Investigation and analysis method of interlayer oxidation zone sandstone type uranium deposit mineral substance sources

Abstract

The invention belongs to the field of working methods of geological technologies, and particularly relates to a survey and analysis method for sources of interlayer oxidation zone sandstone type uranium ore metallogenic substances. Comprising the following steps of 1, investigating and screening a target horizon through a basin sedimentary stratum and a uranium content background value; 2, deducing a sediment source area by adopting a deposition structure measurement method and the like; step 3, carrying out a target layer rock ore test, and establishing a rock mineralogy basis for mineral substance traceability comparison analysis; 4, investigating and deducing mineralogical characteristics of geoplast rocks in the source area, and comparing and analyzing the mineralogical characteristics with a target horizon to determine a sediment source area; and 5, investigating distribution, migration and enrichment rules of uranium elements in the uranium mineralization system, and determining an mineralization action system and changes in combination with regional structure evolution analysis to respectively determine an inner uranium source and an outer uranium source of the uranium ore deposit. The method is divided into two parts of sediment source investigation and analysis and uranium source investigation and analysis so as to solve the problems that an existing analysis method is relatively shallow in investigation and analysis depth, investigation and analysis objects are mostly limited to geologic bodies of modern sediment source areas of basins, material sources and uranium sources are confused and the like.

Description

Technical Field

[0001] This invention belongs to the field of geological technical working methods, specifically relating to a method for investigating and analyzing the source of ore-forming materials in sandstone-type uranium deposits with interlayer oxidation zones. Background Technology

[0002] The investigation of ore-forming material sources is a crucial aspect of mineral geology, playing a key role in ore genetic analysis and mineralization prediction. Commonly used investigation and analysis methods include isotopic tracing, geochemical characteristic comparison, fluid inclusion analysis, mineral association and alteration characteristic analysis, and combined geological structure and geochronology analysis. In the 1990s, my country began prospecting for sandstone-type uranium deposits and gradually developed methods for investigating and analyzing the ore-forming material sources of sandstone-type uranium deposits. However, problems remain, such as shallow investigation and analysis depth, analysis objects being mostly limited to modern sedimentary source areas in basins, and confusion between sedimentary and uranium sources. There is a need to explore simpler and more accurate investigation and analysis methods based on the mineralization characteristics of sandstone-type uranium deposits. Summary of the Invention

[0003] The purpose of this invention is to provide a method for investigating and analyzing the source of ore-forming materials in sandstone-type uranium deposits with interlayer oxidation zones. This method consists of two parts: sedimentary source investigation and analysis and uranium source investigation and analysis. Based on the basic theories of sedimentology and geochemistry, it uses comparative analysis of the petrological characteristics of the ore-bearing sandstone and uranium element migration analysis as the basic methods. It applies evidence obtained by sedimentary tectonic measurement, U-Pb isotope dating and other methods to systematically investigate and trace the source of ore-forming materials.

[0004] The technical solution adopted in this invention is: a method for investigating and analyzing the source of ore-forming materials in sandstone-type uranium deposits with interlayer oxidation zones, comprising the following steps:

[0005] Step (1): Screen target strata by investigating the sedimentary strata and background uranium content in the basin;

[0006] Step (2): Use methods such as sedimentary tectonic measurements to infer the sediment source area;

[0007] Step (3): Conduct rock and mineral testing of the target strata to establish the petrological basis for comparative analysis of mineral provenance;

[0008] Step (4): Investigate and infer the mineralogical characteristics of the rocks in the source area, compare and analyze them with the target stratigraphic position, and determine the source area of ​​the sediments;

[0009] Step (5): Investigate the distribution, migration and enrichment patterns of uranium elements within the uranium mineralization system, and, in conjunction with regional tectonic evolution analysis, determine the mineralization system and its changes, and identify the uranium source within and outside the uranium deposit.

[0010] The steps (1) mentioned above include: conducting field geological surveys of sedimentary characteristics in the work area, establishing a basic stratigraphic sequence, measuring and statistically analyzing the background value of uranium content in groups, and selecting high background value strata that are conducive to the mineralization of sandstone-type uranium deposits in the interlayer oxidation zone as target strata.

