A method for predicting deep prospecting target areas of alkali-replacement uranium deposits

Abstract

The present invention belongs to the technical field of uranium ore, and specifically relates to a method for predicting deep prospecting target areas of alkali-metasomatic uranium ore, comprising: step 1, constructing a mineralization model; step 2, extracting regional mineralization core elements and constructing a geological prospecting model; step 3, using a combination mode of geophysical and geochemical prospecting methods to locate uranium-thorium ore bodies in sodium-metasomatic bodies; and step 4, predicting and evaluating deep mineralization potential. The method of the present invention is based on a multivariate information prediction and evaluation model, including evaluation of mineralization geological factors, evaluation of ground geophysical and geochemical anomalies, and evaluation of uranium, thorium, and potassium anomalies in deep wells, so as to narrow the scope of the exploration target area, indicate deep mineralization information, and improve prospecting efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of uranium mines, and in particular relates to a method for predicting deep prospecting target areas of alkali-replacement type uranium mines. Background Art

[0002] Theoretical research on deep mineralization prediction of uranium deposits faces important challenges and development opportunities, especially for concealed uranium deposits. In the past, the prediction of deposit scale was mainly based on the research results of mineralization depth, vertical range of mineralization, main factors affecting the formation depth of deposits, determination of mineralization depth, determination of mineralization pressure, and zoning of deposits of different types of uranium deposits. In recent years, with the deepening of uranium deposit exploration and development, the research on theoretical and technical methods related to deep prospecting and mineralization prediction has made significant progress, broadening the prospecting space of deep uranium deposits. Deep mineralization comprehensive evaluation technology is a technical method to evaluate the deep mineralization potential through systematic analysis of multivariate information such as deep ore-controlling geological elements, deep geophysics, geochemistry and radioactive comprehensive anomalies.

[0003] The mineralization process of alkali-metasomic uranium deposits is characteristic, and the favorable geological factors for mineralization are easier to extract. The comprehensive anomaly extraction of physics, geochemistry and radioactivity is more effective.

[0004] However, the existing deep mineralization prediction and comprehensive evaluation methods of alkali-replacement uranium deposits have obvious defects: ① The research content is limited to the systematic analysis of the "prospecting signs and mineralization elements" of alkali-replacement uranium deposits; ② The prediction and evaluation reference model only "relies solely on the constructed geological prospecting model"; ③ The prospecting target area delineated by this prediction and evaluation method is based on a relatively single basis and cannot indicate deep mineralization information. In the process of mineral exploration, it cannot improve the prospecting efficiency well. Summary of the invention

[0005] The purpose of the present invention is to provide a method for predicting deep prospecting target areas of alkali-metasomic uranium deposits. The method is based on theoretical research on alkali-metasomic uranium mineralization, extracts core mineralization geological elements according to a constructed uranium mineralization model, applies comprehensive detection technologies such as geology, geophysics, and geochemistry, conducts comprehensive detection of deep structures, lithology, mineralization geological bodies, radioactive anomalies, etc. in prospecting areas, and extracts prediction elements such as geology, geophysics, and geochemistry related to deep and comprehensive alkali-metasomic uranium deposits.

[0006] The technical solution to achieve the purpose of the present invention is:

[0007] A method for predicting deep prospecting target areas of alkali-replacement uranium deposits, specifically comprising the following steps:

[0008] Step 1: Construct mineralization model;

[0009] Step 2: Extract the core elements of regional mineralization and construct a geological prospecting model;

[0010] Step 3: Use a combination of geophysical and geochemical exploration methods to locate uranium-thorium ore bodies in sodium metasomatic bodies;

[0011] Step 4: Predict and evaluate deep mineralization potential.

[0012] The step 1 comprises:

[0013] Step 1.1: Conduct field geological surveys and literature research to determine the geographical information and formation age of various geological elements in the study area;

[0014] Step 1.2, divide each geological element into three stages: early, middle and late stages of hotspot action based on the formation time;

[0015] Step 1.3: Using the typical cross-section or three-dimensional analysis map of the region as the base map, mark each geological element in stages based on its modern geographical location.

