A supplementary method for geological mapping based on initial resistivity

Abstract

The application discloses a geological mapping supplementing method based on first branch resistivity, which comprises the following steps: drawing a regional geological map according to existing geological information, and counting the stratum lithology corresponding to the regional geological map; the geological information is collected by a plurality of measuring points; acquiring regional electromagnetic data according to the regional geological map, extracting the first branch resistivity of any measuring point in the electromagnetic data, and drawing a first branch resistivity plane map; converting the first branch resistivity plane map into a first branch resistivity lithology distribution plane map according to the stratum lithology; obtaining the overlapping area of the regional geological map and the first branch resistivity lithology distribution plane map, and correcting and supplementing the regional geological map to obtain a final regional geological map. Through the above scheme, the application has the advantages of simple logic, accuracy and reliability, and has high practical value and popularization value in the field of regional geological information processing technology.

Description

Technical Field

[0001] This invention relates to the field of regional geological information processing technology, and in particular to a geological mapping supplementation method based on the resistivity of the first branch. Background Technology

[0002] Currently, my country's regional geological survey is booming. Building upon the comprehensive coverage of medium-scale geological mapping, large-scale regional surveys at scales of 1:50,000 are being conducted to provide technical support for mineral exploration breakthroughs and ecological civilization construction. However, with the improvement of geological mapping techniques and methodologies, traditional methods are insufficient to meet the mapping needs of some areas. In challenging regions such as high-altitude mountainous and canyon areas where reconnaissance is impossible, traditional field geological survey methods struggle to obtain complete geological information, making them inadequate for guiding mapping work.

[0003] Mapping techniques for areas with ambiguous stratigraphic boundaries, overly covered areas, and high mountain and canyon regions urgently need innovation, especially in geological mapping auxiliary discrimination methods, which have room for further improvement. In this paper, the first resistivity refers to the resistivity value collected at the highest frequency point in the regional electromagnetic data. Currently, there is little mention of technical methods for using first resistivity to identify shallow lithology and assist in geological mapping.

[0004] Therefore, there is an urgent need to propose a simple, accurate, and reliable method for supplementing geological mapping based on the resistivity of the first branch. Summary of the Invention

[0005] To address the above problems, the present invention aims to provide a geological mapping supplementation method based on the resistivity of the first branch. The technical solution adopted by the present invention is as follows:

[0006] A geological mapping supplementation method based on the resistivity of the first branch includes the following steps:

[0007] A regional geological map was drawn based on existing geological information, and the lithology of the strata corresponding to the regional geological map was statistically analyzed; the geological information was collected from several measuring points.

[0008] Regional electromagnetic data are obtained from the regional geological map. The first resistivity of any measuring point in the electromagnetic data is extracted and a first resistivity plane map is drawn.

[0009] Based on the stratigraphic lithology, the first resistivity plan map was converted into the first resistivity lithology distribution plan map.

[0010] The overlapping area between the regional geological map and the first resistivity lithology distribution plan map is obtained, and the regional geological map is corrected and supplemented to obtain the final regional geological map.

[0011] Furthermore, based on existing geological information, a regional geological map is drawn, and the lithology of the corresponding strata is statistically analyzed, including the following steps:

[0012] Investigate the geological region corresponding to the area to be mapped and collect geological information;

[0013] A regional geological map was drawn based on the geological information, and the coordinate values ​​of the stratigraphic boundaries were extracted.

[0014] Based on the coordinate values ​​of the stratigraphic boundaries, the lithology of the corresponding strata on the regional geological map is statistically analyzed.

[0015] Furthermore, based on the regional geological map, regional electromagnetic data is obtained, the first-line resistivity of any measuring point in the electromagnetic data is extracted, and a first-line resistivity planar map is drawn, including the following steps:

[0016] Regional electromagnetic data is obtained based on regional geological maps; the regional electromagnetic data includes magnetotelluric data, audio magnetotelluric data, transient electromagnetic data, controlled-source audio magnetotelluric data, and time-frequency electromagnetic data.

[0017] The regional electromagnetic data is preprocessed using denoising, outlier removal, and smoothing algorithms.

[0018] Extract the first resistivity of all measuring points in the preprocessed regional electromagnetic data;

[0019] Based on the first resistivity of all measuring points, construct a dataset of first resistivity values ​​and build a two-dimensional first resistivity data matrix corresponding to the measuring point locations.

[0020] Based on the two-dimensional resistivity data matrix of the first branch, a plane map of the first branch resistivity is drawn using contour plots.

