Reverse interlayer oxidation zone sandstone type uranium ore prospecting method

Abstract

The invention belongs to the technical field of sandstone type uranium ore exploration, and relates to a reverse interlayer oxidation zone sandstone type uranium ore prospecting method. Comprising the following steps: step 1, identifying a reverse interlayer oxidation zone; 2, determining the width (a) of the transition zone; 3, determining a uranium equivalent content background value of the target layer; 4, measuring the occurrence of the target layer; 5, determining the geochemical environment where the stratum denudation line is located; and 6, determining a prospecting method according to the geochemical environment of the stratum denudation line rock. According to the method, the reverse interlayer oxidation zone prospecting principle is determined, and the prospecting direction is correctly determined. By applying the method, the reverse interlayer oxidation zone is identified in the Daradarik region in recent years, a new round of sandstone-type uranium ore prospecting work is started, a plurality of sandstone-type industrial uranium ore holes are newly found, one mining place is implemented, and the prospecting success rate is obviously improved.

Description

Technical Field

[0001] The invention belongs to the technical field of sandstone-type uranium ore exploration, and relates to a method for prospecting for inverted interlayer oxidation zone sandstone-type uranium ore. Background Art

[0002] Surface oxygenated water infiltrates and migrates along the gently inclined slope of the basin, forming a positive interlayer oxidation zone. If the infiltrating oxygenated water contains uranium, the uranium will be precipitated and enriched into mineralization near the redox conversion interface. In areas where positive interlayer oxidation zones develop, the direction and location of uranium mineralization are inferred and determined based on the surface or under the loose covering layer. That is, the oxidized sand body develops in the direction of the basin. The principle of prospecting and prediction is to use the outcrops of the oxidation zone as a clue to search for uranium ore bodies in the transition zone and reduction zones in the direction of the basin.

[0003] In areas with strong structures, the strata are uplifted and tilted in the opposite direction, forming an inverted interlayer oxidation zone in morphology. The above-mentioned prospecting prediction principles cannot be used to find uranium ore bodies in transition zones in this type of interlayer oxidation zone. Therefore, it is necessary to establish an effective prospecting method for sandstone-type uranium deposits in inverted interlayer oxidation zones. Summary of the invention

[0004] The technical problem solved by the invention is to provide a method for prospecting sandstone-type uranium deposits with an inverted interlayer oxidation zone, determine the prospecting principle of the inverted interlayer oxidation zone, correctly establish the prospecting direction, and improve the prospecting efficiency.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] The inversion interlayer oxidation zone sandstone type uranium ore prospecting method comprises the following steps:

[0007] Step 1, identification of inverted interlayer oxidation zone;

[0008] The notable feature of the inverted interlayer oxidation zone is that along the same dipping sand body, the elevation of the oxidation zone is lower than the elevation of the transition zone, and the elevation of the transition zone is lower than the elevation of the reduction zone.

[0009] Step 2, determining the width of the transition zone (a);

[0010] It is required that several sandstone-type interlayer oxidation zone uranium ore drill holes have been constructed in the exploration area, and several drill holes that expose the same target layer are selected vertically along the front line of the oxidation zone, and at least one of the selected drill holes exposes the mineralized transition zone.

[0011] Based on the exposed ore-bearing boreholes, if the hole spacing between adjacent boreholes is less than the basic engineering spacing and there is no ore in the adjacent boreholes, the width of the ore body is extrapolated by one-fourth of the actual engineering spacing. If the hole spacing between adjacent boreholes is greater than or equal to the basic engineering spacing and there is no ore in the adjacent boreholes, the width of the ore body is extrapolated by one-fourth of the basic engineering spacing.

[0012] If multiple consecutive drill holes expose transitional uranium mineralization or a uranium ore body, the drill hole that exposes the edge of the uranium mineralization or uranium ore body is used as the reference, and the width of the ore body is extrapolated outward according to the above method. This method is applied to determine the width of the transition zone (a) based on the width of the ore body.

