Discussion on mineralization of mercury in the Qinling geosyncline

Abstract: The mercury and antimony ore in Qinling are all produced in the Qinling trough, which is often distributed in zones and relatively concentrated. The distribution of deposits (points) is controlled by both sedimentary rock layers and fault structures. Minerals are concentrated in two ore belts and two ore fields. A total of 19 mercury strontium deposits have been identified in the Qinling area. Proved reserves: The mercury mine in Shaanxi Province ranks second in the country and the Yankuang mine ranks sixth. Reserves controlled by the ore-bearing strata: Lower Devonian mercury accounted for 84.4%, and Triassic scorpion accounted for 57.8%. The article summarizes the metallogenic regularity and predicts the prospect of mineralization.
Key words: Qinling geosyncline; mercury strontium resources; sedimentary rock strata; poly ore fault series; ore source layer 1 Qinling area mercury sag geological overview Qinling area mercury and antimony ore deposits are restricted by geosyncline: mercury antimony ore western slope of the ridge, Dingjiashan, mansion, bronze ditch, trough sand and coal mine copper and other deposits, mercury mine have Mu black trench, Charnod, west ditch, Majiashan deposits, antimony ore containing cliffs Bay , Shuitoutou deposit, associated mercury, antimony ore, lead- dragon, Jiuyi, Lalma deposit, a total of 15 industrial deposits, accounting for 83.33% of the total number of Qinling deposits; The ore-forming areas include four industrial deposits such as Gaolinggou, Caiwa, Palm Valley and Dahegou, accounting for 16.67% of the total number of Qinling deposits (Table 1).

Table 1 Summary of the mercury sulphide metallogenic belt (field) in the Qinling trough

The Qinling Mercury Antimony Mine is spread in NWW direction, from Tongde County in Qinghai Province to the east, through Luqu County, Lintan County, Suichang County, Xihe County, Zhouqu County, Hui County, Shaanxi Province of Gansu Province. Fengxian County, Shanyang County, Xunyang County, Shangzhou City, Danfeng County, and Lushi County of Henan Province in the east, a total of 12 provinces and 12 counties. The distribution range is over 1 100 km and the width is 60-210 km (Fig. 1).
There are two ore belts and two ore fields in the whole Qinling, and the two ore fields from the west to the east, from new to old, are now described later.
1.1 Triassic arsenic-tungsten-mercury antimony ore is produced in the Triassic flysch, from the east to the west: the Dachangtan-Yawan area of ​​the Suichang area is dominated by antimony ore, including the cliffs of Xihe County. large Bay antimony ore known throughout the country, is the focus of mine in Gansu Province, the mine also associated silver, selenium; Lintan hole in the dam area next MINXIAN deer Seoul to mercury-based, such as the West ditch mercury, antimony ore was point output; Tongde County, west of Mu had black trench and Charnod mercury, arsenic also produced, tungsten, gold mining, ore-bearing rock is far and near-source source ramp phase of the Upper Triassic sandstones of four rock containing Gravel sandstone and slate . [next]

Fig.1 Metallogenic geological map of Qinling mercury sulphide ore
1. Delimitation domain of geotectonic unit 2. Regional deep fault zone 3. Geological boundary 4. Mercury deposit 5. Antimony deposit 6. Mercury antimony deposit I. North China platform II. Qinling fold system III. Yangtze quasi-floor qlyd. Qinling Yudi trough qlmd. Qinling
Hld. North China continental margin trough TFld. Tongde-Fengxian polymetallic mercury strontium ore-forming Pt. Proterozoic metamorphic rock deposit and number: 1. Muhegou 2. Charno 3. Majiashan 4. Xigou River 5. Cliff Bay 6. Gaoling Ditch 7. Cai concave 8. Dahegou
9. Water eye head 10. Palm ear ditch 11. Mansion 12. Bronze ditch 13. Xipoling 14. Dingjiashan 15. Large trough
16. Sand copper ditch 17. Lerma 18. Lead 硐 mountain 19. Nine 塬