[0016] The geological elements in step 1 include: igneous rocks, metamorphic rocks, sedimentary rocks, regional structures, and uranium deposits.

[0017] The step 2 comprises:

[0018] Step 2.1, through regional rock geochemical analysis, identify and extract geological elements representing magmatic rocks formed under the action of hotspots;

[0019] Step 2.2, using isotope tracing technology to identify and extract the deep migration pathways of mineralizing materials;

[0020] Step 2.3, by studying the ore body occurrence rules of regional uranium deposits, identify and extract the ore-forming geological bodies closely related to uranium mineralization;

[0021] Step 2.4: Identify and extract regional alteration characteristics, replacement mineral assemblage characteristics and uranium mineral characteristics through the study of typical uranium deposit alteration types and uranium mineralization;

[0022] Step 2.5: According to the distribution range or influence scale of the geological elements extracted in steps 2.1-2.4, the above geological elements are sorted in order from large to small and from outside to inside as the targets that need to be explored in sequence during the geological prospecting process, that is, a geological prospecting model is constructed.

[0023] The extraction of the core mineralization elements in step 2 is limited to the late stage of the hotspot effect of the mineralization model.

[0024] The step 3 comprises:

[0025] Step 3.1: Based on the geological elements of magmatic rocks, deep seismic detection is used to establish a seismic model to identify deep rock masses and their impact range;

[0026] Step 3.2: Focus on the deep migration pathways of mineralizing materials, use gravity survey to detect crust thickness and crust thinning zones, compile gravity survey profiles, and interpret deep and large faults;

[0027] Step 3.3: Based on the regional alteration characteristics, use the alteration mapping technology to compile an alteration distribution map and delineate the regional chlorite and epidote alteration zones;

[0028] Step 3.4: Based on the characteristics of the replacement mineral assemblage, use high-precision magnetic measurement technology to compile high-precision magnetic anomaly interpretation;

[0029] Step 3.5: Based on the characteristics of uranium minerals, carry out ground energy spectrum measurement and radon gas measurement to identify surface positive radioactive anomalies and deep radioactive anomalies respectively, compile radioactive anomaly analysis maps, and delineate deep uranium-thorium anomalies in combination with the extension of mineralized geological bodies.

[0030] The step 4 comprises:

[0031] Step 4.1: Comprehensively evaluate the interpretation results obtained by the geophysical and geochemical exploration methods carried out in step 3, including scale, size, strength, depth, etc.

[0032] Step 4.2: Based on the above evaluation information, identify the overlapping area of ​​multiple information as the prediction prospect area and evaluate its mineralization potential.

[0033] The beneficial technical effects of the present invention are:

[0034] 1. The prediction and evaluation method of the present invention not only systematically studies the "prospecting signs and mineralization elements" of alkali-metasomic uranium deposits, but also uses the geophysical and geochemical characteristics of mineralization elements to further construct a physical and chemical prospecting and evaluation model;

[0035] 2. The prediction and evaluation method of the present invention not only extracts favorable geological factors for mineralization by constructing a uranium mineralization theoretical model and a prospecting application model, but also integrates geophysical anomalies, geochemical anomalies, radioactive halos and other mineral prospecting geochemical signs associated with favorable geological factors;

[0036] 3. The prediction and evaluation method of the present invention is based on a multivariate information prediction and evaluation model, including evaluation of mineralization geological factors, evaluation of ground geophysical and geochemical anomalies, and evaluation of energy spectrum uranium, thorium, and potassium anomalies in deep wells, so as to narrow the scope of the exploration target area, indicate deep mineralization information, and improve the efficiency of prospecting. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The deep-source uranium mineralization model diagram of the sodium metasomatic hotspot in the central part of the Ukrainian shield provided by the present invention;

[0038] Figure 2The seismic model diagram of the New Ukraine-Kirovgrad-Korsun-New Myrgorod rock mass provided by the present invention;

