A method for identifying and locating concealed uranium-bearing structural alteration zones in granite areas

Abstract

The present invention discloses a method for identifying and locating a hidden uranium-containing structural alteration zone in a granite area, comprising the following steps: Step 1: Select typical uranium-containing structural alteration zones in the area through surface survey; Step 2: Collect samples perpendicular to the outcrop system of the uranium-containing alteration zone, and send them to the laboratory for analysis and testing; Step 3: Determine the migration law of elements in the structural alteration zone, and select the type combination of elements that migrate in and out; Step 4: Collect samples of deep geological information in a large-scale area of ​​the target area, and extract deep geological information through sample analysis; Step 5: Construct a mathematical model that can characterize the identification and prediction and positioning of uranium-containing structural alteration zones. The method for identifying and locating hidden uranium-containing structural alteration zones in granite areas provided by the present invention can effectively identify hidden uranium-containing alteration zones in the granite area of ​​northern Guangdong, and can quickly complete the identification, prediction and positioning and screening of uranium-containing structural zones in blank areas, and has the advantages of high recognition accuracy, low cost, rapidity, and strong applicability.

Description

Technical Field

[0001] The invention relates to the technical field of geological prospecting and prediction, and in particular to a method for identifying and locating a concealed uranium-containing structural alteration zone in a granite area. Background Art

[0002] The northern Guangdong region is a humid and semi-humid low mountain and hilly landscape area with dense vegetation, severe loose soil coverage, and few geological outcrops in the field, which seriously restricts the prospecting effect of surface surveys in the region. The existing identification and positioning of structural alteration zones mainly rely on surface surveys, trenching and drilling exposure. The former is mainly suitable for areas with good surface outcrops. Due to the severe loose soil coverage in the granite area of ​​northern Guangdong, it is difficult to obtain good prospecting clues through surface surveys; while trenching and drilling exposure are too costly and difficult to adapt to the identification and positioning prediction of large-scale uranium-bearing structures in the early stage. All these have seriously restricted the development of uranium prospecting in the granite area of ​​northern Guangdong.

[0003] Hydrothermal uranium deposits in northern Guangdong are mostly controlled by tectonic alteration zones and are closely related to hydrothermal alteration. Affected by the mineralization hydrothermal action, mineralization alteration generally has good zoning in the horizontal or vertical direction. Taking the Mianhuakeng uranium deposit in northern Guangdong as an example, the alteration of the surrounding rocks on both sides of the ore body is silicification, reddification, sericitization, kaolinization, and normal granite. The tectonic alteration zones around the deposit that meet the above zoning characteristics are all important vein zones for ore bearing and have important prospecting and exploration value; while the vein zones that do not meet the above zoning rules are irrelevant vein zones and have no exploration value. Different alteration types must have certain differences in trace elements, especially uranium-containing hydrothermal alteration and non-uranium-containing hydrothermal alteration. By extracting these differences, the hidden uranium-containing tectonic alteration zones can be effectively identified and screened. Previous researchers focused on the concentration of uranium, but ignored the controlling role of tectonic alteration zones in uranium mineralization, resulting in inaccurate ore body prediction. Various methods that can reflect deep uranium mineralization geological information are integrated through the technical means proposed in this patent to form a set of methods suitable for identifying and locating hidden uranium-bearing structural alteration zones in the granite area of ​​northern Guangdong, which will have important guiding significance for the exploration of hydrothermal alteration zone-type uranium deposits in South China. Summary of the invention

[0004] The invention discloses a method for identifying and locating a concealed uranium-bearing tectonic alteration zone in a granite area, aiming to provide a method capable of identifying and locating a concealed uranium-bearing tectonic alteration zone in a granite area in northern Guangdong. The method has the advantages of high recognition accuracy, strong applicability, low cost and rapidity, and is very suitable for the identification, positioning and screening of concealed uranium-bearing tectonic zones in northern Guangdong.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for identifying and locating a hidden uranium-bearing structural alteration zone in a granite area specifically comprises the following steps:

[0007] Step 1: Select typical uranium-bearing structural alteration zones in the region through surface survey;

