1. The origin of the name of the mineral deposit and related information
Black rock series, also known as black shale, is a rock containing more organic carbon (C The general name of dark gray to black siliceous rock, carbonate rock, mudstone (including sedimentary tuff) and their corresponding metamorphic rock combinations with organic matter ≥1%) and sulfide (mainly iron sulfide) (Fan Delian et al., 1973). The 1989 International Geological Comparison Program Project 254 "Metallic Black Shale and Related Deposits" defined "black shale" as "a black (or gray) fine-grained (silt sand or finer) sedimentary rock, usually argillaceous. , contains quite high organic matter (C organic > 0.5%)." "Metallic black shale" refers to "black shale rich in various metals, the amount of which is equivalent to 1 to 2 times the U.S. Geological Survey standard reference material SDO-1 shale" (Huyck, 1991) . This is a narrow definition that limits “black shale” to sedimentary rocks and does not consider its rock combinations and rock formations (Liu Chunyong and Wang Yongjiang, 2007). Tu Guangchi (1999) defined black rock series deposits as layer-bound deposits occurring in epimetamorphic clastic rock series with high content of organic carbon (generally >0.5%). Clastic rock systems often contain carbonate rocks, siliceous rocks and volcanic rocks, but are mainly sand and slate. This definition more comprehensively reflects the basic characteristics of black rock series deposits.
The reason for the black color of rocks is the presence of organic carbon, finely dispersed sulfides and particles in ultra-fine sizes (such as nanometer scale). Black rock series is often a combination of two or more rocks, although sometimes it is dominated by end-member rocks. Sozinov (1990) divided black rock series (black shale) into 4 types based on rock type and material composition: terrigenous black shale formation, siliceous black shale formation, carbonate black shale formation and volcanic siliceous formation. (carbonate) black shale construction.
Black rock series has obvious economic significance as a concentration layer of rare metals and an abnormal concentration layer or source layer of certain mineralizing elements (Ye Jie et al., 2000). In the past 20 years, the importance of black rock series mineralization has attracted increasing attention. Au, Cu, Ni, Mo, PGE and other mineral deposits (or mineralized areas) related to black rock series have been discovered in many parts of the world. To this end, the International Union of Geological Sciences has specially set up geological comparison programs IGCP-199, 254, 357, 429, etc., the Global Sedimentary Geology Program (GSGP, 1986) and the "Solid Earth Science and Society" (1993) prepared by the US National Committee. Consider it an important research content. IGCP-254, which refers to "Metallic Black Rock Series and Related Ore Deposits", has been widely used in research on the geology and geochemistry of black rock systems, ore-bearing formations, formation environment and mineralization around the world. Black rock series and mineralization have always been hot topics in current mineral deposit science research. Many relevant international symposiums have been held, such as "Black Shale" in 1980 and "Black Shale Biogeochemistry" in 1985. There are special topics for discussion. At the 8th Scientific Symposium of the International Association on the Origin of Mineral Deposits held in Ottawa, Canada, in 1990, and the International Academic Symposium on the Origin of Gold Deposits held in Shenyang, China, in 1991, many domestic and foreign scholars expressed their opinions on the origin of gold deposits in some parts of the world (Canada, Poland, South Africa, and Colombia). , Spain and other countries and regions) conducted academic exchanges on the characteristics and origin of metal deposits related to black rock series.
2. New progress in research on black rock series and mineralization
In recent years, important progress has been made in the research on mineral deposits related to black rock series at home and abroad. Black rock series not only Provides minerals and has economic value in itself. Wang Denghong (1997) summarized the relationship between black rock series and mineralization as follows: ① The black rock series itself contains minerals, such as Ni, Mo, Mn, Au, U, V, Ag, Pt, Pd, Cu, Zn, Co and other minerals Produced directly in the black rock system. The Dayong and Cili nickel-molybdenum deposits in Hunan are both found in black dolomitic shale and black silty shale, and the Chattanooga shale in the United States is rich in U (Leventhal, 1991). ② The black rock series serves as a source layer to provide minerals for the formation of epigenetic deposits, such as the Muruntau gold mine, the Kumtor gold mine, the Polish copper-bearing shale Cu-Ag deposit, and the Colombian emerald deposit (Cheilletz et al. , 2001), Guangxi Dachang tin polymetallic deposit (Pa?ava et al., 2003).