Carboniferous Pb, Zn 1.2 - mercury, antimony minerals plated iron ore zone factory - slate town fracture Carboniferous Yuanjiagou the group flint south strips limestone, which mainly mineralized East mercury, antimony, West The segment is dominated by strontium mineralization. Among the metallogenic belts are the Xipoling medium-sized mercury-minonium ore and the Dingjiashan small-scale mercury-mining mine in Shanyang County.
1.3 Devonian Mansion - Huilongyu Mercury Mine is located on both sides of the Nanyangshan (Honghe-Shuanghe) fault, and the ore-bearing rocks are lagoon facies dolomite and tectonic rocks. The ore field consists of a small mercury ore deposit such as a large mercury mine, a medium-sized antimony deposit, a large trough and a sand-copper ditch in the Guantong and Qingtonggou. The ore field is a backbone mine in Shaanxi Province and one of the three super-large mines in China.
1.4 Yuan Dynasty Jiezhou-Danfeng-Lushi Minefield is produced in the Qinling Group of marble, gneiss, mica quartz schist, breccia and tectonic rocks. The deposit is distributed in the EW to the Shangzhou-Guanpo EW. On the south side of the fault zone, there are Gaolinggou, Caiwa and Dahegou medium-sized strontium deposits, as well as a small strontium deposit in the palm-ear groove. The ore field belongs to the single-dragon metallogenic type, and the industrial value of the earthworm ranks second in the Qinling area.
Mercury deposits in the Qinling area are concentrated in the Xunyang County of southern Shaanxi and Tongde County in the eastern part of Qinghai Province. The former accounted for 85.2% of the total Qinling, and the latter accounted for 13.2% of the total reserves. The reserves are only 1.6%.
The Yankuang mines in the Qinling area are concentrated in three sections: the Shuitou Mine in the Yawan-Suichang County of Xihe County, and the proven reserves account for 57.8% of the total reserves of the Qinling Mine; the Shangzhou-Danfeng-Lushi Mine, The proven reserves accounted for 24% of the total reserves of the Qinling Mountains; the reserves in the Xunyang area accounted for 18.2% of the total reserves of the Qinling Mine.
The mercury reserves in the Lower Devonian strata accounted for 84.4% of the total, the Triassic strata mercury reserves accounted for 12.4% of the total, and the Lower Carboniferous strata mercury reserves accounted for 3.2% of the total. 57.8% of the ore reserves accounted for the Triassic strata, 24% of which occurred in the Proterozoic strata, 16.1% in the Lower Devonian strata, and only 2.1% in the Lower Carboniferous strata. . [next]
2 Metallogenic types and geological characteristics of mercury in the Qinling trough 2.1 Sediment remodeling The genesis of this type of deposit refers to the transformation of the source layer through the fault structure, and the new ore source is superimposed and enriched. Including Cliff Bay, Shuiyantou, Xigou River, Xipoling, Dingjiashan, Majiagou, Leading Mountain, Gongguan, Qingtonggou, Shatonggou, Dacao and other mines, accounting for 11 places, accounting for the total number of deposits in the Qinling area 57.89%. Take the Yawan Bay Mine, the Mansion Mercury Mine, and the Majiashan Mercury Mine as an example.
2.1.1 Cliff Bay Yankuang Mine is located in Xihe County in the south of Gansu Province, 38 km from the SW direction of the county (East 105°08′00′′, north latitude 33 °42′27′′). The minerals are found in the Middle Triassic limestone and slate. Near-mine alterations include silicification, sericitization, chlorite, fluorite; ore metal minerals such as stibnite, pyrite, galena, sphalerite , chalcopyrite, magnetite, fluorite ore, etc.; composed of 42 industrial ore bodies, generally 50-200 m long, 2.28-9.03 m thick, the main ore body of No. 6 is 1 000 m long and 5.96 m thick. With an oblique depth of 515 m, the ore body is layered, beaded, and lenticular; the metal grade w(Sb) is 2.86%, accompanied by Ag, Se, etc. The mine is identified as a large antimony ore by exploration, which is the five major antimony ore in China. One (the other four is Hunan Tin Mine, Zhaxi River, Guizhou Banpo and Yunnan Muli Mine).
