Shabaosi Gold Mine, Mohe County, Heilongjiang Province

Shabaosi gold mine is located in the northern section of Daxing 'anling Mountain in the northwest of Mohe County, Heilongjiang Province, and belongs to the virgin forest coverage area. It is a large-scale rock-gold deposit discovered by the Third Armed Police Gold Detachment in the sediment survey of1990 ~1:50000 stream system, and the deposit has reached the level of detailed investigation (Qi Jinzhong et al., 2000).

1 regional metallogenic geological environment

1. 1 geotectonic unit

Geographically, it belongs to Ergon Block, located at the northeast end of Ergon Fold Belt and the west of Upper Heilongjiang Fault Depression. The gold deposit is located on the north side of the NE Uma-Si Lowka River fault (Qi Jinzhong et al., 2000).

1.2 regional stratum

The strata exposed in this area are schist, gneiss, amphibole, granulite and migmatite of Mesoproterozoic Xinghua Dukou Group. Marbles and schists of the Cambrian Ergon Formation in Paleozoic; Devonian crystalline limestone and marl, etc. Mesozoic is the most developed stratum in this area, and the unconformity covers Paleozoic. The early period (early and middle Jurassic) was fluvial clastic deposits, which formed coal-bearing lines of glutenite, sandstone and shale in Xiufeng Formation, Erzhan Formation and Emuhe Formation of Jurassic. In the late period (Late Jurassic-Cretaceous), intermediate-basic and intermediate-acid volcanic lava and tuff were formed, which constituted a part of the volcanic belt in Daxing 'anling. Regional epigenetic gold deposits mainly occur in sandstone of Middle Jurassic, and some gold mineralization points occur in Dukou Group of Xinghua (Qi Jinzhong et al., 2000).

1.3 regional tectonic framework

The NE-trending Delbe dry lithospheric fault extending from Inner Mongolia is a first-class fault structure in northwest Heilongjiang. In addition, there are two groups of secondary shell fractures in this area: NE NEE and NW NWW. Among them, the NE-NEE fault structure consists of a series of nearly parallel faults with the length of 100 ~ 200 km, and the northeast section of the fault zone has craters arranged in series. The NW-NWW strike fault structure is also an important structural zone in the region, which is composed of several parallel faults with equal distance, and a series of craters are distributed along this linear structure. The NW-trending structure intersects with the NE-trending linear structure, forming the basic fault structure pattern in this area (Qi Jinzhong et al., 2000).

1.4 regional magmatism

The exposed magmatic rocks in the area are complex, mainly Zhangguangcailing granite, monzogranite and syenite, and the Sm-Nd age is 614×106 ~ 638×106a. Variscan granites are mostly NE-trending batholiths, characterized by adamellite, granodiorite and alkaline granite, and their K-Ar age is 268×106 ~ 312×106a. There are also Yanshanian granites, mainly distributed in the Cunhe River and Longgou River in the Arctic. The lithology is mainly granodiorite and granite porphyry, which are mostly dendritic or dendritic. K-Ar age is 92×106 ~126×106a. In addition, there are a series of dikes, including pegmatite dike, fine-grained dike, granodiorite dike, granodiorite dike, diorite dike and felsic dike, and the related minerals are Au, Ag, Hg, Pb and Mo. (Qi Jinzhong et al, 2000).

1.5 metallogenic unit

The gold metallogenic units are Tianshan-Xing 'an metallogenic domain, Inner Mongolia-Daxinganling metallogenic province and Ergong metallogenic belt.