③The black rock series changes the properties of the ore-forming fluids, leading to the precipitation of metal minerals. For example, the copper-rich and silver-rich ores in the Kuperschifer copper deposit in Poland may be caused by the biological interaction between the copper-containing solution in the underlying Rotliegendes layer and the Kuperschifer black shale layer. The H2S generated by the reduction of sulfate reacts, resulting in a large amount of copper precipitation and mineralization (Michalik et al., 2001). Pa?ava et al. (2003) believed that the black rock series played an important role in the precipitation of tin in the Dachang tin polymetallic deposit in Guangxi.
Scholars have conducted a certain degree of research on the black shale system in Central Europe, South China, Canada, the Baltic Sea region and Siberia, Russia, but there are still differences in the understanding of the origin of metal deposits (Mao Jingwen, 2001b ). In the highly researched Lubin-Glogow area of ??Poland, the establishment of a deposit model is mainly based on the following facts: ① 20% of the copper is produced in the Kupferschifer black shale system, 50% is produced in the underlying Weissliegendes sandstone, and 30% is produced in the Kupferschifer black shale system. In the overlying Zechstein limestone; ②Cu mineralization is closely related to the reduction interface; ③The main copper-bearing mineral is chalcocite, accompanied by bornite and chalcopyrite, and outwards are lead and zinc sulfides; ④ Although there are several mineralization stages, the main mineralization stage is the Early Triassic, and the radioactive isotope age of illite formed during the diagenetic stage is 190-216 Ma (Bechtel et al., 1999), which was determined using hematite paleomagnetic data. The age is 220~250Ma (Jowett, 1986). Regarding early contemporaneous sedimentation, Karnkowski (1999) described the Permian Rotliegenedes Basin in Poland developed on highly deformed Paleozoic basement. The basin consists of a group of interconnected secondary basins distributed along the northwest direction in Bosnia and Herzegovina. The fragile zone between the rigid massif and the East European craton (Blundell et al., 2001) is called an inland basin (Bechtel et al., 1999). These basins are mainly composed of Early Permian volcaniclastic rocks, lavas, and clastic sedimentary rocks. The Kupferschiefer bituminous calcareous or dolomitic shale between the Permian and Triassic overlies or coexists with these clastic sedimentary rocks. Although the contemporaneous Kupferschifer black shale contains sulfide, it does not constitute an ore deposit. The copper-rich and silver-rich massive copper ore may be caused by the biological interaction between the copper-containing solution in the underlying Rotliegendes layer and the Kupferschifer layer. The H2S generated by reduction and stored in the fractures reacts, resulting in large amounts of copper precipitation and mineralization (Blundell et al., 2001; Michalik et al., 2001). Recently, through the study of noble gas isotopes, it is believed that deep fluids participated in the mineralization in the Triassic, which provides new ideas for further in-depth research on the black shale copper deposits in this area.
Mo-Ni-PGE deposits are developed in the widely exposed black shale systems in South my country and the Yukon region of Canada. Although the formation times are different, the material components and output states are relatively similar. That is, the thickness is thin, intermittent, and the ore bodies appear along the same layer. As for its origin, the understanding of submarine jets has been dominant for many years. It is believed that the underlying Mo-W-rich granite body may serve as the ore-forming heat source and the source area of ??Mo-Re-Os, and is related to the Ni-PGE-Fe of submarine jets. -V-Co mixed mineralization (Coveney et al., 1991; Horanetal., 1994; Lott et al., 1999; Li Shengrong et al., 2000). Recently, it has been suggested that they are a normal sedimentation product of an evaporative-reducing environment (Mao et al., 2002). In South my country, precise Re-Os isotope dating of nickel-molybdenum ores yielded age data of 541.3±16 Ma (Mao Jingwen et al., 2001b).
The black shale system also has an important impact on epigenetic mineralization. For example, the Cretaceous black shale of the Colombian emerald deposit, which is considered to be the ore-bearing mineral, reacted with the basin brine and was replaced by sodium. Action and cation exchange lead to mineralization, and beryllium mainly comes from clay rocks (Cheilletz et al., 2001).
