Temporal and Spatial Distribution and Metallogenic Regularity of Copper Deposits in China (Part II)

Typical deposit (zone)

(1) Jiangxi Dexing Copper ( Molybdenum ) Ore Field

Dexing Copper (Molybdenum) Mine is a super-large copper (molybdenum) ore field in China, located 25km northeast of Dexing City (formerly Dexing County) in Jiangxi Province. The minefield covers an area of ​​about 14km2 and consists of three deposits: copper plant (super large), Fujiawu (large), and cinnabar red (large). The accumulated proved reserves totaled 9.658 million tons of copper, of which the available reserves were 8.424 million tons and the molybdenum was 196,000 tons. The copper plant is a super-large deposit with 5.245 million tons of copper and 128,000 tons of molybdenum; 2.537 million tons of copper in Fujiawu deposit and 168,000 tons of molybdenum; 1.84 million tons of copper in the cinnabar red deposit, which is available for use. The reserves are 606,000 tons. The average grade of the deposit: copper plant, copper 0.46%, molybdenum 0.01%; Fujiawu, copper 0.5%, molybdenum 0.03%; cinnabar red, copper 0.42%, molybdenum 0.01%. The three deposits are associated with beneficial components such as gold , silver , antimony , selenium , antimony and sulfur, which have considerable comprehensive utilization value.

1. A brief history of deposit discovery, exploration and development  

The development of Dexing Copper Mine has a long history. According to historical records, it has been recorded in the Tang and Song Dynasties until the Yuan, Ming and Qing Dynasties. Smelting slag is still visible in the area around the cinnabar red. Before the founding of New China, Jiangxi Geological Survey Xia Xiangrong, Liu Hui Si in the autumn of 1939 had been to Dexing geological survey and mineral resources, with a "mineral Dexing County Zhi", mentioned Tongchang of pyrite and cinnabar red and pointed In the nearby area, pyrite has been mined.

After the founding of the People's Republic of China, from 1954 to 1959, the 409th and 40th teams of the Central South Geological Bureau of the Ministry of Geology conducted census exploration of the copper and Zhusha red mines. In the geological evaluation work of the copper plant in 1956, it was found that in addition to the contact zone between the phyllite and the granodiorite porphyry, the copper ore body also saw copper mineralization in the local porphyry. The study confirmed that the copper mine copper mine is a porphyry copper deposit. Subsequently, in July 1956, it was transferred to large-scale geological exploration work and invested in drilling more than 80,000 meters. In November 1959, the copper mine survey and exploration brigade submitted the "Decision Reserve Report of Jiangxi Dexing Mine Area (including Zhusha Red Copper Mine Area)", and proved the copper reserves of 3.63 million tons, and made the surrounding rock alteration and distribution of the copper deposit. In-depth research, one of the earlier achievements of the world porphyry copper deposit research, played an important role in guiding the exploration of the mining area and the general exploration of the mine.

In the 1970s, for the country to build a large copper mine production base in Jiangxi, the Jiangxi Provincial Geological Bureau organized geological, geophysical exploration, drilling and scientific research, testing and other superior technical forces. In 1975, large-scale geology was carried out on the copper and Zhushahong mining areas. During the work battle, 11 rigs were started to do a lot of geological exploration work. In May 1978, the “Reconstruction Geological Report of Copper Mines in Tongchang Mining Area of ​​Dexing County, Jiangxi Province” was submitted, and the newly added copper reserves were 1.96 million tons. The associated minerals such as sulfur, molybdenum, gold, silver and antimony have been studied and evaluated in detail, all of which have reached the scale of large deposits and improved the comprehensive utilization value of the deposits.

In 1982, the detailed geological report of the copper deposit in the Zhusha Red Mining Area of ​​Dexing County, Jiangxi Province was submitted. The discovered reserves were 1.844 million tons, of which the available reserves were 606,000 tons, and the associated sulfur and molybdenum were calculated. Mineral reserves such as gold and silver.

In December 1957, hydrothermal alterations and mineralization similar to those of copper plants were discovered on the cliffs and steep valleys of the eastern side of the official hat.

In the spring of 1958, the first hole was drilled and the vertical thickness of the mine was 400m. In the same year, the Fujiawu copper deposit was transferred to preliminary exploration.

In 1963, the “Geological Exploration Report of Fujiawu Copper-Molybdenum Mining Area in Dexing, Jiangxi Province” was submitted, and the proven copper reserves were 1.419 million tons and molybdenum 113,000 tons.

In 1978, the fourth team of Jiangxi Metallurgical Geological Exploration Company submitted the "Guijiawu Copper (Molybdenum) Mine Geological Exploration Summary Report", adding new copper reserves of 1.154 million tons, molybdenum 54,800 tons, and gold, silver, cobalt , Elements such as antimony, selenium and tellurium have been studied and evaluated in detail.

So far, the accumulated proven reserves of Fujiawu deposits are 2.573 million tons, molybdenum 168,000 tons, and associated sulfur 8.834 million tons.

2. Geological characteristics of the ore field  

(1) Geological overview The geotectonic location of Dexing Ore Field is located at the southern margin of the eastern section of the Yangtze River in the Yangtze River. The regional structure is controlled by the northeastern deep fault zone between the Jiangnan Tailong and Qiantang depressions, and is located in the northwestern plate of the fault zone. The strata in the area are mainly composed of the shallow metamorphic rocks of the Shuangqiaoshan Group in the Neoproterozoic. Its original rock is muddy, silty and volcanic tuff deposits. The ore-controlling structure is based on the east-west fault tectonic system. The close relationship with mineralization is the early Yanshanian medium-acid shallow intrusion, including granodiorite porphyry, quartz diorite, fine-grained rock and lamprophyre. ).

(2) ore-bearing rock mass The copper and molybdenum mineralization of the three deposits of Tongchang, Fujiawu and Zhushahong are controlled by three superficial granodiorite porphyry bodies, which are distributed in the west-west side of the west, and the single rock masses are placed on the northwest side. The depth is not equal to the cylindrical rock column, and the surface exposure is 0.7km2, 0.16km2 and 0.06km2 respectively. According isotopic age determination: TONGCHANGHE granodiorite porphyry Age 179 mA (Rb-Sr method), Fujiawu granodiorite porphyry 157Ma (whole rock potassium argon method).

