North-north east direction

The NE-trending structures of the eastern Guangxi rock mass and its adjacent areas are mainly fault structures, and a few are distributed in the eastern part of the rock mass in the form of lahui lamprophyre filling. The ne-trending fault zones of Beijiang, Baishun-Shaoshan and You Shan-Xiazhuang are distributed in the rock mass from west to east (Figure 4- 1 and attached drawings).

The NE-trending fault structures often accommodate, utilize, inherit, transform and develop the EW and NE structural belts. The faults are compressional-torsional, sinistral-torsional, diabase dikes, compressional zones and isochronous fault zones. Faults are grouped into regions. Altered rocks with different structural deformations are widely developed, filled with various fine (micro) Shi Ying, pitchblende, pyrite, goethite, fluorite and calcite, accompanied by Yingshi, chloritization and Yili petrochemicals.

Early activities and the east-west zone control endogenous minerals, such as tungsten ore; The late activity combined with the east-west and north-east structures controlled the distribution of hydrothermal uranium deposits.

(1) NE-trending fault zone

The NNE fault zone is widely developed in this area, especially the uranium ore field in the eastern part of the rock mass, which is later than the EW and NE structures. From west to east, it is Guiweishan, Mingzhu Lake, Xinqiao-Xiazhuang, 6009, 6004, 102( 103,10, 104,16).

1. Guiweishan Yingshi fault zone

The fault zone is located in the west of Liling Village, wengyuan county, from Zhutongjian to Guiwei Mountain. The fault strike is 45 ~ 50 (individually 60 ~ 80), and it tends to the southeast with an inclination of 75 ~ 80. The fault zone extends over 8km, with a width of 0.5 ~ 3m and a maximum width of 5m, and the range of rocks affected by different degrees of stress and deformation is wider (Figure 4-6).

Figure 4-6 Schematic Diagram of Deformation and Alteration Rock Profile at the Side Edge of Guiweishan Yingshi Fault Zone

Faults extend slowly in strike and dip. The predecessors thought that the fault was a secondary structure of Huangpi Yingshi fault zone. Due to the recombination of NNE structures in the later period, the strike of the structural belt is "S" type, and the structure is more complicated and mixed. As far as the nature of the fault is concerned, it is a left-handed compression-torsion fault zone, because it dislocates diabase veins and the southeast plate is relatively displaced to the northeast.

In order to understand the characteristics of different deformed and altered rocks in Guiweishan Yingshi fault zone under lateral stress, the distribution characteristics of main element oxides and trace elements were studied in laboratory, which are summarized as follows.

Macro-and micro-characteristics of deformed altered rocks in Guiweishan Yingshi fault zone and its lateral margin (1).

1) Fine-grained biotite granite with weak fracture failure (X 197). This belt is located in the footwall (1 1.5 m) far away from the main fault zone, with grayish white and fractured granite structure. There are obvious tourmaline and garnet crushed in the rock, and illite is filled in the cracks. Muscovite fractured and disappeared in waves. The fracture edge of feldspar is serrated. There are cracks in time, and some of them are wavy extinction, as shown in Figure 4-6.

2) Strongly broken clay (illite) altered granite (X 198) This zone is close to the main section, and the petrochemistry of illite and kaolin is obviously enhanced, and iron oxide staining appears. Part of the muscovite in the rock becomes illite, which is roughly oriented. Feldspar crystals are crushed, and they are fine in time, and so on. The granite structure is still preserved locally;

3) Granitic clayey mylonite alteration zone (X 199) This zone is 3 m away from the main fault zone, and the rock is grayish white with mylonite structure. Potassium feldspar shows residual spots or metasomatic residues. It is mottled and undulating in time. Illite and kaolinite account for feldspar residual spots and mica debris;

4) The center of the fault zone is siliceous altered mylonite zone (X200), and the rocks in this zone are white, yellowish brown, mylonite structure and massive. Mineral composition of the rock: it accounts for more than 80% of the whole rock in time. In addition to seasonable, there are a small amount of illite, kaolinite and chlorite residues. They appear in the form of polymers. The residual spots of rough spar develop into sub-particles, wave extinction and band extinction.