A systematic study of the Devonian shale and ore-forming fluids in the Dachang tin polymetallic ore deposit in Guangxi not only proves that the layered and vein-like tin polymetallic deposits in the area are both part of a granite-related mineralization system. It is also found that a large amount of organic matter exists in the ore-forming fluids in the form of CO2, CH4, etc., and these organic matters are considered to come from the surrounding rocks (Pasava et al., 2001). Germanium is a sparse element, but it is widely present and enriched in many coal seams with black mud shale as the main rock. In southwestern my country and the Far East of Russia, germanium is found to be highly enriched in coal and form independent deposits, even reaching super large scale (Hu et al., 2000; Seredin et al., 2001). Although there is still controversy over the origin of germanium, the richness of germanium in coal still reflects the important control effect of organic matter on germanium mineralization. Since the black rock series is the product of a strong reducing environment, a large number of rare minerals and their combinations are found in many mining areas (Distler et al., 2001), including many elemental metals, metal alloys or intercompounds, sulfate minerals, and phosphates. , tungstates, tellurides, Pt-Cu-Fe metal solid solutions, arsenic platinum ore, sulfur platinum ore, Sn-Sb solid solution, Ni-Sb solid solution and a large number of Fe-Ni-S and Cu-S mineral series.
3. Spatiotemporal distribution and characteristics on a global scale
(1) Distribution of black rock series type deposits
There are several widely distributed black rock deposits around the world areas of the system, such as the Paleoproterozoic PGE-Au-U rock system related to organic carbon in Poland, the Palentine Neoproterozoic black shale in the Bohemian Massif in Europe that is significantly enriched in platinum group elements, and the periphery of the Yangtze Craton in my country. Sinian System, the upper part of the Riffian in Siberia, Russia, the Lesser Himalayas in India, northern Pakistan, Iran, southern France, the Soviet Union, Mongolia, southern Australia, Canada, the bottom of the Lower Cambrian in the Yangtze Massif and Tarim Massif in my country, and the Yukon Territory in Canada The Middle and Upper Devonian, the Indiana Devonian in the central United States, the Mississippian (C1), the Oklahoma West Sicilian (C2-3), and the Upper Permian Kuperschifer (about 60 10,000 km2) and the Neoproterozoic and Paleozoic strata in Central Asia, black rock series are distributed.
The unique characteristics of these black rock series are that they contain a large amount of organic matter and rich PGE, Cu, Ni, Mo, Au, U, V, Mn, Fe, Co, Bi, Cr, Se and other metallic elements (Meyers et al., 1992). These elements form certain-scale deposits under appropriate conditions, such as the Huangjiawan nickel-molybdenum-platinum group element deposit in Zunyi (Mao Jingwen et al., 2001), the Muruntau gold mine in Uzbekistan (Wilde et al., 2001), and the Lubin-glogow area in Poland. The Kupferschiefer copper deposit (Oszczepalski, 1999; Michalik et al., 2001), the Dry Valley gold and platinum deposit in Russia (Tu Guangzhi, 1999), the Yellowknife gold deposit in Canada, the Bendigo deposit in Australia (640t), Storr gold deposit, Goldpipe deposit (160.5t), Mansfield copper-bearing shale (Permian) in Central Europe, lead-zinc-rich Monte shale in Australia, black rock series silver deposit in Morocco, Black rock series uranium deposits in Kentucky, USA (Precambrian), black shale containing gold and silver (Cretaceous) in Kansas, USA, etc. These deposits are concentrated in Central Asia, Eastern Siberia, China's Yangtze Platform, Central Europe, southern Australia, eastern North America, Alaska, Brazil, Ghana in Africa and other regions.
(2) Characteristics of black rock series type deposits
1) Black rock series type deposits are widely distributed around the world, and their ore-bearing strata are of various ages, from the Proterozoic to the Early Mesozoic Era.
2) Black rock series type deposits vary greatly in mineralization scale, and the ore body shape, surrounding rock alteration intensity and type are diverse.
It can be divided into two categories according to the shape of the ore body. One is layered metal mineralization, which forms a mineral belt that is tens of meters thick, sometimes 100-200m, and several kilometers long. It usually forms a large or super-large mineral deposit, which is a black rock series. The most important type of deposits, such as the Dry Valley gold-platinum deposit and the North Natal gold deposit; the second one is syngeneic-epigenetic copper, nickel, molybdenum, vanadium deposits in carbonaceous rock series, and associated platinum group minerals. , the thickness of its precious metal mineralization layer is very small (several millimeters to more than ten centimeters, generally only a few centimeters), but it extends long and has high precious metal content, such as the Zeichstein copper deposit in Poland and the Nickel nickel-zinc-platinum deposit in Canada. , molybdenum-nickel-platinum deposits in Guizhou and Hunan, China, etc.
3) Mineralization is obviously layer-controlled and often occurs with carbon-containing original sedimentary rocks. The deposit occurs in the black carbonaceous sedimentary-metamorphic rock system, which is controlled not only by sedimentary lithofacies, but also by hydrothermal action to a certain extent, and has the characteristics of a layer-controlled deposit (Liu Hongwen, 2002).