(3) Wall rock alteration Surrounding wall rock alteration porphyry deposit in contact with a profile, symmetric concentric annular zoning; order from inside to outside of quartz - sericite of tape, chlorite - muscovite of water and potassium feldspar with - green clay Petrochemical belt. The hydrothermal alteration zone of the three deposits of Tongchang, Fujiawu and Zhushahong.  

(4) Distribution of ore bodies The ore body is mainly produced in the contact zone between the granodiorite porphyry and the surrounding rock, and is partially in the porphyry. According to the proportion of reserves that have been discovered, it accounts for about 2/3 of the surrounding rock and about 1/3 of the altered porphyry. The ore bodies of the three deposits are all distributed to the northwest side, and the ore body is large in scale and complete in shape. It looks like a ring from the plane. It looks like a hollow cylinder in the cross section. The ore bodies of the Tongchang deposit occur in the strong and medium alteration zones of the granodiorite porphyry and the outer contact zone. The spatial shape is hollow cylindrical, and the rock body is obliquely inserted to the north. The dip angle is nearly the same as that of the rock mass. The maximum vertical depth is more than 1000 m. The ore body on the porphyry body is larger than the lower ore body, and there are 2/3 ore bodies. Contact tape on the outside. The same is true for the ore body output of the Fujiawu deposit. It is 1100m long from east to west and 625m wide from north to south. The outer ring of the mine is 2800m long, the width of the ring is 200-500m, the thickness is 200-300m, and the extension is 600-950m. The ore body of the cinnabar red deposit is endowed with the inner and outer contact zones of the granodiorite porphyry. The ore body is pulsed and lenticular. There are 6 main ore bodies, and the length of the main vein is 100-1200m. The vertical thickness is 37~176.1m, the controlled tendency extends over 500~800m, and the vertical mineralization depth is more than 800m, but the bottom boundary is not seen. The largest ore body is produced in the upper part of the contact belt.

(5) Ore type and mineral combination According to the degree of oxidation in the ore, it is divided into primary sulfide ore, oxidized ore, and mixed ore. The three deposits are mainly composed of primary sulfide copper ore, accounting for more than 85% to 90% of the total copper reserves, oxide copper ore not exceeding 5% to 12%, and mixed copper ore less than 5%. According to the ore structure structure, the ore structure types of the three deposits are inconsistent. The Fujiawu deposit is dominated by disseminated structures, while the Zhushahong and Tongchang deposits are dominated by fine vein-disseminated structures. The ore structure is a crystalline structure, a metamorphic structure, a solid-solution separation structure and a pressurized structure, wherein the metamorphic structure is most developed. The main mineral combinations are chalcopyrite and pyrite, followed by chalcopyrite, arsenic antimony ore and porphyrite. The gangue minerals are mainly quartz, sericite, water muscovite, illite, chlorite, etc., followed by carbonates and sulfates.

(6) Type of deposit The Dexing copper (molybdenum) ore field belongs to the typical porphyry copper (molybdenum) deposit in China, but has different understandings of the source of ore-forming materials. One is that ore-forming elements and ore-forming fluids are homologous to granodiorite porphyry, both of which are sources of deep or upper mantle; the other is that ore-forming materials are mainly from deep or upper mantle, and some are from surrounding rocks. The ore-bearing fluid is mainly from the deep source in the early stage, and the atmospheric precipitation is the main in the late stage. The main metallogenic stage is the multi-general and multi-source view of the mixed effect of magmatic water and surface circulating water.  

(2) Tibet Yulong Copper (Molybdenum) Deposit  

Yulong Copper (Molybdenum) Mine is one of China's super-large copper (molybdenum) deposits. It is located in the west of Qingnidong District, Jiangda County, eastern Tibet, 8km north of Sichuan-Tibet Highway, with an altitude of 4560-5120m and a total mining area of ​​2.1km2. Accumulated proven reserves: 6.62 million tons of copper (6.5 million tons of available), 150,000 tons of molybdenum, 6.59 million tons of iron (the amount of ore), 1.78 million tons of pyrite , 59,800 tons of tungsten and zinc , 铋 , gold, silver, cobalt, etc. have already found considerable reserves. The average grade of the deposit is 0.94% copper and 0.028% molybdenum.  

1. A brief history of deposit discovery, exploration and development  

"Yulong" Tibetan means "malachite ditch". The folk rumors opened here in the late Qing Dynasty, and several mining pits and mining sites are still visible on the surface of the Yulong mining area.

In 1966, the first geological team of Tibet reported that the local herdsmen said that "Yulonggou is a bright and dazzling stone in the clear weather." So he took the heavy snow into the ditch and found most iron caps and a large number of malachite turns. He thought that the deposit was like Daye Iron Mine and deserved further work. In 1967, it was investigated by the Tibet First Geological Brigade and considered to be an skarn-type deposit mainly composed of iron and copper.

In 1971, the First Geological Brigade of Tibet used geological, geophysical surveying, surveying, drilling, and pit exploration to discover the layered copper ore body in the eastern part of the mining area, and discovered the copper mineralization in the altered monzonitic granite . Up to 1.7%, copper-molybdenum mineralization was also found in the biotite feldspar porphyry in the southern part of the mining area. In the same year, the 1971 Geological Survey Report of the Yulong Copper-iron Mine in Jiangda County, Tibet and the Opinions on Geological Work in 1972, it is recommended that the main body of the contact zone be first exposed. So far, the Yulong deposit has been initially confirmed, and the view of the existence of porphyry deposits is first proposed. In 1978, the “Geological Report of the Yulong Copper-Molybdenum Mine in Jiangda County, Tibet” was submitted to evaluate this super-large porphyry copper (molybdenum) deposit. At present, China Nonferrous Metals Industry Corporation and the People's Government of Tibet Autonomous Region are preparing to build Yulong Copper Mine.