[0013] Step 3, determining the background value of uranium equivalent content in the target layer;

[0014] According to the exploration stage, the line and point distances of the ground survey are carried out in accordance with the corresponding specifications, and the uranium equivalent content of the target layer is measured using the FD-3013 gamma radiation instrument. The average value of non-abnormal values ​​is calculated as the background value.

[0015] Step 4, measuring the occurrence of the target layer;

[0016] In the selected uranium exploration area, a good outcrop location of the target stratum is found on the surface, and the geological compass is used to accurately measure the rock formation occurrence elements, including dip and inclination.

[0017] Step 5, determining the geochemical environment of the stratum erosion line;

[0018] By observing the color characteristics of ground rocks and measuring the uranium equivalent content, it was determined that the stratigraphic erosion line was located in the rock geochemical environment, and there were five situations in total.

[0019] A: The rock at the stratum denudation line is normal rock, mainly gray, and the uranium equivalent content is the background value, without high or abnormal content. It is determined that the stratum denudation line is located in the reduction zone;

[0020] B: The rocks in the stratum denudation line are gray, and the uranium equivalent content is high and high, which is one to five times the background value. It is determined that the stratum denudation line is located in front of the transition zone with a high uranium content;

[0021] C: The rocks along the stratum denudation line are mainly gray in color, with some oxidized spots or lumps. The uranium equivalent content is much higher than the background value, more than five times the background value. It is determined that the stratum denudation line is located on the side of the transition zone close to the reduction zone;

[0022] D: The rocks in the stratigraphic denudation line are characterized by the simultaneous appearance of primary gray, oxidized yellow, and brown-red. The uranium equivalent content is much higher than the background value, more than five times the background value. It is determined that the stratigraphic denudation line is located in the transition zone close to the oxidation zone.

[0023] E: The rocks at the stratigraphic erosion line are oxidized colors such as brown-red and yellow, and the uranium equivalent content is less than the background value, which indicates that the stratigraphic erosion line is located in the oxidation zone.

[0024] Step 6, determining the prospecting method according to the rock geochemical environment of the stratum erosion line;

[0025] The stratigraphic erosion line may be located in five different geochemical environments, and different drilling arrangements are used for prospecting in different geochemical environments.

[0026] 6.1 Prospecting method when the stratum denudation line is located in the reduction zone: The stratum denudation line is located in the reduction zone, indicating that the surface is far from the transition zone and the interlayer oxidation zone. In this case, the specific location of the hidden interlayer oxidation zone cannot be determined, and only drilling can be used for "blind exploration". According to the stratum and structural occurrence, the first hole is constructed at a depth of 1000m to expose the target layer. The horizontal distance of the borehole from the stratum denudation line along the dip is L = tan (α) * 1000. If the first borehole exposes the oxidation zone, the second borehole can be constructed at an appropriate position between the first borehole and the target layer in the anticline outcrop according to the thickness ratio of the oxidized sand body to the unoxidized sand body and the oxidation intensity. This can be deduced by analogy until the transition zone uranium ore body is explored. If the first hole still exposes the reduction zone, it means that the oxidation zone and the transition zone are buried too deep (> 1000m), the hidden position is uncertain, and it is difficult to continue exploring.

[0027] 6.2 The stratum erosion line is located in the uranium high field in front of the transition zone. Prospecting method: The stratum erosion line is located in the uranium high field in front of the transition zone. It can be determined that the stratum erosion line is part of the transition zone. The uranium ore body is close to the surface. The drilling target position is arranged according to the slant distance of half the width of the transition zone to the width of the transition zone. That is, the horizontal distance from the stratum erosion line along the dip direction is

[0028] 6.3 The stratum denudation line is located on the side of the transition zone close to the reduction zone. Prospecting method: The stratum denudation line is located on the side of the transition zone close to the reduction zone, indicating that the uranium ore body in the transition zone has been partially denuded. In this case, the drilling target location is deployed at a position of one-quarter to half of the transition zone width, that is, the horizontal distance from the stratum denudation line along the dip direction.