[0011] The steps (2) mentioned above include: conducting sedimentary bedding structure measurements, lithofacies paleogeographic analysis, etc., determining the direction of paleocurrents, and roughly inferring the source area of ​​sediments.

[0012] The steps (3) mentioned above include: collecting rock and mineral test samples from the target stratum, identifying the rock and mineralogical characteristics, establishing the rock and mineralogical basis for mineral source tracing analysis, and determining the key elements and main contents of comparative analysis.

[0013] Step (4) as described above includes: conducting geological surveys of the inferred source area sequentially along the inferred source direction, and comparing and analyzing the petrological characteristics with those of the target strata until a geological body with a source relationship is matched. The formation age of stable minerals such as zircon in the target strata can be determined by using the U-Pb isotope method, thereby clarifying the temporal relationship between the target strata and the geological body in the inferred source area, and assisting in determining the sediment source.

[0014] Step (5) as described above includes: systematically investigating the distribution characteristics of uranium in the target strata, ore-forming fluid recharge area, and other ore-forming systems. It involves identifying the migration and enrichment patterns of uranium in the target strata sandstone under interlayer oxidation to determine the uranium source within the deposit; testing the age of uranium minerals to determine the uranium mineralization age; and, in conjunction with regional tectonics and evolution, establishing an oxygen- and uranium-bearing water recharge-discharge system for the mineralization period. It also involves investigating the distribution and migration patterns of uranium in the recharge area to determine the uranium source outside the deposit.

[0015] The beneficial effects of this invention are as follows: Based on the working principle of ore-forming source investigation, and grounded in the metallogenic theory of sandstone-type uranium deposits in interlayer oxidation zones, this invention utilizes petrological and mineralogical correlation and uranium element migration measurements as fundamental methods. Combined with sedimentary-tectonic studies and U-Pb isotope dating, it comprehensively studies methods for investigating and analyzing the ore-forming source of sandstone-type uranium deposits in interlayer oxidation zones. This results in a practical and efficient technical method that can play a significant role in the analysis of mineralization conditions and prospect prediction of sandstone-type uranium deposits, and has considerable applicability. This invention has been applied to uranium deposits on the southern margin of the Ili Basin, yielding new insights into the ore-forming source and promoting a deeper understanding of the metallogenic theory and metallogenic model of sandstone-type uranium deposits in interlayer oxidation zones. Attached Figure Description

[0016] Figure 1 This is a flowchart illustrating the investigation and analysis method for the source of ore-forming materials in sandstone-type uranium deposits with interlayer oxidation zones, as described in this invention.

[0017] Figure 2This is a simplified geological map of the Ili Basin region in the first application embodiment of the present invention.

[0018] Among them: 1. Quaternary; 2. Pliocene; 3. Miocene; 4. Jurassic; 5. Triassic; 6. Permian; 7. Carboniferous; 8. Devonian; 9. Silurian; 10. Precambrian; 11. Granite and other rock masses; 12. Geological boundaries; 13. Unconformities; 14. National borders.

[0019] Figure 3 This is a schematic diagram of the tectonic evolution and ore-forming source of the southern margin of the Ili Basin in the first application embodiment of the present invention.

[0020] Among them: 1. Quaternary; 2. Neogene; 3. Jurassic; 4. Triassic; 5. Sangonghe-Toutunhe Formation; 6. Triassic-Badawan Formation; 7. Permian; 8. Carboniferous; 9. Silurian; 10. Precambrian; 11. Intrusive rocks mainly composed of granite; 12. Geological boundary; 13. Fault; 14. Uranium orebody. Detailed Implementation

[0021] The mineralization of sandstone-type uranium deposits in interlayered oxidation zones is characterized by long duration, multiple phases, and complex sources of ore-forming materials. The mineralization mechanism necessitates a time-segmented, comprehensive comparative analysis method for investigating the sources of these materials. Based on these characteristics, this invention establishes a method for investigating and analyzing the sources of ore-forming materials, grounded in petrology and uranium geochemistry, and incorporating theories and methods from structural geology, sedimentology, and mineralogy. Its application in the southern margin of the Ili Basin has innovatively proposed a new understanding of ore-forming material sources, distinct from previous methods. Practice has demonstrated that this invention is theoretically sound, rationally designed, and offers precise and convenient application results.