2.1.2 Mansion Mercury Mine This mine is located 30 km north of Xunyang County, Shaanxi Province (east longitude 109°20'21′′, north latitude 33°05′51′′). The strontium mercury deposits mainly exist in the dolomite of the Lower Devonian Gongguan Group, followed by the bio-grey rocks in the Middle Devonian Shijiagou Formation, and the ore bodies are formed in the tectonic belt. The anticline, Luojiagou-Lishugou fault and Zhujianhe fault control, the ore body is roughly equidistantly filled at the intersection of the main fault and the secondary fault (Fig. 2), showing irregular veins and lenticular shape, and the extension depth is longer than the extension. The content of strontium from the shallow part to the deep part has an increasing trend. The north slope of the anticline is a single mercury ore, the south wing is a mercury strontium ore, and the Chenjiawan-Chongdonggou and the bench slope-Daqinggou structure are strongly deformed with strontium ore. Mainly, near-mineral alterations are silicified, carbonated and recrystallized ; ore minerals are mainly composed of cinnabar and stibnite, and minor minerals are scutellite, red samarium, sulphur, copper, etc., metal The minerals include pyrite, sphalerite, galena, etc.; the salinity w (NaCl) eq of quartz liquid inclusions is 5.6% to 12.3%, the cations are mainly calcium, magnesium , sodium and potassium, and the anions are sulfates. Fluorine and chlorine are dominant; the uniform temperature of gas inclusions is concentrated in two intervals of 80 °C to 105 °C and 145 °C to 175 °C. The composition of carbon, oxygen and sulfur isotope shows that the gangue mineral composition and ore-forming sulfur source are mainly composed of ore-bearing strata; the isotopic age of galena is 1-22.2 billion years, which is related to the formation of ore-control faults in the Yanshanian period. Consistent; there are hundreds of small blind ore bodies in this deposit, 58 large ore bodies, and the extension is 2 to 3 times longer. The ore body is several meters to 800 meters long and 0.5 to 5 meters thick. The ore type is single. Mercury ore and mercury strontium are mainly mixed ore, followed by monoterpene ore; metal element content w (Hg) 0.3% to 0.4%, w (Sb) 1.44% to 1.62%, w (Au) 0.14 × 10 ^-6 to 20 ×10 ^-6 ; The source of the study suggests that the first is that the Yudigou ancient volcanic rocks provide initial enrichment for the strata, and the other is that the deep ore source of the Yanshanian crust movement migrates to the ideal part and is integrated into the ore; the deposit is identified through exploration. Mercury is a large-scale, medium-sized metallogenic scale. The eastward 6.4 km is the Qingtonggou mercury-niobium deposit. The ore-forming scale is similar, and there are three small deposits, such as the large trough, 6 km to the east, and the south side of the mine. There are also small deposits such as Dazhaizi and Shatonggou; there are also 13 mines distributed around. The mansion-Huilong Mercury Mine Field is referred to as “Xunyang Mercury Ore Field” (also known as “large-scale mercury mine field in the mansion”) and is one of the four major mercury mines in China (the other three are Guizhou Wanshan and Wuchuan). Wood oil plant and Muhaigou, Qinghai). This ore field is now the backbone mine base of Shaanxi Province.