[0029] 6.4 The stratum denudation line is located on the side of the transition zone close to the oxidation zone. Prospecting method: The stratum denudation line is located on the side of the transition zone close to the oxidation zone, indicating that the uranium ore body in the transition zone has been mostly denuded. In this case, the drilling along the dip direction reveals the target position and the drilling is arranged at a position one-quarter of the transition zone width, that is, the horizontal distance from the stratum denudation line along the dip direction.

[0030] 6.5 The stratigraphic erosion line is located in the oxidation zone. Prospecting method: According to the structural characteristics of the working area, if it is a monocline structure, it means that the transition zone has been tilted and completely exposed to the surface, and the ore body has been completely eroded and has lost its prospecting significance.

[0031] If it is an anticline, it is necessary to cross the anticline to find out the geochemical environment of the target layer. There are two situations:

[0032] 1) The target surface layer is a reduction zone, and the surface transition zone is located in the core of the anticline. It has been eroded and no longer exists, thus losing its prospecting significance.

[0033] 2) If the target surface layer is an oxidation zone, it is only necessary to use the principle of prospecting for positive interlayer oxidation zones, take the oxidation zones as clues, and arrange drilling exploration towards the center of the basin.

[0034] Where L is the horizontal distance from the borehole to the stratum denudation line along the dip direction;

[0035] a is the width of the transition zone;

[0036] α is the formation inclination.

[0037] The remarkable effects of the present invention are: improving the prospecting efficiency of sandstone-type uranium deposits in interlayer oxidation zones in structural tilted areas, reducing prospecting costs, and the method is convenient and quick.

[0038] This method was determined after repeated exploration and verification during the exploration of interlayer oxidation zone sandstone-type uranium deposits on the northern edge of the Tarim Basin. From 2019 to 2022, this method was used in the Ridaliq area of ​​the Tarim Basin, where tectonic uplift occurred, to successfully explore more than a dozen interlayer oxidation zone sandstone-type industrial uranium ore holes and a large number of uranium mineralized holes, and the mineral deposits were confirmed. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 A flow chart of a method for prospecting uranium deposits in an inverted interlayer oxidation zone sandstone type;

[0040] Figure 2 Schematic diagram of the five geochemical environments in which rocks in the stratigraphic denudation line are located;

[0041] Figure 3 Reversed interlayer oxidation zone prospecting prediction model diagram;

[0042] Figure 4 Profile of exploration line 0 in the Zidalik area on the northern edge of the Tarim Basin. DETAILED DESCRIPTION

[0043] The technical solutions and beneficial effects of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments.

[0044] See attached Figure 1 A method for prospecting for inversion interlayer oxidation zone sandstone-type uranium deposits comprises the following steps:

[0045] Step 1: Identification of the inverted interlayer oxidation zone. The significant feature of the inverted interlayer oxidation zone is that the elevation of the oxidation zone along the same target sand body is lower than the elevation of the transition zone, and the elevation of the transition zone is lower than the elevation of the reduction zone. Figure 2 shown.

[0046] Step 2, determining the width of the transition zone (a);

[0047] It is required that several sandstone-type interlayer oxidation zone uranium ore drill holes have been constructed in the exploration area, and several drill holes that expose the same target layer are selected vertically along the front line of the oxidation zone, and at least one of the selected drill holes exposes the mineralized transition zone.

[0048] Based on the exposed ore-bearing boreholes, if the hole spacing between adjacent boreholes is less than the basic engineering spacing and there is no ore in the adjacent boreholes, the width of the ore body is extrapolated by one-fourth of the actual engineering spacing. If the hole spacing between adjacent boreholes is greater than or equal to the basic engineering spacing and there is no ore in the adjacent boreholes, the width of the ore body is extrapolated by one-fourth of the basic engineering spacing.