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0023] like Figure 1 As shown, the method for prospecting for coiled uranium deposits provided by this invention includes the following steps:

[0024] Step (1) Target strata are screened by investigating the sedimentary strata and background values ​​of uranium content in the basin.

[0025] The survey scale is generally selected from 1:50,000 to 1:25,000. The scale can be appropriately increased for areas with complete stratigraphic exposure and key survey areas. The main methods are profile measurement and route geological survey, focusing on investigating stratigraphic distribution and sedimentary structure characteristics, establishing a basic stratigraphic sequence, and selecting strata with stable mud-sand (gravel) interbedded structures for further evaluation.

[0026] While conducting geological surveys, surface gamma-ray total emission or gamma-ray energy spectrum measurements can be performed to roughly determine the radioactive characteristics of sedimentary strata. Samples can then be taken from strata with high radioactivity values ​​for uranium content analysis. Samples should be taken as far away as possible from areas of post-oxidative alteration to maintain the original geochemical environment and accurately reflect the background value (initial uranium content) of the rocks.

[0027] Strata with both a stable mud-sand interbedded structure and a high uranium background value were selected as target strata for the investigation of ore-forming source.

[0028] Step (2) Use methods such as sedimentary structure measurement to infer the sediment source area.

[0029] Measuring various types of bedding structures formed by sedimentation reveals a correlation between different sedimentary structures and paleocurrent direction: asymmetric ripple marks with steep slopes indicate current direction; the maximum flattened surface of gravel points upstream; the pre-sedimentary surface of cross-bedding indicates current direction; and the uplifted surface of rippled bedding points upstream. Statistical analysis of the measured data can roughly infer the direction of the source area, providing orientation for the investigation and analysis of ore-forming material origins.

[0030] Step (3) Conduct rock and mineral testing of the target strata and establish a petrological basis for comparative analysis of mineral origin.

[0031] Rock and mineral testing was conducted on each target stratigraphic system to identify the basic characteristics of the rocks and mineralogical features, establishing the objects and content for source tracing and comparative analysis of minerals. Typically, the host rocks of sandstone-type uranium deposits are mainly composed of quartz, rock fragments, and feldspar, followed by small amounts of mica and heavy minerals. The variations in the types and contents of these components, as well as other rock and mineralogical characteristics, can reflect the rock and mineralogical features of the parent rocks in the source area to a certain extent, thus forming the basis for source tracing and comparative analysis of minerals.

[0032] First, an increase in the content of stable components, represented by quartz, indicates a longer sediment transport route and a greater distance from the source region; conversely, an increase in unstable components, mainly rock fragments and feldspar, indicates a shorter sediment transport distance and near-source deposition. Based on the changes in the content of stable and unstable components in different target strata, the relative distance of the source region can be determined.

[0033] Secondly, rock fragments, as the main component, are clastic particles produced by the mechanical fracturing of parent rocks. Rock fragments of different lithologies correspond to parent rocks of different lithologies, providing direct evidence for sediment provenance correlation. When rock fragments are abundant and diverse, special or regular rock fragment assemblage characteristics can accurately identify the provenance area.

[0034] It can also be used to conduct special identification of heavy minerals in rocks and geochemical element testing to assist in the source analysis of ore-forming materials. However, compared with the rock fragment comparison method, the latter has the advantages of simple principle, high accuracy and direct identification of parent rock lithology. Therefore, rock fragment comparison analysis is preferred.

[0035] Step (4) Investigate and infer the mineralogical characteristics of the rocks in the source area, compare and analyze them with the target stratigraphic position, and determine the source area of ​​the sediment.

[0036] Following the inferred sediment source direction, investigations were conducted sequentially on the mountain (erosion source area). Based on medium- to large-scale geological maps, the lithological distribution and petrological characteristics of each geological body were identified, and compared with the petrological characteristics of the target strata until the sediment source of the target strata was determined. It should be noted that even within the same sedimentary unit, different target strata may contain different source areas.