Fig. 2 Metallogenic geological map of Xunyang mercury mine ore field
1. Geological boundary 2. Fracture system 3. Antimony deposit and ore P. Permian C. Carboniferous D3. Upper Devonian
D2. Middle Devonian D3. Lower Devonian S2. Middle Silurian [next]

2.1.3 Majiashan Mercury Mine This deposit is located at SSW 12 km (East of 106°05′, north latitude 33°39′05”) in Huixian County, Gansu Province. Mercury is produced in the Middle Devonian limestone and consists of 17 ore bodies. The composition has a length of 50-106 m, a width of 2-13.75 m, a depth of about 30 m, a single-mercury ore type, and a grade w(Hg) of 0.502%, which has been examined as a medium-sized scale.

Table 2 Summary of characteristics of the mercury strontium deposit in the Qinling trough

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2.2 Metamorphic type This type of deposit includes Gaolinggou, Caiwa, Dahegou and Zhangergou mines, all of which are monoterpenoid. The geological characteristics of this type of deposit are described by taking Gaolinggou and Dahegou deposits as examples.
2.2.1 Gaolinggou antimony ore is located at SEE15 km in the urban area of ​​Shangzhou City, Shaanxi Province (110°06'15" east longitude, 33°52'06" north latitude). The strontium ore is produced at the junction of the interbedded fissures and transverse fractures of the top and bottom of the graphite- bearing marble in the Qinling Group of the Proterozoic. The surrounding rock alterations are silicified and strontium mineralized; the mineralized zone is more than 2 000 m long and consists of two The composition of an industrial ore body, length 155 ~ 286 m, thickness of 0.776 ~ 4.47 m, ore body shape is layered; ore minerals are mainly stibnite, natural gold is second; ore grade w (S b) 5.58 %～11.55%, w(Au)0.1×10 ^-6 ～1.6×10 ^-6 ; After detailed investigation, it is a medium-sized scale with associated Au mine.
2.2.2 Dahegou Mine is located 33 km south of Lushi County, west of Henan Province (111°01' east longitude, 33°46'07 north latitude). The antimony deposit is produced in the Proterozoic Qinling group mica quartz schist and calcareous schist, angle In the tectonic fracture zone of conglomerate and shallow granulite, the mineralized rock is dominated by tectonic breccia, followed by fractured rock; composed of 11 ore bodies, length 60-640 m, thickness 1-7 m, ore body The shape is lenticular; the ore mineral is stibnite, which is breccia, cluster-like, disseminated, and the metal grade w(Sb) is 1.04%-9.33%. It is a medium-sized scale.
2.3 Fault zone type Qinling geothermal fault zone type mercury deposits, Muhegou and Charno. Take Muhuigou large-scale mercury deposit as an example: the mine is located 32km south of Tongde County in the eastern part of Qinghai Province (100°36'31" east longitude and 34°58'18" north latitude). The deposit is located in the EW-trending fault zone of Muhegou. The mercury deposits are located in the rhythmic layer of the slightly metamorphic breccia sandstone and slate of the Middle Triassic. The mercury mineralization is steeped by the SN and NW. The torsion fault zone is controlled, and the ore body shape is vein-like and long strip-shaped, so some scholars have classified it into the type of fractured mercury ore. It consists of 5 ore belts, of which the No. 1 belt is 625 m long and the general ore belt is 100-200 m long. There are 6 mercury ore bodies with a length of 15 to 85 m and a thickness of 0.58 to 5.95 m. The ore mineral has cinnabar. The stibnite, scheelite and a small amount of pyrite, the metal content w (Hg) 0.186%, w (Sb) 0.1%, w (WO3) 0.01% ~ 0.5%; after detailed investigation and identification is a large scale, it is China One of the four major mercury mine bases. The mine is 9km eastward for the Sharno medium-sized mercury deposit. The two are in the same fault zone, and the ore-forming characteristics are consistent and form the backbone mine of Qinghai Province.
2.4 Micro-dissemination type This type of mercury-minonium ore is a companion product of gold ore, including the nine-mercury gold deposit and the Lalma uranium selenium-mercury-gold deposit. The remarkable feature is that all kinds of metal minerals are dyed. Take the Lalma deposit as an example: the mine is located at SS E48km in Luqu County, Gannan (100°41'45" east longitude, 34°12'51" north latitude). The ore body is produced in the fracture zone of the Lower Silurian sandy slate, siliceous slate and carbonaceous slate. The mineralization is restricted by the small braided structure, which is characterized by the Russian-tooth phase fault in the southern margin. It is the inner rotation surface, with the Cambrian Lalma Formation slate and the Lower Silurian lower case group carbonaceous sericite slate as the vortex, and the northern edge of the Russian-Baiyigou compression-torsion zone as the external rotation surface, fracture The system and various ore bodies converge to the Russian capital to the west, spreading the hot springs to the east. The metallogenic tectonic fracture zone is nearly 3km long and 100-250m wide. All kinds of ore bodies are layered and lenticular. However, due to the destruction of the ore-forming structure, the ore body loses continuity, resulting in up to 55 ore bodies. Generally, it is 36-52m long, 1.71~31.57m thick, and the main ore body is 720m long. It is mainly composed of gold ore body and selenium ore body. There are only 2 antimony ore bodies and 4 mercury ore bodies. The altered species are silicified. , barite and the like; natural gold ore minerals, stibnite, selenium and mercury, cinnabar, barite, pyrite, galena, sphalerite, selenium sulfur antimony ore, pitchblende, uranium, vanadium, calcium Mineral, silicon-calcium uranium ore; metal content w (Au) 2.1 × 10 ^-6 (up to 63 × 10 ^-6 ), w (Se) 29.436 × 10 ^-6 , w (Cu) 0. n%, w ( V) 0.056%, (up to 0.41%); Zn, P, W, Pt, Sb, Hg, etc. are also higher; the mine has been found through exploration, gold is a large scale, uranium, selenium, mercury, antimony Small.
