There are metallic minerals such as gold, iron, copper, lead, zinc, tungsten, tin and molybdenum, and nonmetallic minerals such as sulfur, arsenic, fluorite, dolomite and crystal in the Baolun gold mine area, including large-scale iron-rich ore 1, 2 large-scale gold mines, 2 medium-sized gold mines and 65,438 small-scale gold, copper, lead and zinc mines (points).
The gold deposits are mainly distributed in the eastward-trending Dimethyl-Bumo Gezhen ductile shear zone and Baolun area, including Baolun large-scale gold deposit, Hongfumenling large-scale gold deposit, Tuweishan and Bumo two medium-sized gold deposits, Niu Bei and Fengshui mountain four small-scale gold deposits, and several gold spots have also been found in Tonganling volcanic basin and Wang Xia east-west fault zone. The types of gold deposits are mainly ductile shear zone type and time-dependent pulse type, in addition to volcanic gold spots.
Control of 1. structure on mineralization
The regional Jiusuo-Lingshui fault zone is the dividing line between two metallogenic units, and the depression zone on the edge of Sanya platform is south of the fault zone. Its main mineralization is the series of phosphorus-manganese deposits related to chemical deposition in the Middle Cambrian and the series of iron, copper, lead, zinc, gold and silver deposits related to the late Yanshanian igneous process. However, the Wuzhishan fold belt north of the fault has been mineralized in various periods since Neoproterozoic, especially in Hercynian-Indosinian period, and the metallogenic series of gold, tungsten, tin, lead, zinc and silver deposits related to magmatic hydrothermal and dynamic metamorphism is extremely developed.
The distribution of polymetallic minerals such as gold, lead, zinc and copper is obviously controlled by the edges of uplift and fault depression. Fault structures directly control the output of each ore body, and the ore-controlling structures of polymetallic ores such as gold, lead, zinc and copper mainly include three groups of faults in NW direction, NE direction and EW direction.
The ring structure or ring body with the diameter of 10 ~ 25 km formed by acidic and intermediate acidic intrusive rocks and volcanic structures is closely related to the deposit. In the combination of diamond, triangle and square images, minerals such as gold, lead, zinc and copper are densely distributed. Among them, the area of Wang Ba rhombic ring structure is 3 182km2. There are 34 ring structures, and most polymetallic minerals such as lead and zinc are distributed along the edge of a single ring structure and the outer NE-trending and NW-trending faults.
2. Strata controls mineralization.
It is mainly manifested in three aspects: ① Cladding group and Paleozoic strata, as source beds, have high contents of gold and polymetallic elements, which are closely related to the formation of known gold, copper, lead and zinc deposits (spots), and are important source beds; ② Strata obviously controls sedimentary metamorphic deposits, such as Shilu iron mine; ③ For skarn deposits, strata are only favorable surrounding rocks, such as Zhenhaishan-Motianling lead-sulfur deposit, Tonganling iron-sulfur copper deposit and 508 iron-copper-sulfur deposit.
3. Ore-controlling effect of intermediate-acid magmatic rocks
Most of the gold and copper deposits (spots) in this area are distributed in the interior of acid magmatic rocks, the inner and outer contact zones and their surrounding areas, indicating that acid magmatic rocks have obvious control over mineral distribution. Intrusions such as Limuling rock mass in Indosinian period and Qianjia rock mass in Yanshan period directly controlled the distribution of copper, lead, zinc and other minerals in the region. In the Indosinian Jianfengling rock mass, there is a Baolun gold deposit in the outer contact zone. Niulaling and Tonganling volcanic basins and their surrounding areas control the distribution of copper, lead, zinc, iron, sulfur and other minerals.
4. Relationship between metamorphism and mineralization
There are mainly regional metamorphism, dynamic metamorphism and gas-liquid metamorphism. Regional metamorphism caused the Tuolie Formation in this area to be metamorphic in different degrees, forming phyllite, metamorphic siltstone and quartzite. Dynamic metamorphism is mainly developed in fault structures, forming mylonitized phyllite or phyllite and cataclastic rock. Gas-liquid metamorphism is also developed in the fault structure, which causes strong wall rock alteration and gold mineralization in the structural belt and its surrounding rock. The main alteration types are silicification, sericitization, chloritization, metal sulfide mineralization and carbonation.
