Geochemical Tracing Methods for Concealed Sandstone-Type Uranium Deposits

Abstract

This application relates to the field of tracer exploration or detection, and provides a geochemical tracing method for concealed sandstone-type uranium deposits. The method provides that by measuring the Mo and Th content in the ground atmosphere and soil, it identifies anomaly zones in the Mo element measurement, anomaly zones in the Mo-Th ratio, and comprehensive anomaly zones. Further measurement of the Mo content in the ground atmosphere is then performed in the comprehensive anomaly zones to determine favorable mineralization areas within the exploration area. According to the method provided in this application, it can effectively identify concealed sandstone-type uranium mineralization information and determine favorable uranium mineralization areas within the exploration area.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of tracer exploration or detection, and in particular to a geochemical tracer method for concealed sandstone type uranium deposits. BACKGROUND

[0002] In order to explore uranium deposits in an exploration area, many methods are provided by the prior art. However, due to different geological structures, different geological processes, complex environments, and much detection interference information in the exploration area, the methods of the prior art cannot effectively explore the favorable ore-forming positions in the exploration area. SUMMARY

[0003] In order to solve at least one aspect of the above problems, embodiments of the present application provide a geochemical tracer method for concealed sandstone type uranium deposits, comprising: performing a soil gas measurement in an exploration area to determine Mo and Th element contents in the soil gas; performing a soil measurement in the exploration area to determine Mo and Th element contents in the soil; determining a Mo element anomaly area of the soil gas measurement according to the Mo element content obtained by the soil gas measurement; determining a Mo and Th element ratio anomaly area of the exploration area according to the Mo and Th element contents obtained by the soil gas measurement and the Mo and Th element contents obtained by the soil measurement; determining a comprehensive anomaly area according to the Mo element anomaly area of the soil gas measurement and the Mo and Th element ratio anomaly area; selecting a position with the highest Mo element content of the soil gas measurement in the comprehensive anomaly area, and performing a soil gas measurement at different depths at the position to obtain Mo element contents at different depths; determining a relationship between the Mo element content and the measurement depth according to the Mo element contents at different depths; and determining a favorable ore-forming section in the exploration area according to the relationship.

[0004] According to the method provided by the present application, deep sandstone type uranium mineralization information can be effectively identified, and a favorable ore-forming section in the exploration area can be delineated. BRIEF DESCRIPTION OF DRAWINGS

[0005] Other objects and advantages of the present application will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating the principles of the present application by way of example only.

[0006] Figure 1 is a flowchart of a geochemical tracer method for concealed sandstone type uranium deposits according to an embodiment of the present application;

[0007] Figure 2 is a flowchart of a method for determining a Mo element anomaly area of a soil gas measurement according to an embodiment of the present application;

[0008] Figure 3 is a flowchart of a method for determining a ratio anomaly area according to an embodiment of the present application. DETAILED DESCRIPTION

[0009] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions will be described clearly and completely below in connection with the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are one embodiment but not all embodiments of the present application. Based on the described embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0010] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present application should be understood as the common meanings understood by those of ordinary skill in the art to which the present application belongs.

[0011] In the description of the embodiments of the present application, the meaning of "a plurality of" is at least two, for example, two, three, etc., unless otherwise explicitly and specifically limited.

[0012] The present inventors have found that when obtaining abnormal information related to sandstone-type uranium deposits (bodies) by geo-gas measurement, near-surface information will interfere.

[0013] The present inventors have found that Mo element, which is often associated with U element in sandstone-type uranium deposits, has greater geochemical activity, and the atomic weight of Mo element is much smaller than that of U element, and is more likely to migrate upward under the action of geological forces. At the same time, the present inventors have found that the nano-particles rich in Mo element in the geo-gas flow have better indicating effect than U element and V element when Mo element is used as an indicating element. There are still some problems to be solved when Mo element is used as an indicating element to determine the favorable metallogenic section in the exploration area.

[0014] Therefore, the present application provides a concealed sandstone-type uranium geochemical tracing method capable of effectively reducing near-surface information interference and obtaining deep mineralization information.

[0015] Some embodiments of the present application will be described in detail below in connection with the accompanying drawings. The following embodiments and features in the embodiments can be combined with each other without conflict.