5) Strong-strain, illite, kaolinite and zeolitic granite cataclastic rock zone (X20 1) This zone is close to the upper wall of the main fault zone, and the boundary of residual potash feldspar in the rock is smooth, with lattice twins and wave extinction. Plagioclase is a metasomatic residue with little content. The rocks are mainly timely and illite, and some are mylonite. Most of the areas are covered by rocks, and metasomatic feldspar can also be seen. Muscovite was replaced by illite, and some of them showed cleavage bending and wave extinction, or their structures changed. Kaolinite is an aggregate of feldspar and illite. Zeolite and kaolinite are associated to form needle-like aggregates;

6) Strong illite and kaolinite crushed fine-grained granite belt (X202), which is 2.2 m away from the upper wall of the main belt, with grayish white rocks, light green micro-belts and massive structures. The main minerals in rocks are potash feldspar, plagioclase, quartz and muscovite. Stress alteration minerals are mainly illite and kaolinite, followed by chlorite, illite mixed clay minerals and calcite. The twin of plagioclase is fuzzy, showing residual spots, which are explained by illite and kaolinite veinlets. Time-dependent manifestations are residual spots, crack development, wave extinction and positive biaxial crystals;

7) Crushed granite belt with strong chlorite, montmorillonite, illite mixed clay and kaolinite (X203). The belt is 3.5 meters away from the upper wall of the main belt, and the rocks are grayish white and slightly green, with broken granite structure and massive structure. The main minerals are chlorite, illite and kaolinite, followed by feldspar, montmorillonite, illite clay minerals and zeolite.

The main element oxides of deformed and altered rocks on both sides of Guiweishan Yingshi fault zone also show the characteristics of activation and migration under the thermal action, which reflects the strength of stress to some extent.

(2) The characteristics of macro-element oxides of deformed rocks in Guiweishan Yingshi fault zone and its side edge.

See Table 4-5 for the contents of main element oxides in the Yingshi fault zone in Guiweishan and the deformed rocks on its side.

Table 4-5 Main Element Oxides of Deformation Altered Rock in Guiweishan Yingshi Fault Zone (%)

As can be seen from Table 4-5, the change of major element oxide composition of deformed and altered rocks in Guiweishan Yingshi fault zone has the following characteristics:

1) The siliceous mylonite in the main structural zone of Guiweishan Yingshi fault zone is a strong deformation and alteration zone, which is characterized by high content of SiO2 _ 2, FeO and Fe2O3, while the oxides of other major elements are obviously low.

2) The three samples of the footwall of the main tectonic belt can be divided into two types of tectonic deformation rocks, namely, those with strong alteration near the belt (X 199) and those with weak alteration near the vein (X 198, X 197). Compared with near-zone and near-zone tectonic deformation rocks, it has higher FeO, MgO, Al2O3, H2O ++ and LOS, and lower Fe2O3, MnO, CaO, K2O, Na2O and P2O5. According to the characteristics of decreasing element oxide content, this zone should be a large number of plagioclase hydrolysis zones.

3) The near zone and far zone tectonic deformation rocks (X 198, X 197) in the footwall of the main tectonic belt are two kinds of rocks with little difference in main element oxides. Judging from the contents of K2O and Na2O, their dynamic deformation and alteration are obviously weaker than those in the main structural zone.

4) The three kinds of deformed and altered rocks in the upper wall of the main structural belt can also be divided into two types, namely, the strongly altered structural deformed rocks in the near zone (X20 1, X202) and the weakly altered structural deformed rocks in the far zone (X203). Their main element oxides are very similar, the Na2O content is obviously reduced, and the Al2O3, H2O ++ and LOS are higher, which should be plagioclase hydrolyzed rocks.

(3) Variation characteristics of trace elements and CO2 content in the deformed rocks in Guiweishan Yingshi fault zone and its side edge.

See Table 4-6 for the analysis results of trace elements and CO2 in Guiweishan Yingshi fault zone and its structural deformation altered rocks on both sides. From the analysis results in Table 4-6, we can see the following trends:

Table 4-6 Trace Elements and CO2 Analysis Results of Deformation Altered Rock in Guiweishan Yingshi Fault Zone (10-6)

1) The siliceous altered mylonite zone in the main zone of Guiweishan Yingshi fault zone has the highest content of elements such as Cu, Sb, Mo and S, and the other elements are very low, which is the superposition of geothermal fluids and the concentration of stress and deformation.

