(Hunan Changsha Institute of Nuclear Industry 230 4 100 1 1)
[Abstract] Xiangyangping uranium deposit in Guangxi is located in the middle of Miaoershan rock mass. On the basis of scientific research and evaluation, the 230 Institute of Nuclear Industry has carried out the general survey for seven years. During this period, the alteration characteristics of magmatic rocks, structures, ore bodies, ores and surrounding rocks in the mining area have been basically identified. The shape, scale, occurrence, spatial distribution characteristics and ore-controlling laws of metallogenic structures in this area are summarized. The distribution law and prospecting criteria of uranium mineralization in this area are roughly found out, and it is considered that the contact interface between rock masses at different stages has a certain control effect on uranium mineralization. The genesis and ore-controlling factors of the deposit are preliminarily identified, and it is considered that Xiangyangping deposit is a large-scale uranium deposit with good development and utilization prospects.
[Keywords] Uranium deposit; Xiangyangping; Miaoershan rock mass
Xiangyangping uranium deposit is located in Ziyuan County, Guangxi Zhuang Autonomous Region, in the middle of Miaoershan rock mass (figure 1). On the periphery of Shazijiang deposit, 60km south of Ziyuan County in Guilin, Guangxi and 74km north of Xinning County in Shaoyang, Hunan, there is a simple highway leading to 202 provincial highway.
1 discovery and exploration process
The geological work of Xiangyangping uranium mine began in 1960s. 1965 The general survey campaign in northern Guangxi organized by the former 309th Brigade started the uranium geological work in Miaoershan area. The anomaly areas such as Zhangjia, Shazijiang-Shuanghuajiang, Malin, Yangjiazhuang-Shen Chong, Hujiatian-Shangxiaodi were delineated by 1∶25000 ground gamma survey.
1988 ~ 199 1 year, 230 Research Institute and 3 10 Brigade of Central South Geological Exploration Bureau listed the peripheral areas of Shazijiang and Menggongjie as uranium prospecting targets in the Aviation Geological Survey of Guangxi Resource Area according to the rhombic block fault model [3].
During the period of 1988, the 306th Brigade of Central South Geological Survey entered the south-central part of Miaoershan rock body for the second round of uranium exploration, and carried out work on Shazijiang deposits such as Xiangyangping, Menggongjie and Shuanghuajiang deposits and their surrounding areas.
From 65438 to 0998, Zhou Weixun and Zhang Jinye, the exploration constituency group of Dufu Uranium Mine in South China, listed this area as one of the favorable prospects of Dufu Uranium Mine around Doulishan rock mass [4].
In 2002-2003, Institute 230 of Nuclear Industry carried out special scientific research work on uranium geology, and put forward suggestions for re-understanding and further evaluation of Menggongjie deposit, Shazijiang deposit and their surrounding Xiangyangping area [5 ~ 6].
In 2005-2006, the 230 Institute of Nuclear Industry systematically evaluated the uranium resource prospect in Li Daping-Xiangyangping area, Ziyuan County, Guangxi Province, and concluded that Xiangyangping uranium deposit and Shazijiang deposit were in the same geodynamic and uranium metallogenic geological background, and the scale, occurrence, material composition, geophysical and geochemical anomalies caused by wall rock alteration and mineralization of the ore-bearing faults were similar to those of Shazijiang deposit F, with similar fault zones and many uranium mineralization points and zones on the surface, so the prospecting clues were clear and definite.
Figure 1 Regional Geological Schematic Diagram of Miaoershan
1- four yuan; 2- Cretaceous; 3- Triassic; 4- Permian; 5- Carboniferous; 6- Devonian; 7- Ordovician; 8- CAMBRIAN; 9- Sinian system; 10-Banxi Group; 1 1- rock mass or stratum boundary; 12- fracture; 13— Miaoershan complex granite body; 14-Yuechengling composite granite body; 15- Workspace
From 2006 to 2008, the 230 Institute of Nuclear Industry conducted a uranium survey in Li Daping-Xiangyangping area ahead of schedule without completing the evaluation project. At the beginning of the census in 2006, through the comprehensive analysis of previous data and many field geological investigations, Pishuping area was taken as the key construction area at the beginning of the census. In 2006-2008, the drilling area was 4022 1m, which revealed many good industrial ore bodies. On 20 10, the general survey report of Pishuping area in Xiangyangping area was submitted, and Pishuping area was submitted as a detailed prospect area, and Xiangyangping deposit developed into a medium-sized uranium deposit [8 ~ 9].