[0049] If multiple consecutive drill holes expose transitional uranium mineralization or a uranium ore body, the drill hole that exposes the edge of the uranium mineralization or uranium ore body is used as the reference, and the width of the ore body is extrapolated outward according to the above method. This method is applied to determine the width of the transition zone (a) based on the width of the ore body.

[0050] For example, in the Zhidalik area on the northern edge of the Tarim Basin, this method was applied to determine the width of the transition zone as a = 200m.

[0051] Step 3, determining the background value of uranium equivalent content in the target layer;

[0052] According to the exploration stage, the line and point distances of the ground survey are carried out in accordance with the corresponding specifications, and the uranium equivalent content of the target layer is measured using the FD-3013 gamma radiation instrument. The average value of non-abnormal values ​​is calculated as the background value.

[0053] For example, in the Zhidalik area on the northern edge of the Tarim Basin, the uranium equivalent content of the target layer was measured using the FD-3013 gamma radiation instrument, and the average value of non-abnormal values ​​was found to be 25 ppm.

[0054] Step 4, measuring the occurrence of the target layer;

[0055] In the selected uranium exploration area, a good outcrop location of the target stratum is found on the surface, and the geological compass is used to accurately measure the rock formation occurrence elements, including dip and inclination.

[0056] For example, in the Zhidalik area on the northern edge of the Tarim Basin, the target layer of the VIII1 cycle of the lower section of the Kuche Formation (N2ka) has good surface outcrops. Near the No. 0 exploration line, the formation dip measured by the geological compass is 10°∠25°. Figure 4 shown.

[0057] Step 5, determine the rock geochemical environment of the stratum erosion line;

[0058] Through the observation of the color characteristics of the ground rocks and the measurement of the uranium equivalent content, it is determined that the stratum denudation line is located in the rock geochemical environment. There are five situations, such as Figure 2 shown.

[0059] A: The rock at the stratum denudation line is normal rock, mainly gray, and the uranium equivalent content is the background value, without high or abnormal values. It is determined that the stratum denudation line is located in the reduction zone. Figure 2 Middle A position.

[0060] B: The rock of the stratum denudation line is gray, and the uranium equivalent content appears high field and high field, which is one to five times the background value. It is determined that the stratum denudation line is located in front of the transition zone. The uranium is high field, such as Figure 2 Middle B position.

[0061] C: The rocks of the stratum denudation line are mainly gray in color, with oxidized spots or lumps. The uranium equivalent content is much higher than the background value, more than five times the background value. It is determined that the stratum denudation line is located on the side of the transition zone close to the reduction zone. Figure 2 Middle C position.

[0062] D: The stratum denudation line is characterized by the simultaneous appearance of primary gray, oxidized yellow, and brown-red. The uranium equivalent content is much higher than the background value, more than five times the background value. It is determined that the stratum denudation line is located on the side of the transition zone close to the oxidation zone. Figure 2 Middle D position.

[0063] E: The rocks along the stratum denudation line are brown-red, yellow and other oxidized colors, and the uranium equivalent content is less than the background value. It is determined that the stratum denudation line is located in the oxidation zone, such as Figure 2 Middle E position.

[0064] For example, in the Zhidalik area on the northern edge of the Tarim Basin, at the location of the sand body denudation line of the lower Kuche Formation (N2ka) VIII 1 cycle, the uranium equivalent content measured by the FD-3013 γ radiation instrument was 95 ppm, which was 3.8 times the background value, and the surface rocks were gray. Based on this, it was determined that the rocks in the stratum denudation line were in a geochemical environment with a high uranium field in front of the transition zone, such as Figure 4 shown.

[0065] Step 6: Determine the prospecting method based on the rock geochemical environment of the stratum erosion line.

[0066] The stratum denudation line may be located in five different geochemical environments. Different drilling arrangements are used for prospecting in different geochemical environments, such as Figure 3 shown.

