Discrimination method of red sand body genesis under arid paleoclimate

Abstract

This application provides a method for determining the genesis of red sandstone bodies under arid paleoclimate conditions. The method includes: identifying the target stratigraphic interval containing a fluvial red sandstone body controlled by arid paleoclimate in the exploration area; determining the paleowater depth of the fluvial microfacies within the target stratigraphic interval based on the sedimentary facies type of the fluvial facies; obtaining the macroscopic characteristics of the red sandstone body within the fluvial facies; obtaining the microscopic characteristics of the red sandstone body within the fluvial facies; determining whether the red sandstone body is of primordial origin based on the paleowater depth of the fluvial microfacies and the macroscopic and microscopic characteristics of the red sandstone body; if the red sandstone body is of primordial origin, then the exploration strategy of exudative sandstone-type uranium deposits is adopted. This application determines the genesis of red sandstone bodies by comprehensively considering paleowater depth and the macroscopic and microscopic characteristics of the red sandstone body, accurately distinguishing whether the red sandstone body is of primordial origin.

Description

Technical Field

[0001] This application belongs to the field of uranium exploration technology, specifically relating to a method for determining the genesis of red sand bodies under arid paleoclimate conditions. Background Technology

[0002] With the continued and in-depth application of exudative sandstone uranium mineralization in uranium exploration, the accurate determination of the genesis (primary or secondary) of red sand bodies in red-variegated formations has become particularly important. When the main mineralizing sand body in a sandstone-type uranium exploration area is primarily composed of primary red sand bodies, it indicates that the red sand bodies in the exploration area are of primary origin (i.e., primary sedimentary origin), and the exploration strategy for sandstone-type uranium deposits should focus on actively seeking "exudative sandstone-type uranium deposits." Conversely, if the red sand bodies in the exploration area are of secondary origin (i.e., post-mineralization alteration), then the uranium exploration in the area should be adjusted to focus on classic inter-layer oxidation or percolation oxidation "exudative sandstone-type uranium deposits." Therefore, the question of the genesis (primary or secondary) of red sand bodies is one of the key fundamental technologies that determines whether to adopt a "classical exudative" or "exudative" exploration strategy for sandstone-type uranium deposits, and the accurate identification of primary red sand bodies is especially crucial. However, the red sand bodies in the exploration area may be controlled by a variety of complex geological processes, such as weathering differences in the source area, sedimentary facies, sedimentary paleooxidized facies, diagenetic evolution, and ore-forming fluid modification during the mineralization period. It is not easy to accurately determine whether the red sand bodies are of primary or secondary origin. There is an urgent need to develop a set of discrimination technology for primary red sand bodies to serve the exploration of "percolation-type" sandstone uranium deposits. Summary of the Invention

[0003] In view of this, the embodiments of this application are committed to providing a method for determining the origin of red sand bodies under arid paleoclimate. By comprehensively considering paleowater depth and the macroscopic and microscopic characteristics of red sand bodies, the origin of red sand bodies is determined, and the origin of red sand bodies is accurately distinguished as being of primary origin.

[0004] This application provides a method for determining the genesis of red sandstone bodies under arid paleoclimate conditions. The method includes: identifying the target stratigraphic unit containing a fluvial red sandstone body controlled by arid paleoclimate in the exploration area; determining the paleowater depth of the fluvial microfacies within the target stratigraphic unit based on the sedimentary facies type of the fluvial facies; acquiring the macroscopic characteristics of the red sandstone body within the fluvial facies, including spatial occurrence characteristics, the relationship between the spatial occurrence of the red sandstone body and the sedimentary facies, and the spatial superposition relationship between the red sandstone body and the associated mudstone; acquiring the microscopic characteristics of the red sandstone body within the fluvial facies, including petrological characteristics, mineralogical characteristics, and geochemical-isotopic characteristics; determining whether the red sandstone body's genesis is primordial based on the paleowater depth of the fluvial microfacies and the macroscopic and microscopic characteristics of the red sandstone body; and if the red sandstone body's genesis is primordial, then the exploration strategy of exudative sandstone-type uranium deposits is adopted for exploration.

[0005] In one specific embodiment of this application, the above-mentioned determination of the target stratigraphic segment containing the riverine red sand body controlled by the arid paleoclimate of the exploration area includes: determining the paleoclimate characteristics of the stratigraphic segment containing the red sand body based on the paleoclimate data and / or structural features of the stratigraphic segment containing the red sand body; and determining the target stratigraphic segment containing the riverine red sand body controlled by the arid paleoclimate of the exploration area based on the paleoclimate characteristics.