[0021] Furthermore, based on the stratigraphic lithology, the first resistivity planar map is converted into a first resistivity lithology distribution planar map, including:

[0022] Based on the first resistivity value dataset, the rate of change of resistivity D is calculated. i,j Its expression is:

[0023]

[0024] Among them, Y (i+c1，j) Y represents the resistivity value of the first branch in the (i+c1)th row and jth column; (i，j+c2) Y represents the resistivity value of the first branch in the i-th row and j+c2-th column; (i，j) This represents the resistivity value of the first branch in the i-th row and j-th column.

[0025] Preset a threshold for the rate of change, and calculate the rate of change D. i,j Measurement points exceeding the rate of change threshold, and the rate of change D i,j Connect the measurement points that are greater than the rate of change threshold;

[0026] The rate of change D i,j The coordinates of the measuring points corresponding to the rate of change threshold are used as the spatial location data of the lithological transformation surface boundary, and several planar map partitioning modules are established; the planar map partitioning module is a closed region;

[0027] Calculate the arithmetic average of the resistivity of the first branch in each partition module of the plan view;

[0028] Based on the arithmetic mean of the first resistivity, the lithology corresponding to the partition module of the planar map is distinguished, and the planar map of the first resistivity lithology distribution is drawn.

[0029] Furthermore, the arithmetic mean of the resistivity of the first branch within each planar section is calculated. Based on this arithmetic mean of the resistivity of the first branch, the lithology corresponding to each planar section is distinguished, including:

[0030] Extract the resistivity value of the first branch at any measuring point within the planar partition module;

[0031] Calculate the arithmetic average of the resistivity of the first branch within the planar partition module;

[0032] The arithmetic mean of the resistivity of the first component is used as the statistical resistivity value of the planar partitioning module;

[0033] The statistical resistivity values ​​of two adjacent planar map partition modules are compared. If the statistical resistivity values ​​of two adjacent planar map partition modules differ significantly, it indicates that they are not of the same lithology, and the two regions do not need to be merged. If the statistical resistivity values ​​of two regions differ slightly, they need to be merged. Furthermore, when the logarithmic ratio of the lithological resistivity of two regions differs by more than 1.5, they are considered to be clearly different lithologies. The lithology corresponding to the planar map partition modules is determined by combining the rock physical properties and statistical resistivity values, thus obtaining the first resistivity-based lithological boundary.

[0034] Furthermore, the overlapping area between the regional geological map and the first resistivity lithology distribution planar map was determined, and the regional geological map was corrected and supplemented, including:

[0035] The planar partitioning modules in the regional geological map and the first resistivity lithology distribution planar map are obtained respectively;

[0036] The overlap rate R between the planar map partitioning module of the regional geological map and the planar map partitioning module of the first resistivity lithology distribution map is obtained. IOU Its expression is:

[0037]

[0038] Among them, S A Indicates the stratigraphic distribution range of a regional geological map; S B This indicates the lithological distribution range of the first resistivity-lithological distribution plan;

[0039] If the overlap rate R IOU If the value is ≥0.85, the regional geological map is corrected and supplemented using the first resistivity lithology boundary corresponding to the first resistivity lithology distribution plan map to obtain the final regional geological map.

[0040] Otherwise, the regional geological map will not be corrected or supplemented using the first resistivity lithology boundary corresponding to the first resistivity lithology distribution plan map.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The present invention cleverly obtains regional electromagnetic data based on regional geological maps, extracts the first resistivity of any measuring point in the electromagnetic data, and draws a first resistivity plane map. Its advantage is that it effectively combines geophysical data to comprehensively judge the surface geological conditions of the region.

[0043] (2) Based on the lithology of the strata, the present invention converts the first resistivity plane map into the first resistivity lithology distribution plane map, which, combined with rock physics, establishes the conversion relationship between resistivity and lithology, providing sufficient basis for the subsequent modification of geological maps.

[0044] (3) The present invention obtains the final regional geological map by finding the overlapping area between the regional geological map and the first resistivity lithology distribution plan map, and by correcting and supplementing the regional geological map. Its advantage is that it can be combined with the existing geological survey results, reasonably judge the differences between different source data, and obtain more realistic and complete geological map information.

[0045] (4) This invention obtains the rate of change of resistivity, establishes a planar partitioning module based on the rate of change of resistivity, obtains the arithmetic mean of the first resistivity of each closed area, distinguishes the lithology corresponding to the planar partitioning module based on the arithmetic mean of the first resistivity, and draws a planar map of the first resistivity lithology distribution. This is used to compare the superimposed geological map of the region with the planar map of the first resistivity lithology distribution, mark the location of the lithology region, and verify the reliability of the resistivity lithology distribution.