4) The mineralization elements are diverse, such as gold, silver, platinum group elements, radioactive elements, rare earth elements, nickel, copper, chromium, vanadium, molybdenum, lead, tungsten, cobalt and other elements appearing at the same time . But it is usually dominated by certain elements. For example, southern my country is dominated by a combination of Ni and Mo elements, Canada's Yukon is dominated by Ni, Russia's Dry Valleys is dominated by Au, and Poland's Zeichstein is dominated by Cu. The PGE associated with these deposits is enriched in wall rock alteration zones and dispersed sulfide mineralization zones or sulfide-sulfur arsenide mineralization zones (Gistrel et al., 1997).
5) Mineralization mostly occurred in the Precambrian and Paleozoic (Cambrian, Carboniferous, and Permian), but hydrothermal superposition mostly occurred in the post-collision stage. The original rock was constructed as a carbon-containing marine or terrigenous carbonate-terrigenous clastic rock-based sedimentary rock system, and the depositional environment was a foreland basin. The background of increased regional hydrothermal values ??is mostly attributed to mantle thermal tectonics (Liu Hongwen , 2002).
(3) Black rock series gold deposits
Black rock series gold deposits are an important type of black rock series gold deposits and one of the most industrially valuable gold deposit types in the world. one. In Central Asia, black rock series type gold deposits are also called Mulungtau type gold deposits. In recent years, some scholars, from the perspective of mineralization, believe that the formation of this type of gold deposit is mainly controlled by shear structures and is related to accretionary structures or collisional orogeny in time and space, classifying them as orogenic gold deposits (Goldfarb et al. al., 1998). From the 1960s to the 1980s, Soviet geologists attached great importance to gold deposits produced in black rock systems, and made important breakthroughs in prospecting in the South Tianshan Mountains, Central Tianshan Mountains, Zhaisan and Baikal in East Siberia, and successively discovered the Murontau , Kumtor, Bakirchik and a series of large and super large gold deposits and Dry Valley super large gold and platinum deposits. In the 1990s, Chinese geologists also successively discovered Savayalton, Dashankou, Sahentuohai and Sarbulak black rock series-type gold deposits in the Tianshan Mountains and Junggar in southwest China. Gold mines such as Murungtau, Kumtor, Chalkula, Daugiztau, Savayatun, and Dashankou in the Tianshan Mountains of Central Asia, Bakirchik gold mine and Sarbulak gold mine in Junggar, The formation of the Dry Valley platinum deposits in Russia's Baikal-Patom Plateau is closely related to the black rock series. The ore-bearing black rock series contains a large amount of organic matter, and the gold content is significantly higher than the regional background value, showing that carbonaceous matter has a strong adsorption effect on gold. It can be seen that the black rock series that hosts the ore is the source layer of gold and provides the main source of material for mineralization. Carbonaceous phyllite or carbonaceous slate has poor permeability, which is conducive to the unloading of ore-forming fluids and the formation of ore bodies.
The geological characteristics of the black rock series gold deposits in Central Asia can be summarized as follows:
1) The black rock series gold deposits are shear zone type gold deposits (or orogenic gold deposits) ), its ore-controlling faults are ductile shear zones, ductile-brittle shear zones and brittle fracture fracture zones, and its mineralization is controlled by the evolution of shear zones. The ore-bearing shear zones are large-scale, generally ranging from several kilometers to tens of kilometers in length. Gold mineralization in the ductile shear zones has the characteristics of concentrated and local enrichment in sections. Regional deep faults or plate suture zones generally develop near mining areas, and ore-controlling shear zones are related to these structures.
2) The age of the ore-hosting rock series of black rock series-type gold deposits is mainly Neoproterozoic Riffian and Wendeian, Middle Ordovician-Early Silurian, Late Silurian-Early Devonian , Devonian, Early Carboniferous and Late Carboniferous.
3) The rock formations of the black rock series are a set of terrestrial fine clastic rock-carbonate formations with relatively high carbon content (generally >0.5%) far away from volcanic institutions, and are sometimes intercalated with Pyroclastic rocks. Various marine macrofossils are rarely seen in carbonaceous rocks.