From 2009 to 2010, in order to expand the prospecting results, the 230 Institute of Nuclear Industry conducted a uranium survey in Li Daping section of Xiangyangping area. On the one hand, the structural belt groups F800, F805 and F9 in Pishuping section are exposed through a few working systems, and it is found that there are many mineralization and enrichment centers in F9 structural belt group. On the other hand, the focus of the general survey gradually shifted to Li Daping section, focusing on the mineralization of the F 10 structural belt group and its intersection with the F9 structural belt group, and finally revealed a good uranium mineralization in the north-central part of the F 10 structural belt [10 ~ 13].
From 20 1 1 to 20 12, No.230 Institute of Nuclear Industry continued to carry out uranium prospecting in the Li Daping section and the northern section of F7 belt in Xiangyangping area, and achieved good prospecting results in both the F 10 structural belt and the northern section of F7 belt, and submitted two detailed exploration areas, Li Daping and the northern section of F7 belt.
20 13 Xiangpingping uranium deposit entered the detailed investigation stage. At first, the Institute of Nuclear Industry 230 systematically controlled the main ore bodies in the northern section of F7 belt in the east of the deposit. At present, the main ore bodies exposed in F7 10 structural belt have good continuity from line 7 ~ 0 to line 7 ~ 12.
2 The basic characteristics of the deposit
Xiangyangping uranium deposit is located in the middle of Miaoershan granite dome, on the west side of Xiangcaoping fault, on the south side of Menggongjie-Shazijiang fault zone, and in the southwest corner of Douzhashan rock mass. The deposit is located on both sides of the contact interface between Xiangcaoping rock mass and Douzhashan rock mass (Figure 2).
2. 1 magmatic rocks
The exposed rocks in the mining area include Xiangcaoping rock mass in Indosinian period, Douzhashan rock mass in the second phase of early Yanshan period and fine-grained granite vein (γm) in late Yanshan period.
Xiangcaoping rock mass in Indosinian period: exposed by bedrock, invaded the eastern granite on a large scale and exposed in a large area in the mining area. The lithology is mainly medium-coarse grained porphyritic biotite granite, and the main minerals are potash feldspar (34.6 1%), plagioclase (19.05%), quartz (34.23%) and biotite (4%). The average uranium content in rocks is 33.88× 10-6, thorium content is 34. 13× 10-6, and Th/U is 1.0 1. The isotopic ages of the rock mass by K-Ar method are 172 ~ 200ma, the whole rock by R b-Sr method is 260Ma[ 14], and the zircon by U-Pb method is (2112) Ma [15].
Douzhashan rock mass in the early Yanshan period: in Xiangcaoping rock mass, rock branches are mainly exposed in the northeast of the mining area, and there are also sporadic exposures in Pishuping section in the south. The lithology is medium-fine grained or fine grained mica granite, and the main minerals are potash feldspar (3 1.6%), plagioclase (25.8%), quartz (34.5%), biotite (3%) and muscovite (4%). The average uranium content in rocks is 26.66× 10-6, thorium content is 21.18×10-6, and Th/U is 0.79. The early isotopic age of biotite measured by K-A r method is 155 ~ 180 Ma, and the modern isotopic age shows the late Indosinian, in which R b-Sr isotopic age is (214 3) Ma [14] and muscovite Ar-Ar isotopic age is.
Late Yanshanian fine-grained granite (γm): It occurs mostly in dikes or branches, and the rocks are grayish white with fine-grained granite structure. The main minerals are Yingshi (30%), feldspar (60%) and muscovite (10%). It is homogeneous in time, and the particle size is 1 ~ 2mm. The average uranium content in rocks is 23. 13× 10-6, thorium content is 4.47× 10-6, and Th/U is 0. 19.
Fig. 2 Geological schematic diagram of Xiangpingping uranium deposit.