[0046] In summary, this invention has the advantages of simple logic and high accuracy and reliability, and has high practical and promotional value in the field of regional geological information processing technology. Attached Figure Description

[0047] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope of protection. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 This is a logic flowchart of the present invention.

[0049] Figure 2 This is a geological map of the DLDQS region in this invention.

[0050] Figure 3 This is a resistivity lithology distribution map in this invention.

[0051] Figure 4 This is the regional geological map of the DLDQS region after correction based on the resistivity lithology distribution map in this invention. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the present invention will be further described below with reference to the accompanying drawings and embodiments. The embodiments of the present invention include, but are not limited to, the following embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0053] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0054] The terms "first" and "second," etc., used in the specification and claims of this embodiment are used to distinguish different objects, not to describe a specific order of objects. For example, "first target object" and "second target object," etc., are used to distinguish different target objects, not to describe a specific order of target objects.

[0055] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0056] In the description of the embodiments in this application, unless otherwise stated, "multiple" means two or more. For example, multiple processing units means two or more processing units; multiple systems means two or more systems.

[0057] like Figures 1 to 4 As shown, this embodiment provides a geological mapping supplementation method based on the resistivity of the first branch, which includes the following steps:

[0058] Step 1: Obtain and draw basic geological maps of the region.

[0059] (1) Determine the field geological survey area: Combine satellite remote sensing images to select areas suitable for investigation and study, focusing on mineral resources, water resources, geological disaster points, etc. In accordance with the technical requirements of regional geological survey, based on existing geological data, carry out regional geological survey work to systematically identify the regional strata, rocks, structural features and metallogenic geological conditions.

[0060] (2) Conduct field geological surveys using traditional methods; use multiple stratigraphic division and lithostratigraphic methods to map, identify the age, rock assemblage, and contact relationships of different types of strata in the survey area, and establish the stratigraphic sequence of the survey area.

[0061] (3) Drawing a regional geological map: Summarize field geological survey data, analyze test results (thin section identification, geochemical analysis, isotopic dating), and combine with regional background data to clearly draw the stratigraphic distribution range, contact relationships, and other basic elements, obtaining a geological map with clear stratigraphic boundaries and accurate rock mass distribution. This map includes coordinate data of stratigraphic and rock mass boundaries, as well as information such as stratigraphic age, lithology, contact relationships, and distribution area. In this embodiment, drawing a regional geological map is a mature existing technology and will not be elaborated upon here.

[0062] (4) Extracting stratigraphic boundary coordinates: Based on the large-scale regional geological map, extract the corresponding coordinate values ​​and delineate the boundary coordinate information. The boundary coordinate information consists of four columns: the first column is the longitude coordinate, the second column is the latitude coordinate, the third column is the stratigraphic code for that point, and the fourth column is the lithological description. The arrangement is based on the same stratigraphic stratum, with longitude arranged from east to west, and values ​​arranged from largest to smallest; and latitude arranged from north to south, and values ​​arranged from largest to smallest.

[0063] (5) Statistically analyze the corresponding lithology of the strata, which corresponds to the lithology distribution map based on resistivity in step 3.

[0064] The second step is to acquire regional electromagnetic data and collect the resistivity information of the first branch.

[0065] (1) Collection of regional electromagnetic observation data: The types of regional electromagnetic observation data may include magnetotelluric data, audio magnetotelluric data, incidental electromagnetic data, controlled-source audio magnetotelluric data, time-frequency electromagnetic data, etc. The observation data can generally be converted into frequency domain data, with observation frequencies ranging from 1000 Hz to 0.0001 Hz. The number of frequency points and frequency bands vary depending on the observation target and time. Among them, regional electromagnetic observation data includes measurement point number, observation frequency, resistivity value, and phase value.

[0066] (2) Preprocessing of electromagnetic observation data: When collecting regional electromagnetic data, there are often problems such as power frequency interference, instrument noise, insufficient acquisition time, and poor acquisition quality. The data quality is comprehensively evaluated and analyzed by judging the trend of the resistivity curve and the data of the measuring points on both sides. If the curve only has local jump points, it is deleted. If the overall data is good, the original form is preserved without much editing. If the measuring point data is not good, it is deleted.