[0037] When using rock fragment comparison analysis to trace the origin of ore-forming materials, different types of rock fragments at the target stratum should have corresponding geological bodies of the same lithology in the inferred source area. Simultaneously, the main lithologies of the geological bodies widely distributed in the inferred source area should all have corresponding rock fragments at the target stratum. Otherwise, the rationality of the inferred source area should be considered, and the next mountain (erosion source area) should be selected for comparison analysis.

[0038] The characteristics of heavy minerals and their assemblages can be used to assist in the analysis of the sedimentary source of the target strata: a high content of heavy minerals reflects a close source distance, while a low content of heavy minerals indicates a far source distance; a higher content of stable heavy minerals than unstable heavy minerals indicates a longer transport distance; abundant zircon indicates the presence of a large area of ​​intermediate to acidic magmatic rocks in the source area; garnets mostly come from metamorphic rocks, etc.

[0039] The age of the parent rock can also be determined by measuring the formation time of the stable components of the target stratum, thereby establishing a connection with the age of the geological bodies in the source area. Typically, U-Pb dating is performed on stable heavy minerals such as zircon, and the age of the parent rock is determined based on the zircon age, which helps verify the accuracy of the source area determination.

[0040] Step (5) Investigate the distribution, migration and enrichment patterns of uranium elements within the uranium mineralization system, and, in conjunction with regional tectonic evolution analysis, determine the mineralization system and its changes, and identify the uranium source within and outside the uranium deposit.

[0041] Uranium sources in sandstone-type uranium deposits with interlayer oxidation zones are divided into two types: one is the ore-bearing uranium source provided by the ore-bearing strata themselves, referred to as the internal uranium source; the other is the ore-bearing uranium source brought into the ore-bearing strata by atmospheric precipitation from uranium-rich geological bodies in mountainous areas after the depositional period of the ore-bearing strata, referred to as the external uranium source. After systematically investigating the distribution, migration, and enrichment patterns of uranium elements within the uranium mineralization system, the internal uranium source is first determined by combining the results of sedimentary source investigation, and then the external uranium source is determined by combining sedimentary-tectonic evolution and uranium mineralization age testing.

[0042] First, the surrounding mountains of the basin were investigated. One type was the source area of ​​the target strata, providing uranium within the mineralization zone. The other type consisted of mountains that, after the target strata were deposited, formed a basin-mountain oxygen- and uranium-bearing water recharge-discharge system, providing uranium outside the mineralization zone. Because the various geological bodies within the mountains were in an open oxidizing environment, uranium experienced varying degrees of loss and migration. After measuring the uranium content of each geological body, the initial uranium content and uranium migration coefficient of each body were calculated using the U-Pb isotope method, thereby revealing the distribution and migration of uranium.

[0043] Secondly, investigate the uranium content and variation characteristics of the target strata. Based on the uranium content (background value) of the primary rock zone, investigate the distribution, migration and enrichment patterns of uranium under the action of interlayer oxidation zones, and analyze whether the ore-bearing strata themselves provide uranium sources within uranium mineralization.

[0044] Third, investigate the tectonic, sedimentary, and hydrodynamic changes of the target strata during the basin-mountain evolution process, use U-Pb isotope dating and other methods to identify the series of mineralization periods of the uranium deposit, determine the main body and changes of the oxygen- and uranium-bearing water recharge and discharge system of the target strata in the main mineralization periods, and then determine the oxygen- and uranium-bearing water recharge routes and the source of uranium elements in the water in different mineralization stages, and finally determine the external uranium source of the uranium deposit.

[0045] Example 1:

[0046] This patent will be further explained in detail by taking the investigation and analysis of multigenetic uranium sources in sandstone-type uranium deposits in the interlayer oxidation zone on the southern margin of the Ili Basin as an example.

[0047] (1) Investigate the sedimentary characteristics of the cover layer on the southern margin of the basin, and combine the background values ​​of uranium content in different strata to preliminarily screen the target strata for uranium source investigation and analysis.