1- Upper Sinian Laobao Formation siliceous rocks; Dark mudstone of shallow sea facies in Doushantuo Formation of Upper Sinian; 3- gravel sandstone of Nantuo Formation of Lower Sinian; 4- Indosinian coarse-grained biotite granite; 5— Middle-fine grained mica granite in the second stage of early Yanshan period; 6- Late Yanshanian fine-grained granite veins; 7-fault zone and its number; 8- Mining Area
Rietmann index (δ) < 2, Wright alkalinity (τ) > 3 of granites in different periods in the mining area belong to calcium-alkaline combination, and Al2O3/(Cao+K2O+Na2O) > 1 belongs to aluminum supersaturation type. The content of SiO2 _ 2 is stable, the content of K20 and Na2O is high, the alkali is rich, the K2O/Na2O ratio is low, and the content of K+ and Na+ in the rock is balanced. The contents of Fe3 ++ and Fe2 ++ are generally low. Al203 content is high (> 13%) and TiO 2 content is low. From the old to the new, Ca2+, K+, Fe2 ++ and Fe3 ++ gradually decreased, Na+ gradually increased, and K2O/Na2O value decreased (table 1).
Table 1 chemical composition of granite in different periods of Xiangpingping uranium deposit
2.2 structure
F7 fault zone: it is exposed in the east of the mining area, passes through Shazijiang deposit to the north, and extends for more than 2,700 meters. Its main body strikes NNE, and its occurrence is105 ~10 ∠ 75 ~ 85, which is one of the main ore-controlling silicification faults. The fault zone consists of secondary faults such as F700-F7 19, which are mainly compressive and torsional, and the lithology is mostly variegated silicified cataclastic granite and granite cataclastic rock. Siliceous veins are developed in the fault zone and filled in the silicified granite cataclastic rocks in the form of veins, veinlets and reticulate veins.
F8 fault zone: It is one of the main metallogenic fault zones of the deposit, belonging to the regional secondary structure Sha Meng fault. It enters Shazijiang deposit from the north, which is the most important ore-controlling fault of Shazijiang deposit. It stretches southward like a broom and consists of F800 fault, F802 fault and F805 fault.
F800 fault zone: The overall strike of F800 fault zone is NNE, extending for 4,000m, running through the mining area, and the occurrence is110 ~125 ∠ 65 ~ 85, which is one of the main metallogenic faults of the deposit. It is composed of secondary faults, such as F800- 1-F800-9, with compression and torsion. The lithology is mainly cataclastic rock, granite cataclastic rock and breccia, which are mostly filled with white siliceous veins and black-red microcrystals.
F802 fault zone: the extension length is 4500 m, the general strike is N N E, and the dip is SE, and it is composed of F802, F802- 1 and other faults. The fault is compressive and torsional, and the lithology is mainly granite cataclastic rock and siliceous breccia. The breccia is dominated by black chalcedony, and white and gray siliceous veinlets are developed in the fractures.
F805 fault zone: this zone runs through the whole area in the northeast direction, intermittently extends to the north outside the mining area, and southward to the intersection of the 55 exploration line and the F9 fault zone in Pishuping section, with a total length of over 10km, a width of 3-5m, a maximum width of 25m, and an occurrence of10 ~140. Lithology is mainly cataclastic rock and granite cataclastic rock, and most faults are filled with siliceous veins.
F9 fault zone: exposed in the west of the mining area, with special landform and S-shaped distribution, which is extremely out of harmony with other fault zones in the area. The general strike is SN, inclined to the west, with an inclination of 25 ~ 49, with an exposed length of about 6,200m and a width of several meters to 70m. The local expansion and contraction are frequent, and the fracture lithology is mainly mylonite, breccia, silicified granite cataclastic rock and cataclastic granite, and the white massive time pulse with a scale of several meters to more than 100 meters is developed in the center.
F 10 fault zone: it extends intermittently, with a length of about 7 ~ 8 km and a width of 0.5~70m, mainly exposed in Li Daping section, with an outcrop of 3,700 m in the mining area and an occurrence of 95 ~1/kloc-0 ∠ 50 ~ 85, which is one of the main metallogenic faults of the deposit. The fault extends steadily to the north and intersects F9 fault zone to the south. Influenced by the east-west extension of F9 fault zone, it intersects with F9 fault zone, and its southern part is concealed in the footwall of F9 fault zone. Lithology is mainly cataclastic granite and granite cataclastic rock, with mylonite and structural breccia in some sections, and black microcrystal quartz veins are mixed with a large amount of collophanite.