[0067] 6.1 Prospecting method of stratum denudation line located in reduction zone: The stratum denudation line located in reduction zone indicates that the surface is far away from transition zone and interlayer oxidation zone. In this case, the specific location of hidden interlayer oxidation zone cannot be determined, and only drilling can be used for "blind exploration". According to the occurrence of stratum and structure, the first hole is constructed at the depth of 1000m to expose the target layer. Figure 3The ZK1-1 borehole shown in the figure has a horizontal distance L=tan(α)*1000 from the stratum denudation line along the dip. If the first borehole reveals an oxidized zone, a second borehole can be constructed at an appropriate position between the first borehole and the target layer at the anticline outcrop according to the thickness ratio of the oxidized sand body to the unoxidized sand body and the oxidation intensity, such as Figure 3 The ZK1-2 borehole shown in the figure can be deduced in this way until the transition zone uranium ore body is explored. If the first hole still reveals the reduction zone, it means that the oxidation zone and transition zone are buried too deep (>1000m), the hidden position is uncertain, and it is difficult to continue exploring.

[0068] 6.2 The stratum erosion line is located in the uranium high field in front of the transition zone. Prospecting method: The stratum erosion line is located in the uranium high field in front of the transition zone. It can be determined that the stratum erosion line is part of the transition zone. The uranium ore body is close to the surface. The drilling target position is arranged according to the slant distance of half the width of the transition zone to the width of the transition zone. That is, the horizontal distance from the stratum erosion line along the dip direction is like Figure 3 ZK2-1 drilling is shown.

[0069] 6.3 The stratum denudation line is located on the side of the transition zone close to the reduction zone. Prospecting method: The stratum denudation line is located on the side of the transition zone close to the reduction zone, indicating that the uranium ore body in the transition zone has been partially denuded. In this case, the drilling target location is deployed at a position of one-quarter to half of the transition zone width, that is, the horizontal distance from the stratum denudation line along the dip direction. like Figure 3 ZK3-1 drilling is shown.

[0070] 6.4 The stratum denudation line is located on the side of the transition zone close to the oxidation zone. Prospecting method: The stratum denudation line is located on the side of the transition zone close to the oxidation zone, indicating that the uranium ore body in the transition zone has been mostly denuded. In this case, the drilling along the dip direction reveals the target position and the drilling is arranged at a position one-quarter of the transition zone width, that is, the horizontal distance from the stratum denudation line along the dip direction. like Figure 3 The ZK4-1 drilling is shown.

[0071] 6.5 The stratigraphic erosion line is located in the oxidation zone. Prospecting method: According to the structural characteristics of the working area, if it is a monocline structure, it means that the transition zone has been tilted and completely exposed to the surface, and the ore body has been completely eroded and has lost its prospecting significance.

[0072] If it is an anticline, it is necessary to cross the anticline to find out the geochemical environment of the target layer. There are two situations:

[0073] 1) The target surface layer is a reduction zone, and the surface transition zone is located in the core of the anticline. It has been eroded and no longer exists, thus losing its prospecting significance.

[0074] 2) If the target surface layer is an oxidation zone, then it is only necessary to use the principle of prospecting for the positive interlayer oxidation zone, take the oxidation zone as a clue, and arrange drilling exploration towards the center of the basin. Figure 3 The ZK5-1 drilling is shown.

[0075] For example, in the Zhidalik area on the northern edge of the Tarim Basin, the lower Kuche Formation (N2ka) VIII1 sand body, the stratum strike of exploration line 0 is 10°∠25°, the stratum erosion line is located at the uranium anomaly position in front of the transition zone, and the horizontal distance from the stratum erosion line along the dip direction is In the actual production process, the drilling was arranged at L = 110m, and the results revealed uranium mineralization in the transition zone, such as Figure 4 shown.

[0076] Under the guidance of this prospecting method, an inverted interlayer oxidation zone has been identified in the Zhidarik area in recent years, a new round of sandstone-type uranium prospecting has been initiated, a number of new sandstone-type industrial uranium holes have been discovered, and a mineral deposit has been identified, significantly improving the success rate of prospecting.