[0048] A scale of 1:50,000 was chosen as the basic working scale for the geological survey, revealing that the sedimentary cover of the southern margin of the Ili Basin includes the Triassic (T), Jurassic (J), Neogene (N), and Quaternary (Q) strata. Among them, the Middle-Upper Triassic Xiaoquangou Group (T) 2-3 The xq formation is characterized by stable, thick layers of interbedded mud and sand (gravel). The Jurassic Badaowan Formation (J1b), Sangonghe Formation (J1s), Xishanyao Formation (J2x), and Toutunhe Formation (J2t) are coal-bearing clastic rock formations with interbedded mud, sand, and mud (coal). The Neogene mud-sand interbedded sediments are relatively stable. The Quaternary mud and sand are unstable interbedded, with poor continuity of interlayer sand bodies and no confined groundwater. Overall, except for the Quaternary, the other strata possess the sedimentary structural conditions for the formation of sandstone-type uranium deposits with interbedded oxide zones.

[0049] Background values ​​of uranium content in the target strata were measured by group sampling. The lithology of the samples was mainly sandstone and conglomerate. Among them, samples from the Triassic Xiaoquangou Group, Jurassic Badaowan Formation, Sangonghe Formation, Xishanyao Formation and Toutunhe Formation were collected from a primary gray reducing geochemical environment, while samples from the Neogene and Quaternary were collected from a primary oxidizing geochemical environment (Table 1).

[0050] Sample analysis results indicate that the average background uranium content of the Triassic and Jurassic primary gray reduced rocks is greater than 4×10⁻⁶. -6 In particular, the average background value of uranium content in the Sangonghe Formation, Xishanyao Formation, and Toutunhe Formation is greater than 6×10⁻⁶. -6 This is a favorable mineralization stratum for sandstone-type uranium deposits in the interlayered oxidation zone, and is a key stratum for investigation and research. The background uranium content of the Neogene and Quaternary primary yellow oxidized rocks is approximately 2×10⁻⁶. -6 The environment, with uranium content around 100%, is below the average for sedimentary rocks and lacks uranium precipitation and enrichment, ruling out the possibility of sandstone-type uranium mineralization in the interlayer oxidation zone.

[0051] Table 1. Statistical table of uranium content in primary rocks of sedimentary cover layers on the southern margin of the Ili Basin.

[0052]

[0053] (2) The direction of paleocurrent in the Triassic and Jurassic systems was measured, and the direction of sediment source and possible source areas were roughly inferred.

[0054] The main bedding structures in the sedimentary strata along the southern margin of the Ili Basin include ripple marks, oriented gravel, cross-bedding, and wavy bedding. Paleocurrent directions determined by sedimentary structural measurements are concentrated in the range of -17º to 27º (Table 2), indicating a general northward flow. The sediment source area is located south of the southern margin of the Ili Basin, possibly in the Chabuchar Mountains, Adengtao Mountains, or Harke Mountains.

[0055] Table 2. Statistical Table of Measurements Indicating Paleocurrent Direction by Sedimentary Structures

[0056]

[0057] (3) Conducted petrological studies on the Triassic and Jurassic systems, and established the basis for tracing the origin of ore-forming materials.

[0058] The system collected Triassic and Jurassic rock and mineral samples, which were identified as mainly lithic sandstone, feldspathic lithic sandstone, and sandy conglomerate. All were high-alumina silicate mineral assemblages, with quartz content ranging from 15% to 60%, feldspar content from 9% to 23%, and lithic fragment content from 21% to 73%. Overall, the Sangonghe Formation, Xishanyao Formation, and Toutunhe Formation showed a higher proportion of stable minerals such as quartz, indicating a relatively long provenance transport distance. The Xiaoquangou Group and Badaowan Formation showed an increased proportion of unstable components such as lithic fragments, indicating relatively proximal sedimentary characteristics. The Neogene strata showed an average quartz content below 20%, while the average content of unstable components such as lithic fragments exceeded 50%, indicating a proximal and short-term sedimentary characteristic (Table 3).

[0059] Table 3. Statistical table of main material composition and content of sandstone in the target stratum.