Carbonaceous rocks are mainly carbonaceous shale, carbonaceous slate, carbonaceous muddy shale, carbonaceous siliceous muddy shale, graphitized carbonaceous shale, carbonaceous muddy slate, carbonaceous siltstone, etc. . The mineral deposits are all produced in carbonaceous terrestrial fine clastic rocks, while gold deposits are not produced in carbonate rocks, but carbonate rocks can illustrate the formation environment of the black rock series (Liu Chunyong et al., 2007).
4) The formation environment of black rock series gold deposits should be a quiet coastal and shallow sea environment. The sea water is rich in CO2 and shallow, which is conducive to the formation of organisms and the development of carbonate rocks. The shallow sea is rich in carbonaceous matter. The reducing environment is the most basic condition for the formation of black rock series, and the carbon-rich material in the reducing environment is conducive to the adsorption of gold (Liu Chunyong et al., 2007).
5) The wall rock alteration of black rock series gold deposits is mainly silicification, pyrite, sericitization, chloritization, carbonation, and graphitization, with low-temperature hydrothermal fluids. Characteristics of mineralization: some deposits develop biotitization, albite, potassium feldsparization, etc., such as the Mulongtau ore field.
6) The mineralization types are gold-bearing quartz vein type, quartz fine vein type, quartz network vein type and altered rock type. The mineral combinations in the ore are complex and there are many types of minerals. For example, 90 minerals were discovered in the Murungtau gold mine, nearly 100 minerals were discovered in the Kumtor gold mine, 75 minerals were discovered in the Dry Valley gold-platinum deposit, and Sava Yalton More than 40 minerals have been discovered in gold mines. Metal sulfides are mainly pyrite, arsenopyrite, and natural gold, followed by pyrrhotite, chalcopyrite, galena, and stibnite. In some deposits, scheelite, sphalerite, and bismuth minerals appear . Gold is mostly produced in the form of wrapped gold and cracked gold.
7) Although the formation ages of the ore-hosting rock series of black rock series-type gold deposits in Central Asia vary greatly, from the Neoproterozoic to the Carboniferous, the mineralization ages are concentrated in the Late Carboniferous to the Triassic For example, the metallogenic age of the Kumtor gold mine is 284-288 Ma (40Ar/39Ar plateau age, Mao et al., 2004), the formation age of the altered rocks of the Mulungtau gold mine is 285-250 Ma, and the gold main mineralization age is The age is 280 Ma (Sm-Nd isotope age of scheelite, Kempe et al., 2001). The 40Ar/39Ar plateau age of sericite in gold-bearing quartz is 245-220 Ma (Wilde et al., 2001). Silver mineralization The age is 224-219 Ma (Kostitsyn, 1996), and the main metallogenic period of the Savayalton gold deposit is the Triassic (the Rb-Sr isochron ages of the quartz fluid inclusions in the gold-bearing quartz veins are 246 Ma and 231 Ma. Chen Fuwen et al. , 2003; Ye Qingtong, 1999; The 40Ar/39Ar plateau age and Rb-Sr isochron age of quartz in gold-bearing quartz veins are 213~206 Ma, Liu et al., 2007), the main metallogenesis of Bakirchik gold deposit The lead isotope age of the ores in the period is 300±15 Ma, and the mineralization age is the Late Carboniferous-Early Permian. The lead isotope age of the fluids during the magmatic hydrothermal superposition reform period is 230±10 Ma, and the age is the Early-Middle Triassic (Syromyatnikov, 1999).
(4) Spatiotemporal distribution of black rock series-type gold deposits in Central Asia
Black rock series-type gold deposits are a very important type of gold deposits in the Central Asian metallogenic domain. Western my country Neighboring countries have approximately 7,703t of gold reserves, accounting for 16% of the world's total gold reserves in 2000. Countries with larger reserves include Uzbekistan (5,300t), Kazakhstan (1,050t), Tajikistan (573t), and Kyrgyzstan (540t) ( Dai Zixi et al., 2001). According to the statistics of 33 large-scale independent gold mines in 6 countries in the west (Dai Zixi et al., 2001), the main types of gold mines are black rock type (30%), hydrothermal type (21%), and quartz vein type (15%). and continental volcanic rock type (9%). It can be seen that black rock series type gold deposits play a decisive role in Central Asia. The main characteristics of the black rock series type gold deposits in the Central Asian metallogenic domain are listed in Table 10-1, and they can be roughly divided into four zones in terms of spatial distribution (Figure 10-1).