[0039] Figure 3 The north-south gravity exploration profile of the central part of the Kirovohrad block in Ukraine provided by the present invention is Figure 3 In the figure, 1-Conradson surface; 2-Moho surface; 3-isodensity line; 4-regional fault;

[0040] Figure 4 The regional chlorite-epidote distribution map of the Kirovograd block provided by the present invention;

[0041] Figure 5 This is a radioactivity measurement analysis diagram of the periphery of a mineral deposit in central Ukraine provided by the present invention. DETAILED DESCRIPTION

[0042] The present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0043] Taking the prediction of deep uranium mineralization of a uranium deposit in the Kirovograd block in central Ukraine as an example, the present invention provides a method for predicting deep prospecting target areas of alkali-metasomic uranium deposits, which specifically includes the following steps:

[0044] Step 1: Constructing a mineralization model

[0045] Step 1.1, conduct field geological surveys and literature research to determine the geographical information and formation age of various geological elements in the study area, such as igneous rocks, metamorphic rocks, sedimentary rocks, regional structures and uranium deposits (geological element geographical information can be obtained through field geological surveys and literature research, and the formation age of geological elements can be determined through literature research and isotope dating analysis and testing);

[0046] Step 1.2, the geological elements are divided into three stages: early, middle and late stages of hotspot action based on the formation time. The early stage is characterized by the appearance of crustal remelting magmatic rocks and pre-enriched uranium mineralization, the middle stage is characterized by the appearance of high-temperature gas-liquid metasomatic pegmatites, and the late stage is characterized by the appearance of uranium deposits and crust-mantle remelting granites;

[0047] Step 1.3: Using the typical regional profile or three-dimensional analysis map as the base map, mark each geological element based on its modern geographical location in different stages (i.e., before mineralization, during mineralization, and after mineralization).

[0048] For example, the Kirovograd Block in central Ukraine has constructed a deep-source uranium mineralization model of sodium metasomatic hotspot in the central Ukrainian Shield based on the above steps, such as Figure 1 shown.

[0049] First, through field geological surveys and literature research, the geographical information and formation age of the geological elements in the study area were clarified. The ages of the main magmatic, metamorphic and metasomatic processes in the region are as follows:

[0050] (1) Magmatic rocks and metasomatism series:

[0051] 1) Austronesian series: metabasic rocks and ultrabasic rocks (3.7±0.2)Ga;

[0052] 2) Konksk-Verkhovite series: metavolcanic rocks (3.25±0.2)Ga;

[0053] 3) New Krivoy Rog Suite: amphibolite (2.19) Ga, granite (2.0-1.89) Ga;

[0054] 4) New Ukraine-Kirovgrad Block: granite (2.06-2.02Ga);

[0055] 5) New Ukraine Complex: 2.03-2.02 Ga;

[0056] 6) Potassium-substituted pegmatite granite: 2.0-1.9Ga;

[0057] 7) Gdansk-Glewa suite: intrusive granites (2.0-1.89) Ga;

[0058] 8) Middle Archean mixed gneiss pegmatite-type dikes: 1.96Ga;

[0059] 9) Iron-magnesium-sodium replacement: 1.8-1.7 Ga;

[0060] 10) Sodium metasomatism: 1.84~1.80Ga;

[0061] 11) Korsun-New Myrgorod Batholith: 1.74Ga;

[0062] 12) NW-SE-trending basic dyke: 1.60Ga;

[0063] 13) Late alkaline metasomatism: 920 and 750 Ma;

[0064] (2) Mineralization series:

[0065] 1) Uranium deposits in Paleoproterozoic conglomerates: about 2.8Ga;

[0066] 2) Lithium mineralization in granite-mixed pegmatites: 2.0Ga;

[0067] 3) Major sodium-replacement uranium deposits: Vatujin uranium deposit 1.75Ga, Michurin uranium deposit 1.76Ga, Huangshui uranium deposit 1.75Ga, and New Konstantinov deposit 1.80Ga;

[0068] 4) Magmatic titanium ore: 1.75Ga;

[0069] 5) Vein sulfide pitchblende: 220Ma.