2 Geological characteristics of mining area

2. 1 ore-bearing strata

The following strata are mainly exposed in the mining area: Lower Devonian Niqiuhe Formation of Paleozoic, which is composed of slate, crystalline limestone and argillaceous rock, and is in unconformity or fault contact with the underlying marble stratum. Siliceous bands and pyrite veinlets can be seen in slate and limestone, and pyrite is extremely rich locally, but the gold content is extremely low (only 10× 10-9). Erzhan Formation of Mesozoic Jurassic is widely distributed, in which both gold ore bodies and mineralized bodies occur (Figure 1). Its lithology is mainly a set of terrigenous sedimentary rocks and volcanic tuffaceous sedimentary rocks, including sandstone, siltstone, tuffaceous sandstone and coal line interlayers of various sizes. The ore-bearing property of sandstone is related to the grain size of sandstone, and ore bodies are mostly found in medium-fine grained sandstone. In addition, the grade of lithologic gold with high carbon content is obviously improved (Qi Jinzhong et al., 2000).

Figure 1 Geological Schematic Diagram of Shabaosi Gold Mining Area

(According to the Third Armed Police Gold Detachment 1994)

Q— Quaternary loose sediments; -Medium-grained sandstone with thin layers of fine sandstone and coal lines; Siltstone; Fine grained sandstone; -Medium grained sandstone;

-Coarse grained sandstone (including volcanic tuff interlayer); Crystalline limestone and marl; -Marble and timely marble; P/γδπ— fracture zone/granodiorite porphyry dike. Ⅰ ~ Ⅲ —— Gold ore bodies and their numbers. 1- unconformity geological boundary; 2- Measuring fault; 3— Fault with unknown properties and speculation.

2.2 magmatic rocks in mining area

There is no outcrop of bedrock and rock plants in Shabaosi mining area. However, there is a Yanshanian granite factory near the north of the mining area 10km, with an area of 3 ~ 4km2. According to the results of remote sensing interpretation, rock plants are just exposed in the center of the ring structure of Shabaosi, indicating that the ring structure of Shabaosi is a thermal ring formed by magmatic activity. It is worth noting that the discovered Shabaosi gold deposit, Laogouyan gold deposit and Sanyanyan gold deposit are all on the edge of the thermal ring, indicating that the thermal ring has obvious control over the formation of gold deposits. There are many dikes exposed in Shabaosi mining area, among which granodiorite porphyry dike is the largest. The dike is > >150m long and 0.5 ~ 1 m wide, and the strike is north-south. Ore body ⅲ is located near the contact zone of dike. At the edge of dike, Jurassic sandstone has obvious signs of keratinization due to baking metamorphism. The mineral composition of dikes is obviously divided into two generations. The early generation mineral particles are coarse and the late generation mineral particles are fine, and the early generation minerals are broken, filled and wrapped by the late generation minerals, reflecting that the dike is the product of tectonic activity infiltration during magma crystallization differentiation. Judging from lithology and occurrence, the dike may be the product of homology with granite plants in the north of the mining area.

Besides granodiorite porphyry, Jurassic sandstone also contains dikes such as quartz porphyry, diorite porphyry and felsic, as well as volcanic tuffaceous breccia, rhyolite and a large number of volcanic sedimentary rocks. According to its formation time, it can be roughly divided into three periods.

Volcanic activity before the formation of Middle Jurassic: a set of volcanic tuffaceous breccia near the unconformity between Jurassic sandstone and Devonian limestone. On the profile, the rock formation is large lenticular, the thickest of which can reach more than 60m, and the overall trend is close to SN. The volcanic breccia has a high gold content (up to 23× 10-9).

2) Volcanic activity co-deposited with the Middle Jurassic: Volcanic tuffaceous breccia and tuffaceous sandstone with a thickness of 3m can be seen in the coarse-grained sandstone layer of the Middle Jurassic. The continuity of these strata is generally poor, and the composition changes greatly. Tuffy sandstone with breccia appears locally, with the largest breccia of more than 20 cm, angular, with different sizes, broken locally and mixed components, which is obviously the product of the collapse of surrounding rock during volcanic eruption. The distribution of tuff and vitreous in tuffaceous sandstone is also uneven, with more volcanic glass fragments in some places and less or no volcanic glass fragments in some places.

3) Magmatic activity after Middle Jurassic sedimentation: It is characterized by a series of dikes that intrude into Middle Jurassic sandstone, including porphyry dikes, feiporphyry dikes (including raspberry pyritization) and diorite porphyry dikes, the width of which is generally less than 0.5m. In addition, rhyolite-like extrusive rocks were also found on the sandstone layer of the Middle Jurassic (Qi Jinzhong et al., 2000).