[0008] Step 2: Collect samples vertically from the outcrop system of the uranium-bearing alteration zone and send them to the laboratory for analysis and testing;

[0009] Step 3: Determine the migration law of elements in the tectonic alteration zone, select the type and combination of elements that migrate in and out, and lay the foundation for establishing a mathematical model for tectonic zone identification and positioning;

[0010] Step 4: Collect large-scale area samples of deep geological information in the target area (such as fractional prospecting, deep penetrating geochemistry, geogas measurement, etc.), extract deep geological information through sample analysis, and lay a data foundation for extracting concealed structural alteration zones;

[0011] Step 5: Construct a mathematical model that can characterize the identification and location of tectonic alteration zones.

[0012] Step 6: Based on the mathematical model, use professional drawing software to draw a contour map to show the distribution of uranium-bearing structural alteration zones in the blank area.

[0013] By fully exploring the migration and enrichment laws of different elements and the corresponding dynamic mechanisms in the process of hydrothermal alteration, combined with deep geological information extraction methods (fractional prospecting, deep penetration geochemistry, geogas measurement, etc.), the same trend characteristics of multiple elements in the process of hydrothermal alteration are strengthened, aiming to achieve the purpose of indirect prospecting by predicting hidden mineral-bearing structural alteration zones.

[0014] In the plan, the collected samples mainly include tectonic alteration samples and deep geological information samples (such as fractional prospecting, deep penetration geochemistry, geogas measurement and other method samples). The tectonic alteration sample collection aims to study the horizontal migration law of elements in the uranium-bearing tectonic alteration zone in the area during hydrothermal alteration. Four representative rock and ore samples in the uranium-bearing tectonic alteration zone were collected. According to the intensity of alteration, they can be divided into four categories: normal granite sample (SL-1), far-mine alteration sample (SL-2), near-mine alteration sample (SL-3), and mineralized center sample (SL-4).

[0015] The purpose of collecting deep geological information samples (quantitative prospecting, deep penetrating geochemistry, geogas measurement and other methods) is to extract deep geological information at each measuring point by analyzing the deep geological information captured by shallow soil samples, so as to prepare data for the use of tectonic alteration zone identification and positioning models. The samples are mainly analyzed for trace elements and rare earth element content (Li, Be, V, Co, Ni, Cu, Zn, Rb, Nb, Mo, Cd, In, Sb, Cs, Ba, Ta, W, Tl, Pb, Bi, Th, U, Zr, As, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, etc.).

[0016] In this preferred solution, step three specifically includes the following steps:

[0017] Step 3.1: Since hydrothermal alteration is in an "open system" and has a "closure problem", the changes in the elements within the band cannot be directly compared with the changes in the percentage content of the elements. It is necessary to identify the inactive components in the sample, readjust the element content, and then compare and identify the element migration;

[0018] Step 3.2: Based on the inactive components, readjust the content of each component, and use the standardized Isocon diagram to identify the migration patterns of elements in the horizontal direction within the tectonic alteration zone, especially some elements that migrate in or out as a whole. Avoid selecting elements with unclear migration patterns, because the overall migration of elements in or out is crucial to identifying tectonic alteration zones.

[0019] Step 3.1 also includes the following two situations:

[0020] Step 3.1.1: Preliminary identification of inactive components in tectonic alteration samples, using Isocon projection to determine the possible inactive components in the major elements. When some components can be fitted into a straight line passing through the origin in the Isocon projection, then these components are inactive components, and the straight line is called the Isocon line.

[0021] Step 3.1.2: Based on the preliminary identification of the inactive component categories by Isocon diagram, these inactive components and Zr (a recognized inactive element) are used to make a bivariate diagram, and the inactive components of the region are finally determined based on the degree of data dispersion. Al2O3 is usually selected in northern Guangdong;

[0022] Step 3.2 specifically includes the following two steps:

[0023] Step 3.2.1: Use Isocon diagram to standardize trace and rare earth elements and screen the types of elements that migrated into the tectonic alteration zone. The main elements in the Shulouqiu area in northern Guangdong are Li, V, Rb, Mo, Cs, W and U;

[0024] Step 3.2.2: Use Isocon diagram to standardize trace and rare earth elements and screen the types of elements migrating from the tectonic alteration zone. The main elements in the Shulouqiu area in northern Guangdong are Th, Ba, La, Ce, Pr, Nd and Sm.