2. Geological characteristics of the deposit  

(1) Geological overview The Yulong mining area is located in the west wing of the Qingnidong-Haitong complex anticline in the Sanjiang fold belt, and the axis of the short-axis anticline of the Hengxingcuo-Ganlong pull is inclined to the south. The exposed strata in the mining area are the upper middle Triassic. In the northern part of the mine, the lacustrine red clastic rock of the Jiajiala Formation is about 1 050 m thick. The sides of the ore body are exposed to the shallow sea-phase limestone sandstone of the Bolipila Formation, with a total thickness of about 50 m, which is widely distributed in the mining area. The A-sula group marine sand shale , with a thickness greater than 600m, is distributed in the southern part of the mining area. (Figure 3.7.3).

(2) ore-bearing rock mass Himalayan intrusive rock distribution in the mining area, mainly acidic granodiorite and granite - quartz ivernite. The ore-bearing rock mass is a biotite II long granite porphyry complex rock with an isotopic age of 37-55 Ma. The exposed area of ​​the rock mass is 0.64km2, which looks like a pear shape on the plane. Most of the rock mass is silicified and silicified, and it is transformed into black mica granite porphyry and potassium long granite. Both alteration and mineralization are controlled by the complex porphyry body.

(3) Alteration type The deposit has a distinct typical "central" symmetrical alteration characteristic. Centered on the rock mass, it is divided from the inside to the outside: the inner zone is potassium, silicidation, sericitization, claying ; the middle zone is skarnization, marble or hornification, clayification, shale lithification (Strong) silicidation and sericitization; the outer zone is crystalline limestone or hornite and shale lithology; the normal rock is limestone or sandstone.

(4) Distribution of ore bodies The ore body is located in the porphyry and surrounding rock and is composed of three main ore bodies, as shown in Figure 3.7.3 (The No. III ore body in the figure is the No. IV and V mines divided by the Tibet First Geological Brigade. Merged into a body). The No. I ore body is a cylindrical ore body composed of mineralized porphyry and mineralized horns in the near contact zone. It is nearly equiaxed, with an exposed surface area of ​​0.6 km2 and an average thickness of 331 m. The average grade of copper is 0.52%, molybdenum is 0.028%, and copper reserves account for 38.4% of the total area. The ore bodies II and III are respectively distributed in the outer contact zone on the east and west sides of the No. I ore body, and the two ore bodies are closed in a ring shape. The average thickness of the No. 2 ore body is 44m, the average copper grade is 1.7%, and the copper reserves account for about 22% of the whole area. The average thickness of No. III ore body is 69m (represented by the original V-type ore body), the average grade of copper is 2.5%, and the copper reserves account for about 39.4% of the whole area.

(5) Ore type and mineral combination There are three types of ore: one is fine vein-disseminated ore, accounting for 82% of the ore's ore, mainly distributed in the No. I ore body. The ore is subdivided into two types of fine veins in porphyry and horn rock, the former being the main one. The main metal minerals are pyrite, chalcopyrite, molybdenite, followed by copper blue, chalcopyrite, beryllium copper, a small amount of porphyrite, magnetite, hematite and limonite, etc. It is a rock-forming mineral in porphyry and horn rock. The second is copper-bearing limonite ore. Copper is present in limonite. Iron is in the form of limonite and magnetite. The gangue mineral is mainly kaolinite. The third is copper-bearing pyrite ore. The main ore is distributed in the middle and lower part of the layered ore body, accounting for about 7.6% of the total industrial ore. The main minerals are pyrite, Lanhui copper or copper, followed by porphyrite, copper blue and chalcopyrite. The vein-like ore-like ore structure is mainly a self-formed-semi-automorphic crystal structure, metasomatous and metasomatic residual structure, and the ore structure is a fine vein-disseminated structure; the copper-bearing limonite ore is soil-like, colloidal, porous and massive. And a small amount of breccia structure; copper-bearing pyrite ore is mainly staggered veins and densely infiltrated structures.

(6) Type of deposit At present, the Yulong deposit is generally referred to as a porphyry copper (molybdenum) deposit, and is actually a porphyry-type, skarn-type and hydrothermal vein-type "trinity" composite deposit.  

(3) Heilongjiang Duobaoshan Copper (Molybdenum) Ore Field  

The Duobaoshan copper (molybdenum) ore field is located in the north of Nenjiang County, Heilongjiang Province, 149km away from Nenjiang Town. The ore field is composed of Duobaoshan, Tongshan and Xiaoduobaoshan. It is one of the large copper mines in China. Total proven reserves: copper 2,440,000 t, the average grade of 0.47%; molybdenum 81,000 t, average grade of 0.016%, and the probe is eligible rich rhenium, gold, silver, selenium and platinum group metals and other mineral Reserves.  

1. A brief history of deposit discovery, exploration and development  

The Duobaoshan Copper Mine is a newly discovered copper (molybdenum) deposit in 1958. Its discovery and exploration history is roughly divided into two stages: the first stage from 1958 to 1971. In 1958, the third detachment of the Heilongjiang Geological Bureau of the Ministry of Geological Bureau discovered copper mineralization during the 1:200,000 regional geological survey on the periphery of the mining area, and carried out aerial survey and ground magnetic survey. The second exploration team of the bureau conducted a census exploration of the No. 1 and No. 2 ore belts, and obtained copper reserves of 190,000 tons and molybdenum of 12,000 tons. At the same time, the No. 3 ore belt was discovered. In addition, the Tongshan No. 1 ore body was discovered during the 11:1 10,000 geological mapping in the mining area.

The second stage was from 1972 to 1983. In 1972, when the Geological Team of the Bureau carried out the census work in the Duobaoshan ore field, it discovered the No. 4 ore belt and the Tongshan No. II and No. III ore bodies, which made the Duobaoshan become a large porphyry copper (molybdenum) deposit. In September 1983, the “Special Investigation and Initial Exploration Geological Report of Duobaoshan Copper Deposit in Nenjiang County” was submitted, and the available copper metal reserves were 2.37 million tons, molybdenum 80,000 tons and considerable associated gold, silver, antimony and selenium. And the reserves of platinum group metals. In 1988, the monograph of the Duobaoshan porphyry copper deposit was published.