F 1 1 fault zone: it intermittently extends about 2km, with a width of 0.5 ~ 1m and an occurrence of 15 ~ 25 ∠ 55 ~ 64. Mainly exposed in Li Daping and Laopeng, there are many secondary parallel faults. Lithology is mainly cataclastic granite and granite cataclastic rock.
2.3 characteristics of ore bodies
Ore body shape and scale: In the prospecting stage, the industrial ore bodies are 333+334 1, mostly in the form of veins, flat lenses or small lenses, mainly occurring in F7, F8, F9 and F 1. 1 is breaking through. The scale of ore bodies is mainly small, with a total of X ore bodies exceeding 50t. The strike length of most ore bodies is100 ~150m, and the dip length is 50 ~100 ~ 800m. The strike length of the main ore body (over 50 tons) is 100 ~ 800 meters, and the dip extends 50 ~ 250 meters.
Occurrence, occurrence elevation and buried depth of the ore body: the occurrence of the ore body is basically consistent with the occurrence of the fracture zone where it is located. The general occurrence of most ore bodies is 90 ~ 1 10 ∠ 50 ~ 85, and the occurrence of ore bodies in F9 fault zone is 240 ~ 280 ∠ 12 ~ 45, showing a trend of steep upward and slow downward.
The vertical elevation of ore bodies is 660 ~ 1586 m, and the vertical amplitude is 926m, all of which are concealed ore bodies with a buried depth of 50 ~ 800 m. ..
Ore body grade and thickness: average thickness of ore body 1.05m, thickness variation coefficient of 92%, ore body grade of 0.050% ~ 0.350%, average grade of 0.65,438+065,438+09%, and grade variation coefficient of 52%.
2.4 ore characteristics
Ore types: mainly uranium-hematite type, uranium-pyrite type, uranium-chalcedony type, uranium-fluorite type and uranium-calcite type, of which the first two types are the most common, mainly disseminated and veinlets distributed in the silicified zone and the broken granite on both sides.
Ore structure: mainly colloid structure, metasomatic residual structure, vein structure, reticulate vein structure, disseminated structure and breccia structure.
Mineral composition of ore: The main uranium minerals are pitchblende, uranium black, uranium amphibole, uranium mica and copper-uranium mica. Associated metal minerals are simple, mainly hematite, pyrite, limonite and a small amount of stibnite. Gangue minerals mainly include quartz, microcrystalline quartz (chalcedony), feldspar, hydromica, sericite, chlorite, and a small amount of calcite and fluorite.
Chemical composition of the ore: Al2O3, K2O and Na2O in the ore are obviously lower than those in the surrounding rock, and the content of Fe2O3 is much higher than that in the surrounding rock, with a maximum of 38.6438+09%. The composition of trace elements in ores and rocks is similar, and the contents of elements such as Cr, Rb, Sn, Nb, Zr, Ta and Bi in ores are similar to those in surrounding rocks (Table 2). Cu, As, Mo and Sb are several times to dozens times higher than the average value of surrounding rocks, but they do not meet the requirements of comprehensive utilization. Co, Ni, W and H g are several times to dozens times lower than those of surrounding rocks, and the contents of these elements increase from mineralization center to peripheral rocks in turn, with the highest content of W in surrounding rocks being 3359× 10-6, which deserves attention in comprehensive prospecting.
Table 2 Contents of Some Trace Elements in Ore, Structure and Surrounding Rock of Xiangpingping Uranium Deposit (wB/ 10-6)
3 Main achievements and innovations
3. 1 main achievements
1) A total of 98,692.86 meters of drilling work has been put into Xiangyangping uranium deposit, with drilled holes 18 1, including 89 industrial holes, 34 mineralized holes, 49 abnormal holes and 9 non-mineralized holes, with a breakthrough rate of 67.96%. Xiangyangping uranium deposit is close to the scale of a large deposit.