5. Relationship between gravity and magnetic anomalies and mineralization
The polymetallic deposits (spots) of gold, copper, lead and zinc in this area are closely related to the gradient zone of gravity and magnetic anomalies, and the relationship between the distribution of different minerals and gravity and magnetic anomalies is as follows: lead and zinc deposits (spots) are mostly distributed in the transitional zone between local low gravity and high gravity; Gold and copper minerals are mostly distributed at the edge of high gravity; Copper, lead and zinc deposits (spots) are mostly distributed in the high magnetic transition zone with high local magnetic force but low magnetic force or low magnetic force, that is, the aeromagnetic anomaly abrupt change zone.
6. Relationship between geochemical field and mineralization
The main manifestations are as follows: ① The geochemical field in the depression belt of Sanya platform margin is characterized by background fields such as Au, Cu, Ag, Hg, Pb, Fe, Cd, Sn, Bi, P and Mn, and there are corresponding gold, copper, lead, phosphorus, manganese and iron ore deposits. ② The characteristics of geochemical field in the eastern part of Baisha Basin in Wuzhishan fold belt show that the main ore-forming elements in this area are mostly in low background, but they are evenly distributed, and the corresponding minerals are Shimenshan molybdenum mine, lead-zinc mine, Nanhao copper mine, lead-zinc mine, Hongshi iron mine, Nangai gold mine and Shi Tian fluorite mine. ③ The background value of main ore-forming elements in the geochemical field of Baisha sag in Wuzhishan fold belt is low, and the scale of element anomaly is small, with only some gold-silver mineralization points and lead-zinc deposits. ④ The geochemical field in the west of Wuzhishan Fold Belt is characterized by the low-middle background of main ore-forming elements, but some geological bodies have high background of elements such as Au, Ag, Pb and Zn, and there are large-scale comprehensive geochemical anomalies such as Jianfengling, Macaque Ridge and Wang Xia. The corresponding minerals are many large and medium-sized gold deposits, Shilu iron-copper-cobalt deposits, Baolun gold deposits, Wangxiajin, copper, lead and zinc polymetallic deposits (spots) distributed along the NE Gezhen ductile shear zone.
7. Relationship between remote sensing geological anomalies and mineralization
Interpretation of regional geological structures (linear structures and ring structures) in remote sensing images and extraction of regional mineralization and alteration information are carried out. On this basis, the regional metallogenic prediction and analysis are carried out, and the 12 prospecting area is delineated, including 8 major prospecting areas, including Baolun gold prospecting area, Momo gold prospecting area, Jianfengling gold, silver, lead and zinc polymetallic prospecting area, Qianjia-Shimenshan lead, zinc, silver and molybdenum polymetallic prospecting area and Houling.
8. Relationship between tectonic stress field and mineralization
Changes in the direction and magnitude of tectonic stress field caused by the transformation of regional tectonic system. The sudden change of stress state leads to the change of rock deformation and fluid action, and some pre-existing cracks are opened, which leads to fluid immiscibility, reduced pressure boiling, fluid mixing and replacement, and the chemical composition and physical and chemical properties of the original ore-forming fluid will also change obviously, leading to mineralization.
The simulation results show that the stress distribution is different at different depths, different parts and fault zones. In the process of dextral shear deformation in the process of mineralization, the shallow part mainly shows obvious compression; The maximum principal compressive stress in the deep part gradually decreases, and the extrusion environment gradually transitions to the tensile environment, which is beneficial to the convergence of fluids and the precipitation of ore-forming materials. From the strain point of view, the plane, profile and three-dimensional simulation results show that the fault zone has the characteristics of high strain. In the early stage of deformation, some collapse spaces such as tension cracks and small folds can be formed in the fault zone, which provides a place for fluid transportation and placement. If the ore-forming fluid infiltrates at this time, the time-dependent gold deposits distributed on the fault zone can be formed. Further deformation in the fluid and strain hardening caused by silicon precipitation make these collapse spaces disappear, and abnormal high pressure is formed in the process of fluid convergence. At this time, the migration and location of fluid is no longer simply controlled by the fault zone, but is caused by hydraulic fracturing, which forms various fractures in the fault zone or in the hard rocks on both sides of the fault zone. With the precipitation of minerals, the timely vein-like ore bodies and altered rock-type ore bodies controlled by fault zones have been formed in Baolun Gold Mine.