Table 10-1 Main black rock series gold deposits in Central Asia
1. Baikal fold belt on the southern edge of the East Siberian Craton
This belt is located in Russia On the southern edge of the East Siberian Craton, the Dry Valley (СухойЛог) gold and platinum deposit in this belt has a gold reserve of 1550t, the Olympiada (Οлимпиада) gold mine has a gold reserve of 700t, the Soviet (Советское) gold mine has a gold reserve of more than 100t, and to the south The Zonghaoba (ЗунХолба) gold mine located in the Eastern Sayan Mountains has a gold reserve of approximately 150t. These four super-large gold deposits all occur in the Neoproterozoic Liffian carbonaceous epimetamorphic clastic rock series (Сафонов, 1997; Tu Guangchi, 1999). The ore-hosting rock series in the Dry Valley mining area is middle and late Liffian terrestrial carbonaceous sediments, about 800m thick, which have experienced greenschist phase metamorphism. The rock combinations are quartz-sericite-chlorite schist, metasiltstone and Fine sandstone. Schist is rich in carbonaceous material (2% to 7%), and is enriched in gold and platinum. The ore body occurs in the core of the nearly east-west trending anticline, with the fold axis dipping southward and superimposed by large overthrust structures. The main ore bodies occur in the gently tilted (30°-35°), thick (up to 200m) post-folding stage nearly east-west schistified mineralization zone. The ore-hosting rock series in the Olimpiada mining area is the Early Riffian schist section, and the rock combinations from bottom to top are mica quartz schist, mica-carbonate-quartz schist, and carbonaceous muscovite-sericite-quartz-carbonate schist. and mica quartz schist. The ore body mainly occurs in the contact zone between the lower section of mica quartz schist and carbonaceous schist and carbonate rock (Wang Lin (translated), 2001).
2. Zhaisan Junggar Belt
This belt is located from Zhaisan Junggar in Kazakhstan to North Junggar in Xinjiang. It extends northwest and is adjacent to the suture of the Siberian Plate and the Kazakhstan-Junggar Plate. Belt (Figure 10-1). A black rock series-type gold mineral belt developed at the intersection of the northwest-to-west Kalba fault and the nearly east-west trending Kuzlov fault on the southwestern edge of the Kuzlov Depression in the Variscan fold belt of Zhaisan-Junggar in Kazakhstan. The gold mineral belt is distributed along the Kuzlov ductile shear zone, with a length of more than 10 kilometers. More than a dozen gold deposits have been discovered, including Zhelek, Baldzhaar, Kuruzon, Bolshevik, Holodnekluchi, Bakelchik, Promerutnoye, and Grubllog. and mineral points. Among them, the Bakelchik deposit is the largest, with high ore body grade and good continuity. The proven gold reserves are 277t (it is also reported that 416t), and the average gold grade is 9.4×10-6. The five gold deposits of Bolshevik, Holodnekluchi, Bakurchik, Promerutnoye and Grubllog constitute the Bakurchik gold deposit. The resources of the ore field are estimated to be 1200t, with a grade of 1.5 ×10-6～4×10-6 (Dai Zixi et al., 2001; Liu Chunyong, 2005a).
The strata exposed in the area are mainly Lower Carboniferous argillaceous siltstone, siliceous siltstone, calciferous chert, sandstone and limestone, and Lower-Middle Carboniferous marine flysch-like sandstone. , siltstone, and the Upper Carboniferous Bakirchik Formation is the main ore-hosting rock system. It is composed of interbedded continental carbon-containing fine clastic rocks such as sandstone and carbonaceous siltstone. It has obvious stratigraphic rhythms and is rich in plant fossils. Intercalated with siderite lenses and thin coal seams, locally intercalated with tuff and volcanic rocks. The organic carbon content in the ore-bearing rock series is high, ranging from 0.2% to 1.5%~2.0%. The organic carbon content in local carbonaceous metasomatic rocks is as high as 13.38%~15.17% (Dai Zixi et al., 2001). The organic carbon content in carbon pitch lenses is as high as 13.38%~15.17%. 20.5%～54.1% (Daukeev et al., 2004). The abundance of As, Mo, P and Cl in the ore-bearing rock series is high, and siderite and pyrite-containing carbonaceous silt mudstone are the rocks with the highest gold content. The pyrite formed by sedimentation has a high gold content, with an average content of 0.52×10-6 and a maximum of 1.24×10-6 (Zhang Hongchang et al., 1986). The deposit is controlled by ductile shear zones and faults, and late magmatic hydrothermal activity superimposes the early gold mineralization. The lead isotope age in the ores during the Gold Master metallogenic period is 300±15Ma, and the mineralization age is the Late Carboniferous-Early Permian. The lead isotope age in the fluid during the magmatic hydrothermal superposition reform period is 230±10Ma, and the age is the Early-Middle III epochs (Daukeev et al., 2004).