The Duobaoshan copper (molybdenum) ore field is one of the few large-scale porphyry copper (molybdenum) ore deposits with a copper reserve of over 2 million tons in China, and is associated with a variety of beneficial components for comprehensive development and comprehensive utilization. considerable. The existing external construction conditions have also improved, and the selection and selection of equipment for cold storage has also been greatly improved. These have created favorable conditions for the recent development of Duobaoshan Copper (Molybdenum) Mine. The relevant departments have already applied the Duobaoshan Copper (Molybdenum) Mine. Made a research on the development of technical economics.  

2. Geological characteristics of the ore field  

(1) Geological overview The Duobaoshan ore field is located at the junction of the Daxinganling uplift belt and the Songliao subsidence belt. The large anticline of the Wooli River passes through the mining area, and the Nenjiang large fault passes through the west side. The regional tectonic line is northeast, but the ore field is northwest. The extension direction of the granodiorite and ore body is northwestward, so the regional tectonic line is nearly orthogonal to the ore tectonic line, which plays an important role in controlling the magma emplacement and ore-forming fluid activities. The main mineralized areas develop at the locations where the structures meet.

The exposed strata in the mining area are mainly composed of the Guanwuhe Formation clastic rocks of the Middle Ordovician and the Upper Ordovician Duobaoshan Formation volcanic rocks and a small amount of clastic rocks and carbonate interbeds. The Carboniferous system is distributed in the local depressions. Sedimentary strata of the Permian continental basin.

(2) ore-bearing rock mass The magmatic rocks in the area are developed, and the Haixi sloping granitoids are exposed in the northeast, and the Duobaoshan granodiorite complex rock mass (292 Ma) is closely related to mineralization. (More) Long granite small rock mass cut through granodiorite and ore belt (250 Ma measured by potassium argon method), so the diagenesis and mineralization age should belong to the middle of the Hercynian. The deposit has a certain relationship with the granodiorite porphyry, and the formation of the deposit has a close genetic relationship with the granodiorite porphyry (Fig. 3.7.4).

(3) Wall rock alteration The surrounding rock of the deposit is altered and the space is distributed in a belt-like shape. The alteration center is a silicified porphyry, and the outward-ordered elliptical-like K-bearing petrochemical zone, biotite zone, sericitization zone and barrenite Belt.

1) Silicified porphyry belt (quartz core) Distributed in the center of the deposit, some porphyry and its adjacent rocks are fragmented and filled with potassium feldspar and albite network veins . The strong silicified parts have been replaced by massive quartzite , and the weak ones are only interspersed with sparse network veins.

2) Potassium belt The quartz potassium feldspar sub-band is distributed around the quartz core, with the decrease of the number of quartz veins and the increase of potassium feldspar content, and the transition to the quartz potassium long petrochemical sub-band. Its mineralization is similar to that of quartz core, with weak copper-molybdenum mineralization and small molybdenum ore bodies. Copper and molybdenum ore bodies can be formed only when strong crushing and crystallization are repeated or accompanied by superposition of sericitization and carbonation. In the outer ring of the potassium zone, the amount of quartz and potassium feldspar is reduced, and the content of biotite is increased to form a transition zone.

3) sericitizing zone It is roughly distributed around the potassium belt and is 100-400 m wide. The spatial distribution is basically consistent with the NW-trending structural crush zone and the physicochemical zone. The belt is divided into two sub-bands, that is, the inner belt is a quartz-silica nebula sub-belt. The copper mineralization is continuous and stable, often forming a thick ore body; the outer belt is a chlorite-seri sericization sub-belt, and some areas Due to the superposition of late copper-containing network veins, the copper grade is improved and the ore body becomes thick and stable.

4) Qinglan lithification belt The surrounding sericitization zone is distributed around the periphery of the alteration zone.

The deposit corresponds to the surrounding rock alteration zone. The mineralization is basically divided into three zones from the inside to the outside: 1 Copper-molybdenum mineralization zone: mainly copper-bearing ore, distributed in the edge and surrounding of the porphyry. The localized mineralized area forms an independent small molybdenum ore body. 2 The copper mineralization zone is basically consistent with the sericitization zone, and the ore body is positively correlated with the scale of silicidation and sericitization and the occurrence is basically the same. The central part of the ore body is often dominated by porphyrite, followed by chalcopyrite, and pyrite is almost absent. 3 Pyrite mineralization zone: The zone is roughly distributed around the copper ore belt. A less intense pyrite halo is formed on the outside of the main ore body, and a discontinuous distribution of pyrite belt is often formed outside and at the top of the copper ore belt.

(4) ore body combination The ore field consists of 215 ore bodies of four ore sizes. Among them, there are 14 main ore bodies, and the No. 3 ore body is the largest in size. The No. X ore body is 1400m long, 23~340m wide and 300~1000m deep. The ore bodies in the deposits are complex in shape and arranged in geese. For example, the ore bodies of the Duobaoshan No. 50 exploration line are arranged by geese and coincide with the northwest-oriented fissures. When the ore bodies in the ore belt are thick and can be combined together, they form a stable thick ore body or ore belt. If the size of the ore body is small, it can only form a few meters to 20 meters thick in the ore belt. Ore body group. The central part of the thick ore belt is relatively stable, and the edge of the ore body is often sharply split and pinched.

(5) Ore mineral combination The main mineral ore pyrite, chalcopyrite, bornite, and molybdenite; secondary mineral magnetite, hematite, rutile, galena, sphalerite and pyrrhotite. The structure of the ore is relatively simple. The ore structure is mainly his shape and semi-self-shaped granular structure. The small amount is self-shaped granular, microcrystalline lattice-like and opaque structure, and the residual residue and the lattice-like structure. The ore structure is mainly in the form of disseminated, fine veins, veins and breccia.