[0067] (3) Extracting the first resistivity value of the measuring point: The first resistivity refers to the resistivity value collected corresponding to the highest frequency point of the curve. This data can reflect the lithology near the surface well. The extraction method is to statistically analyze the frequency range of resistivity data in the region, determine the highest frequency point value in the region, and extract the resistivity value corresponding to the highest frequency of all measuring points in the region. This first resistivity... number The values ​​form a dataset. Columns 1 and 2 of this dataset represent latitude and longitude / geographic coordinates. Longitudes are arranged from east to west, with values ​​in descending order. Latitudes are arranged from north to south, with values ​​in descending order. The coordinate system is then transformed to match the geological coordinates from the first step. Figure 1 The third column contains the resistivity values ​​of the first branch at each measuring point, which are used to prepare for drawing the resistivity planar diagram of the first branch.

[0068] The third step is to convert the first resistivity planar map into a planar lithology distribution map.

[0069] (1) Determining Regional Rock Properties: Based on the regional geological background and field geological mapping results, determine the lithological characteristics of the regional strata. Generally, sandstone, siltstone, and mudstone are typically classified as having low to medium resistivity; limestone, conglomerate, rhyolite, andesite, tuff, siliceous rock, and gabbro are typically classified as having medium to high resistivity; marble, eclogite, and slate are typically classified as having high resistivity. The actual rock property statistics are adjusted and improved based on the lithology of surface outcrops. Resistivity values ​​can be determined by measuring the resistivity of samples in the laboratory or by statistically analyzing formation resistivity using well logging data.

[0070] (2) Based on the first resistivity value dataset, calculate the rate of change of resistivity D. i,j By calculating the resistivity change rate in the plane, the first derivative value of each point can be obtained, thus enabling the plotting of the resistivity change rate in the plane. Measurement points with larger resistivity change rates indicate drastic lithological changes. Points with larger resistivity change rates (i.e., greater than a preset change rate threshold) are selected and connected. The coordinate values ​​of the faster-changing measurement points within each block boundary are used as the spatial location data of the lithological transformation surface boundary, establishing a planar plot partitioning module.

[0071] (3) By filtering the measuring points whose coordinates are included in the coordinate range of each partition in the previous step, the first resistivity value of each measuring point in the partition is extracted, the arithmetic average of the first resistivity of all measuring points in each closed domain is calculated, and this value is used as the statistical resistivity value in each closed area to judge the resistivity change law of adjacent closed areas, and to provide reference data for lithology determination in the next step of lithology plan map.

[0072] (4) Based on the physical characteristics of the rock, mark the possible lithologies corresponding to the statistical resistivity values ​​in each closed area, draw the first resistivity lithology distribution plan map, and use it to compare the superimposed regional geological map and the first resistivity lithology distribution plan map to mark the location of the lithology area and verify the reliability of the resistivity lithology distribution.

[0073] The fourth step is to determine the overlapping area between the regional geological map and the first resistivity lithology distribution plan map, and to revise and supplement the regional geological map.

[0074] (1) Calculate the area within the stratigraphic boundary of the regional geological map and the area of ​​each sub-region of the first branch resistivity lithology distribution plan in the first step, and obtain the overlap rate of each area.

[0075] Among them, R IOU The ratio value is between {0, 1}, when R IOU When the resistivity is ≥0.85, it indicates a high degree of agreement between the regional geological map and the first resistivity-lithology distribution plan map; therefore, the stratigraphic boundaries of the regional geological map are revised using the first resistivity-lithology boundary. When 0.5 < R IOU When R < 0.85, it indicates that the regional geological map and the first resistivity lithology distribution plan map have a generally average degree of agreement. When selecting the stratigraphic boundaries for revising the regional geological map, the results of field geological surveys should be the primary reference, and the stratigraphic boundaries interpreted by remote sensing geology can be revised. When R ≤ 0.5, it indicates that the regional geological map and the first resistivity lithology distribution plan map have a low degree of agreement. The stratigraphic boundaries of the regional geological map should not be revised using the first resistivity lithology boundary.

[0076] (2) By obtaining the intersection and union ratio of the entire region, the adoption level is divided, and the regional geological boundary is revised by the first resistivity lithology boundary to generate the final regional geological map.

[0077] Specific examples Figures 2 to 4 As shown, taking the DLDQS area as an example, and using the method of this embodiment for geological mapping supplementation, the final result is as follows. Figure 4 The final regional geological map shown.

[0078] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any changes made based on the design principles of the present invention, or any non-creative modifications made thereon, shall fall within the scope of protection of the present invention.