(2) Metallogenic regularity and prospecting criteria of the deposit.
Baolun gold mine is quite different from other gold mines in metallogenic regularity and prospecting criteria. First of all, because the surrounding rock is sericite phyllite, sericitization developed in general gold deposits is difficult to identify here and cannot be used as a prospecting indicator. Secondly, the amount of ore formed in sulfide stage of the deposit is very small, which is not the most important gold-forming stage, so the development degree of sulfide is not a prospecting indicator. These two signs are the strongest in general gold mines.
1. Metallogenic law
1) The output of each gold ore body is strictly controlled by the structure, which is basically confined to the NNW structural fracture zone. Where V 1- 1, V 1-2, V 1-3, V 1-4, V 1-5, V 1-6 and v/. V 1- 12 ore bodies are distributed in the Tr 1 structural fracture zone, V2- 1 and V2-2 ore bodies are distributed in the Tr2 structural fracture zone, and V3- 1, V3-2 and V3-3 ore bodies are distributed in the Tr3 structural fracture zone and V4-65438. V 1 1- 1，V 1 1-2，V 1 1-3，V 1 1-4，V 13-4。 Where V 1 1- 1, v1-2, v1/kloc-3, v1-.
2) The ore-forming site is close to the rock mass, but not inside the rock mass. This study basically denies the possibility that the ore-bearing structural fracture zone extends northward into Jianfengling granite mass on a large scale. Although some small-scale fractures and time-related veins have been found at the edge of the rock mass, their scale, nature, morphological characteristics and ore-bearing property are obviously different from those of the gold-bearing fracture alteration zone developed in Silurian, and their comparability is poor. The ore body is mainly located near the outer contact zone of Jianfengling granite, and the host rock is carbonaceous sericite chronological phyllite of Tuolie Formation of Lower Silurian. The intensity of mineralization decays rapidly in the distance, which can be clearly reflected from the results of general survey and evaluation. In the structural fracture zone in the south of the mining area, the intensity of gold mineralization is very low. At present, only chronological pulse, weak mineralization and hydrothermal alteration have been found.
3) The ore bodies are arranged in parallel at nearly equal distance on the plane, and they are pointed out and reappeared on the section.
4) The ore bodies in each vein zone are located on the S side, and the lateral direction is basically parallel to the distribution direction of Jianfengling rock mass, with a lateral included angle of 45 ~ 50.
5) Ore-bearing dikes are the product of multi-stage geological mineralization, with small spacing, which is sometimes difficult to distinguish with naked eyes.
6) The metal mineral assemblage in the ore body has certain vertical zonation. Generally speaking, the upper part of the ore body is mainly composed of natural gold and quartz, and the lower part is composed of sulfide-bismuth-quartz.
7) Medium-temperature metallogenic conditions are one of the important signs of Baolun gold deposit, which should be paid attention to in the prediction.
8) Black chronocline is the result of comprehensive action of micro-cracks and CO2 inclusions, which developed in the main metallogenic stage, so black chronocline generally has high gold content.
2. Prospecting signs
Due to the complexity of the structure-alteration-mineralization network, it is difficult for a single geological, geophysical, geochemical or remote sensing method to meet the requirements of mineralization prediction in different degrees. It is becoming more and more important to synthesize geological, physical, chemical and remote sensing data, selectively extract mineralization information and enhance indicator information, and make comprehensive prospecting prediction. According to the above research and mining practice, we put forward the following comprehensive prospecting criteria:
The NNW-trending structure of1is the ore-storing structure of gold-silver polymetallic deposits in this area. The main prospecting structural indicators in the mining area are chronological pulse, shale, silicification, pyritization, chloritization and sericitization, among which chronological pulse is the most important prospecting indicator, and the alteration intensity and type of surrounding rock can be used as auxiliary indicators.