[0070] Secondly, according to the evolution characteristics of hotspot geological elements, (1) 3, 4, 5) and (2) 1) are divided into the early stage; (1) 6, 7, 8) and (2) 2) are divided into the middle stage; (1) 9, 10, 11, 12, 13) and (2) 3, 4, 5) are divided into the late stage.

[0071] Third, the classified geological elements are identified according to the early, middle and late stages of hotspot action, and the spatial distribution characteristics of the geological elements are based on modern characteristics.

[0072] Step 2: Extract the core elements of regional mineralization and build a geological prospecting model

[0073] The extraction of core mineralization elements is limited to the late stage of hotspot action in the mineralization model.

[0074] Step 2.1, through regional rock geochemical analysis, identify and extract geological elements representing magmatic rocks formed under the action of hotspots;

[0075] Step 2.2, using isotope tracing technology to identify and extract the deep migration pathways of mineralizing materials;

[0076] Step 2.3, by studying the ore body occurrence rules of regional uranium deposits, identify and extract the ore-forming geological bodies closely related to uranium mineralization;

[0077] Step 2.4: Identify and extract regional alteration characteristics, replacement mineral assemblage characteristics and uranium mineral characteristics through the study of alteration types and uranium mineralization of typical uranium deposits.

[0078] Step 2.5: According to the distribution range or influence scale of the geological elements extracted in steps 2.1-2.4, the above geological elements are sorted in order from large to small and from outside to inside as the targets that need to be explored in sequence during the geological prospecting process, that is, a geological prospecting model is constructed.

[0079] For example, based on the above steps, a geological prospecting model for sodium-replacement uranium deposits in the central Ukrainian shield was constructed in the Kirovograd block in central Ukraine.

[0080] (1) by using the A-type granite geochemical discrimination diagram, the granite tectonic environment discrimination diagram, the Y / Nb-Ce / Nb and Yb / Ta-Y / Nb relationship diagrams, etc., the geological elements representing the magmatic rocks formed under the action of the hotspot are identified and extracted as 11) Korsun-New Myrgorod Batholith in step 1 (1), which represents the intraplate hotspot or mantle plume geotectonic background;

[0081] (2) By utilizing regional magmatic rocks and ores ( 87 Sr / 86 The Sr)i-εNd(t) isotope relationship diagram is used to identify and extract the deep migration channel in this study area as the Subokin-Marshall deep fault;

[0082] (3) The results of the study on regional uranium occurrence patterns show that all uranium ore bodies in the study area are present in sodium metasomatic bodies, so the uranium mineralization geological bodies in the study area are identified and extracted as sodium metasomatic bodies;

[0083] (4) Through the study of typical mineral deposits such as Vatujin and Michurin, the regional alteration in this study area is chlorite and epidote. The sodium metasomatic stage has mineral assemblages such as aegirine-sodium iron amphibole-albite-magnetite, and the calcium-magnesium metasomatic stage has mineral assemblages such as actinolite-sodium iron amphibole-magnesium iron amphibole; the uranium minerals are mainly titanouraninite and pitchblende;

[0084] (5) According to the influence range of the above geological factors, from large to small and from inside to outside, the geological prospecting factors such as ① mantle plume and crust thinning zone and rock body rich in deep fluid (here is the Korsun-New Myrgorod batholith), ② deep fluid migration channel (Subokin-Marshall deep fault), ③ regional alteration (chlorite and epidote alteration zone), ④ characteristic mineral combination (mineral combination in sodium metasomatism, calcium-magnesium metasomatism and calcium metasomatism alteration zone) and ⑤ radioactive high field caused by ore body (radioactive characteristics of radioactive minerals such as uranium) are taken as the exploration targets that need to be identified in the geological prospecting process, that is, they are combined into a geological prospecting model.

[0085] Step 3: Use a combination of geophysical and geochemical exploration methods to locate uranium-thorium ore bodies in sodium metasomatism.