[0006] In one specific embodiment of this application, the above-mentioned determination of the paleowater depth of the microfacies of the fluvial facies in the target stratigraphic section includes: performing sedimentary facies analysis on the target stratigraphic section to determine the sedimentary facies, subfacies, and microfacies of the fluvial facies; determining the fluvial facies sedimentary facies map, as well as the planar distribution and development scale of the subfacies and microfacies; and determining the paleowater depth of the microfacies of the fluvial facies based on the planar distribution of the microfacies and microfacies of the fluvial facies.

[0007] In one specific embodiment of this application, the above-mentioned determination of the paleowater depth of the microfacies of the fluvial facies based on the microfacies and planar distribution of the microfacies includes: determining the paleowater depth of the microfacies of the fluvial facies based on the microfacies and planar distribution of the microfacies, and in conjunction with the paleowater depth geochemical index of the target stratigraphic section.

[0008] In one specific embodiment of this application, the above-mentioned acquisition of the macroscopic characteristics of red sand bodies in the target stratigraphic segment includes: statistically analyzing the thickness of red sand bodies in fluvial facies to obtain statistical data on red sand body thickness; drawing a contour map of red sand body thickness based on the statistical data; determining the spatial occurrence characteristics of red sand bodies based on the contour map; overlaying the contour map of red sand body thickness with a fluvial sedimentary facies map to determine the relationship between the spatial occurrence of red sand bodies and sedimentary facies; determining the thickness data of mudstone associated with red sand bodies based on the statistical data; drawing a contour map of mudstone associated with red sand bodies based on the thickness data; and determining the spatial overlay relationship between mudstone associated with red sand bodies and red sand bodies based on the contour map.

[0009] In one specific embodiment of this application, the above-mentioned acquisition of the microscopic characteristics of red sandstone bodies in fluvial facies includes: performing petrological analysis on the red sandstone bodies in fluvial facies to determine their petrological characteristics, including the primary sedimentary structures of the red sandstone bodies, whether the red sandstone bodies have developed carbonaceous debris or mobile organic matter, the contact relationship between the red sandstone bodies and gray sandstone bodies, and the color of the mudstones associated with the red sandstone bodies; performing mineralogical analysis on the red sandstone bodies in fluvial facies to determine their mineralogical characteristics, including the color of the constituent grains of the red sandstone bodies, the type and content of iron-bearing minerals, and the type and content of clay minerals; and performing geochemical-isotopic analysis on the red sandstone bodies in fluvial facies to determine their geochemical-isotopic characteristics, including the oxidation and fluid characteristics of the red sandstone bodies.

[0010] In one specific embodiment of this application, the determination of whether the genesis of the red sandstone body is of primary origin based on at least one of the paleowater depth characteristics of the fluvial microfacies and the macroscopic and microscopic characteristics of the red sandstone body includes: determining whether the red sandstone body is a red sandstone body in fluvial sedimentation based on the paleowater depth of the fluvial microfacies; determining whether the red sandstone body is a red sandstone body associated with thick regional red mudstone, distributed in a planar pattern at the basin margin-basin center, with its thickness center limited to the main channel, based on the macroscopic characteristics of the red sandstone body; and determining whether the red sandstone body has the following characteristics: the rocks are mainly warm-toned in red, brownish-red, or dark red; there is a lack of or thin dark yellow sandstone bodies; the red sandstone body is clean; it is mainly composed of hematite and limonite mineralization; and its geochemical characteristics include "low organic carbon content, low sulfur content, and low Fe content". 2+ Low; Fe 3+ High, Fe 3+ / Fe 2+ A red sand body with "high oxygen isotope positive bias and carbon isotope negative bias"; if the judgment results are all yes, then the formation of the red sand body is determined to be the original formation cause.

[0011] This application, by analyzing paleowater depths of fluvial facies microfacies and the macroscopic and microscopic characteristics of red sand bodies, determines whether the formation of red sand bodies is of primary origin. This provides a method for identifying the primary origin of red sand bodies—a method that combines macroscopic understanding of overall patterns with microscopic corroboration of detailed evidence—and comprehensive judgment of sand body genesis. This approach can provide accurate criteria for determining exploration strategies in exudative sandstone uranium deposits, thus supporting decision-making in the exploration of exudative sandstone uranium deposits. This research enriches the metallogenic theory of exudative sandstone uranium deposits and can directly guide prospecting work in sandstone-type uranium deposits in sedimentary basins of northern China, demonstrating significant application potential. Attached Figure Description

[0012] Figure 1The diagram shown is a flowchart illustrating a method for determining the origin of red sand bodies under arid paleoclimate conditions, provided in an embodiment of this application.