(6) Type of deposit The formation of this deposit is closely related to the granodiorite porphyry, so the deposit is generally classified as a porphyry copper (molybdenum) deposit. However, the understanding of the source of ore-forming materials is still inconsistent. Some emphasize the use of magma-hot liquids; others emphasize the role of the surrounding rock system. For example, Du Qi research believes that the Duobaoshan porphyry copper (molybdenum) metallogenic system is a long-term system for pumping surrounding rock and sometimes discharging upward along the magmatic hydrothermal activity center. Copper is mainly derived from surrounding rock and provides a large amount of water from surrounding rock.  

(4) Wunuge Tushan Copper (Molybdenum) Deposit, Inner Mongolia  

The Wunuge Tushan Copper (Molybdenum) deposit is located in the northeast of Xinbaerhuyou Banner, Inner Mongolia, about 22km south of Manzhouli City. It is a large porphyry copper (molybdenum) deposit discovered in the eastern part of Inner Mongolia since 1980s. Accumulated proven reserves: 1.268 million tons of copper, 0.46% of copper grade, 258,000 tons of molybdenum, 0.055% of the average grade of molybdenum, and the discovery of considerable associated mineral reserves such as antimony, silver and gold.

1. A brief history of deposit discovery, exploration and development  

In Manzhouli to Xinbaerhuyouqi area, there were only 1:100 million geological survey data before the 1970s, and it was difficult to find mines. Although the "eight eight one" copper mine was found in the Badaguan copper mine in the northeastern Manchuria from 1974 to 1978, the scale was small and no major progress was made in prospecting. In 1977, the 706 team and the geophysical exploration team of the Heilongjiang Non-ferrous Geological Survey Bureau traced a small copper mine spot near the Manukuri to the "Wu Nuktou Mountain" (in accordance with the correct translation of the Mongolian language, "Unug spit", meaning fox), and A geochemical anomaly of nearly 5km2 was discovered. In 1979, 10 holes were designed and constructed, and almost the hole was seen in the mine. This large porphyry copper (molybdenum) deposit was finally discovered. In 1983, the “Geological Evaluation Report of the Wunugetushan Copper (Molybdenum) Deposit in Xinbalhuyouqi, Inner Mongolia Autonomous Region” was submitted. The reserves have been discovered: 2.232 million tons of copper and 412,000 tons of molybdenum, including 1.268 million tons (D-class reserves) and 257,000 tons of molybdenum on the national reserve balance sheet. The associated sputum and silver reserves have reached large and medium-sized, and there are other beneficial associated components.

The economic construction conditions of the district are good, the transportation is convenient, the water and electricity supply is guaranteed, and the mining area is a hilly grassland area, which can be used to build a large and medium-sized copper-molybdenum mine in the near future. The relevant design department has done pre-development planning and demonstration research work.  

2. Geological characteristics of the deposit  

(1) Geological overview The Wunuge Tushan Copper (Molybdenum) deposit (referred to as Wushan) is one of the large deposits in the Manzhouli-Xinbaerhuyouqi copper polymetallic metallogenic belt, located in the northeastern part of the ore belt. This ore belt is located on the side of the Erguna-Galidong fold system that is connected with the Haixi fold system of the Daxing'anling, which is the northwestern direction of the north side of the Ergun-Hulun deep fault. The Wushan deposit resides beside the secondary fault of the Hanigou in the northwest. The exposed strata in the area are mainly the Upper Ordovician carbonates and the intermediate-acid volcanic rocks of the Upper Paleozoic Devonian. The distribution of the deposits in the area is scattered and remains in the rock mass. The Jurassic upper-middle-acid volcanic complex is also widely distributed in the periphery of the mining area, mainly Anshan , Yingan , rhyolite and clastic rocks. The structure of the mining area is dominated by the northeast-oriented white ash plant-Wunuge spit anticline, and its axis is occupied by the biotite monzonitic granite. The tectonic fault is more developed in the NE-trending and NW-trending groups (Fig. 3.7.5).

(2) ore-bearing rock mass There are many stages of volcanic porphyry intrusion in the mining area. In order, it is a rhyolitic crystal condensate lava-slanted long granite porphyry (two long granite porphyry) - Ying'an breccia lava (Yingan porphyry) - rhyolite - syenite porphyry, with medium Acidic-acidic-alkaline evolution characteristics. Close to the mineralization is the two long granite porphyry (single-grain zircon uranium lead method dating 188Ma), in addition to the mineralization intrusive rock mass still has granite porphyry, quartz porphyry, etc., its composition is more It is acidic, vein-like, and rock-like filling in the NE-trending tectonic fault. It is a magmatic differentiation product in the main metallogenic period, and it itself is also affected by mineralization and has ore-bearing properties. The deposit is controlled by sub-volcanic channels formed by the interlaced structures of the northwest and northeast of the western margin of the biotite monzonitic granite and the annular fractured alteration zone produced by the subvolcanic structure (Fig. 3.7.5).

Q4. Quaternary; D2w. Devonian zhongtun Wunuer Formation; J3a. Jurassic Upper Anshanite; ξiπ. Ying'an breccia lava; γχπ. granitic syenite; γiπ. Gang porphyry; λiπ. rhyolite crystallized tuff lava; γβ. biotite granite; αμ/δμ. Anshan shale / diorite porphyry; λπ. rhyolite porphyry; γπ. granite porphyry; IH Illite-water muscovite zone; QS. Quartz-silicaitization zone; Q-Kf. Quartz potassium zone; 1. Fault; 2. Ring fracture; 3. Subvolcanic rock neck structure; 4. Breccia Tube structure; 5. geological boundary; 6. alteration boundary line; 7. ore body boundary; 8. copper ore body; 9. molybdenum ore body  

(3) Wall rock alteration The surrounding rock alteration of the deposit is extensively developed, with a large scale and obvious zoning. The alteration zone is about 3.5km long in the north, about 2km wide in the northwest, and has an area of ​​about 7km2. The altered zone surrounds the second-long granite porphyry with a central surface-type alteration feature. It can be divided into three zones from the inside to the outside: the inner zone is the quartz potassium feldspar zone; the middle zone is the quartz-sericite tape; the outer zone is The illite-water muscovite band gradually weakens the alteration strength (Fig. 3.7.5).