2.3 Ore-controlling structure

Fault structures developed in the mining area mainly include NE-trending, NW-trending and near-SN-trending structures. Among them, NE-trending faults are mainly found in Devonian limestone and Cambrian marble, forming a schist zone with a width of several meters. The fault strike is 25 ~ 30, with an inclination of E and an inclination of about 30. According to the included angle between foliation and fault plane in the fracture zone, it is judged as a reverse fault. Moreover, the fault is not developed in Jurassic sandstone, which indicates that it was mainly active before mineralization. The NW-trending fault strike is 280 ~ 3 10, and the dip angle is 1 1 ~ 42, which obviously dislocates the Jurassic sandstone layer and No.2 ore body, showing as an active fault after mineralization, mainly showing dextral translation and sliding, but the activity scale is small and the damage to the ore body is not great.

The near SN- trending structures in the mining area are well developed, showing a series of faults and structural fracture alteration zones with nearly parallel strike. The three veins found in the mining area all occur in these structural fracture alteration zones. SN- trending faults can be divided into two types according to their occurrence, namely steep dip faults and gentle dip faults. ① The steeply inclined fault is located in the west of the mining area, and the 1 fault is located in the middle of the mining area. Ore body Ⅲ is located in the upper wall of the fault. Its strike is generally 15 ~ 345, and it tends to the west with an inclination of 60 ~ 70. The fracture length is > 1~30 cm, the crushing bandwidth is 3 ~ 5 m, and the fault gouge with the thickness of 1 ~ 30 cm can be seen. Two sets of scratches can be seen on the fault plane. According to the steps on the profile, it is determined that the fault is a left-handed reverse fault before mineralization and a normal fault when mineralization occurs. In the fracture zone, it can be seen that the angular fault breccia is cemented by silica and filled with mineralized time pulse. ② The gently dipping fault is located in the middle of the mining area, with strike near SN and west dip angle of 5 ~ 15. Faults mainly develop along the unconformity surface between Jurassic sandstone and Devonian limestone, which controls the distribution of gently inclined No.2 ore body and forms a structural fracture alteration zone with a width of more than ten meters near No.2 ore body. The nature of fault activity is similar to that of steep dip fault. The trend surface analysis shows that there are two SN- oriented grooves on the unconformity surface between Jurassic sandstone and Devonian limestone, which are consistent with the occurrence positions of 1 and No.2 ore bodies.

In addition to the fault structure, a series of wide and gentle folds are developed in Jurassic sandstone, with almost vertical axial plane and nearly north-south hinge direction. However, the control of folds on ore bodies is not obvious. From the above analysis, it can be seen that the ore-controlling and ore-hosting structures in Shabaosi mining area are a series of nearly north-south faults. Before mineralization, these faults showed reverse faults. The metallogenic period is a normal fault. However, the tectonic activity in the mining area is weak after mineralization (Qi Jinzhong et al., 2000).

2.4 surrounding rock alteration

The wall rock alteration in the mining area is extremely developed, and the most important ones are silicification, pyritization and argillization.

2.4. 1 silicification

This area is widely developed, forming dense and hard silicified sandstone, which is distributed in strips, or forming timely veinlets along sandstone joints and cracks.

Pyritization

This is the most important mineralization alteration in this mine, characterized by fine-grained and fine-grained disseminated pyritization, which is locally veined or massive, coexisting with veined time and showing multi-stage.

overlying strata

It is also particularly developed in mining areas. A wide clay zone (up to 20m) is often formed near the fault fracture zone, and fine clay veins are formed locally, which are distributed along joints and fractures. Clay minerals are generally formed by alteration of feldspar, and some are formed by alteration of volcanic ash. By X-ray analysis, its main mineral components are kaolinite, illite and montmorillonite.

