by obtaining the average ground elevation within 1° of longitude and latitude centered at each elevation point, and then calculating the Moho surface depth according to the principle of static equilibrium of buoyancy based on the average density difference between the crust and the mantle; The Moho gravity response is calculated by forward gravity modeling based on the depth of the Moho and the average density difference between the crust and the mantle to obtain the Moho gravity response. 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, characterized in that: In step S3, matching the residual gravity anomaly corresponding to each extended height with the ground structural data includes: matching and analyzing the residual gravity anomaly corresponding to each extended height with the ground structural 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 structural gravity anomaly.

5. The gravity four-story section interpretation method according to claim 1, 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 measuring point; the vertical axis is the gravity anomaly value; The drawing of the elevation-geological profile includes: drawing a measuring point elevation curve with the horizontal axis of the three gravity anomaly profiles as the horizontal axis and the elevation of the gravity measuring point as the vertical axis; The strata, stratum boundary positions and fault positions that the gravity profile passes through are read from the geological map, and the stratum boundaries, stratum 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 building 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 using the gravity anomaly profiles of different layers in the gravity four-story profile, including explaining the shallow structure 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-layer Moho gravity response profile is used to explain the Moho surface fluctuation.

7. The interpretation device for the gravity four-story building 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 profile; The calculation module for 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 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; The drawing module of the gravity four-story building profile is used to draw three gravity anomaly profiles, namely, a shallow gravity anomaly profile, a deep gravity anomaly profile, and a Moho surface gravity response profile, according to the upper, middle, and lower layers, and then draw an 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 achieving comprehensive geological interpretation of the gravity four-story profile; The central control module is equipped with a control software module for controlling the signal flow and data processing in the Bouguer gravity anomaly acquisition module, the Moho surface 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 comprehensive geological interpretation module.

8. The interpretation device according to claim 7, characterized in that The drawing module of the gravity four-story building profile includes a gravity three-story building 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 of 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 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-layer Moho gravity response profile is used to explain the Moho surface fluctuation.

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