[0013] Figure 2 The diagram shown is a flowchart illustrating a method for determining the origin of red sand bodies under arid paleoclimate conditions, provided in another embodiment of this application.

[0014] Figure 3 The diagram shows the paleoclimate evolution during the depositional period of the red sandstone strata (Yaojia Formation) in the southwestern Songliao Basin.

[0015] Figure 4 The image shows the distribution of river channels in the Yaoxia section of the southwestern Songliao Basin.

[0016] Figure 5 The image shows contour maps of the thickness of the red sand body in the Yaoxia segment of the southwestern Songliao Basin.

[0017] Figure 6 The diagram shows the superposition of the thickness of the red sand body in the Yaoxia section of the southwestern Songliao Basin and the river channel in the Yaoxia section.

[0018] Figure 7 The image shows contour maps of the thickness of red sandstone bodies associated with red mudstones in the Yaoxia section of the southwestern Songliao Basin.

[0019] Figure 8 The diagram shows the thin section characteristics of the red sandstone body (a) and associated red mudstone (b) in the Yaoxia section of the southwestern Songliao Basin. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] Figure 1 The diagram shown is a flowchart illustrating a method for determining the origin of red sand bodies under arid paleoclimate conditions, according to an embodiment of this application. Figure 1 As shown, the method for determining the origin of red sand bodies under this arid paleoclimate includes the following steps.

[0022] S100: Determines the target stratigraphic segment containing the fluvial red sand bodies controlled by the arid paleoclimate in the exploration area.

[0023] S200: Determine the paleowater depth of the microfacies of the fluvial facies in the target stratigraphic section based on the sedimentary facies type of the fluvial facies in the target stratigraphic section.

[0024] S300: Obtain the macroscopic characteristics of red sand bodies in fluvial facies. Macroscopic characteristics include spatial occurrence characteristics, the relationship between the spatial occurrence of red sand bodies and sedimentary facies, and the spatial superposition relationship between red sand bodies and associated mudstone.

[0025] S400: Obtain the microscopic characteristics of red sand bodies in fluvial facies. Microscopic characteristics include petrological features, mineralogical features, and geochemical-isotopic features.

[0026] S500: Based on the paleowater depth of the fluvial microfacies and the macroscopic and microscopic characteristics of the red sand body, determine whether the formation of the red sand body is of primary origin.

[0027] S600: If the formation of the red sandstone body is due to the original formation process, then the exploration approach of exudative sandstone-type uranium deposits will be adopted.

[0028] According to the technical solution provided in this application, by considering the paleowater depth of the fluvial facies microfacies and the macroscopic and microscopic characteristics of the red sand body, it is determined whether the red sand body is of primary origin. This provides a method for discriminating the primary origin of red sand bodies by "grasping the overall laws macroscopically, corroborating detailed evidence microscopically, and comprehensively judging the origin of the sand body." This method can provide accurate criteria for determining the exploration strategy of exudative sandstone uranium deposits, thus serving the decision-making of exploration strategies in the exploration of "exudative" sandstone uranium deposits. This research can enrich the metallogenic theory of exudative sandstone uranium deposits and can also provide direct guidance for prospecting work on sandstone-type uranium deposits in sedimentary basins in northern China, showing great application potential.

[0029] Figure 2 The diagram shown is a flowchart illustrating a method for determining the origin of red sand bodies under arid paleoclimate conditions, provided in another embodiment of this application. Figure 2 The embodiment shown is Figure 1 This is a variation of the illustrated embodiment. The following example uses the widely developed red sand bodies in the lower segment of the Yaojia Formation in southwestern Songliao Basin as an example. Figure 2 The discrimination method of the illustrated embodiment will be described.

[0030] like Figure 2 As shown, with Figure 1 The difference in the illustrated embodiment is that steps S110 and S120 are... Figure 1 A specific implementation of step S100 in the illustrated embodiment.

[0031] S110: Determine the paleoclimate characteristics of the strata containing the red sand bodies in the exploration area based on paleoclimate data and / or structural features.