2) Determine three detailed survey scenic spots (Pishuping area, Li Daping area, northern section of F7 fault zone) and three general survey scenic spots (Laopeng area, northern section of F805, south extension of F7, F8 and F9). Among them, Pishuping prospect area is located between No.64 and No.47 exploration lines, including structural belt groups such as F800, F805 and F9, with an area of1.88km2; ; Li Daping exploration area is located between exploration lines D72 and D59, including structural belt groups such as F 100, F10, F 102 and F 105, with an area of1.49km2; The detailed exploration of the northern section of F7 fault zone is located between 7-23 and 7-44 exploration lines, including F703, F704 and F7 1. Syntectonic belt group, with an area of 0.75km2, is the first to carry out a new round of detailed survey in the northern section of F7 fault zone, and the prospecting results have made further breakthroughs.
3) The spatial distribution and ore-controlling law of faults in the deposit are roughly found out. The basic framework of the mining area structure is mainly composed of five groups of faults, namely, nearly North-South, North-East, East-West, North-West and North-East. Among them, nearly North-South and North-East faults are the most developed and are the main ore-controlling and ore-hosting faults. There are F7, F8, F9, F 10, F 1 1 fault zones at roughly equal intervals from east to west, and each fault zone consists of a series of secondary faults, which are densely developed and appear in strips, or parallel or intersecting or pinching out. The distribution of uranium ore bodies, mineralized bodies and abnormal points in the area is controlled by the intersection and clamping parts of these faults, structural variation parts and cutting Xiangcaoping rock mass, Douzhashan rock mass and their contact zones.
4) The characteristics of hydrothermal alteration in this area have been roughly identified. The hydrothermal activity in the mining area is developed and has a wide range of activities, which is closely related to uranium mineralization. According to the relationship between alteration and mineralization, it can be divided into three stages: before mineralization, during mineralization and after mineralization. The alteration before mineralization is mainly chloritization and hydromica, mostly superimposed, and widely distributed in the surrounding rocks on both sides of the fault. Hematitization, pyritization, silicification and potassization are the main alteration during the metallogenic period, and superposition with early chloritization and hydromica is beneficial to mineralization. The alteration after mineralization is mainly kaolin and muscovite, which mostly exist in the fracture development area. Silicification, hematitization, pyritization, potash feldspar and purple-black fluorination, which are closely related to uranium mineralization, have the characteristics of multi-stage superimposed multi-stage hydrothermal activities, forming yellow-green alteration zone and red alteration zone. Red (black) microcrystal chronological veins, purple-black fluorite veins and flesh-red calcite veins are common in the mineralization center, and hematitization, silicified and potash granite cataclastic bodies are on both sides. Secondary uranium minerals usually occur in the red microcrystal time pulse, mainly developed in F7 fault zone, F8 fault zone, the footwall of F9 fault zone and the south of F 10 fault zone. The black microcrystal pulse is mostly associated with dark colloidal pyrite, and the purple-black fluorite pulse is slightly later than the black microcrystal pulse, and the fleshy red calcite pulse is later than the purple-black fluorite pulse. This group of veins is mainly developed in the north-central part of F 10 fault zone, the main belt of F9 fault zone and the north of F8 fault zone. The multiple superposition of ore-forming veins in each period is particularly beneficial to mineralization.
5) It is found that the contact zone of rock mass has a certain control effect on mineralization. Douzhashan rock body intrudes into Xiangcaoping rock body in the mining area in the form of rock branches, and a rock branch with nearly east-west distribution is formed in Li Daping section in the middle of the mining area, surrounded by a large number of secondary bulges, and its shape is extremely complicated. At present, many boreholes reveal that there is industrial uranium mineralization in the fault zone near the contact zone between Douzhashan rock mass and Xiangcaoping rock mass, and the overall transverse direction of the ore body is consistent with the strike of the contact zone of rock mass. Geochemical analysis shows that the REE distribution patterns of uranium ore, Douzhashan rock mass and Xiangcaoping rock mass are similar, among which the REE content and distribution curve of uranium ore and Douzhashan rock mass are highly consistent (Figure 3), indicating that uranium mineralization in this area has the homology of ore and rock [17 ~ 18], and the role of rock contact zone in the mineralization process of Xiangyang Ping uranium mine can not be ignored. The contact boundary between Douzhashan rock mass and Xiangcaoping rock mass is complex and changeable, and there are many granite domes in the deep part. Therefore, prospecting along the contact boundary between two rock masses, especially the occurrence change of deep rock masses, has a good guiding significance.