[0016] As shown in the accompanying drawings, the present application provides a concealed sandstone-type uranium geochemical tracing method, which comprises the following steps: Figure 1

[0017] S101, determining the contents of Mo element and Th element in the geo-gas in the exploration area to obtain the distribution of Mo element and the distribution of Th element as a reference object in the geo-gas.

[0018] S102, determining the contents of Mo element and Th element in the soil in the exploration area to obtain the distribution of Mo element and the distribution of Th element as a reference object in the soil.​

[0019] S103 determining a Mo element anomaly area in the geo-gas survey according to the Mo element content obtained in the geo-gas survey.

[0020] S104 determining a Mo element and Th element ratio anomaly area in the exploration area according to the Mo element content and the Th element content obtained in the geo-gas survey and the Mo element content and the Th element content obtained in the soil survey.

[0021] S105 determining a comprehensive anomaly area according to the Mo element anomaly area in the geo-gas survey and the Mo element and Th element ratio anomaly area. Specifically, in some embodiments, the Mo element anomaly area in the geo-gas survey and the element ratio anomaly area can be superimposed, and the overlapping area of the two anomalies is the comprehensive anomaly area, so as to effectively reduce the interference of the near-surface information and highlight the Mo element anomaly from the deep part. In other embodiments, the Mo element anomaly area and the Mo element and Th element ratio anomaly area can also be processed in different ways to obtain the comprehensive anomaly area.

[0022] S106 selecting a position with the highest Mo element content in the geo-gas survey in the comprehensive anomaly area, and performing geo-gas survey at different depths at the position to obtain the Mo element content at different depths, so as to further judge the deep ore-forming potential of the comprehensive anomaly area and better trace the deep uranium deposit.

[0023] S107 determining the relationship between the Mo element content and the survey depth according to the Mo element content at different depths, so as to evaluate the possibility of the existence of a concealed uranium ore body in the deep part.

[0024] S108 determining a favorable ore-forming section in the exploration area according to the relationship between the Mo element content and the survey depth.

[0025] In order to effectively identify deep sandstone-type uranium mineralization information, a concealed sandstone-type uranium geochemical tracing method in the above embodiments is provided. There is no specific sequence between steps S101 and S102, and simultaneous performance of steps S101 and S102 can improve the exploration efficiency. There is also no specific sequence between steps S103 and S104.

[0026] The inventors of the present application found that the Mo element content in the geo-gas survey has both endogenous part from the deep part and supergene part from the near-surface soil, and when obtaining the Mo element anomaly from the deep part through the geo-gas survey, the near-surface information will interfere. At the same time, the inventors of the present application found that the geochemical activity of Th element in the soil is low and generally difficult to migrate and activate, which makes the Th content in the soil relatively stable, so in steps S101 and S102 in the above embodiments, Th element is selected as the reference object.

[0027] In some embodiments, step S101, which involves obtaining the content of Mo and Th elements in the geogas in the exploration area, can be performed in the following manner:

[0028] In the exploration area, active gas extraction is used to conduct ground-atmosphere measurements at a predetermined scale. Specifically, a deep hole is first formed at or near the measurement point; for example, a hole approximately 75 cm deep can be drilled using a steel rod. A spiral sampler is screwed into the deep hole, and a filter (which can contain a microporous membrane with a 1 μm pore size), a collector (which can contain a high-purity quartz fiber membrane, for example, with a purity greater than 99%), and a quantitative gas extraction cylinder are sequentially connected to the spiral sampler. These components can be connected using rubber tubing. 6–9 L of gas is extracted using the quantitative gas extraction cylinder, the collector is removed and sealed, and the content of Mo and Th elements captured by the high-purity quartz fiber membrane is tested. In this embodiment, using a high-purity quartz fiber membrane as the collection medium avoids the drawbacks of previous methods using organic polyurethane foam as the collection medium, which required a cumbersome ashing and dissolution process before analysis. The membrane can be dissolved simply by adding hydrofluoric acid during the testing process, simplifying the testing procedure and improving the stability and reproducibility of the test results.

[0029] like Figure 2 As shown, in some embodiments, step S103, which determines the Mo element anomaly region in ground-atmosphere measurements, includes the following steps:

[0030] S201 calculates the average value and standard deviation of multiple Mo element contents obtained through geothermal measurements, where the average value is represented by C and the standard deviation is represented by S.