In addition to the above alterations, wall rock alterations such as carbonation, sericitization, chloritization, graphitization and limonitization are also well developed. Among them, graphitization is unique in this mine, which often appears in the mineralized zone in the form of veins or blocks, and is associated with fine pyrite, with local elongation and directionality.

The zoning characteristics of wall rock alteration are obvious, which can be generally divided into argillaceous-clayey zone, silicified-pyritized zone and chlorite-sericitized zone according to the distance from fault plane. There is a gradual transition between zones, and ore bodies mainly occur in silicified pyritization zones (Qi Jinzhong et al., 2000).

3 Geological characteristics of ore bodies

3. 1 deposit (entity) characteristics

In the mining area, three gold mineralization zones are circled, and the overall trend of each mineralization zone is SN, which is roughly parallel to the output. The surface outcropping zone Ⅲ is the longest, reaching 1050m, with the interval of 200-400 m. The geological characteristics of each zone and its main ore bodies are as follows.

3.1.1I ore belt

The mineralized body is located in the east of the mining area, which is mainly composed of dense massive silicified sandstone with silicified bands inside. Three ore bodies are enclosed in this ore belt. The ore bodies are mainly lenticular or plate-shaped, all of which are distributed in SN direction, which is consistent with the overall strike of the ore belt, with an inclination of E and a dip angle of 5. A single ore body is 100~350m ~ 350 m long, 6.8 ~ 34.2 m wide and 5 ~ 6 m deep (there is no ore below marble), with the highest grade13.06x10-6 and the lowest grade1.

3.1.2 Ⅱ ore belt

Located in the middle of the mining area, it is the largest ore belt in the mining area. Four ore bodies are circled in this zone, mainly ⅱ- 1 (accounting for 70% of the proven reserves). The ore body is 260m long and150m deep, branching southward, narrowing and disappearing. In section, it branches to the west until it is pointed out. The middle thickness is 28.38m, the average thickness is 14.02m, the highest grade is 9.88× 10-6, the lowest grade is 1.22× 10-6, and the average is 4.00× 10-6. The ore body is mainly composed of silicified sandstone, with an overall strike of nearly north-south, west dip and dip angle of 5 ~ 20, which is layered and occurs along the bed. Controlled by SN- trending gently dipping fault structure.

3.1.3 Ⅲ ore belt

Mineralized bodies are located in the west of the mining area, which are mainly structural fractured altered sandstone, siltstone, carbonaceous sandstone and strongly silicified argillaceous rock. The delineated ore bodies 16 are all vein-shaped, with dip angles of 240-280 and dip angles of 60-70, with a maximum of 8 1. The largest ⅲ- 1 ore body is 400m long, with a vertical depth of more than 200 m, a thin southern section (with an average thickness of 3.29m) and a low grade (3.3 1× 10-6). The northern section is thickened (9.89 meters) with high grade (4.8 1× 10-6), and the ore body tends to the south. In fact, the ore belt is a nearly N-S structural fracture alteration belt, and the ore body is obviously controlled by the fault structure (Qi Jinzhong et al., 2000).

3.2 Ore Composition and Ore Type

The content of metal minerals in the ore is very small, accounting for 1.44% ~ 1.95% of the total ore, but the types are complex. The main metal minerals are pyrite, arsenopyrite, sphalerite, chalcopyrite, galena, molybdenite, pyrrhotite, magnetite, limonite, graphite, white iron ore and copper-zinc-nickel alloy. The main precious metal minerals are natural gold, silver-gold ore, copper-gold ore and natural silver. There are also rich types of gangue minerals, the main gangue minerals are quartz and feldspar, followed by calcite, chlorite, barite, biotite, muscovite and epidote, with more clay minerals, and the main components are kaolinite, illite and montmorillonite.

There are two main types of ore mineralization, namely, altered sandstone type and structural broken altered rock type, the former is the main industrial type. According to the different degree of oxidation, these two kinds of ores can be divided into oxidation type and primary type.