The Sarbulak small gold deposit discovered in North Junggar, Xinjiang is a black rock series gold deposit. It is located in the southwest of Fuyun County and is adjacent to the Irtysh Deep Fault Zone in the northwest. It is affected by the Sarbulak Constraints from fault zones. The Irtysh Deep Fault Zone is the boundary between the Siberian Plate and the Kazakhstan-Junggar Plate. The exposed strata in the mining area are mainly the Middle Devonian Beitashan Formation and Yundukala Formation, and the Lower Carboniferous Nanmingshui Formation and Nalinkala Formation. The Beitashan Formation is a set of basic-intermediate basic volcanic sedimentary structures, and the Yundukala Formation is a set of basic volcaniclastic rocks composed of andesitic tuff, tuffaceous siltstone and fine sandstone. The Nanmingshui Formation is composed of marine and continental alternating flysch-like structures, and its lithology is mainly coarse sandstone, tuffaceous sandstone intercalated with siliceous rock and limestone lenses.
The Nalinkala Formation is a set of volcaniclastic rocks and carbonaceous terrestrial clastic rocks. It is an ore-hosting rock series and can be divided into upper, middle and lower sections according to lithology (Wang Denghong et al., 2002 ): The lower part of the lower section is carbonaceous silt sandstone and tuffaceous sandstone; the middle part is conglomerate, gritstone, tuffaceous coarse sandstone, tuffaceous medium fine sandstone and carbonaceous siltstone; the upper part is bioclastic limestone intercalated with mudstone. . The middle section is the main mineralization layer, the lower part is carbonaceous siltstone and carbonaceous argillaceous siltstone; the middle part is lithic crystal tuff, carbonaceous tuff sandstone intercalated with carbonaceous silt sandstone and conglomerate lenses. The lower part of the upper section is composed of carbonaceous tuffaceous siltstone interbedded with tuffaceous sandstone, which forms the surrounding rock of the surface ore body; the upper part is interbedded with tuffaceous sandstone, gravelly tuff sandstone, and carbonaceous siltstone. The organic carbon content in the ore-bearing rock series ranges from 0.02% to 5.4%, with an average of 2% (Wang Denghong et al., 2002). The Sarbulak gold deposit is controlled by the Sarbulak fault zone, and the gold ore body is mainly filled in the cataclastic rocks and breccias in the local expansion of the ductile-brittle shear zone. The mineralization age is at the end of the Late Carboniferous. Li Huaqin et al. (1998) measured the Pb-Pb age of the ore arsenopyrite to be 304 Ma, and the Rb-Sr age of the ore-free quartz vein fluid inclusions to be 285 Ma.
Figure 10-1 Distribution of major black rock series gold deposits in Central Asia and the main metallogenic zones of black rock series gold deposits in Xinjiang
3. Central Tianshan Belt
< p> This belt is located in the Caledonian-Valiscian fold belt of the Central Tianshan Mountains in Kyrgyzstan and Kazakhstan. It extends northeastward and is close to the Nikolaev suture that separates the Central Tianshan Mountains and the Southern Tianshan Mountains. The Kumtor super-large gold mine in Kyrgyzstan, the Ishtanbergy large-scale gold mine and the Chalkula super-large gold mine in Kazakhstan have been discovered. These gold deposits are all present in the black rock system. Controlled by shear and fracture zones.The Kumtor super-large gold mine is located in the Issyk-Kul area in eastern Kyrgyzstan, with an altitude of 3200-4150m and a straight-line distance of 60km from the China-Kyrgyzstan border. The deposit is located in a narrow strip 15km long and 0.1-0.4km wide. Its northwest and southeast boundaries are defined by faults, and its south west and northeast are covered by Quaternary systems and glaciers. Controlled reserves are 300t, plus prospective reserves reach 590t, with an average grade of 3.6×10-6 (Yakubchuk et al., 2002; Mao et al., 2004). The Kumtor gold deposit is located in the Central Tianshan magmatic arc and is very close to the Nikolaev suture, so it is usually included in the South Tianshan metallogenic belt. The Paleoproterozoic Kuilyu Formation metamorphic rocks are exposed in the area and were intruded by Liffian granite. The Upper Riffian Kashkasui Formation angularly unconformable overlies it and is composed of conglomerate, metasandstone and basalt-rhyolite bimodal volcanic rocks. . The ore-bearing surrounding rock is the Wende System Jetym Formation unconformably overlying the Kashkasui Formation in the Upper Rife, and is composed of slightly metamorphosed continental carbonaceous flysch. It can be further divided into three subgroups: Jetymtau, Jakbolata and Baikonur. The lithologies are carbonaceous phyllite, slate with conglomerate and siltstone, carbonaceous phyllite, slate with limestone and sandstone, and conglomerate, phyllite and sandstone. The mudstone part contains chlorite-hematite-magnetite and pyrite interlayers. The ore-bearing rock system is rich in carbonaceous matter, with a carbon content of 1% to 10%, and is partially graphitized. Above the ore-bearing rock series are Cambrian-Lower Ordovician chert slate, dolomite and limestone. Middle Devonian-Lower Carboniferous red sandstone and limestone angularly unconformably overlie the basement. The mineralized zone extends for 10km along the Kumtor overthrust fault and tilts to the southeast with an inclination angle of 30° to 50°.