2) There are two deformed and altered rock zones in the main fault zone, including hydrothermal altered mineral group and thermodynamically altered deformed mineral group. Therefore, there are many groups of elements with the highest content and higher content, but in terms of element composition, the deformation and alteration rocks in the footwall are characterized by the superposition of high, medium and low temperature elements, that is, there are groups of elements with higher contents of W, Sn, Bi, Sb, Cu, Pb, Zn and F, so the deformation and alteration rocks in the footwall of siliceous mylonite belt are likely to be beneficial to uranium enrichment.

3) This phenomenon shows that there is a trend of element activation and migration in the part where tectonic stress is concentrated, while the part where tectonic stress is relatively weak is conducive to the possibility of multi-element precipitation.

To sum up, the characteristics of Guiweishan Yingshi fault zone are as follows:

(1) The strike of this fault zone is between the ne-trending and NNE-trending structures, that is, the NE-trending faults are utilized, reformed and merged to form the NE-trending "S"-shaped structural belt, that is, some of them are close to the NE-trending distribution.

(2) The Guiweishan Yingshi fault zone is characterized by the gradual weakening of rocks, minerals, deformation and phase transition from the main zone (center) to both sides, especially in the footwall zone.

(3) Compared with the main structural belt, the deformation of the footwall near and far zone in the main structural belt is obviously weakened. Therefore, the contents of SiO2, Fe2O3 and FeO are high, while the contents of Al2O3, MgO, CaO, K2O, Na2O and P2O5 are low. The change characteristics of the oxide of this element show that plagioclase and biotite in rocks are hydrolyzed in large quantities during the alteration and deformation.

(4) From the composition of trace elements, the deformation and alteration zone of siliceous mylonite in the main zone of Guiweishan Yingshi fault zone is characterized by the highest content of Cu, Sb, Mo and S and the low content of other elements. There are two deformed and altered rock belts in the main fault zone, which are thermodynamically altered altered mineral groups caused by hydrothermal fluid. The highest and higher element groups often appear in the element groups, especially the deformed and altered rock in the footwall structure has the superposition of high, medium and low temperature elements (W, Sn, Bi, Sb, Cu, Pb, Zn, F) and deep heat (Zn, F). This phenomenon shows that there is a trend of element activation and migration in the part where tectonic stress is concentrated, but it is beneficial to the possibility of multi-element precipitation in the part where tectonic stress is relatively weak.

2. Mingzhu Lake Yingshi Fault Zone

The fault zone is located 500 meters west of Shuihuangdong Village, Zhuangyan Township, wengyuan county, and its northeast end intersects with Huangpi Yingshi Fault Zone, but it does not pass through Huangpi Fault Zone and extends to Sun Dong in the southwest. The fracture is 6 ~ 8 km long and1~10m wide, and the stress-deformation influence zone is as much as 30 m, and the controlled depth is 280 m. The strike of the fault is 25 ~ 35, the intersection angle between the northeast end and Huangpi fault is greater than 35, and it tends to the northwest (southeast) with an inclination angle of 70 ~ 80. The fault has experienced two main activities, in which extensional breccia, cataclastic rock and mylonite were formed in the early stage and filled with white block-like chronology. However, in the later stage, the NNE structure merged with the tension-torsion fault, expanded along its direction, and branched and compounded. Some sections are not only slippery, but also have tensile properties. Some sections are gentle and wavy, showing compression and torsion, and diabase veins are dislocated to the left, which is a left compression and torsion fracture.

From the trace element analysis data of deformed altered rocks in different structural positions (Table 4-7), it can be seen that:

Table 4-7 Trace Elements of Deformation Altered Rocks in Mingzhu Lake Yingshi Fault Zone (10-6)

(1) siliceous deformation and alteration rock is the main zone of structural fracture, and the deformation and alteration rock zone (X2 19) is dominated by coarse-grained Shi Ying, with high contents of W, Li and S and the lowest contents of other elements.