Claims

1. A method for prospecting uranium deposits in an inverted interlayer oxidation zone sandstone type, characterized in that: The method specifically comprises the following steps: Step 1, identification of inverted interlayer oxidation zone; Step 2, determining the width of the transition zone (a); Step 3, determining the background value of uranium equivalent content in the target layer; Step 4, measuring the occurrence of the target layer; Step 5, determining the geochemical environment of the stratum erosion line; Step 6: Determine the prospecting method based on the rock geochemical environment of the stratigraphic erosion line.

2. A method for prospecting for inversion-type interlayer oxidation zone sandstone-type uranium deposits as claimed in claim 1, characterized in that: In the method for identifying the inverted interlayer oxidation zone in step 1, the significant feature of the inverted interlayer oxidation zone is that the elevation of the oxidation zone along the same target sand body is lower than the elevation of the transition zone, and the elevation of the transition zone is lower than the elevation of the reduction zone.

3. A method for prospecting for inversion-type interlayer oxidation zone sandstone-type uranium deposits as claimed in claim 2, characterized in that: Determining the width of the transition zone (a) in step 2 requires that a number of sandstone-type interlayer oxidation zone uranium ore drill holes have been constructed in the exploration area, and a number of drill holes are selected vertically along the oxidation zone front line to expose the same target layer, and at least one of the selected drill holes exposes the ore-bearing transition zone; Taking the exposed ore-bearing boreholes as the benchmark, if the hole spacing between adjacent boreholes is less than the basic engineering spacing and there is no ore in the adjacent boreholes, the width of the ore body is extrapolated by one-fourth of the actual engineering spacing; if the hole spacing between adjacent boreholes is greater than or equal to the basic engineering spacing and there is no ore in the adjacent boreholes, the width of the ore body is extrapolated by one-fourth of the basic engineering spacing; If multiple consecutive drill holes expose transitional uranium mineralization or a uranium ore body, the drill hole that exposes the edge of the uranium mineralization or uranium ore body is used as the reference, and the width of the ore body is extrapolated outward according to the above method. This method is applied to determine the width of the transition zone (a) based on the width of the ore body.

4. A method for prospecting for inversion-type interlayer oxidation zone sandstone-type uranium deposits as claimed in claim 3, characterized in that: The step 3 determines the background value of the uranium equivalent content of the target layer. According to the exploration stage, the ground survey line distance and point distance are measured according to the corresponding specifications. The uranium equivalent content of the target layer is measured using the FD-3013 gamma radiation instrument, and the average value of non-abnormal values ​​is calculated as the background value.

5. A method for prospecting for inversion interlayer oxidation zone sandstone type uranium deposits as claimed in claim 4, characterized in that: The step 4 measures the strike of the target layer. In the selected uranium exploration area, a good outcrop position of the target stratum is found on the surface, and a geological compass is used to accurately measure the strike elements of the stratum, including the dip, strike and inclination.

6. A method for prospecting for inversion-type interlayer oxidation zone sandstone-type uranium deposits as claimed in claim 5, characterized in that: The step 5 is to determine the geochemical environment where the stratum erosion line is located. By observing the color characteristics of the ground rocks and measuring the uranium equivalent content, it is determined that the stratum erosion line is located in the rock geochemical environment. There are five situations in total: A: The rock at the stratum denudation line is normal rock, mainly gray, and the uranium equivalent content is the background value, without high or abnormal content. It is determined that the stratum denudation line is located in the reduction zone; B: The rocks in the stratum denudation line are gray, and the uranium equivalent content is high and high, which is one to five times the background value. It is determined that the stratum denudation line is located in front of the transition zone with a high uranium content; C: The rocks along the stratum denudation line are mainly gray in color, with some oxidized spots or lumps. The uranium equivalent content is much higher than the background value, more than five times the background value. It is determined that the stratum denudation line is located on the side of the transition zone close to the reduction zone; D: The rocks in the stratigraphic denudation line are characterized by the simultaneous appearance of primary gray, oxidized yellow, and brown-red. The uranium equivalent content is much higher than the background value, more than five times the background value. It is determined that the stratigraphic denudation line is located in the transition zone close to the oxidation zone. E: The rocks at the stratigraphic erosion line are oxidized colors such as brown-red and yellow, and the uranium equivalent content is less than the background value, which indicates that the stratigraphic erosion line is located in the oxidation zone.