(4) ore body combination A total of 33 copper ore bodies and 13 molybdenum ore bodies were identified in the district. Among them, there are 5 copper ore bodies in the northern section and 2 molybdenum ore bodies. The orebodies are mainly distributed in the porphyry and contact belts. They are controlled by the surrounding porphyry faults, and the ore body is inclined to the north; the copper ore body of the southern part is 28 Article, 11 molybdenum ore bodies. From the distribution of ore bodies in the north and south ore sections, the ore body of the northern ore section is large in scale and good in continuity. The copper and molybdenum reserves account for 80% of the total reserves. The main ore body is 2150 m long, the extension depth is more than 600 m, and the thickness is 70-380 m. The size of the ore body in the southern part of the mine is small and the continuity is poor. The copper and molybdenum reserves account for 20% of the whole area.

(5) Ore combination The main metal mineral combination in the ore is closely related to the alteration and zoning, and has obvious zoning. From the quartz potassium long petrochemical belt, the order is: 1 magnetite-pyrite-molybdenite combination; 2 pyrite-molybdenite-chalcopyrite combination and pyrite, chalcopyrite combination; 3 yellow Iron ore-chalcopyrite-lead-zinc mine combination. The ore types are primary sulfide ore, oxidized ore and mixed ore. Among them, primary sulfide ore is the main, and oxidized ore and mixed ore are only partially developed. The ore structure is dominated by his shape-semi-automorphic granular structure, followed by metasomatic structure, inclusion structure, solid solution decomposition structure, leaf plate structure, edging structure, semi-self-shaped-self-morphing crystal structure, etc. Dip-like and fine vein-disseminated structures, occasionally a mass-like structure. The ore structure has obvious zoning characteristics, from the center of the alteration to the fine-grained dissemination to the fine veins. The metal elements in the ore also have horizontal zoning characteristics, which are ordered from the center to the outside: Mo-Mo, Cu-Cu-Cu, Pb, Zn-Pb, Zn-Fe. They basically correspond to each other and have a certain superposition to generate typical porphyry alterations and industrial ore bodies.

(6) Type of deposit At present, the deposit is generally classified into the type of sub-volcanic hydrothermal vein-infiltrated porphyry copper (molybdenum) deposit. However, there is an inconsistent understanding of the source of mineral resources. Some believe that the ore-forming materials such as copper and molybdenum of the deposit are derived from the deep crust and upper mantle; some believe that the ore-forming fluid is a mixture of magmatic water and Tianshui.  

(5) Hubei Tonglushan Copper-iron Deposit  

The Tonglushan copper-iron deposit is located in Tonglushan Town, Daye County, Huangshi City, Hubei Province. It is the largest skarn-rich copper-rich iron deposit in China. Accumulated proven reserves: 11.13 million tons of copper, 1.78% of copper grade, 56.819 million tons of iron ore, and associated with a large number of gold, silver and rare metal minerals, the comprehensive utilization value is huge.

1. A brief history of deposit discovery, exploration and development  

The Tonglushan mining area has a long history of development. According to the ancient mining and copper smelting sites discovered in the mining process in 1973, the pit mining began in the late Shang Dynasty and continued to the Tang, Song, Yuan, Ming and Qing dynasties, and successively collected and refined here.

Before the founding of New China, from 1923 to 1934, Xie Jiarong, Liu Jichen, Ye Liangfu, and Zhu Xiren had done geological surveys and mapping work in the area. Since the founding of New China, since 1952, the iron and copper minerals survey has been carried out by the 429th team of the Ministry of Geology, the census team of the Central South Nonferrous Metals Bureau, the 412 team of the Central South Geological Bureau, and the Bayi III team of the East China Branch of the Geological Bureau of the Ministry of Metallurgy. In 1959, the Hubei Geology Bureau Edong Geological Brigade further worked, affirming that the Lulu Mountain is a very rich copper-rich iron deposit. From 1960 to 1961, drilling was used as the main means for preliminary exploration. From 1962 to 1966, he was transferred to detailed exploration. In 1964, the report on the reserves of ore bodies I, II and III of the Tonglushan copper-iron deposit in Daye, Hubei Province was submitted. In 1966, the report on the reserves of ore bodies III-VIII and XI of the Tonglushan copper-iron deposit in Daye, Hubei Province was submitted. From 1967 to 1982, the largest skarn-type copper-rich iron deposit with millions of tons of copper reserves in China was discovered. In 1983, the final summary report of geological exploration of the Tonglushan copper-iron deposit in Daye, Hubei was submitted. . In 1985, the Provincial Reserve Committee approved the detailed survey report of the mining area, which can be used as the basis for mine design and provided a large copper production base for the development of non-ferrous metal industry in Central and South China.

The large-scale construction of the mine began in 1965, and the mining and selection design of the mine was carried out by the Changsha Nonferrous Metals Design Institute based on the geological exploration results submitted in 1964. The mining capacity is 4000t/d (exposed for dew and pit mining is 2000t/d), the upper part of mines I, II and V is open-pit mining, and the lower part of mines III and VI is underground mining. Since it was put into production in 1971, it has been continuously produced for more than 20 years. Since the "Eighth Five-Year Plan", the second phase of the project has been rebuilt and expanded based on the geological results submitted in 1983. The annual production capacity of copper concentrate is over 10,000 tons. It is one of the eight mining enterprises with an annual output of 10,000 tons of copper concentrates. The geological exploration work has made great contributions to the development of the copper industry in Central and South China.  

2. Geological characteristics of the deposit  

1) Geological overview. The Tonglushan deposit is located in the western part of the Lower Yangtze depression, at the northwestern end of the Yangxin rock mass, and the north part of the north-northwest concealed anticline. The strata of the mining area are exposed as marble and dolomite marbles of the Lower Triassic Daye Group, and they are island arcs and traps remain in the quartz diorite porphyry and quartz diorite. 3.7.6).