[0032] For example, S111: Paleoclimatic data from the depositional period of the Yaojia Formation, the stratum containing the red sandstone bodies in the southwestern Songliao Basin, were collected and analyzed. It was found that the Songliao Basin, where the Yaojia Formation is located, was generally a humid to semi-humid subtropical environment during the Cretaceous, but experienced three cooling periods, four warming periods, and three semi-arid periods. The warming-arid event during the Late Cretaceous Coniac-Santo stages of the Yaojia Formation may have had a direct impact on the Yaojia Formation. Furthermore, data analysis suggests that a global extreme heat event (OAE2, Bonarelli event) around 94 Ma may have had a significant impact on the Yaojia Formation. The depositional period of the Yaojia Formation in the southwestern basin was within an overall hot and arid paleoclimatic background. That is, the Yaojia Formation, the stratum containing the red sandstone bodies in the exploration area, experienced a distinct paleoclimatic evolution history from oscillating warming (relatively warm-warm-relatively warm-warm-extremely warm) to a slow relative cooling (extremely warm-relatively warm). (Refer to...) Figure 3 , Figure 3 The diagram shows the paleoclimate evolution during the depositional period of the red sandstone strata of the Yaojia Formation in the southwestern Songliao Basin.

[0033] S112: Analysis of the construction characteristics of the stratum containing the red sandstone body in the southwestern Songliao Basin (Yaojia Formation) reveals that the overall structure is a red-colored variegated structure dominated by red sandstone bodies, red mudstone interbedded with thin layers of gray sandstone bodies. Furthermore, red beds (red sandstone bodies) and carbonate deposits were found in this structure, with a small amount of gypsum visible in some areas. These special rocks, typical of arid climates, further confirm the hot and arid paleoclimate background during the deposition of the stratum containing the red sandstone body (Yaojia Formation).

[0034] S120: Based on paleoclimate characteristics, the target stratigraphic segment containing the fluvial red sand body controlled by the arid paleoclimate in the exploration area is determined.

[0035] For example, S121: Based on the paleoclimate characteristics determined by S111 and S112, the red sand body segment in the Yaoxia Formation with a hot and arid climate background, which was affected by the Late Cretaceous Bonarelli thermal event, is selected as the target segment.

[0036] In at least one embodiment of this application, steps S210 to S230 are Figure 1 A specific implementation of step S200 in the illustrated embodiment.

[0037] S210: Perform sedimentary facies analysis on the target layer to determine the sedimentary facies, subfacies, and microfacies of the fluvial facies.

[0038] For example, S211: Based on the above-defined arid paleoclimate-controlled southwestern Yaoxia section of the Songliao Basin, a systematic study of sedimentology, including rock color, lithology, lithofacies, sedimentary sequence, and paleontology, was conducted. It was found that the southwestern Yaoxia section is a terrestrial braided river sedimentary system with a typical "sand-mud" structure, mainly composed of red medium-coarse sandstone interbedded with thin layers of red mudstone. It can be further divided into braided river facies (the main facies of the exploration area) and braided river delta facies (the local facies of the northeastern part of the exploration area). It can be further divided into subfacies such as channels, floodplains, and braided river delta plains. On this basis, microfacies such as braided channels, mid-channel bars, floodplains, and braided river plain distributary channels can be further subdivided.

[0039] S220: Determine the fluvial sedimentary facies diagram, as well as the planar distribution and development scale of subfacies and microfacies.

[0040] For example, S221: Through the compilation of a series of basic maps including the thickness of the sand body, mudstone thickness, and sand-to-soil ratio in the Yaoxia Formation, this case study reconstructed the sedimentary facies in the braided river sedimentary system identified in the target layer of the Yaoxia Formation, and clarified the planar distribution and development scale of distributary channels in the braided river channels and braided river delta plain facies. (Refer to...) Figure 4 , Figure 4 The diagram shows the distribution of river channels in the Yaoxia section of the southwestern Songliao Basin.

[0041] S230: Determine the paleowater depth of the microfacies of the fluvial facies based on the microfacies and the planar distribution of the microfacies.

[0042] Specifically, in some embodiments, the paleowater depth of the section containing the red sand body can be directly estimated based on the fluvial microfacies determined in S210 and the planar distribution characteristics of the microfacies determined in S220. In other embodiments, after estimating the paleowater depth of the section containing the red sand body based on the fluvial microfacies determined in S210 and the planar distribution characteristics of the microfacies determined in S220, the paleowater depth conditions in different areas of the exploration area are further comprehensively determined by combining the paleowater depth geochemical indicators of the target section, thereby making the paleowater depth estimation results of the fluvial microfacies more accurate.