(2) The siliceous mylonite in Yili Petrochemical Company is a deformed and altered rock zone on the main zone (X2 18). The residual spots in the rock are surrounded by strip-shaped chronological aggregates and mylonite recrystallization microcrystal aggregates, forming a complex siliceous mylonite altered rock zone in Yili Petrochemical Company. The trace elements are Sn, Bi, Sb, Cu, Zn, Rb, Be, Nb and F. The time in the near zone increases obviously, and the content of illite decreases relatively. The content of trace elements molybdenum, lead and cesium is the highest, followed by tungsten, tin, copper, zinc, lithium, rubidium, beryllium, niobium and fluorine ... According to the distribution characteristics of the above trace elements, it can be concluded that the early siliceous mylonite zone with coarse-grained white quartz is characterized by tungsten enrichment. Due to the repeated activities of tectonic thermal fluid, especially the activation and migration of elements in the late period of NNE tectonic activity, a large number of layered new minerals are enriched, and all kinds of fine spar and pyrite are filled in the lateral deformation and alteration zone with relatively weak stress, that is, the plastic brittle deformation and alteration zone. Here, high, medium and low temperature elements are relatively concentrated, which is the part where Th and U elements are relatively enriched. According to previous data, Mingzhu Lake Yingshi fault zone controls Mingzhu Lake, 668 deposit and many abnormal zones, especially the compound part connected with diabase is the most favorable for mineralization.

3. Xinqiao-Xiazhuang Yingshi Fault Zone

This area is located 500 m southeast of Maoshan Village, Dazhuang Township, quannan county, and reaches Xiangzhuang Village, Zhuangyan Township, wengyuan county, which can extend out of the study area to the south and west. The strike of the fault varies greatly from northeast to southwest. The northeast strike of the new bridge is 65 ~ 90, and it tends to the southeast with an inclination angle of 65 ~ 68. The south direction gradually changes to NNE-E (30 ~ 55), and it tends to the southeast with an inclination of 34 ~ 45. The fault strike in Xiazhuang area is15 ~ 40, inclined to the northwest (southeast) with an inclination of 60 ~ 85. The total length of the fault is about 15 km, the width is 3 ~ 10 m, and the widest point is 40 m (Figure 4- 1). Affected by it, the deformation range of rocks and minerals is wider, with the control depth of 200 m in the north and 580 m in Xiazhuang area.

This fault zone is the product of multi-stage tectonic activity: (1) Early east-west fault and northeast torsional fault were partially filled with diabase veins. (2) In the later period, the NE compression-torsion structure was compounded on the NE torsion fault of the EW fault. Granite and diabase are crushed under stress to form breccia, which is cemented by white time to form deformed rocks such as breccia and cataclastic rock. (3) The late NNE structural transformation and utilization resulted in today's arc-shaped structure protruding in the north and west, and a hinge area in Xiazhuang area in the south, spreading in an "S" shape (Figure 4-7), and at the same time, a variety of deformed and altered rocks were formed. The main active period is followed by the metallogenic period, which is filled with red, gray-black fine (micro) Shi Ying and purple fluorite, pyrite, pitchblende and calcite. There are still activities after the mine, such as hot springs in Xinqiao area in the north (still existing), mylonite cementation and cataclastic rocks in Xiazhuang area in the south.

Fig. 4-7 Schematic diagram of S-shaped structure and ore control of Yingshi fault zone in xia zhuang (Team 293).

The fracture shape in Xiazhuang area is complex, with compound branches, and the middle expansion converges to both ends, extending in an "S" shape. Parallel structures (No.9 silicified zone, 10, 15, 13) are developed in the upper wall, and there is a left zone (width 100 ~ 65438+) in the lower wall. The rocks in the upper and lower walls are squeezed and twisted, forming mylonitized altered rocks with oriented minerals. The section is gentle and wavy (Figure 4-8). The early fault is a combination of an east-west NE torsional fault and an NE compressive-torsional fault zone, and the late fault is the clearest NE compressive-torsional left-lateral structural trace at present, which controls the 664 deposit and some abnormal zones and points.

Characteristics of deformation and alteration rocks in different structural parts of Xinqiao Yingshi fault zone (1)

1) Siliceous mylonite zone (X045) is the main fracture zone, with white and grayish white rocks and dense massive structure. Microscopically, it has a mylonite crystal structure. The rocks are mainly composed of timely (99%) and a small amount of illite (1%) (Table 4-8). The coarse crystals are extruded into strips with waves, extinction, subgrain, deformation lines and so on. And are biaxial orthogonal crystals. Cracks are formed in the strip-shaped chronoclastic rocks, and the mylonite along the cracks is dissolved by pressure, recrystallized and precipitated, forming comb-shaped chronotropic or fine-grained chronotropic rocks, thus forming composite siliceous mylonite. A very small amount of flaky illite is arranged along the intergranular and fracture orientation of long-time strain, and together with long-time recrystallization strain, mylonite structure is formed.