2) Mineral-bearing rock mass. The Tonglushan rock mass is an Yanshanian intrusion, mainly composed of quartz two long diorite porphyry, which is an ore-bearing rock mass. It has an irregular elliptical shape on the plane, and the mushroom-like rock strain that is inclined to the southeast in the section is closely symbiotic with the skarn ore body. The diagenetic age is 157-137 Ma, slightly earlier than the ore-forming age of 145-115 Ma. The rock is a porphyritic structure, and its chemical composition is low- magnesium iron-rich alkali. It belongs to the normal series of calc-alkaline rocks with weak supersaturation of silica. To the depths, the plaque-like structure in the rock gradually disappears and transitions to the quartz diorite.

3) Wall rock alteration. The Tonglushan deposit has significant alterations in the rock mass and in the marble near the contact zone. There are mainly four types of alteration: one is alkaline metamorphism, which appears in the magmatic rock beside the skarn, and is divided into sodium metamorphic and potassium metasomatism; the second is calcareous metamorphism, in the side of the skarn. the contact strip is generated, and diopside into basic petrochemical plagioclase; Third skarnization, carbonate rock mainly based account, is intimately associated with the copper and iron ore, that is, occurrence skarn ore The main rock of the body; the fourth is hydrothermal alteration, mainly phlogopization, chlorite, serpentine, carbonation and silicification.

4) Ore body combination. The deposit consists of 12 ore bodies (groups) of varying sizes. The main ore body is distributed in the skarn, forming three ore belts, as shown in Figure 3.7.6.

(1) The north-northeast ore belt (main ore belt) consists of seven ore bodies (groups) such as I, III, IV, V, VI, XI and XII. The ore belt is about 2100m long from north to south and 300~350m wide. The ore body is mostly layered or lenticular. The ore belt is dominated by rich ore bodies, and its buried depth is deep in the middle and south, and a large ore body group is formed centering on the No. III ore body. The ore body can be up to 140m thick and has a maximum extension of 800m.

(2) The NEE ore body consists of four ore bodies, namely VII, VIII, IX and X. The ore belt is 1850m long and 100m wide. The ore body is irregularly lenticular, small in scale, scattered in sporadic, and poor in continuity.

(3) The north-west westward ore belt is mainly composed of some small ore bodies between the No. 2 ore body and the No. 6-4 exploration line.

5) Type of ore. The ore type of the deposit is more complicated, and there are iron ore, copper iron ore, copper ore, copper sulfur ore, and molybdenum ore.其中,铜铁矿石是矿床中的主要矿石类型,占全区铜总储量的76.7%,占铁总储量的85.2%,原生铜铁矿石含铜0.49%~8.08%,含全铁27.89%~54.17%;其次是铜矿石,占全区铜储量的23.3%,原生铜矿石含铜0.6%~6.59%。

矿石结构,主要有结晶结构、固溶体分解结构、溶蚀交代结构、压力结构和胶状再结晶结构。矿石构造,主要有块状-浸染状构造或充填交代而呈细脉状构造、角砾状构造。氧化带矿石形成蜂窝状或粉末状构造。

矿床伴生多种有益组分,其中金、银、钴等具有巨大经济价值,储量可观;硫、 铟 、硒、碲、铼等,也有综合利用价值,可综合开采,在选冶过程中可综合回收利用。

6) 矿床类型。该矿床被公认为典型的岩浆期后接触交代型高中温热液矿床,即夕卡岩型矿床。但也有的认为少部分厚板状富矿体为岩浆型矿体的可能性。

(六)甘肃白银厂铜多金属矿田 

白银厂铜多金属矿田位于甘肃省白银市境内。矿田由折腰山、火焰山、铜厂沟、小铁山和四个圈等铜矿和多金属矿区所组成,总面积约25km2。累计探明储量:铜131.4万t、铅40.4万t、锌80.8万t、硫1636万t、黄铁矿矿石量379.5万t以及伴生金、银、 镉 、铟、 铊 、硒等可观储量,是我国大型铜和多金属矿田之一,是白银有色金属公司的主要矿产基地。  

1.矿床发现、勘查、开发简史 

白银厂矿山开采历史悠久,在折腰山、火焰山矿区迄今还可随处见到炼金、银的碎块瓦钵等物。据史料记载可追溯到唐朝或更早。

新中国成立前,1937~1947年先后来此调查矿产的有霍世诚(1937)、陈贲(1940)、王之玺(1940)、甘肃省矿产测勘总队(1941~1943)、梁文郁、刘隆、刘增乾(1944)、宋叔和、徐昌沛(1946)。

新中国成立后,对白银厂矿田开始进行大规模的地质勘探工作。1950年宋叔和率队前往开展工作。1951~1952年确定了白银厂折腰山、火焰山、铜厂沟等三个矿区的次生富集带普遍存在,发现深部原生带黄铜矿,确认有开采价值。

1953年地质部六四一队在矿区详查基础上转入大规模地质勘探和科研工作并首次应用物探方法进行探矿。1954年底,由宋叔和、李铭德组织编写了我国第一部大型有色金属矿床的储量报告,提交储量:铜66.7万t,硫1280万t,黄铁矿矿石储量735万t。1956年底提交了《白银厂矿区勘探成果报告》,提交铜储量86.31万t(其中含1954年中间报告68.7万t),完成国家总计划任务的118.2%。还提交了黄铁矿、伴生硫、金、银储量。

白银有色金属公司矿山投产后,做了大量矿山地质工作扩大了矿区储量,并对富铜矿和共生铅锌矿进行了重新评价,有关院所、院校等对矿床地质和金、银及稀散元素等做了大量地质查定与评价工作。

白银有色金属公司根据大量可靠的地质勘探成果,于五六十年代陆续建成了折腰山、火焰山、小铁山等矿山。1956~1959年为矿山基本建设时期,白银厂露天矿开采设计由原苏联有色冶金设计院1956年编制。折腰山矿区为一号露天采场,火焰山为二号露天采矿。两采场设计服务年限19年。设计规模:矿岩总量10880万m3,剥离废石9530万m3,采出铜矿石4096万t(金属56.6万t)、采出黄铁矿920万t。两采场经20多年来强化开采,现已陆续闭坑,转入地下接替开采。小铁山等仍在开采之中。