[0025] In this preferred embodiment, step five specifically includes the following steps:

[0026] Step 5.1: Calculate the single element background value based on the analysis results of the area deep geological information sample, and then calculate the single element loss of the single sample point;

[0027] Step 5.2: Superposition of increment-contrast values ​​of elements with the same trend in the hydrothermal alteration process can highlight the enrichment or depletion trend and suppress isolated point anomalies, which can reflect the advantages of the migration law of elements with the same trend and strengthen the multi-element linear anomaly characteristics;

[0028]

[0029] Reflect the rules of element enrichment or depletion in tectonic alteration zones;

[0030] Step 5.1 includes the following steps:

[0031] Step 5.1.1: Eliminate using loop culling The single element content of deep geological information samples and the background value of element j in the measurement area are calculated Then calculate the migration (enrichment) or migration (depletion) of element j at sample point i during hydrothermal alteration (Δx ij ),in

[0032] Step 5.1.2: Normalize the single sample point single element increment-contrast value;

[0033]

[0034] Where: x ij —The content of element j at measuring point i; —Regional background content of element j; C ij —Increment-contrast value of element j at measuring point i; S—variance of element j.

[0035] In this preferred solution, step six specifically includes the following steps:

[0036] Step 6.1: Blank area sample points with the same trend element increment-contrast value (C i ) Data collation;

[0037] Step 6.2: Blank area sample points with trend element increment-contrast value data (C i ) Gridding, using professional drawing software to draw contour maps;

[0038] Step 6.3: Identify the hidden uranium-bearing structural alteration zone based on the linear characteristics of the same trend element increment-contrast value;

[0039] From the above, it can be seen that a method for identifying and locating a concealed uranium-bearing tectonic alteration zone in a granite area specifically includes the following steps: Step 1: Select a typical uranium-bearing tectonic alteration zone in the area through surface survey; Step 2: Collect samples vertically to the outcrop system of the uranium-bearing alteration zone, and send them to the laboratory for analysis and testing; Step 3: Determine the migration law of elements in the tectonic alteration zone, and select the type combination of elements migrating in and out; Step 4: Collect large-scale area deep geological information samples in the target area (such as fractional prospecting, deep penetration geochemistry, geogas measurement and other methods), extract deep geological information, and lay a data foundation for extracting concealed tectonic alteration zones; Step 5: Construct a mathematical model that can characterize the tectonic alteration zone; Step 6: Use professional drawing software to draw an isovalue map based on the mathematical model to show the distribution of uranium-bearing tectonic alteration zones in blank areas. The method for identifying and locating a concealed uranium-bearing tectonic alteration zone in a granite area provided by the present invention has the technical effect of being able to achieve a high recognition accuracy rate for concealed uranium-bearing alteration zones in the granite area of ​​northern Guangdong, and is relatively low in cost, and can quickly complete the identification and predictive positioning of a large area of ​​uranium-bearing tectonic alteration zones. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of sample collection in a tectonic alteration zone in a method for identifying and locating a concealed uranium-bearing tectonic alteration zone in a granite area proposed by the present invention.

[0041] Figure 2 This is the method for distinguishing the horizontal in-migration and out-migration of elements in a tectonic alteration zone (standardized Isocon diagram) adopted by the present invention.

[0042] Figure 3 The invention discloses an application effect of a method for identifying and locating a concealed uranium-bearing structural alteration zone in a granite area in the periphery of the Shulouqiu uranium deposit.

[0043] Figure 1 Legend: 1-medium-grained biotite granite; 2-sericite; 3-cataclasite; 4-silicification; 5-uranium mineralization location; 6-sampling location.