3 Metallogenic regularity of mercury strontium resources in the Qinling trough 3.1 Mercury mineralization conditions in the Qinling geosyncline According to the metallogenic geological characteristics of the above-mentioned mercury samarium, the conditions for metallogenic conditions are shown: the layered ore deposit should have a source layer, such as the Devonian ash. Rock and dolomite strata, Triassic metamorphic sandstone, slate, sandy limestone strata, Proterozoic marble, quartz schist, siliceous slate and gneiss layer, etc. Most of the mercury strontium deposits in the Qinling trough are The ore source layer is the foundation of mineralization, and its mineral source is from the Proterozoic volcanic rocks, with a migration distance of more than 100 kilometers. The second condition is the deep and large fault structure with the crust movement, which captures the ore source from the mantle melt and is in the crust. The medium-low temperature hydrothermal action of mercury strontium mineralization is formed to form a vein-like mineral group, and the filling type is mainly in the Qinling geothermal area, followed by the replacement type. The mineralization of mercury in the study area can be summarized as follows: both the type of layer control and the type of fault, as well as the comprehensive type. In short, the Qinling mercury-mining metallogenic belt is not only more than a thousand kilometers long, but also has a complete metallogenic type, and its ore-forming scale is considerable, and its metallogenic potential is also great. [next]
3.2 The ore field and metallogenic belt are obviously macroscopically the entire Qinling geosyncline. The ore-forming of the mercury-mining ore has two factors: the ore-forming layer and the fault. All the ore deposits have no igneous rocks related to mineralization, which can be used to determine the source of the source. (such as the source of limestone from the source area) and the deep source (the vein type, the source is from the depth of the underground). Therefore, the ore field must be located in the joint or composite area of ​​the multi-fracture system. For example, the mineralization of the Xunyang orefield is restricted by the large-scale braided structure of Ningshan-Xunyang-Shanyang, which is characterized by convergence to the northwest and spreading to the southeast. It becomes a mercury, antimony, gold, lead, zinc, vanadium ore-forming area; the Shangzhou-Danfeng-Lushi ore-forming field is controlled by the large-scale braided structure of Danlu, which is also characterized by the West and the East, becoming the copper and copper. , molybdenum , tungsten, uranium, chrome ore-forming areas; metallogenic belt space is located in the development zone of the source layer, as follows in the Carboniferous and Triassic distribution areas, the ore-forming is obviously layered, and its metallogenic scale is limited, only The Muhegou mercury mine is a large deposit.
3.3 Mercury-based mineralization related minerals According to the above, the formation of mercury strontium has fewer single-mercury single-dip, which are mostly symbiotic and often associated with other metals. Related minerals closely related to mercury ore mineralization are: gold, lead, zinc, copper, molybdenum, tungsten, uranium, vanadium, chromium, selenium, etc.
3.4 Geological model of mercury-mining resources mineralization There are three types of metallogenic geological models of the mercury-salt resources in the Qinling trough. The first is the mineral source layer (including the ore layer), which is the remodeling of the metallogenic model; the second is the fracture type vein type, which is the micro-dissemination type of metallogenic model; the third is the source layer + fracture heat, which is the formation of sediment Metallogenic model of modeling and metamorphic deposits. According to statistics, this study area is dominated by the third metallogenic model. Not only the number of deposits is large, but also the scale of metallogenesis is large. Therefore, based on long-term problems, it is important to use this model to find mercury ore-forming mineralization sections.
4 Prediction of metallogenic resources of mercury in the Qinling geosphere <br> According to the above data, the mercury sorghum resources in the Qinling area are all spread in the geothermal area, including mercury shale symbiotic deposits, mercury deposits, and single strontium deposits. The genesis can be divided into sedimentary remodeling, metamorphic type, fine dissemination type and fault zone type. The ore-forming conditions are the dual factors of the ore source layer and the fracture-guided thermal alteration, and the ore-forming area is the best in the ore-controlling area. The direction of 锑 should be selected in the Paleozoic carbonate construction area, superimposed multi-fracture system joint area.
In the Qinling area, the mercury-bearing ore-forming potential in the geosyncline area is relatively large, and it has a broad prospect of mineralization. According to the metallogenic conditions, it can be divided into three levels: the I-class metallogenic prospecting area can explore extra-large deposits; the second-class metallogenic prospect The area can be inspected for large-scale large deposits; the III-level prospects can find medium-sized deposits. See Table 3 for mineralization.

Table 3 Prediction of mineralization of mercury in the Qinling geosyncline

About the author: Peng Daming (1935-), male, senior engineer, mining area and regional geological research.
Dam Daming (Geological Brigade, 214 Team, Northwest Bureau of Geology, Nuclear Industry, Chenggu, Shaanxi 723200, China)

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