Figure 4-8 Geological Map of 672 Deposit (according to Team 293)

2) The foliate zone of Silicified Yili Petrochemical Company is located near the footwall of the main fault zone. Rock (X 186Sr) is grayish white and yellow-green, and there are fracture zones and mylonite zones locally. Microscopically, the rock shows mylonite crystal structure and clear scaly crystal structure. The main minerals are syenite, plagioclase and illite, followed by microcline, calcite and goethite (Table 4-8). The lattice twins of microcline are deformed in rhombic shape under stress. Plagioclase illite petrification Plagioclase and microcline were recognized in time. At the early stage, the waves disappeared and cracks developed. Illite in mylonite is leaf-shaped, which is roughly oriented or filled along cracks.

3) The granite fracture zone of Tiechloritization is the footwall of the main fault zone and the zone between the near zone and the far zone (X 184). The rocks are gray with uneven goethite staining. Under the microscope, the rocks are mottled and fragmented. The main minerals are plagioclase, Yingshi and alkali feldspar. Altered minerals include iron chlorite, illite, kaolinite, montmorillonite and calcite (Table 4-8). It is worth mentioning that the new mineral iron chlorite is produced in brown fine scale aggregate, which is the illusion of biotite replacement. Compared with the generation environment of magnesium chlorite, iron chlorite is generated under acidic conditions, which is consistent with the strong kaolinization caused by structural superposition in this zone.

Table 4-8 Clay X-ray Quantitative Analysis of Deformation Altered Rock in Xinqiao Yingshi Fault Zone (%)

4) The rocks in chloritization weakly fractured granite belt (X 185) are grayish white, light yellow and massive. Microscopically, the rock is a fractured granite structure. Minerals include plagioclase, microcline, timely and a small amount of residual biotite. Newly-born minerals include magnesite chlorite, illite, illite mixed clay minerals, kaolinite, calcite and so on. Magnesite replaces biotite or granular aggregate to fill cracks or intergranular. Illite is the main component of plagioclase and muscovite.

From the deformation and alteration characteristics of the above zones, it can be seen that the feldspar content gradually increases outward from the main fault zone, but gradually decreases in time. The altered mineral group changed from the main zone (siliceous mylonite) to the Yanshi-illite formation on the structural side; Beside the belt is illite-Yingshi-kaolinite group; The near zone is iron chlorite-kaolinite-illite group; The outer belt is magnesium chlorite-illite-Yimeng mixed clay mineral group.

(2) Macroelement oxide characteristics of deformed rocks in different structural parts of Xinqiao Yingshi fault zone.

See Table 4-9 for the main element oxide content of altered rocks in each structural deformation zone. The main fault zone is a siliceous increasing zone. From the near zone (X 185) to the far zone (X 186Sr) of the main zone, the change trend of main element oxides is that SiO2 _ 2 decreases gradually. On the contrary, Fe2O3, FeO, MnO, MgO, CaO, Na2O and P2O5 all increase to varying degrees, while Al2O3, H2O ++ and P2O5 all increase. This change truly reflects the law of clay spreading from side to outside in rocks. Therefore, the increase or decrease of the oxide content of major elements in each deformation and alteration zone is related to the stress deformation and phase transformation of the fault zone.

Table 4-9 Analysis of Major Element Oxides of Deformation Altered Rock at One Side of Xinqiao Yingshi Fault Zone (%)

Note: The names of sample rocks in the table are the same as (1) 2) ~ 4).

(3) Trace elements and CO2 content of deformed rocks in different structural parts of Xinqiao Yingshi fault zone.

It can be seen from Table 4- 10 that the siliceous mylonite belt (X 185) contains high contents of Mo, Bi, Cu, Zn, Li, Sr and CO2, but the contents of U, Th and other elements are low. Due to the difference of alteration and tectonics, the contents of trace elements in the other three zones have similarities and differences. The contents of elements such as W, Sn, Pb, Cs, Be, Nb and F in the near zone and the far zone are higher than those in the siliceous mylonite zone, but their difference is that the near zone is a high-content element group composed of W, Sn, Be, F, U and Th, while the near zone is a high-content element group. The reasons for this change in trace element content in space are as follows: first, it is related to the alteration and superposition of near east-west compression zone; Secondly, albite, potash feldspar and chlorite developed beside siliceous mylonite are related to illization.