6) The genesis and ore-controlling factors of the deposit have been preliminarily identified. Xiangyangping uranium deposit is of ascending hydrothermal leaching origin, and belongs to Jiang Sha type in granite inner belt sub-series of hydrothermal vein uranium mineralization series. The main ore-controlling factors include the contact zone between large granite rock mass in the form of bedrock and small rock mass in the form of rock plant in the late stage of multi-stage magmatic activity, the NE-trending brittle-ductile strike-slip fault system formed by multi-stage inherited fault structural activity, various hydrothermal veins and alterations formed by multi-stage tectonic-magmatic hydrothermal activity, and secondary uranium enrichment formed by subsequent leaching and superposition.
Fig. 3 REE distribution patterns of granite and uranium ore in different stages of Xiangpingping uranium deposit.
The chondrite value is based on Boynton (1984)[ 19].
Uranium-producing rock bodies are Xiangcaoping rock body and Douzhashan rock body, which are rich in ancient uranium and provide rich uranium sources for mineralization. Multi-stage tectonic-hydrothermal events caused autometamorphism and hydrothermal alteration of rock mass, increased uranium activity in uranium source body and formed ore-bearing thermal fluid. Uranium mineralization is closely related to the NNE structural fracture zone, and the deposit is located on the NNE strike-slip fault zone (such as F7, F8, F9, F 10, etc.). ) through the contact zone between Xiangcaoping rock mass in Indosinian period and Douzhashan rock mass in early Yanshan period. It is mainly controlled by ductile-brittle shear zone marked by Sha Meng fault zone. With ductile shear deformation, hot water solution extracts uranium from surrounding rocks, activates and migrates uranium. With the rapid uplift of the crust, the shear zone enters a relatively open system, and the rising ore-forming hydrothermal solution is mixed with atmospheric precipitation and groundwater, and the solubility of uranium decreases rapidly. Ore-bearing hydrothermal solution is deposited in secondary shear zone, minor shear zone, cracks and joints, and enriched in ore.
3.2 Main experiences and innovations
(1) Field prospecting and deep prospecting are effective technical approaches, and target selection is the key.
In recent years, the geological system of nuclear industry has found successful examples of prospecting in the periphery and deep of old mining areas in Xiangshan, northern Guangdong and northern Guangxi. In the process of determining the prospecting target area of Miaoershan, after many field investigations and a large amount of data analysis, it is considered that Xiangyangping area and Shazijiang deposit in the north are in the same geodynamic and uranium metallogenic geological background, and the scale, occurrence, material composition and wall rock alteration of its main faults are similar to those of ——F8 fault zone, which is the main ore-controlling fault of Shazijiang deposit, and it should have a good prospecting prospect. The 230 Institute of Nuclear Industry boldly chose Xiangyangping area, which was not optimistic at that time, as the key prospecting area. In the general survey of uranium deposits in this area, we adhered to the "trinity" technical idea and layout principle, which is based on geological research, supported by the application of geophysical and geochemical exploration methods, and moderately adjusted while studying during construction, and comprehensively analyzed and studied the three-dimensional prospecting information in the mining area, which greatly improved the efficiency of geological prospecting and finally achieved good prospecting results.
(2) Introduce and apply new metallogenic theories as technical guidance for prospecting, and give play to the role of scientific research in prospecting.
Based on strike-slip structure theory and modern continental dynamics metallogenic series theory, this paper comprehensively analyzes the previous achievements and deeply studies the metallogenic geological conditions and prospecting potential of the mining area. It is considered that a set of NE-NNE sinistral strike-slip fault structural system with similar properties controls the spatial distribution of most ore bodies in the mining area, and multi-stage tectonic-magmatic thermal events are closely related to uranium mineralization.
(3) Strengthen the field geological survey and attach importance to the role of geophysical and geochemical exploration results in prospecting.
Follow the teaching of the older generation of geologists that "there is no geological work without field", take field geological survey as the primary work content, and carry out field basic geological work and geological research throughout. The occurrence and relationship of a series of faults in the mining area are rearranged, many omissions and errors in the original geological map are supplemented and corrected, and the scale of related fault zones is expanded.