Claims

1. A geological mapping supplementation method based on the resistivity of the first branch, characterized in that, Includes the following steps: A regional geological map was drawn based on existing geological information. The lithology of the strata corresponding to the regional geological map was statistically analyzed. The corresponding coordinate values ​​were extracted from the large-scale regional geological map, and the boundary coordinate information was picked out by delineating the boundary. The geological information was collected from several measuring points. Regional electromagnetic data is obtained based on the regional geological map. The first resistivity of each measuring point in the electromagnetic data is extracted, the coordinate system is transformed and consistent with the geological information to draw a regional geological map, and a first resistivity planar map is drawn. The first resistivity is the resistivity value collected at the highest frequency point of the measuring point in the electromagnetic data, which contains the corresponding geographical coordinate information. Based on the stratigraphic lithology, the first resistivity plan map was converted into the first resistivity-lithological zoning plan map, including: The rate of change of resistivity is obtained from the two-dimensional first resistivity data matrix. Its expression is: ； in, Indicates the first Line 1 The resistivity value of the first column; Indicates the first Line 1 The resistivity value of the first column; Indicates the first Line 1 The resistivity value of the first column; Preset a threshold for the rate of change, and calculate the rate of change. Measurement points with a rate of change greater than the threshold, and the rate of change... Connect the measuring points corresponding to the rate of change greater than the threshold; select the measuring points whose resistivity change rate is greater than the preset rate of change threshold, and use the coordinate values ​​of the measuring points within any block boundary that are greater than the preset rate of change threshold as the spatial location data of the lithological transformation surface boundary to establish several candidate partitions of the lithological transformation surface boundary; Extract the first resistivity value of any measuring point within the candidate boundary of the lithological transform surface, calculate the arithmetic average of the first resistivity of all measuring points within any closed candidate boundary of the lithological transform surface, and use the arithmetic average of the first resistivity as the statistical resistivity value within the closed candidate boundary of the lithological transform surface, and determine the resistivity variation pattern of adjacent closed candidate boundary of the lithological transform surface. The difference in statistical resistivity values ​​between two adjacent candidate lithological transition surface boundary zones is determined. If the difference in the logarithmic ratio of the statistical resistivity between the two adjacent candidate lithological transition surface boundary zones is less than or equal to 1.5, the two adjacent candidate lithological transition surface boundary zones are merged; otherwise, they are determined to be different lithologies. By combining rock physical properties and statistical resistivity values, the lithology corresponding to the candidate zones of the lithology transition surface boundary is divided, and the final first resistivity lithology candidate zone is obtained. The first resistivity lithology zone plan map is then drawn. The candidate zones of the lithology transition surface boundary are closed regions. The planar partitioning modules in the regional geological map and the first resistivity lithology distribution planar map are obtained respectively; Obtain the overlap rate between the stratigraphic distribution range on the regional geological map and the corresponding lithological distribution range after lithological division on the first resistivity-lithological zoning plan. The verification expression is: ； in, Indicates the stratigraphic distribution range of a regional geological map; This indicates the lithological distribution range of the first resistivity lithology zoning plan; If overlap rate Then, the regional geological map is corrected and supplemented using the first resistivity lithology distribution plane map corresponding to the first resistivity lithology boundary to obtain the final regional geological map. Otherwise, the regional geological map will not be corrected or supplemented using the first resistivity lithology boundary corresponding to the first resistivity lithology distribution plan map.

2. The geological mapping supplementation method based on the resistivity of the first branch according to claim 1, characterized in that, Based on existing geological information, a regional geological map is drawn, and the lithology of the corresponding strata is statistically analyzed, including the following steps: Investigate the geological region corresponding to the area to be mapped and collect geological information; A regional geological map was drawn based on the geological information, and the coordinate values ​​of the stratigraphic boundaries were extracted. Based on the coordinate values ​​of the stratigraphic boundaries, the lithology of the corresponding strata on the regional geological map is statistically analyzed.

3. The geological mapping supplementation method based on the resistivity of the first branch according to claim 1, characterized in that, Based on the regional geological map, obtain regional electromagnetic data, extract the first-line resistivity of any measuring point in the electromagnetic data, and draw a first-line resistivity planar map, including the following steps: Regional electromagnetic data is obtained based on regional geological maps; the regional electromagnetic data includes magnetotelluric data, audio magnetotelluric data, transient electromagnetic data, controlled-source audio magnetotelluric data, and time-frequency electromagnetic data. The regional electromagnetic data is preprocessed using denoising, outlier removal, and smoothing algorithms. Extract the first resistivity of all measuring points in the preprocessed regional electromagnetic data; Based on the first resistivity of all measuring points, construct a dataset of first resistivity values ​​and build a two-dimensional first resistivity data matrix corresponding to the measuring point locations. Based on the two-dimensional resistivity data matrix of the first branch, a plane map of the first branch resistivity is drawn using contour plots.

Images