The ore bodies in 1 and No.2 ore belts are mainly altered sandstone, and structural fracture altered sandstone is rare. No.3 ore body. The ore body ⅲ is mainly of structural fracture altered rock type, and the ore body is mainly located in the upper wall of the fault. The farther away from the fault plane, the gradual transition to altered sandstone-type ore, and the grade is also reduced. Judging from the mineral composition, the two mineralization types are basically the same.

1) altered sandstone-type ores can be divided into medium-coarse grained sandstone type, fine grained sandstone type and siltstone type according to the size of sand grains. The primary altered sandstone-type ore is gray to gray-black, with dense massive structure, widespread disseminated or veinlet disseminated pyritization, and strong silicification and clayey phenomena. The sand chips are mainly timely and feldspar, and they are mostly angular, subangular or irregular, with a content of 30% ~ 35%. Feldspar is mainly plagioclase, but also contains a certain amount of potash feldspar, mainly angular or subangular, accounting for 25% ~ 40%. In addition, there are a few mica minerals, such as mica, biotite and other debris. Cements are mainly composed of materials with the same composition as detritus, mainly quartz, feldspar and a small amount of mica and clay minerals, followed by carbonaceous, siliceous or argillaceous materials. There are tuff and volcanic glass cements in some thin slices, and some volcanic glass has crystallized. The near-surface altered sandstone-type ore has strong oxidation, and the oxidation thickness is 3 ~ 5 m.

2) Structurally fractured altered sandstone-type ore, the ore is mainly fault breccia, and the composition of breccia is mainly sandstone, which is angular or subangular, with no directionality and great disparity in size, and local breccia can be spliced. Cements are mainly timely (siliceous), pyrite and argillaceous. , strong silicification, massive and dense.

3.3 Ore fabric and metallogenic stage division

The primary ore structure is mainly disseminated or veinlet disseminated, breccia-like, ball-like, (reticulate) vein-like, bundle-like or hairy, raspberry-like. Honeycomb and honeycomb structure can also be seen in oxidized ore, and earthy structure can be seen in strongly weathered ore.

The main structures of the ore are authigenic-semi-authigenic crystals, allomorphs, inclusions, nodules, interstitial, metasomatism and cataclastic structures.

The hydrothermal period of gold deposits can be divided into the following five metallogenic stages:

1) Pyrite-Synchronism stage: Synchronism and pyrite are relatively thick (about 2mm) and are veined in sandstone. At this stage, pyrite has a high degree of automorphism, mainly in {100} crystal form, and its ore-bearing property is poor.

2) Polymetallic sulfide-isochronous stage: The main metal mineral assemblage is pyrite, arsenopyrite, chalcopyrite, sphalerite and white iron ore, which is the main metallogenic stage. At this stage, polymetallic minerals are generally distributed in the form of fine disseminated particles, accompanied by granular or veinlets.

3) Pyrite-Rhythm-Clay mineral stage: Rhythm, pyrite and clay minerals are disseminated in veins, in which clay minerals are distributed at the edge of veins and fine pyrite is distributed at the center of veins.

4) Fine-grained pyrite-isochron stage: Early pyrite and isochron are veinlets, and at this stage, the pyrite content is very small and the mineralization is poor.

5) Yanshi-calcite stage: the mineral assemblage is Yanshi and calcite, and the metal minerals are rare, which are the products of late hydrothermal activity and contain no ore (Qi Jinzhong et al., 2000).

3.4 Weathering characteristics of ore

The main types are secondary weathering and alteration, such as limonite, laterite and malachite.

4 genesis of ore deposit

4. Geochemical characteristics of1element

R-cluster analysis of ore element content shows that Au is closely related to As and S, and As and Sb are the dominant elements in gold ore bodies, indicating that the denudation degree of gold mining area is shallow, so it is necessary to strengthen the prospecting efforts in the deep and periphery of the mining area. The combination characteristics and correlation analysis of trace elements in rocks in mining areas show that arsenic and antimony are associated indicator elements of gold in mining areas, but thallium and tin are not. Arsenic and antimony have strong indications of deep primary halo anomalies, and it is beneficial to find blind ore bodies by using the characteristics of arsenic and antimony primary halo anomalies (Liu et al., 2002).