7. A method for prospecting for inversion-type interlayer oxidation zone sandstone-type uranium deposits as claimed in claim 6, characterized in that: The step 6 is to determine the prospecting method according to the rock geochemical environment of the stratum erosion line. The stratum erosion line may be located in five different geochemical environments. Different drilling arrangements are used for prospecting in different geochemical environments. 6.1 Prospecting method of formation erosion line located in reduction zone: The formation erosion line located in reduction zone indicates that the surface is far away from transition zone and interlayer oxidation zone. In this case, the specific position of hidden interlayer oxidation zone cannot be determined, and only drilling can be used for "blind exploration". According to the formation and structural occurrence, the first hole is constructed at a depth of 1000m to expose the target layer. The horizontal distance of the borehole from the formation erosion line along the dip is L = tan (α) * 1000. If the first borehole exposes the oxidation zone, the second borehole can be constructed at an appropriate position between the first borehole and the target layer in the anticline outcrop according to the thickness ratio of oxidized sand body to unoxidized sand body and the oxidation intensity. This can be deduced by analogy until the transition zone uranium ore body is explored. If the first hole still exposes the reduction zone, it means that the oxidation zone and transition zone are buried too deep (> 1000m), the hidden position is uncertain, and it is difficult to continue exploration. 6.2 The stratum erosion line is located in front of the transition zone Uranium high field prospecting method: The stratum erosion line is located in front of the transition zone The uranium bias is high, which can be used to determine that the stratum erosion line is part of the transition zone. The uranium ore body is close to the surface. The drilling target location is arranged at a slant distance of half the width of the transition zone to the width of the transition zone, that is, the horizontal distance from the stratum erosion line along the dip direction. 6.3 The stratum denudation line is located on the side of the transition zone close to the reduction zone. Prospecting method: The stratum denudation line is located on the side of the transition zone close to the reduction zone, indicating that the uranium ore body in the transition zone has been partially denuded. In this case, the drilling target location is deployed at a position of one-quarter to half of the transition zone width, that is, the horizontal distance from the stratum denudation line along the dip direction. 6.4 The stratum denudation line is located on the side of the transition zone close to the oxidation zone. Prospecting method: The stratum denudation line is located on the side of the transition zone close to the oxidation zone, indicating that the uranium ore body in the transition zone has been mostly denuded. In this case, the drilling along the dip direction reveals the target position and the drilling is arranged at a position one-quarter of the transition zone width, that is, the horizontal distance from the stratum denudation line along the dip direction. 6.5 The stratum denudation line is located in the oxidation zone. Prospecting method: According to the structural characteristics of the working area, if it is a monocline structure, it means that the transition zone is tilted and completely exposed to the surface, and the ore body is completely denuded and loses its prospecting significance. If it is an anticline, it is necessary to cross the anticline to find out the geochemical environment of the target layer. There are two situations: 1) The target layer on the surface is a reduction zone, and the surface transition zone is located in the core of the anticline and has been eroded and no longer exists, thus losing its prospecting significance. 2) If the target surface layer is an oxidation zone, it is only necessary to use the principle of prospecting for the positive interlayer oxidation zone, take the oxidation zone as a clue, and arrange drilling exploration towards the center of the basin. Where L is the horizontal distance from the borehole to the stratum denudation line along the dip direction; a is the width of the transition zone; α is the formation inclination.

Images