[0060]

[0061] The rock fragments from the samples are diverse, generally containing intermediate-acidic igneous tuff, dacite, andesite, and felite fragments. The typical characteristics of the rock fragments from the Sangonghe Formation, Xishanyao Formation, and Toutunhe Formation are: abundant acidic igneous granite fragments, containing a small amount of metamorphic rock fragments; while the typical characteristics of the rock fragments from the Xiaoquangou Group, Badaowan Formation, and Neogene are: relatively abundant basic igneous basalt fragments. This indicates that there may be differences in provenance among the different target stratigraphic levels.

[0062] The heavy mineral and assemblage characteristics in the working area are simple, with heavy mineral content in different strata all less than 1%, especially in the Toutunhe Formation where heavy minerals are rare. This is related to the distant provenance of the Toutunhe Formation and the weakened hydrodynamic environment. Magnetite and epidote are the most common heavy minerals. The Sangonghe Formation, Xishanyao Formation, and Toutunhe Formation contain abundant zircon, and combined with the characteristics of lithic fragment occurrence, they indicate that acidic igneous rocks, especially granites, are widely distributed in the provenance area.

[0063] (4) Investigate the petrological characteristics of the geological bodies in Chabuchar Mountain, Adengtao Mountain and Harke Mountain in turn, and determine the source areas of sediments by comparing and analyzing them with the Triassic and Jurassic systems.

[0064] Based on the 1:50,000 geological mapping results, the Chabuchar Mountains in the southern part of the basin were first investigated along the inferred direction of ore-forming material origin. The Carboniferous Dahalajunshan Formation (C1d) in the core of the Chabuchar Mountains is dominated by tuff and basalt; the Akshak Formation is dominated by limestone, sandstone, and tuff (C1a); and the Ishkilik Formation (C2y) is dominated by conglomerate and basalt. The Permian Wulang Formation (P1w) and Hamister Formation (P2h) on the north and south sides of the Carboniferous system are dominated by basalt, rhyolite, pyrite, and tuff. Intrusive rocks are relatively small in distribution, mainly Carboniferous biotite monzogranite (Table 4).

[0065] Table 4. Stratigraphic and Lithological Characteristics of Chabuchar Mountain

[0066]

[0067] The investigation revealed that no metamorphic rocks are distributed in the Chabuchar Mountains, and the distribution of granite is limited. No prototyping relationship can be established between the granite and metamorphic rock fragments and abundant granite fragments in the Sangonghe Formation, Xishanyao Formation, and Toutunhe Formation within the basin. Basalt is widely distributed in the Chabuchar Mountains, showing a clear correspondence with the basalt fragments commonly found in the Xiaoquangou Group, Badaowan Formation, and Neogene sandstones.

[0068] The survey area was expanded southward to include the Ardentao and Harke Mountains. The Ardentao Mountains consist of a small-scale Carboniferous uplift, with lithology consisting of a suite of intermediate-acidic volcanic and sedimentary rocks (Table 5). No pedigree relationship can be established with the Triassic and Jurassic rocks, which are rich in basalt, metamorphic rocks, and granite fragments. The survey area of ​​the Harke Mountains was mainly on the north slope. The Precambrian and Silurian (S) lithologies are mainly metamorphic rocks such as schist, marble, and phyllite; the Devonian (D) lithologies are mainly distributed on the ridge, consisting primarily of metamorphic quartzite and marble; the Carboniferous lithologies are intermediate-acidic volcanic rocks such as rhyolite and tuff; and intrusive rocks such as granite and granite porphyry are widely distributed. The widely distributed metamorphic rocks such as schist and phyllite and granite in the Harke Mountains have a clear pedigree relationship with the rock fragment assemblage characteristics of the Sangonghe, Xishanyao, and Toutunhe Formations.