The upper wall is Wendeian ore-bearing green slate, and the footwall is Early Paleozoic limestone, chert and carbonaceous rocks. The fault zone appears as 100-250m thick structural mélange, sausage-shaped, shear zone and limonite mineralization. In the Kumtor mining area, the ore bodies are strictly confined within structural zones. All veins are densely arranged and intermittently connected. The mineralization is divided into the South Mineral Zone, the North Mineral Zone, the Northeast Mineral Zone and the Fine Vein Mineral Zone. The ore belt is 500-1000m long, 25-100m thick, and 300-1000m deep. The mineralization is disseminated in fine veins, and there are also some gold-bearing quartz veins with smaller widths. The 40Ar/39Ar plateau age of the whole rock of the sericite quartz alteration rock is 285.5±1.2Ma, the 40Ar/39Ar plateau age of the whole rock of the gold-bearing sericite ore is 288.4±0.6Ma, and the 40Ar/39Ar plateau age of the sericite in the host rock series is 285.5±1.2Ma. 284.3±3Ma, and the 40Ar/39Ar plateau age of sericite in the ore is 285.4±0.2Ma, indicating that the mineralization age is the Early Permian (Mao et al., 2004).
4. South Tianshan Belt
This belt is distributed in the South Tianshan Mountains, starting from Nuratau in the Kizilkum fold belt in the western section of the South Tianshan Mountains in Central Asia, Uzbekistan. It extends south-west, curves eastward to Savayalton on the Sino-Kyrgyzstan border, and then to the northeast along the Tianshan Mountains in southwest China to the Dashankou-Sahentuohai area. It is a very important black rock formation in Central Asia and even the world. Systemic gold mineral belt. The second largest gold mine in the world after the Vitwajesland gold mine in South Africa, the Muruntau gold mine, was discovered in the western section of Uzbekistan in the Zilkum-Kulama area, and was controlled by 1996. The gold reserves are 4416t (of which 1186t have been mined and the remaining gold reserves are 2230t), plus prospective reserves of 5400t, with an average grade of 1.3×10-6 (Graupner et al., 2001). Other black rock series type gold deposits in the area include Daughyztau (Au185.7t, Ag101t), Amantaitau (Au117.7t, Ag16t), Kokpatas (Au620t, Porter, 1998), Besapantau, Myutenbai (Au620t, Porter, 1998), Aristantau, Triada, Boilik, Karasai, Sarybatyr and other gold mines, as well as Kosmanachi, Viso Kofurno, Vysokovoltnoe, Jasaul, Stepnoe and other gold and silver deposits (Shayakubov et al., 1999), these gold and silver deposits (points) belong to Murontau, Amantetau-Dogiztau and Kokpatas 3 This ore field constitutes the Kizilkum black rock series type gold (silver) ore concentration area in the western section of the South Tianshan Mountains.
A large Savayalton gold mine was discovered on both sides of the border between China and Kyrgyzstan in the middle section of the mineral belt. Among them, the Savayalton gold mine in Kyrgyzstan is a gold-bearing quartz vein zone. The gold grade is high, with an average grade of 6.1×10-6~8.7×10-6, and gold reserves of 40t (Dai Zixi et al., 2001; China Geological Survey, 2003). It is also accompanied by antimony, silver, lead, zinc, copper, etc. For example, the gold grade of arsenopyrite-rich quartz vein is 6.5×10-6, antimony is 4.5%, lead is 10%, and silver is 41.5×10-6 (Rui et al. , 2002).