[0031] S202 removes data from multiple Mo element contents that are greater than C+2S and less than C-2S.

[0032] S203 then calculates the average value and standard deviation of the Mo element content in the remaining data. The average value obtained from the recalculation is denoted by C1, and the standard deviation obtained from the recalculation is denoted by S1.

[0033] S204 then removes the data that are greater than C1+2S1 and less than C1-2S1 from the remaining Mo elements.

[0034] S205 Repeat the above steps until no data can be removed from the remaining multiple Mo elements.

[0035] S206 determines the lower limit of anomalies. The remaining Mo element data, Cn+2Sn (mean value + 2 standard deviation), is the lower limit of anomalies. Here, the mean value obtained in the nth calculation is represented by Cn, and the standard deviation obtained in the nth calculation is represented by Sn.

[0036] S207 Based on the lower limit of the anomaly, determine the anomaly zone of Mo element in the ground-gas measurement. The area formed by the measuring points where the Mo element content in the ground-gas measurement is higher than the lower limit of the anomaly is the anomaly zone.

[0037] In the above embodiments, the Mo element data from the ground atmosphere measurement are eliminated using an iterative elimination method to determine the lower limit of anomalies. In other embodiments, the lower limit of anomalies can be determined using other methods.

[0038] like Figure 3 As shown, in some embodiments, step S104, which identifies anomaly zones in the Mo-Th element ratio of the exploration area, includes the following steps:

[0039] S301 calculates the ratio F1 of the Mo content and the Th content at each measuring point in the exploration area, and uses F1 to represent the element distribution characteristics in the geogas.

[0040] S302 calculates the ratio F2 of the Mo and Th element content measured in the soil at each measuring point, and uses F2 to represent the element distribution characteristics in the soil.

[0041] S303 calculates the ratio F1 to F2, F3. F1 > F2 indicates that the Mo element in the ground gas originates more from the deep part. Therefore, the ratio F1 to F2, F3, is more indicative of deep uranium deposits. The value of F3 can reflect the source of the measured Mo element content in the ground gas to a certain extent.

[0042] S304 identifies the abnormal area of ​​element ratios. The area formed by the measuring points where F3 > 1.2 is the abnormal area of ​​element ratios.

[0043] In some embodiments, in step S106 of determining the Mo element content at different depths in the ground gas measurement, the gas sampling depths can be 0.5m, 0.75m, 1m, 1.25m, 1.5m, 1.75m, and 2m, respectively. In other embodiments, other sampling depths with different gradients can be set according to actual needs.

[0044] In some embodiments, step S101, which determines the content of Mo and Th elements in the ground gas, can involve sampling the exploration area using an active gas extraction method at a certain scale. In other embodiments, sampling can also be performed using other methods that have little or no impact on the element content in the ground gas.

[0045] In some embodiments, in step S102 of determining the content of Mo and Th elements in the soil, the sampling point should coincide with the ground-atmosphere measurement point. Specifically, in some embodiments, the content of Mo and Th elements in the soil is obtained through soil geochemical measurements. In other embodiments, the content of Mo and Th elements in the soil can also be obtained through different methods.

[0046] In some embodiments, in step S102 of determining the content of Mo and Th elements in the soil, the sampling depth can be approximately 20–30 cm. After passing the soil sample through a 200-mesh stainless steel sieve, 10–15 g of a -200 particle size sample is taken and sent to the laboratory for testing of the content of Mo, Th, and other elements. In other embodiments, different sampling depths can be adopted according to specific needs, and / or other methods for analyzing the content of Mo, Th, and other elements in soil samples can be used.

[0047] In some embodiments, the above-described exploration methods can be applied to the exploration of concealed sandstone-type uranium deposits. In other embodiments, the above-described exploration methods can be selected based on the specific mineral to be explored, or the elements measured in the above-described exploration methods can be changed to other elements required for actual exploration before using the above-described exploration methods.

[0048] Because the concentration or content of Mo in the ground gas should be higher closer to the ore body when there is a concealed ore body at depth, the higher the Mo concentration at deeper locations measured by the ground gas, the greater the probability of the presence of a concealed uranium ore body at depth. In some embodiments, in step S108 of determining the metallogenic favorable area within the exploration area based on the aforementioned relationship, if the Mo content measured by the ground gas is higher at deeper measurement depths, the comprehensive anomaly area can be considered a metallogenic favorable area. In some embodiments, if the Mo content has a significant correlation with the measurement depth, the comprehensive anomaly area can be considered a metallogenic favorable area. In other embodiments, different methods can also be used to infer the metallogenic favorable area 1D230087.