[0043] For example, S231: The paleowater depths of different microfacies in the Yaoxia section of the river facies determined by S221 are clarified. Based on the paleowater depth experience of modern braided rivers, the paleowater depths of each microfacies in the exploration area are defined as follows: paleowater depth of the floodplain is 0m, braided channel is 0-5m, mid-channel bar is 0-10m, braided river plain channel is 0-10m, and braided river delta plain intermontane bay is 2-15m. Based on this, the paleowater depth of the Yaoxia section of the exploration area during the depositional period is estimated to be no more than 15m.

[0044] In at least one embodiment of this application, steps S310 to S370 are Figure 1A specific implementation of step S300 in the illustrated embodiment.

[0045] S310: Statistical analysis of the thickness of red sand bodies in fluvial facies to obtain statistical data on the thickness of red sand bodies.

[0046] S320: Draw a contour map of the thickness of the red sand body based on the statistical data of the red sand body thickness.

[0047] S330: Determine the spatial occurrence characteristics of the red sand body based on the contour map of the red sand body thickness.

[0048] For example, S311 (corresponding to steps S310 to S330): The thickness of the red sand body in the Yaoxia section of the river facies is statistically analyzed under the initial hot and arid climate background defined above, so as to obtain the red sand body thickness statistics (corresponding to step S310), and the red sand body thickness contour map is made using the red sand body thickness statistics (corresponding to step S320). Figure 5 The image shows the contour map of the red sand body thickness. Combined with... Figure 5 The red sand bodies in the Yaoxia Formation of the Songliao Basin were found to be 0-225 m thick, occurring both at the basin margin and within the basin, and extending over 200 km, covering more than 70% of the exploration area. Vertically, the thickness of the red sand bodies accounts for approximately 75-90% of the thickness of the Yaojia Formation sand bodies. This further clarifies the spatial occurrence characteristics of the red sand bodies in the southwestern Yaoxia Formation of the Songliao Basin (corresponding to step S330).

[0049] S340: Overlay the contour map of red sand body thickness with the fluvial sedimentary facies map to determine the relationship between the spatial occurrence of red sand bodies and sedimentary facies.

[0050] For example, S341: The information obtained in step S311 Figure 5 The contour map of the red sand body in the lower section of Yao shown is the same as the one obtained in step S221. Figure 4 The fluvial sedimentary facies diagrams shown are overlaid to obtain an overlay diagram of the red sand bodies and channels in the Yaoxia Formation of the southwestern Songliao Basin. (Reference) Figure 6 , Figure 6 The diagram shows the superposition of the red sand body thickness and the channel sand body in the Yaoxia section of the southwestern Songliao Basin. (Combined with...) Figure 6 The study found that the planar distribution of the red sand body is closely related to the paleochannel of the Yaoxia section, that is, the thickness center of the red sand body is strictly limited by the paleochannel of the Yaoxia section, indicating that the fluvial deposition in the Yaoxia section has a significant controlling effect on the red sand body.

[0051] S350: Determine the thickness data of the mudstone associated with the red sandstone body based on the statistical data of the red sandstone body thickness.

[0052] S360: Draw a contour map of the thickness of the associated mudstone of the red sandstone body based on the thickness data of the mudstone associated with the red sandstone body.

[0053] S370: Determine the spatial superposition relationship between the red sand body and the associated mudstone based on the thickness contour map of the red sand body.

[0054] For example, S351 (corresponding to steps S350 to S370): Collect thickness data of red mudstone closely associated with the Yaoxia Formation red sandstone body in step S311, and create a contour map of the thickness of the associated mudstone of the Yaoxia Formation red sandstone body, referring to... Figure 7 , Figure 7 The image shows contour maps of the thickness of red sandstone bodies associated with red mudstone in the Yaoxia Formation of the southwestern Songliao Basin. Combined with... Figure 7 The thickness of the associated red mudstone ranges from 0 to 90 m, similar to the red sandstone body in the Yaoxia section. It also occurs in the basin margin to the basin center, and is planar in shape, extending for more than 200 km, accounting for more than 80% of the exploration area. Its distribution is not significantly related to the spatial occurrence of the river channel, but rather similar to the spatial occurrence of the red sandstone body.

[0055] In at least one embodiment of this application, steps S410 to S430 are Figure 1 A specific implementation of step S400 in the illustrated embodiment.

[0056] S410: Petrological analysis of red sand bodies in fluvial facies to determine their petrological characteristics. These characteristics include the primary sedimentary structures of the red sand bodies, the presence or absence of carbonaceous debris or mobile organic matter, the contact relationship between the red and gray sand bodies, and the color of the associated mudstones.