[0069] Table 5 Stratigraphic and Lithological Characteristics of the Atengtao and Harke Mountains

[0070]

[0071] To verify the results of the provenance survey and analysis, detrital zircon dating was conducted on the Triassic and Jurassic systems. The detrital zircon ages of the Xiaoquangou Group and Badaowan Formation are predominantly 257–301 Ma (Permian), followed by 292–352 Ma (Carboniferous). The zircon ages of the Sangonghe Formation, Xishanyao Formation, and Toutunhe Formation are predominantly 298–360 Ma (Carboniferous), followed by 372–440 Ma (Silurian–Devonian). A 1500 Ma (Precambrian) zircon age was also obtained from samples of the Xishanyao Formation. Detrital zircon dating results indicate that the source rocks of the Xiaoquangou Group and Badaowan Formation are relatively simple, mainly from Permian and Carboniferous strata and intrusions, consistent with the compositional characteristics of the Chabuchar Mountain strata and intrusions. The source rocks of the Sangonghe Formation, Xishanyao Formation and Toutunhe Formation are complex, with more than 47% of the zircon ages concentrated in the Carboniferous period. The main source rocks are from the Carboniferous system and large-scale contemporaneous granite bodies, while the secondary source rocks are from the Silurian, Devonian and Changcheng metamorphic rocks, consistent with the source rock results obtained by comparative analysis of petrological and mineralogical surveys.

[0072] (5) The migration and enrichment patterns of uranium elements in the Triassic and Jurassic ore-bearing strata, oxygen- and uranium-bearing water recharge areas during the mineralization period were systematically investigated. Combined with sedimentary-tectonic evolution, the internal and external uranium sources of the uranium deposits were identified respectively.

[0073] The uranium content of different geological bodies in the Chabuchar Mountains and Harke Mountains was measured systematically, and the initial uranium content and uranium migration coefficient of each geological body were calculated using the U-Pb isotope method (Table 6). The table shows that intrusive rocks such as granite and granite porphyry had the highest average uranium content, reaching 10.61 × 10⁻⁶. -6 The average initial uranium content was 21.56 × 10⁻⁶. -6 The average uranium migration rate reached 65.2%; secondly, the average uranium content of intermediate-acidic volcanic rocks such as tuff, rhyolite porphyry, and rhyolite was 6.83×10⁻⁶. -6 The average initial uranium content is 17.55 × 10⁻⁶. -6 The average uranium migration rate reached 42.5%. The aforementioned rock masses and strata provided abundant external uranium sources for uranium mineralization.

[0074] Table 6. Statistical Table of Uranium Content and Migration of Major Geological Bodies in Chabuchar Mountain and Harke Mountain

[0075]

[0076] The migration and enrichment of uranium under interstratal oxidation in the Triassic and Jurassic strata of the southern margin of the Ili Basin were investigated in groups (Table 7). The uranium content in the primary rock zone is the initial uranium content of the sand body. Significant uranium loss was observed in the strongly-to-medium oxidized subzone, while uranium enrichment occurred in the weakly oxidized subzone, uranium ore subzone, and uranium anomaly subzone, with uranium content greater than 1×10⁻⁶. -4 The area is an industrial uranium ore zone. After oxidation, the uranium migration rate of the primary rock zone reached 32.0% to 64.1%, indicating that the initially enriched uranium in the ore-bearing strata was activated by interlayer oxidation to become the internal uranium source of the uranium deposit.

[0077] Table 7. Statistical table of uranium content variation in geochemical zoning of uranium deposits in the southern margin of the Ili Basin (10 -6 )

[0078]

[0079] The temporal relationship between sedimentary-tectonic evolution and uranium mineralization in the working area was clarified. A large-scale sedimentary hiatus occurred in the Ili region during the Cretaceous-Paleogene period. By the Neogene, Neogene sandstone fragments on the southern margin of the Ili Basin shared similar characteristics with the Xiaoquangou Group and Badaowan Formation: abundant basalt fragments, few granite fragments, and no metamorphic rock fragments, indicating that the Neogene source area was the Chabuchar Mountains. Meanwhile, Neogene and Jurassic sandstone fragments in the Zhaosu Basin south of the Chabuchar Mountains contain abundant granite and metamorphic rock fragments, their source still originating from the Harke Mountains. This analysis indicates that since the Neogene (23 Ma), the Chabuchar Mountains have been in a state of long-term uplift, severing the sedimentary connection between the southern margin of the Ili Basin and the Harke Mountains. Simultaneously, U-Pb isotopic dating of uranium minerals on the southern margin of the Ili Basin indicates that the uranium mineralization period was concentrated between 2 and 20 Ma. The above analysis shows that during the mineralization process, the Chabuchar Mountains not only provided a source of material for the Quaternary system, but also provided an external uranium source for the uranium mineralization of the Triassic and Jurassic systems through uranium-rich intermediate-acidic volcanic rocks.