4.2 Characteristics of mineral inclusions

4.2. 1 Inclusion type

There are many fluid inclusions in the early and mid-term veinlets in the mining area, the diameter is generally 2 ~ 5 microns, mainly gas-liquid inclusions, and two phases of LH2O+VH2O can be seen at room temperature, and the gas-liquid ratio is generally 5% ~ 10%. At room temperature, three-phase inclusions show 23 phases of LH2+LCO2+VCO, in which (LH2O+VCO2)/LH2O is generally 65,438+00%, and can reach 30% in some cases. Pure liquid inclusions can only see a single LH2O phase at room temperature. However, in the late stage of fine-grained aging, the inclusions are few and small, generally less than 3 microns in diameter, mainly single liquid inclusions, and gas-liquid inclusions are extremely difficult to see (Qi Jinzhong et al., 2000).

Inclusion composition

The results of fluid inclusion composition analysis show that the gas phase composition of the fluid is mainly H2O, followed by CO2 (accounting for 7. 1mol%), and the contents of N2, H2 and CO are very small. In the liquid phase, Ca2+, K+ and Na+ are the main cations, Ca2+> K+> Na+, F- and Cl- are the main anions, and F-> Cl- (Qi Jinzhong et al., 2000).

The ore-forming fluids Na+/K+= 0.4 ~ 0.5 1, all less than 2, and Na+/(Ca2++Mg2+) = 0.15 ~ 0.18, all less than10.5. It can be seen that the source of ore-forming fluid is multi-source, which not only reflects the nature of magmatic hydrothermal solution, but also shows the medium characteristics of underground hot brine, which is consistent with the characteristics of ore-forming fluid and isotope (Hu et al., 2007).

4.3 Physical and chemical conditions

The timely pulse (veinlet) samples in the mining area were tested, and 26 uniform temperature values were measured, ranging from 124.5 ~ 284.5℃. The measured fluid inclusions are all homogeneous liquid phase, and the homogeneous temperature histogram is multimodal. Combined with microscope observation, the peak value around 250℃ is close to the formation temperature of early pyrite-isochron pulse; The peak value between 200 ~ 230℃ corresponds to the formation temperature of polymetallic sulfide-time in the main metallogenic stage. The peak value between 130 ~ 190℃ corresponds to the formation temperature of pyrite-time-clay minerals. In addition, gas-liquid two-phase inclusions have not been found in some small-scale isochron veins and isochron-calcite veins, so it is speculated that their formation temperature should be lower than 150℃. The average uniform temperature is 206.9℃ (Qi Jinzhong et al., 2000).

The metallogenic pressure is 40.9 MPa, and the corresponding metallogenic depth is 1.5km (Qi Jinzhong et al., 2000). Hu et al. (2007) used the same data and different formulas, and concluded that the metallogenic pressure was 172.4× 105Pa, and the metallogenic depth was 0.575km, indicating that minerals were deposited in situ in shallow and low pressure environment. The average salinity is 5% NaCl (Qi Jinzhong et al., 2000).

The average density of the fluid is 0.9 10/0g/cm3. According to microscopic statistics, the volume fraction of CO2 in three-phase inclusions containing CO2 is 15.8%, and the average density of CO2 is 0.635 g/cm3 (Qi Jinzhong et al., 2000).

The pH value of ore-forming fluid is 8.05 ~ 8.26, which is obviously alkaline. The Eh value is -0.7 1 ~-0.68, which belongs to the relative reducing environment, and the log value is -39.4 ~-39.2, indicating that the oxygen fugacity is low. It can be seen that the ore-forming fluid has the characteristics of weak alkalinity, low oxygen fugacity and relative reducing environment (Hu et al., 2007).