[0057] For example, S411: Petrological studies were conducted on the red sandstone body in the Yaoxia section of the exploration area. The red sandstone body in the Yaoxia section showed sedimentary structures such as platy cross-bedding and wedge cross-bedding on the core, but no carbon debris was found. The mudstone associated with the red sandstone body in the Yaoxia section had a consistent color tone, and its boundary with the gray sandstone body was an irregular bay-shaped contact.

[0058] S420: Mineralogical analysis of red sand bodies in fluvial facies to determine their mineralogical characteristics. These characteristics include the color of the constituent grains, the type and content of iron-bearing minerals, and the type and content of clay minerals.

[0059] For example, S421: Mineralogical microscopic studies were conducted on the red sandstone body in the Yaoxia section of the exploration area. A large amount of hematite mineralization was found filling the intergranular pores of the red sandstone in the Yaoxia section. Locally, enlarged quartz grains were found to contain hematite or limonite mineralization. Hematite mineralization was also found in the red mudstone associated with the red sandstone body in the Yaoxia section.

[0060] S430: Geochemical-isotopic analysis of red sand bodies in fluvial facies was conducted to determine their geochemical-isotopic characteristics. These characteristics include the oxidizing properties and fluid characteristics of the red sand bodies.

[0061] For example, in S431, geochemical-isotope studies of the Yaoxia Formation red sandstone in the exploration area revealed that the TOC content of the red sandstone in the Yaoxia Formation is 0–0.08%, the sulfur content is 0–0.011%, and the Fe content is [missing information]. 3+ The content of Fe is 1.20% to 5.51%. 2+ The content is 0.31% to 1.17%, Fe 3+ / Fe 2+ The values ​​ranged from 2.62 to 4.72, indicating that the red sandstone body in the Yaoxia section exhibited obvious oxidation characteristics. At the same time, carbon and oxygen isotope analysis of the red sandstone body in the Yaoxia section was carried out, and it was found that the red sandstone body had positive oxygen isotope bias and negative carbon isotope bias, indicating that the red sandstone body in the Yaoxia section was mainly controlled by oxidizing fluids.

[0062] In at least one embodiment of this application, steps S510 to S540 are Figure 1 A specific implementation of step S500 in the illustrated embodiment.

[0063] S510: Determine whether the red sand body is a red sand body in fluvial sedimentary deposits based on the paleowater depth of the fluvial microfacies.

[0064] For example, S511: Based on the paleowater depths of the obtained fluvial microfacies, the red sand bodies in the Yaoxia Formation of the southwestern basin were determined to be subfluvial deposits of terrestrial braided river sediments influenced by extreme heat events and situated within a hot and arid paleoclimatic background. The paleowater depths of each microfacies did not exceed 15m. Overall, the terrestrial braided river sediments in the exploration area are likely controlled by the hot and arid paleoclimatic environment of the depositional period, meaning that the red sand bodies in the fluvial sediments under a hot and arid paleoclimatic background are a necessary condition for their original formation.

[0065] S520: Based on the macroscopic characteristics of the red sand body, determine whether the red sand body is associated with thick regional red mudstone, or a red sand body with a planar distribution at the basin margin to the basin center and a thickness center confined in the main channel.

[0066] For example, S521: Based on the systematic study of the macroscopic characteristics of the target layer red sandstone bodies in the exploration area, it was found that the Yaoxia Formation red sandstone bodies are widely distributed across the basin margin and mid-basin, with their thickness center confined within the river channel. Combined with the planar distribution of the red mudstones associated with the sandstone bodies, this indicates that the Yaoxia Formation red sandstone bodies in the exploration area were clearly controlled by both the paleochannel during the depositional period and the hot paleoclimate during the depositional period. Defining the Yaoxia Formation red sandstone bodies as having associated thick regional red mudstones, a planar distribution at the basin margin and mid-basin, and a thickness center confined within the main river channel, is a necessary condition for their original formation.

[0067] S530: Based on the microscopic characteristics of the red sandstone body, determine whether the red sandstone body is characterized by rocks with predominantly warm colors such as red, brownish-red, and dark red; lack of or thinning of brownish-yellow sandstone bodies; clean red sandstone bodies; predominantly hematite and limonite mineralization; and geochemical characteristics such as low organic carbon content, low sulfur content, and low Fe content. 2+ Low, Fe 3+ High, Fe 3+ / Fe 2+ A red sand body with "high oxygen isotope positive bias and carbon isotope negative bias".