[0086] For the geological elements extracted from the geological prospecting model in step 2, select a suitable combination of methods based on their physical and chemical properties, carry out corresponding measurements, and locate the uranium-thorium ore bodies in the sodium metasomatism.

[0087] Step 3.1: Based on the geological elements of magmatic rocks, deep seismic detection is used to establish a seismic model to identify deep rock masses and their impact range;

[0088] Step 3.2: Focus on the deep migration pathways of mineralizing materials, use gravity survey to detect crust thickness and crust thinning zones, compile gravity survey profiles, and interpret deep and large faults;

[0089] Step 3.3: Based on the regional alteration characteristics, use the alteration mapping technology to compile an alteration distribution map and delineate the regional chlorite and epidote alteration zones;

[0090] Step 3.4: Based on the characteristics of the replacement mineral assemblage, use high-precision magnetic measurement technology to compile high-precision magnetic anomaly interpretation;

[0091] Step 3.5: Based on the characteristics of uranium minerals, carry out ground energy spectrum measurement and radon gas measurement to identify surface positive radioactive anomalies and deep radioactive anomalies respectively, compile radioactive anomaly analysis maps, and delineate deep uranium-thorium anomalies in combination with the extension of mineralized geological bodies.

[0092] For example, the Kirovograd Block in central Ukraine used a combination of geophysical and geochemical methods based on the above steps to locate uranium-thorium ore bodies in sodium metasomatism.

[0093] (1) Based on geological elements①, deep seismic detection is used to establish seismic models and identify deep rock masses and their impact ranges, such as Figure 2 As shown, the dotted line in the figure is the influence range of the deep rock mass;

[0094] (2) Based on geological element ②, gravity survey is used to detect crust thickness and crust thinning zones, compile gravity survey profiles, and interpret deep and large faults, such as Figure 3 As shown;

[0095] (3) Based on geological factor ③, use alteration mapping technology to compile alteration distribution maps and delineate regional chlorite and epidote alteration zones, such as Figure 4 As shown;

[0096] (4) For geological elements ④, use high-precision magnetic measurement technology to compile high-precision magnetic anomaly interpretation, such as Figure 5 As shown;

[0097] (5) For geological element ⑤, carry out ground spectrum measurement and radon gas measurement to identify surface radioactive positive anomalies and deep radioactive anomalies, compile radioactive anomaly analysis maps, and delineate deep uranium-thorium anomalies based on the extension of mineralization geological bodies, such as Figure 5 As shown;

[0098] Step 4: Predict and evaluate deep mineralization potential.

[0099] Step 4.1: Comprehensively evaluate the interpretation results obtained by the geophysical and geochemical exploration methods carried out in step 3, including scale, size, strength, depth, etc.

[0100] Step 4.2: Based on the above evaluation information, identify the overlapping area of ​​multiple information as the prediction prospect area and evaluate its mineralization potential.

[0101] For example, the Kirovograd block in central Ukraine was predicted and evaluated for its deep mineralization potential based on the above steps.

[0102] (1) Figure 2 The seismic model shows that the Korsun-Novomirgorod batholith is affecting the Novoukrka batholith in the south from north to south and from deep to shallow, and the impact range basically covers the main uranium mining area in the south;

[0103] (2) Figure 3 Gravity profiles show that there is a deep and large fault between the Korsun-Novomirgorod batholith and the Novokukka magma, which can serve as a channel for the migration of deep mineralization materials;

[0104] (3) Figure 4 The alteration distribution map shows that there is no alteration zone distribution in the Korsun-Novomirgorod batholith, but there is a wide distribution of alteration zones in the Ukrainka lithology to its south, and the alteration zones become more intense closer to the Korsun-Novomirgorod batholith;

[0105] (4) Figure 5 The radioactive anomaly analysis diagram shows that the outer surface of a typical ore deposit in the intense alteration zone shows positive magnetic anomalies, predicting that there may be a mineralization geological body underneath it - a sodium metasomatic body;

[0106] (5) Figure 5 The radon positive anomaly zone overlaps with the magnetic positive anomaly zone, and it is predicted that the mineralized geological body below may contain uranium ore bodies. The extension direction of the known mineralized geological body on the surface or shallow part and the deep intersection area directly below the surface magnetic and radon gas anomaly zone are the predicted areas, where uranium ore bodies may exist.