2) The carbonaceous sericite sychrosite phyllite of Tuolie Formation near the outer contact zone of Jianfengling granite is the main host rock of gold-silver polymetallic deposits in this area. According to the statistics of 33 samples from Tuolie Formation, the average gold content is 8. 15× 10-9, which may be the source bed of gold deposits in this area.
3) There are Indosinian and Yanshanian granitoids near the mining area, and there are fissures in the granitoids that communicate with the strata.
4) Baoban Group is also an important gold-forming horizon in Hainan. There is a large area of metamorphic rocks exposed in the west of the mining area, which is in direct contact with Jianfengling granite, so attention should be paid to prospecting.
5) Black quartz is usually a gold-bearing ore. On the one hand, it is a law derived from mining practice; On the other hand, according to microscopic study, the black age is caused by micro-cracks and CO2 inclusions, which are closely related to the formation of gold. However, there are also cases in which Heiyingshi does not contain ore, which should be comprehensively analyzed according to other signs.
6) The timing of multi-stage and multi-stage repeated action is often one of the conditions for good ore-bearing. This sign appears in black and white in the wild, and the timing with different transparency is interspersed with each other.
7) According to the vertical zoning characteristics of the ore body, if the ore belongs to the natural gold-rutile-chronological combination, it should be the upper part; If it is a sulfide-bismuth-time combination, it belongs to the lower part.
8) Ore-rich inclusions are developed, characterized by CO2-rich inclusions and large primary inclusions with atmospheric liquid ratio, which can be used as prospecting indicators under microscope.
9) Soil geochemical anomalies of indicator elements 9) Anomalies of gold, silver, arsenic, lead, zinc and mercury in soil indicate the existence of mineralized bodies (especially concealed bodies).
10) There are fore halos (Hg, As, Pb, Cu, Zn) and near halos (Au, Ag, Bi, Pb, Sb) superimposed on the tail halos (Mo, W, Sn) in the deep part of the ore body, and Au and its associated Ag, Sb, Bi, Pb, Zn anomalies still extend to the deep part, indicating that the deep part is still there. The fractal dimension of Au in each exploration line is 23 lines > 15 lines >11line > 7 lines > 103 lines, which indicates that the enrichment degree of Au elements increases in turn, while the continuity of ore bodies deteriorates in turn. It can be seen that continuous ore bodies are easier to be found on Line 23, and the ore bodies on Line 103 are less continuous in development, but the ore grade is higher. The exploration line with high fractal dimension of gold grade can consider reducing drilling density, which is beneficial to the effective use of project capital investment.
1 1) Geophysical anomalies (such as natural A-card anomalies) indicate the existence of mineralized fracture zones, which is particularly important for finding concealed gold bodies. * * * It is inferred that there is a 13 structural fracture zone. Most of these 13 structural fracture zones are NNW strike with a width of 40 ~ 100 m, and the six structural fracture zones delineated by one card are respectively related to Tr3(Tr4), Tr2, Tr 1, Tr5, Tr 1 1, TR.
12) On the remote sensing image, the linear and annular structures in the mining area are well developed, especially the intersection of linear and annular structures is a favorable place for mineralization. Extracting the secondary alteration information of primary ore bodies and mineralized rocks from remote sensing images (such as the distribution study of hematite or limonite) can indicate the favorable parts of primary gold mineralization.
13) The migration, reaction and mineral precipitation and accumulation of ore-forming fluids are closely related to the tectonic stress field and its deformation field. Generally speaking, the fluid transport channel (fracture zone) corresponds to the low stress zone, where mineral metasomatism reaction mostly occurs, while mineral filling mostly occurs in the weak strain zone. During the transformation of regional tectonic stress field from east-west compression to SN- direction compression, the fault zone formed a collapse space, and the pumping action led to the rapid rise of fluid and large-scale mineralization.