4.4 Isotopic geochemical markers

4.4. 1 sulfur isotope

The test results of sulfur isotope composition of pyrite in ore show that the sulfur isotope dispersion is large, δ34S is -8.3 ‰ ~ 5.6 ‰, the sample range is 13.9‰, and the average value is-1.4‰. Based on this, it can be considered that the sulfur isotope composition characteristics of Shabaosi gold deposit may be related to shallow mineralization and the participation of atmospheric precipitation (Qi Jinzhong et al., 2000).

4.4.2 Carbon isotope

Carbonaceous materials can be found in Jurassic strata and pyrite veinlets. The carbon isotopic compositions of carbonaceous shale and veinlet graphite in Jurassic sandstone are analyzed respectively. The δ 13C of sedimentary carbon in Jurassic carbonaceous shale is -2 1. 1‰, which is different from the δ 13C of organic carbon in modern sediments (mainly distributed in -27 ‰ ~-20 ‰, Eckelman et al., 6543). Schultz et al, 1976). However, the δ 13C value of veinlet graphite (2 1. 1‰) is consistent with that of carbonaceous shale, reflecting that the carbon in ore-forming hydrothermal solution comes from the stratum itself. In addition, through microscopic observation, many vein graphite and pyrite are generated in the ore, which also confirms that carbonaceous and metallogenic materials in Jurassic sandstone are activated and migrated during the mineralization process (Qi Jinzhong et al., 2000).

Hydrogen and oxygen isotopes

The hydrogen and oxygen isotope analysis of fine pyrite in ore shows that the δ 18O time is 1.6 ‰ ~ 1.8 ‰, and δD is-15‰~- 18‰, which is consistent with the calculated values. However, it is similar to the fluid hydrogen and oxygen isotopic composition in many tertiary and quaternary precious metal deposits in the western United States (Sheehan, 1997). By comparison, it can be considered that the hydrothermal system mainly related to magmatic-tectonic activities is the ore-forming fluid of this kind of deposits (Qi Jinzhong et al., 2000).

Lead isotope

Lead isotope analysis of pyrite in ore was carried out. Generally speaking, the lead isotope test values in mining areas are relatively concentrated. The variation range of 206Pb/204Pb is18.118.2914, and the variation range of 207Pb/204Pb is15.4589 ~/. Three-dimensional topological calculation of lead isotopic composition of ore in Shabaosi mining area shows that lead isotopes are 25 < V 1 < 50, 25 < V2 < 55. This feature is similar to the lead isotopic composition in northwestern Inner Mongolia and eastern Heilongjiang Province. At the same time, compared with the mantle lead represented by volcanic rocks in eastern China, the variation range and trend of V 1 and V2 are very close, indicating that they have the same or similar material sources (Qi Jinzhong et al., 2000).

4.4.5 Geological age

There are diorite, granite, granite porphyry, porphyry and other intrusive rocks in this area, and their Rb-Sr isochron age is133 5 Ma, which belongs to the late Yanshan period (Qi Jinzhong et al., 1999).

Based on the above data analysis, it is preliminarily considered that the deposit is a medium-low temperature hydrothermal deposit (Qi Jinzhong et al., 2000).

5. Technical exploration marks

Through1∶ 50,000 river sediment survey circle,1∶ 25,000 soil survey gold anomaly, 1 ∶ 1 10,000 soil survey gold anomaly, primary gold ore bodies can be effectively searched. The abnormal area of river sediments, soil and rocks gradually decreases, and the maximum and average content of gold gradually increases, which is the characteristic of ore-induced anomalies (Liu et al., 2002).

refer to

Hu, Zhao Chunrong, et al. 2007. Geochemistry of ore-forming fluids in Shabaosi gold deposit, Heilongjiang Province. Gold technology, 18 (2): 5 ~ 10.

Liu, Mu. 2000. Effect of geochemical exploration in Shabaosi gold mining area, Heilongjiang Province. Gold Geology, 18 (12): 44 ~ 47.

Qi Jinzhong, Li Li, Guo Xiaodong. 2000. Geological characteristics of Shabaosi altered sandstone-type gold deposit in northern Daxing 'anling. Geology of the deposit,15 (3):116 ~124.

(Written by Xiao Li)