[0044] Figure 3 Legend: 1-Medium-grained small porphyritic two-mica granite; 2-Medium-grained biotite granite; 3-Compounded compression-torsion fault; 4-Fault structure and number; 5-Measured or inferred geological boundary; 6-Phase change boundary; 7-Mineral deposit; 8-Inferred fault.

[0045] Figure 4 This is an overall schematic diagram of a method for identifying and locating a concealed uranium-bearing structural alteration zone in a granite area proposed by the present invention. DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0047] Reference Figure 1 , Figure 2 and Figure 4 , a method for identifying and locating a hidden uranium-bearing structural alteration zone in a granite area, specifically comprising the following steps:

[0048] Step 1: Select typical uranium-bearing structural alteration zones in the region through surface survey;

[0049] Step 2: Collect samples vertically from the outcrop system of the uranium-bearing alteration zone and send them to the laboratory for analysis and testing;

[0050] Step 3: Determine the migration pattern of elements in the tectonic alteration zone and select the type and combination of elements that migrate in and out;

[0051] Step 4: Collect large-scale deep geological information samples in the target area (such as fractional prospecting, deep penetrating geochemistry, geogas measurement, etc.) to extract deep geological information and lay a data foundation for extracting concealed structural alteration zones;

[0052] Step 5: Construct a mathematical model that can characterize the tectonic alteration zone.

[0053] Step 6: Based on the mathematical model, use professional drawing software to draw a contour map to show the distribution of uranium-bearing structural alteration zones in the blank area.

[0054] In a preferred embodiment, the sample collection mainly includes tectonic alteration sample collection and deep geological information sample collection. The tectonic alteration sample collection studies the horizontal migration law of elements in the hydrothermal alteration process in the study area, collects 4 representative rock and ore samples, and the sample collection is mainly divided into four categories according to the intensity of the alteration, namely, normal granite sample (SL-1), far-mine alteration sample (SL-2), near-mine alteration sample (SL-3), and mineralization center sample (SL-4). The samples are sent to the analysis laboratory for analysis of Al2O3, BaO, CaO, TFe2O3, The contents of K2O, MgO, Na2O, P2O5, TiO2, LOI and elements such as Li, Be, V, Co, Ni, Cu, Zn, Rb, Nb, Mo, Cd, In, Sb, Cs, Ba, Ta, W, Tl, Pb, Bi, Th, U, Zr, As, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu are used to identify the types of elements migrating into and out of the area through standardized Isocon diagrams, laying a theoretical foundation for the identification and positioning of concealed tectonic alteration.

[0055] In a preferred embodiment, the area-based deep geological information samples (quantitative prospecting, deep penetrating geochemistry, geogas measurement and other methods) are collected to extract the geological information of hidden structural alteration, and use the migration law of elements in the known uranium-containing alteration zone to quickly screen the hidden structural alteration zone in the blank area through the established prediction model. The deep geological information samples are mainly analyzed for the content of trace and rare earth elements such as Li, Be, Ni, Cu, Zn, Nb, Mo, Cd, In, Sb, Cs, Ba, Nd, Sm, Ta, W, Pb, Bi, Th, U, Sn, etc.

[0056] In a preferred embodiment, step three specifically includes the following steps:

[0057] Step 3.1: Since hydrothermal alteration is in an "open system" and has a "closure problem", the changes in the elements within the band cannot be directly compared with the changes in the percentage content of the elements. It is necessary to identify the inactive components in the sample, readjust the element content, and then compare and identify the element migration;

[0058] Step 3.2: Based on the inactive components, readjust the content of each component, and use the standardized Isocon diagram to identify the migration patterns of elements in the horizontal direction within the tectonic alteration zone, especially some elements that migrate in or out as a whole. Avoid selecting elements with unclear migration patterns, because the overall migration of elements in or out is crucial to identifying tectonic alteration zones.

[0059] In a preferred embodiment, step 3.1 also includes the following two situations:

[0060] Step 3.1.1: Preliminary identification of inactive components in tectonic alteration samples: When some components can be fitted into a straight line passing through the origin in the Isocon projection, these components are inactive components, and the straight line is called the Isocon line.