[0049] Favorable mineralization areas within the region.

[0050] Regarding the embodiments of the present invention, it should also be noted that, without conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other to obtain new embodiments.

[0051] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. The scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A geochemical tracer method for concealed sandstone-type uranium deposits, characterised in that, The method comprises the following steps: carrying out geoatmosphere measurement in the exploration area to determine the contents of Mo element and Th element in the geoatmosphere; carrying out soil measurement in the exploration area to determine the contents of Mo element and Th element in the soil; determining the Mo element anomaly area in the geoatmosphere measurement according to the content of Mo element obtained in the geoatmosphere measurement; determining the Mo element and Th element ratio anomaly area in the exploration area according to the contents of Mo element and Th element obtained in the geoatmosphere measurement and the contents of Mo element and Th element obtained in the soil measurement; determining the comprehensive anomaly area according to the Mo element anomaly area and the Mo element and Th element ratio anomaly area; selecting the position with the highest content of Mo element in the geoatmosphere measurement in the comprehensive anomaly area, carrying out geoatmosphere measurement at different depths in the position to determine the contents of Mo element in the geoatmosphere at different depths; determining the relationship between the content of Mo element in the geoatmosphere and the measurement depth according to the contents of Mo element in the geoatmosphere at different depths; determining the favorable metallogenic section in the exploration area according to the relationship.

2. The method according to claim 1, wherein in the step of determining the Mo element anomaly area in the geoatmosphere measurement, the following steps are included: calculating the average value and the mean square deviation of a plurality of Mo element contents obtained by the geoatmosphere measurement, wherein the average value is represented by C and the mean square deviation is represented by S, eliminating the data greater than C+2S and less than C-2S from the plurality of Mo element contents; recalculating the average value and the mean square deviation of a plurality of Mo element contents in the remaining data, and the average value obtained by the recalculation is represented by C1 and the mean square deviation obtained by the recalculation is represented by S1, eliminating the data greater than C1+2S1 and less than C1-2S1 from the remaining plurality of Mo element contents, repeating the above steps until no data in the remaining plurality of Mo element contents can be eliminated, determining the lower limit of anomaly, wherein Cn+2Sn (average value+2 mean square deviation) of the remaining Mo element data is the lower limit of anomaly, the average value obtained by the nth calculation is represented by Cn and the mean square deviation obtained by the nth calculation is represented by Sn, and the Mo element anomaly area in the geoatmosphere measurement is determined according to the lower limit of anomaly, wherein the area composed of the measurement points with the Mo element content in the geoatmosphere higher than the lower limit of anomaly is the anomaly area.

3. The method of claim 1, wherein, The step of determining the Mo element and Th element ratio anomaly area in the exploration area comprises the following steps: calculating the ratio F1 of the content of Mo element and the content of Th element in the geoatmosphere measurement of each measurement point in the exploration area, calculating the ratio F2 of the content of Mo element and the content of Th element in the soil measurement of each measurement point in the exploration area, calculating the ratio F3 of F1 and F2, the area composed of the measurement points with F3>1.2 is the ratio anomaly area.

4. The method of claim 1, wherein, In the step of determining the contents of Mo element in the geoatmosphere at different depths, the gas depths are respectively: 0.5m, 0.75m, 1m, 1.25m, 1.5m, 1.75m, 2m.

5. The method according to claim 1, wherein In the step of determining the Mo and Th element content in the soil gas in the survey area by soil gas measurement, The sampling method adopts the active air pumping method.

6. The method of claim 1, wherein, In the step of determining the Mo and Th content in the soil in the survey area by soil measurement, the sampling points coincide with the soil gas measurement points.

7. The method of claim 1, wherein, In the step of determining the Mo and Th content in the soil in the survey area by soil measurement, the sampling depth is 20-30 cm.

8. The method of claim 1, wherein, In the step of determining the favorable metallogenic section in the survey area according to the relationship, the relationship between the Mo element content in the soil gas and the measurement depth is: The deeper the measurement depth, the higher the Mo element content in the soil gas.

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