[0068] It should be noted that a clean red sandstone body can be characterized by the absence of carbonaceous debris or mobile organic matter, and a uniform overall rock color. It has low organic carbon content, low sulfur content, and low Fe content. 2+ Low, Fe 3+ High and Fe 3+ / Fe 2+ The maximum value can be set according to actual conditions, for example, organic carbon content <0.08%, sulfur content <0.01%, Fe 2+ Content <1.17%, Fe 3+ Content > 1.2%, Fe 3+ / Fe 2+ >2.62.

[0069] For example, S531: Based on the systematic study results of the obtained microscopic characteristics of the red sandstone bodies in the Yaoxia section of the exploration area, and referring to... Figure 8 , Figure 8 The diagram shows the thin section characteristics of the red sandstone body (a) and associated red mudstone (b) in the Yaoxia Formation of the southwestern Songliao Basin. Figure 8 The red sandstone bodies in the Yaoxia section of the exploration area were determined to be fluvial deposits of a braided river system influenced by a hot and arid paleoclimate. The paleowater depth was not significant, and thick layers of regional red mudstone were present. The planar distribution of the red sandstone bodies clearly indicates that they were under the dual control of the paleochannel and the hot paleoclimate during the depositional period. The rocks are predominantly warm-toned, including red, brownish-red, and dark red, and exhibit mineralogical characteristics such as obvious hematite and limonite mineralization filling within the intergranular pores. They also exhibit "three lows, two highs, one positive and one negative" (low organic carbon content, low sulfur content, low Fe content, low Fe content). 2+ Low, Fe3+ High, Fe 3+ / Fe 2+ The geochemical characteristics of "high oxygen isotope positive bias and carbon isotope negative bias" also indicate that the red sandstone body is of primary sedimentary origin rather than post-transformation origin.

[0070] S540: If all the judgment results are yes, then the cause of the red sand body is determined to be the original cause.

[0071] S600: If the formation of the red sandstone body is due to the original formation process, then the exploration approach of exudative sandstone-type uranium deposits will be adopted.

[0072] For example, S610: Based on the above comprehensive judgment of the original red sandstone body development characteristics, its formation scale is comprehensively judged. Combined with... Figure 5 It is known that the primary red sandstone bodies in the Yaoxia Formation of the exploration area are distributed throughout the basin margin and basin center, and are of considerable scale. Deep uranium-rich organic formations are developed in the Lower Cretaceous Jiufotang Formation and Shahai Formation below the Yaojia Formation in the area, and multiple deep faults have been developed that cut through the lower uranium-rich formations and the target Yaoxia Formation. In addition, multiple regional unconformities (such as T4) are developed between the Upper and Lower Cretaceous, and combined with the braided river channel sandstone bodies in the Yaoxia Formation, the area possesses the necessary conditions for the formation of uranium deposits in exudative sandstone formations. This indicates that the area may have good potential for uranium deposit formation in exudative sandstone formations. Based on this, the exploration strategy for uranium deposits in exudative sandstone formations in the exploration area can be determined, and then mineralization prediction of uranium deposits in exudative sandstone formations can be carried out.

[0073] It should be noted that the combination of the technical features in the embodiments of this application is not limited to the combination methods described in the embodiments of this application or the combination methods described in specific embodiments. All technical features described in this application can be freely combined or combined in any way, unless they contradict each other.