Table 4- 10 Trace Elements and CO2 Content of Deformation Altered Rock at the Side Edge of Xinqiao Yingshi Fault Zone (10-6)

Note: the names of sample rocks in the table are the same as (1) 1) ~ 4).

Judging from the distribution direction of the above three timely fault zones (Guiweishan, Mingzhu Lake, Xinqiao-Xiazhuang), especially the square angle at the northeast end deviates eastward. This deviation direction is not only different from the east-west structural orientation and the northeast structural orientation, but also the main pressure surface of the NNE compression-torsion structure, but it has the distribution orientation and characteristics between them. At the southwest end, it shows more characteristics of NE tectonic main pressure surface. Therefore, these three fault zones are the products of accommodation, transformation, utilization and merger of NNE fault structures (main pressure surfaces). Their properties, characteristics and ore-controlling effects are basically the same as those of NNE structures. Therefore, these three fault structures belong to the late NNE compression-torsion fault structure, which is an important ore-controlling and ore-guiding structure in the ore field.

4. 102- Shijiaowei silicified fault zone

The fault zone is located in Shijiaowei Village, Zhuangyan Township, wengyuan county, passing through the 670 deposit to the 666 deposit in the north, extending to the south and west, and still showing in the north of Jiuquling. The fault strike is 20 ~ 30, and it tends to the northwest with an inclination of 70 ~ 80. The fault zone is 16 km long, with a single pulse width of 1 ~ 3 m, with some sections up to 4 ~ 30 m and a downward extension of 500 m. The fault zone is composed of F9, 102-2, 102-3, 103.

Figure 4-9 Geological Map of 662 Deposit (according to Team 293)

The active characteristics of the fault zone are: twisting to the left in the early stage, forming a "Chinese" fracture and filling it with white blocks; In the late period after the formation of the NNE main pressure surface, it occurred repeatedly in a pulse-like manner, and was first filled with white fine-grained timely and galena. Later, goethite, pyrite, fluorite, pink calcite, static recrystallization time, pitchblende and so on. Finally, Fang Jieshi, fluorite and comb should be timely. It is filled with Yingshi, illite, chloritization, goethite and kaolinite. 102- Shijiaowei faults are complex in shape and appear in groups. It has the characteristics of sharp extinction or compound lateral branches, and its section is gentle and wavy, and some sections are rough. Left-lateral faults dislocate diabase veins with thrust scratches, mirror images and steps. Rocks are squeezed and distorted to form mylonite, phyllite, cataclastic rock, granite (diabase) cataclastic rock and some breccia. In the rock, the directional arrangement of time-dependent elongation, wave extinction, subgrain and core-mantle structure are developed. According to the deformation characteristics of these rocks and minerals, faults should have the characteristics of compression and torsion, and also have the characteristics of first compression and then torsion, and the early tensile characteristics are partially retained.

The fault zone is the product of the reverse connection between the NE-trending structure and the EW-trending structure and the reconnection of the NE-trending structure. It is one of the important fault zones that control some mineralization points and anomalies in 662, 666, 670 and 678 deposits and ore fields.

5. Taipingan silicified fault zone

The fault zone is located at the northwest 1.5 km of Yandong Village, Guidong Town, Lianping County, extending to Luokeng rock mass in the northeast and passing through the central diabase zone in the southwest. The strike of the fault is 20 ~ 30, and it tends to the southeast (northwest) with an inclination of 70 ~ 75 (see attached figure). The fault is composed of silicified zones No.54, No.5, No.7 and 100 1 and corresponding time pulses, which are distributed to the right. After many intense activities, diabase veins filled with NE extensional faults derived from EW and NE compressive-torsional structures formed cataclastic rocks, and the fractured zones were filled with white coarse grains. Later, it was reconnected with the late NNE compression-torsion structure and compounded with the near NNE structure. Early structural features were utilized and reformed to form cataclastic rocks and mylonite. , filled with various fine-grained quartz, pyrite, calcite, pitchblende, etc. , accompanied by timely, goethite, illite, etc. Finally, it is full of ivory and light calcite.