[0080] In summary, the uranium sources of the Xiaoquangou Group and Badaowan Formation deposits originate from the ore-bearing strata themselves and the uranium source body, primarily composed of intermediate-acidic volcanic rocks, in the Chabuchar Mountains, respectively. The initial enriched uranium in the ore-bearing strata also originates from the Chabuchar Mountains; similarly, the uranium sources of the Sangonghe Formation, Xishanyao Formation, and Toutunhe Formation deposits also originate from the ore-bearing strata themselves and the uranium source body, primarily composed of intermediate-acidic volcanic rocks, in the Chabuchar Mountains. However, the initial enriched uranium in the ore-bearing strata originates from the uranium source body, primarily composed of granite and granite porphyry, in the Harke Mountains.

Claims

1. A method for investigating and analyzing the source of ore-forming materials in sandstone-type uranium deposits with interlayer oxidation zones, characterized in that, Includes the following steps: Step (1): Screen target strata by investigating the sedimentary strata and background uranium content in the basin; Step (2): Use methods such as sedimentary tectonic measurements to infer the sediment source area; Step (3): Conduct rock and mineral testing of the target strata to establish the petrological basis for comparative analysis of mineral provenance; Step (4): Investigate and infer the mineralogical characteristics of the rocks in the source area, compare and analyze them with the target stratigraphic position, and determine the source area of ​​the sediments; Step (5): Investigate the distribution, migration and enrichment patterns of uranium elements within the uranium mineralization system, and, in conjunction with regional tectonic evolution analysis, determine the mineralization system and its changes, and identify the uranium source within and outside the uranium deposit.

2. The survey and analysis method as described in claim 1, characterized in that, The steps (1) mentioned above include: conducting field geological surveys of sedimentary characteristics in the work area, establishing basic stratigraphic sequences, measuring and statistically analyzing the background values ​​of uranium content in groups, and selecting high background value strata that are conducive to the mineralization of sandstone-type uranium deposits in the interlayer oxidation zone as target strata.

3. The survey and analysis method as described in claim 1, characterized in that, Step (2) includes: conducting sedimentary bedding structure measurement, lithofacies paleogeographic analysis, etc., to determine the direction of paleocurrent and roughly infer the source area of ​​sediments.

4. The survey and analysis method as described in claim 1, characterized in that, Step (3) includes: collecting rock and mineral test samples from the target stratum, identifying the rock and mineralogical characteristics, establishing the rock and mineralogical basis for mineral source tracing analysis, and determining the key elements and main contents of comparative analysis.

5. The survey and analysis method as described in claim 1, characterized in that, Step (4) includes: conducting geological surveys of the inferred source area sequentially along the inferred source direction, and comparing and analyzing the petrological characteristics with those of the target strata until a geological body with a source relationship is matched. The formation age of stable minerals such as zircon in the target strata can be determined by using the U-Pb isotope method, thereby clarifying the temporal relationship between the target strata and the geological body in the inferred source area, and assisting in determining the sedimentary source.

6. The survey and analysis method according to any one of claims 1 to 5, characterized in that, Step (5) includes: systematically investigating the distribution characteristics of uranium in the target strata, ore-forming fluid recharge area, and other ore-forming systems. It involves identifying the migration and enrichment patterns of uranium in the sandstone of the target strata under interlayer oxidation to determine the uranium source within the deposit; testing the age of uranium minerals to determine the uranium mineralization age; and, in conjunction with regional tectonics and evolution, establishing an oxygen- and uranium-bearing water recharge-discharge system for the mineralization period. It also involves investigating the distribution and migration patterns of uranium in the recharge area to determine the uranium source outside the deposit.

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