At the beginning of the work, the occurrence and relationship of F9, F800 and F805 in Pishuping area were rearranged through many field geological route investigations, repeated deliberation and discussion. It is considered that a series of secondary faults (F90 1~F907 ~ F907) densely developed in the footwall of the middle section of F9 fault zone divided by predecessors should actually be the southward extension of F805 fault zone group, while the southern section of the original F805 fault zone group is the southward extension of F800 fault (Figure 4), and the scale of these faults is larger than previously recognized. In fact, the whole Pishuping section is located in the intersection and clamping area between F800 and F805 fault zones and F9 fault zone. The results of geophysical and geochemical exploration also show that the profile has obvious abnormal distribution of 2 10 Po, and the field level display is complete, which is obviously controlled by faults. The project team believes that this section should have good metallogenic potential and take it as the key construction section in the initial stage of work. After later drilling verification, many industrial ore bodies were exposed in the above fault zone in this section. With the further development of the general survey, the Pishuping ore section was finally determined as the prospective area for detailed investigation, and the main ore bodies in F9 and F8 zones were controlled.
According to the above working ideas and prospecting mode, the Li Daping section of Xiangyangping uranium mine and the northern section of F7 fault zone have achieved good prospecting results, and then developed into two other detailed investigation areas, controlling the main ore bodies in F 10 and F7 zones.
4 Development and utilization status
There is no Shui Ye test for ore processing in this deposit, but the ore type is very similar to Shazijiang deposit in the adjacent area, so we can refer to its test results. The mining technical conditions and indexes of the deposit are basically the same as those of Shazijiang deposit, especially the ore body of F8 fault zone is in the same ore-bearing structure as Shazijiang deposit, and the mining technical and economic indexes of the deposit can be comparable to Shazijiang deposit. The deposit has not yet been developed and utilized.
5 concluding remarks
The main ore bodies of Xiangyangping uranium deposit extend stably along strike and dip, and the mineral composition of the ore is simple, and the mining technical conditions are almost the same as those of Shazijiang uranium deposit, which should have good development and utilization prospects.
The exploration practice and results of Xiangyangping uranium deposit show that there is still great prospecting potential around and deep in the old mining area. The western, southern and surrounding areas of Xiangyangping uranium deposit, such as Shiwushui, Jinzhucha and Dashuping, have good uranium metallogenic prospects and can be comprehensively explored. If the existing resources of Shazijiang, Baimaochong and Shuanghuajiang deposits in the middle part of Miaoershan are added, this area is expected to develop into a uranium ore field of more than 10,000 tons.
In the process of work, due to various reasons, there are still some problems and shortcomings, mainly including:
1) The mining area is large, with many and dense ore-forming fault structures, and the mineralization extends well along strike and dip. At present, the amount of engineering input is relatively small, and there are only a few drilling projects that are initially controlled in most sections. There are still many areas in the mining area where only a few boreholes are drilled or not verified. Comprehensive analysis shows that these areas have good metallogenic and prospecting prospects (such as the northern section of F805, the southern section of F9 and F6544).
Comparison of structural changes in Pishuping section of Xiangyang uranium deposit before and after work.
A- geological map before work; B- revised geological map
1- Indosinian coarse-grained biotite granite; 2- Medium-fine grained mica granite in the second stage of early Yanshanian; 3- Fine-grained granite veins; 4- silicified fault zone; 5- fault zone and its number
2) In many boreholes, the occurrence and shape of Douzhashan rock mass are concealed in the lower part of Xiangcaoping rock mass, and its spatial relationship with uranium ore bodies needs to be further ascertained.
3) The controlling factors of the contact zone between granite and old strata in the southwest of the mining area and the abnormal field of geophysical and geochemical exploration delineated by predecessors have yet to be ascertained.
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Significant progress and breakthrough in uranium exploration in China —— Examples of newly discovered and proven uranium deposits since the new century.
[Author] Xiao Jianjun, male, born in 1960, is a researcher-level senior engineer. 1982 graduated from east China institute of geology, majoring in radioactive investigation and exploration, and has been engaged in uranium geology for a long time. Hosting and participating in the project won 2 second prizes for ministerial-level scientific and technological progress, 3 third prizes and 5 excellent geological reports.