[0061] Step 3.1.2: Based on the preliminary identification of the inactive component categories using the Isocon diagram, use these inactive components and Zr (a recognized inactive element) to make a bivariate diagram, and finally determine the inactive components in the region based on the degree of data dispersion.

[0062] In a preferred embodiment, step 3.2 specifically includes the following two steps:

[0063] Step 3.2.1: Screen the types of elements that migrate into the tectonic alteration zone, refer to Figure 2 , the standardized Isocon diagram of trace (rare earth) elements shows that the elements such as Mo, Rb, Li, Be, V, W, Cs, U, As, and Tl migrated as a whole during the hydrothermal alteration process;

[0064] Step 3.2.2: Screen the types of elements that migrate out of the tectonic alteration zone, refer to Figure 2 , the trace (rare earth) element standardized Isocon diagram shows that elements such as Th, Ba, La, Ce, Pr, Nd and Sm migrated out;

[0065] In a preferred embodiment, step five specifically includes the following steps:

[0066] Step 5.1: Scan the sample analysis results based on the area-based deep geological information (fractional exploration, deep penetration geochemistry, geogas measurement and other methods), calculate the single element background value, and calculate the single element loss of the sample point;

[0067] Step 5.2: Superposition of increment-contrast values ​​of the same trend elements in the hydrothermal alteration process can highlight the enrichment or depletion trend, suppress isolated point anomalies, reflect the advantages of the migration law of the same trend elements, and strengthen the multi-element linear anomaly characteristics;

[0068]

[0069] Reflects the rules of element enrichment or depletion in tectonic alteration zones.

[0070] In a preferred embodiment, step 5.1 comprises the following steps:

[0071] Step 5.1.1: Eliminate using loop culling The single element content of deep geological information samples and the background value of element j in the measurement area are calculated Then calculate the migration (enrichment) or migration (depletion) of element j at sample point i during hydrothermal alteration (Δx ij ),in

[0072] Step 5.1.2: Normalize the single-point single-element increment-backing value;

[0073]

[0074] Where: x ij —The content of element j at measuring point i; —Regional background content of element j; C ij —Increment-contrast value of element j at measuring point i; S—variance of element j.

[0075] In this preferred solution, step six specifically includes the following steps:

[0076] Step 6.1: Blank area sample points with the same trend element increment-contrast value (C i ) Data collation;

[0077] Step 6.2: Blank area sample points with trend element increment-contrast value data (Ci ) Gridding, using professional drawing software to draw contour maps;

[0078] Step 6.3: Based on the linear characteristics of the same trend element increment-contrast value, identify the hidden uranium-bearing structural alteration zones, such as the No. 1, 3, and 9 zones outside the Shulouqiu uranium deposit;

[0079] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for identifying and locating a hidden uranium-bearing structural alteration zone in a granite area, characterized in that: The specific steps include: Step 1: Select typical uranium-bearing structural alteration zones in the region through surface survey; Step 2: Collect samples vertically from the outcrop system of the uranium-bearing alteration zone and send them to the laboratory for analysis and testing; Step 3: Determine the migration pattern of elements in the tectonic alteration zone and select the type and combination of elements that migrate in and out; Step 4: Large-scale area deep geological information sample collection in the target area, including fractional prospecting, deep penetrating geochemistry and geogas measurement methods, extracting deep geological information through sample analysis, laying a data foundation for extracting concealed structural alteration zones; Step 5: Construct a mathematical model that can characterize the identification and predictive location of tectonic alteration zones; Step 6: Use professional drawing software to draw contour maps based on the mathematical model to show the distribution of uranium-bearing structural alteration zones in the blank area; The step five specifically includes the following steps: Step 9.1: Calculate the regional background content of element j based on the analysis results of the deep geological information samples Calculate the migration of element j in or out of sample point i Δx ij ; Step 9.2: Superposition of increment-contrast values ​​of the same trend elements in the hydrothermal alteration process can highlight the enrichment or depletion trend and suppress isolated point anomalies, which can reflect the advantages of the migration law of the same trend elements in the hydrothermal alteration process and strengthen the multi-element linear anomaly characteristics; It reflects the migration rules of elements in or out of the tectonic alteration zone as a whole; Where: C ij —Increment-contrast value of element j at sample point i; C i -i sample point same trend element increment - lining value; —Regional background content of element j; Δx ij —The amount of element migration into or out of sample point j; The step 9.1 comprises the following steps: Step 9.1.1: Eliminate using loop culling The single element content of deep geological information samples is used to calculate the regional background content of element j in the survey area. Then, the deep geological information sample analysis results are used to calculate the migration of element j in or out during the hydrothermal alteration process at sample point i, Δx ij ,in S — j element variance; Step 9.1.2: Normalize the increment-contrast value of the j element of the i sample point; Where: x i j—the content of element j at measuring point i; the rest are the same as above.