[0074] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for determining the origin of red sand bodies under arid paleoclimate conditions, characterized in that, include: Determine the target stratigraphic segment containing the fluvial red sand bodies controlled by the arid paleoclimate in the exploration area; Based on the sedimentary facies type of the fluvial facies in the target stratigraphic section, determine the paleowater depth of the microfacies of the fluvial facies in the target stratigraphic section; The macroscopic features of the red sand bodies in the fluvial facies are obtained, wherein the macroscopic features include spatial occurrence characteristics, the relationship between the spatial occurrence of the red sand bodies and sedimentary facies, and the spatial superposition relationship between the mudstone associated with the red sand bodies and the red sand bodies. The microscopic features of the red sand bodies in the fluvial facies are obtained, wherein the microscopic features include petrological features, mineralogical features, and geochemical-isotopic features; Based on the paleowater depth of the microfacies of the river facies and the macroscopic and microscopic characteristics of the red sand body, determine whether the formation of the red sand body is of primary origin; If the formation of the red sandstone body is due to its original formation, then the exploration approach for exudative sandstone-type uranium deposits will be adopted. The determination of the paleowater depth of the microfacies of the fluvial facies in the target stratigraphic segment includes: Sedimentary facies analysis was performed on the target layer to determine the sedimentary facies, subfacies, and microfacies of the fluvial facies. Determine the fluvial sedimentary facies diagram, as well as the planar distribution and development scale of the subfacies and microfacies; Based on the microfacies of the river facies and the planar distribution of the microfacies, the paleowater depth of the microfacies of the river facies is determined; The step of determining whether the formation of the red sand body is of primary origin based on the paleowater depth characteristics of the river facies microfacies and the macroscopic and microscopic characteristics of the red sand body includes: Based on the paleowater depth of the microfacies of the fluvial facies, determine whether the red sand body is a red sand body in the fluvial facies sediments; Based on the macroscopic characteristics of the red sand body, determine whether the red sand body is associated with thick regional red mudstone, or a red sand body with a planar distribution at the basin margin to the basin center and a thickness center confined in the main channel; Based on the microscopic characteristics of the red sandstone body, it is determined whether the red sandstone body is characterized by a predominantly warm-toned rock, a lack of brownish-yellow sandstone bodies, clean red sandstone bodies, predominantly hematite and limonite mineralization, and geochemical features such as low organic carbon content, low sulfur content, and low Fe content. 2+ Low; Fe 3+ High, Fe 3+ / Fe 2+ The red sandstone body is characterized by a high oxygen isotope bias and a negative carbon isotope bias. Its warm tones include red, brownish-red, and dark red. The clean red sandstone body is free of carbonaceous debris or mobile organic matter. The rock has a uniform color overall, low organic carbon content (<0.08%), low sulfur content (<0.01%), and low Fe content. 2+ Low is Fe 2+ Content <1.17%, Fe 3+ High for Fe 3+ Content > 1.2%, Fe 3+ / Fe 2+ High for Fe 3+ / Fe 2+ >2.62; If all three of the above judgments are true, then the formation of the red sand body is determined to be the original formation cause.

2. The discrimination method according to claim 1, characterized in that, The target stratigraphic segment containing the fluvial red sand bodies controlled by the arid paleoclimate in the exploration area includes: Based on the paleoclimate data and / or structural features of the strata containing the red sand bodies in the exploration area, the paleoclimate features of the strata containing the red sand bodies are determined. Based on the paleoclimatic characteristics, the target stratigraphic segment containing the riverine red sand body controlled by the arid paleoclimatic environment in the exploration area was determined.

3. The discrimination method according to claim 1, characterized in that, The step of determining the paleowater depth of the microfacies of the river facies based on the microfacies and the planar distribution of the microfacies includes: Based on the microfacies of the fluvial facies and their planar distribution, and in conjunction with the paleowater depth geochemical indices of the target stratigraphic section, the paleowater depth of the microfacies of the fluvial facies is determined.

4. The discrimination method according to claim 1, characterized in that, The process of obtaining the macroscopic features of the red sand bodies in the target layer includes: The thickness of the red sand bodies in the river facies was statistically analyzed to obtain statistical data on the thickness of the red sand bodies. Based on the statistical data on the thickness of the red sand body, a contour map of the red sand body thickness was drawn. The spatial occurrence characteristics of the red sand body are determined based on the contour map of the red sand body thickness. The thickness contour map of the red sand body and the fluvial sedimentary facies map are overlaid to determine the relationship between the spatial occurrence of the red sand body and the sedimentary facies. The thickness data of the mudstone associated with the red sandstone body were determined based on the statistical data on the thickness of the red sandstone body. Based on the thickness data of the associated mudstone of the red sand body, a contour map of the thickness of the associated mudstone of the red sand body was drawn; The spatial superposition relationship between the red sand body and the associated mudstone is determined based on the thickness contour map of the red sand body.

5. The discrimination method according to claim 1, characterized in that, The process of obtaining the microscopic features of the red sand bodies in the fluvial facies includes: Petrological analysis was performed on the red sand body in the fluvial facies to determine the petrological characteristics of the red sand body, wherein the petrological characteristics include the primary sedimentary structure of the red sand body, whether the red sand body has developed carbonaceous debris or mobile organic matter, the contact relationship between the red sand body and the gray sand body, and the color of the mudstone associated with the red sand body. Mineralogical analysis was performed on the red sand body in the river facies to determine its mineralogical characteristics, including the color of the constituent grains, the type and content of iron-bearing minerals, and the type and content of clay minerals. Geochemical-isotopic analysis was performed on the red sand bodies in the fluvial facies to determine their geochemical-isotopic characteristics, wherein the geochemical-isotopic characteristics include the oxidizing and fluid characteristics of the red sand bodies.

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