[0107] The present invention is described in detail above with reference to the accompanying drawings and embodiments, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the field without departing from the purpose of the present invention. The contents not described in detail in the present invention can adopt the existing technology.

Claims

1. A method for predicting deep prospecting target areas of alkali-replacement uranium deposits, characterized in that: The specific steps include: Step 1: Construct mineralization model; Step 2: Extract the core elements of regional mineralization and construct a geological prospecting model; Step 3: Use a combination of geophysical and geochemical exploration methods to locate uranium-thorium ore bodies in sodium metasomatic bodies; Step 4: Predict and evaluate deep mineralization potential; The step 2 comprises: Step 2.1, through regional rock geochemical analysis, identify and extract geological elements representing magmatic rocks formed under the action of hotspots; Step 2.2, using isotope tracing technology to identify and extract the deep migration pathways of mineralizing materials; Step 2.3, by studying the ore body occurrence rules of regional uranium deposits, identify and extract the ore-forming geological bodies closely related to uranium mineralization; Step 2.4: Identify and extract regional alteration characteristics, replacement mineral assemblage characteristics and uranium mineral characteristics through the study of typical uranium deposit alteration types and uranium mineralization; Step 2.5, according to the distribution range or influence scale of the geological elements extracted in steps 2.1-2.4, the above geological elements are sorted in order from large to small and from outside to inside as the targets that need to be explored in sequence during the geological prospecting process, that is, a geological prospecting model is constructed; The step 3 comprises: Step 3.1: Based on the geological elements of magmatic rocks, deep seismic detection is used to establish a seismic model to identify deep rock masses and their impact range; Step 3.2: Focus on the deep migration pathways of mineralizing materials, use gravity survey to detect crust thickness and crust thinning zones, compile gravity survey profiles, and interpret deep and large faults; Step 3.3: Based on the regional alteration characteristics, use the alteration mapping technology to compile an alteration distribution map and delineate the regional chlorite and epidote alteration zones; Step 3.4: Based on the characteristics of the replacement mineral assemblage, use high-precision magnetic measurement technology to compile high-precision magnetic anomaly interpretation; Step 3.5: Based on the characteristics of uranium minerals, carry out ground energy spectrum measurement and radon gas measurement to identify surface positive radioactive anomalies and deep radioactive anomalies respectively, compile radioactive anomaly analysis maps, and delineate deep uranium-thorium anomalies in combination with the extension of mineralized geological bodies.

2. The method for predicting deep prospecting target areas of alkali-replacement uranium deposits according to claim 1, characterized in that: The step 1 comprises: Step 1.1: Conduct field geological surveys and literature research to determine the geographical information and formation age of various geological elements in the study area; Step 1.2, divide each geological element into three stages: early, middle and late stages of hotspot action based on the formation time; Step 1.3: Using the typical cross-section or three-dimensional analysis map of the region as the base map, mark each geological element in stages based on its modern geographical location.

3. The method for predicting deep prospecting target areas of alkali-replacement uranium deposits according to claim 2, characterized in that: The geological elements in step 1 include: igneous rocks, metamorphic rocks, sedimentary rocks, regional structures or uranium deposits.

4. The method for predicting deep prospecting target areas of alkali-replacement uranium deposits according to claim 3, characterized in that: The extraction of the core mineralization elements in step 2 is limited to the late stage of the hotspot effect of the mineralization model.

5. The method for predicting deep prospecting target areas of alkali-replacement uranium deposits according to claim 4, characterized in that: The step 4 comprises: Step 4.1, conduct a comprehensive evaluation of the interpretation results obtained by the geophysical and geochemical exploration methods carried out in step 3, including scale, size, strength, depth; Step 4.2: Based on the above evaluation information, identify the overlapping area of ​​multiple information as the prediction prospect area and evaluate its mineralization potential.

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