The fracture structure is complex in shape, appearing in groups and belts, and spreading in a "multi" shape. The fracture is gentle and wavy, and some areas are straight. The oblique scratches on the section show that the upper wall is a rising wall, and there are pinnate cracks on both the upper and lower walls, and the upper wall is strongly developed. Crushing and fracturing are the main characteristics of metamorphic rocks, which develop in granite or break into breccia, cataclastic granite and cataclastic rock. From the above characteristics, it can be considered that the fracture is mainly compressive and torsional, twisting to the left. The fault controls the 674 deposit and Taipingan and Yang Gong pits.

6. Hirata silicified fault zone

The silicified fault zone is located at the southeast 1.3 km of Guidong Village, Guidong Town, Lianping County, and intersects with the silicified fault zone in Ma Shishan in the southwest, with a great change in orientation in strike distribution and an arc protruding to the southeast. The fault strike is 20, inclined to the northwest (southeast), and the dip angle is 65 ~ 75 (see attached figure). The fault is 4.5km long, 0/~ 4m wide, 20m local and 80m controlled. Faults are distributed in and controlled by the north-south long and narrow strata between Guidong rock mass and Donggualing rock mass. The fracture is composed of silicified zones with different sizes. The fault has experienced three major tectonic activities. First of all, the tensional "inner" fracture caused by the strong activity of the Ma Shishan silicified fault zone along the NE-trending fault zone is mainly manifested as a broken rock zone, with white coarse particles locally filled in time; The second time is the recombination of NE-trending compressive and torsional faults, forming cataclastic rocks filled with white and light yellow fine-grained quartz, pyrite and pitchblende. Accompanied by timely and Yili petrochemical; After the third mineralization, it is broken to form cataclastic rocks and breccia, which are filled with comb-like time to form structural mud.

The fault zone is composed of dense single faults and fracture groups, which are distributed in a "multi" shape. Therefore, the structural section is smooth and flat. There are secondary pinnate fractures in the footwall and footwall of the fault zone, especially in the footwall. The rocks are crushed into lenticular structures, and cataclastic rocks and breccia (siliceous and argillaceous cementation) are formed. In some areas, the foliation is developed and the minerals are arranged in a directional way, which is basically consistent with the parallel main faults. According to the occurrence of faults and the characteristics of deformed rocks, faults are mainly sinistral and have both compression and torsion. However, the NE-trending compression-torsion fault is reconnected on the Ru-shaped tension-torsion fault (middle) derived from the Ma Shishan fault, so the fault shows the characteristics of compression, tension and torsion.

This fault controls the mineralization point of Pingtian. Mineralization is better and more concentrated in the composite parts where secondary faults are connected with NE compressional and torsional faults, diabase veins and pass through argillaceous, carbonaceous and iron-bearing sandstone.

(2) NNE-trending rock mass structure

The NE-trending structure is a fault structure formed in the late period of this area, and the thermal activities related to it are mainly the timely phenomenon and filling time pulse in the late period of the early grayish macular rock intrusion. The distribution of dikes is mainly NNE. For example, the Lahui lamprophyre veins in the 674 deposit are all NNE, parallel or in groups.

All kinds of veins produced in the NNE are distributed along the NNE silicified fault zone, which has been introduced before and will not be described here.

To sum up, the formation of the rock mass in eastern Guangxi is controlled by the intersection of three groups of deep and large fault zones: east-west, northeast and northwest. Xia zhuang ore field is located at the intersection of NNE deep fault (You Shan-xia zhuang), Huangpi-Longnan fault, NW deep fault and Dadongshan-Zhangzhou east-west fault. The intersection and composite position of multidirectional deep fault structural belts are the necessary spatial conditions for upwelling of deep mantle-derived materials, magmatism of heavy lava and emplacement of hydrothermal solution. The fault structure of Xiazhuang ore field in the eastern part of Guidong rock mass is particularly developed, which has the characteristics of multi-direction, great property change, frequent activity, large scale and equal spacing distribution. Near-east-west, northeast-east and northeast-east three groups of fault structures are not only located in the intersection, compounding and cutting parts, but also constitute the structural pattern of ore field circular traps.

The core factor controlling uranium mineralization is the superposition of hot spots and structures, so the hot spots in the eastern part of Guidong rock mass have the characteristics of multi-stage magmatic intrusion, structural activity and thermodynamic deformation and metamorphism, multi-stage hydrothermal activity and mineralization, various types of metasomatic alteration and superposition of different geochemical elements in roughly the same space. These thermal activities control the spatial distribution of uranium ore fields, deposits and orebodies (attached figure).