2. The method for identifying and locating a hidden uranium-bearing structural alteration zone in a granite area according to claim 1, characterized in that: The sample collection includes tectonic alteration zone sample collection and deep geological information sample collection.

3. The method for identifying and locating a hidden uranium-bearing structural alteration zone in a granite area according to claim 1, characterized in that: The analysis of the tectonic alteration zone samples includes the migration patterns of different elements during the hydrothermal alteration process in the study area, and the analysis of the contents of major, rare earth and trace elements.

4. The method for identifying and locating a hidden uranium-bearing structural alteration zone in a granite area according to claim 1, characterized in that: The step three specifically includes the following steps: Step 3.1: Since hydrothermal alteration is in an "open system" and has a "closure problem", the changes in the elements within the band cannot be directly compared with the changes in the percentage content of the elements. It is necessary to identify the inactive components in the sample, readjust the element content, and then compare and identify the element migration situation; Step 3.2: Use standardized Isocon diagrams to identify the migration patterns of elements in the horizontal direction within the tectonic alteration zone, including some elements that migrate in or out as a whole.

5. The method for identifying and locating a hidden uranium-bearing structural alteration zone in a granite area according to claim 4, characterized in that: The step 3.1 also includes the following two situations: Step 3.1.1: Preliminary identification of inactive components in tectonic alteration zones: When some components can be fitted into a straight line passing through the origin on the Isocon projection map, these components are inactive components. This straight line is called the Isocon line. The distance between the component projection point and the Isocon line reflects the degree of migration of the component. The components above the Isocon line migrate in and are enriched during the hydrothermal alteration process, while the element components below the Isocon line migrate out and are depleted. In this way, the preliminary identification of inactive components in tectonic alteration zones can be completed; Step 3.1.2: Based on the preliminary identification of the inactive component categories by the Isocon diagram, use these inactive components and Zr to make a bivariate diagram, and finally determine the best inactive component for the region based on the degree of data dispersion.

6. The method for identifying and locating a hidden uranium-bearing structural alteration zone in a granite area according to claim 4, characterized in that: The step 3.2 specifically includes the following two steps: Step 3.2.1: Use Isocon diagram to screen the types of elements that migrate into the tectonic alteration zone; Step 3.2.2: Use the Isocon diagram to screen the types of elements migrating from the tectonic alteration zone.

7. The method for identifying and locating a hidden uranium-bearing structural alteration zone in a granite area according to claim 1, characterized in that: The purpose of the area collection of deep geological information samples is to extract deep geological information and use the element migration law in the alteration zone to construct a mathematical model to predict the hidden structural alteration zone in the blank area.

8. The method for identifying and locating a hidden uranium-bearing structural alteration zone in a granite area according to claim 1, characterized in that: The fourth step is to analyze the deep geological information samples to analyze the trace elements and rare earth content.

9. The method for identifying and locating a hidden uranium-bearing structural alteration zone in a granite area according to claim 1, characterized in that: The step six comprises the following steps: Step 11.1: Blank area sample points with trend element increment-contrast value data C i tidy; Step 11.2: Blank area sample points with trend element increment-contrast value data C i Gridding, using professional drawing software to draw contour maps; Step 11.3: Identify the concealed uranium-bearing structural alteration zone based on the linear characteristics of the same trend element increment-contrast value.

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