白银厂矿田的资源发现和勘探成功,为白银有色金属公司的生产发展提供了可靠的矿物原料保证,使之成为集采、选、冶、加工、化工等融为一体的特大型有色金属联合企业,驰名中外。昔日荒无人烟的白银厂如今已建成一座新型铜工业城市。  

2.矿田地质特征 

(1)地质概况白银厂矿田位于北祁连加里东褶皱系东延部分。出露地层以下古生界海底火山喷发沉积和海相碎屑岩为主。矿床赋存在中寒武统富钠质海底火山喷发细碧角斑岩中,其中夹有千枚岩、硅质岩、大理岩及各类火山角砾岩和集块岩。矿田为一复式背斜构造。各矿区均位于以石英角斑岩、石英角斑凝灰岩为核心的短轴背斜构造内。矿体与中粒石英角斑凝灰岩关系密切,与地层大致呈整合产出,明显受层位控制。

π1xy.含角砾集块石英角斑岩;π2y.含角砾石英角斑凝灰熔岩;π3y.含角砾石英角斑凝灰岩;α1xy.含角砾集块角斑凝灰岩;α2y.含角砾角斑凝灰熔岩;π1.石英角斑岩;π2.石英角斑凝灰熔岩;π3.石英角斑凝灰岩;π0.石英钠长斑岩;λ0. 辉绿岩 ;α1.角斑岩;Ps.硅质千枚岩;P.凝灰质千枚岩;φ3.细碧玢岩凝灰岩;β1.细碧岩;β3.细碧质凝灰岩;π2xy.含角砾集块石英角斑凝灰熔岩;α3.角斑凝灰岩;α0.钠长斑岩;1.磁黄铁矿矿筒;2.矿体;粗实线为断层,细实线为地质界线

(2)含矿火山岩系 矿田含矿火山岩系,从基性的细碧岩类到酸性石英角斑岩类,从浅成侵入到喷发沉积岩类均有,而且分异完好。其岩性种类,主要为石英角斑凝灰岩、石英钠长斑岩、细碧玢岩等,其次为中基性火山-沉积岩(含凝灰质、泥钙质、泥硅质千枚岩等)。矿田内潜火山岩较发育,基性、中性、酸性火山岩均有对应的超浅成侵入体。其中,酸性潜火山岩在空间上与矿床关系较密切。

(3)围岩蚀变矿田围岩蚀变发育,主要有硅化、绢云母化、绿泥石化、黄铁矿化、 重晶石化、绿帘石化、硫酸盐化、 高岭土化等。其围岩蚀变与矿体关系的主要特征:

1)无长石带是组成含矿蚀变带的核心,矿体都赋存在此带内,向外依次为假象无长石带—长石中等交代—长石弱交代—原岩带。

2)无长石带规模大,其内部分带性(绿泥石化带)及规律性明显者,矿床规模亦较大。

3)含矿无长石带内各蚀变带的各类矿物组合及分布复杂,基本在无长石带中从下往上构成次生石英岩亚带→绢云母石英岩亚带→石英云母亚带的一次或多次重复现象。矿体多位于两亚带之中,前者仅含浸染状矿石。

矿床氧化带明显,由矿床侵蚀出露,黄铁矿氧化较深,氧化带下有次生富集矿石。可划分为:风化带(铁帽)、淋失带、次生硫化富集带。

(4)矿体分布矿田中的五个矿床,按矿石组合可分为两大类型:一是块状黄铁矿和含铜黄铁矿型矿床,即折腰山(大型)、火焰山(中型);二是以铜、铅、锌为主的多金属黄铁矿床,即小铁山(大型)、铜厂沟、四个圈(小型)等矿床。

矿体形态多为透镜状、扁豆状、似层状、脉状等,有的分支复合。矿体产状与围岩基本一致。总走向295°~320°,倾向南西,倾角50°~70°。矿田共有600多条矿体。其中,折腰山矿区共有231条矿体,块状矿石矿体长400m,厚50~80m,延深150~200m,浸染状矿体数十米至1300m,斜深大于600m;火焰山矿区共有221条矿体,块状矿石矿体长450m,厚17~70m,斜深200m;铜厂沟矿区共有156条矿体,均为浸染状矿石矿体,长50~300m,厚2~4m,斜深76~228m;小铁山矿区共有12条矿体,长100~1000m,厚0.8~5.9m,斜深50~530m;四个圈矿区共有32条矿体,长50~200m,厚1~14.7m,斜深18.5~135m。

(5)矿石类型和矿床平均品位矿石类型按矿物组成,可分为块状含铜黄铁矿矿石、块状铜铅锌矿石、块状铅锌矿石、块状黄铁矿及浸染状铜矿石、浸染状铜铅锌矿石、浸染状铅锌矿石等。按氧化程度分为氧化、次生和原生带三种自然类型的矿石。矿区平均品位,见表3.7.6。

(6)矿床类型现普遍将白银厂矿田划归为与火山岩有关的海相火山岩型块状硫化物矿床。

(七)福建紫金山铜金矿床

紫金山铜金矿床是80年代在我国东部陆相火山岩区勘查的一个大型铜金矿床,位于福建省上杭县城北15km处。矿田范围40km2,由紫金山、中寮、龙江亭等矿区及二庙沟、新屋下等矿化异常点组成。紫金山矿区位于矿田中部,面积约4.37km2。现已在该矿区北西矿段经详查探获铜矿储量108.7万t,铜平均1.09%,共生金矿已达到中型规模,金平均品位4.69g/t,并伴生银、硫铁矿、 明矾石等多种有益矿产。  

1.矿床发现、勘查、开发简史 

紫金山矿区采金历史悠久,据史料记载宋康定年间,采金达到鼎盛时期,故得名紫金山,在矿区已发现古采硐。

1953年就有人到紫金山地区进行地质调查。1960~1984年间,福建省地质局所属地质队、物探队等为发现和评价紫金山大型铜金矿床做了大量前期地质工作。1985年认为本区属于与次火山岩有关的矿化类型,深部有找矿前景,果断决定上机掘硐探,1986年发现一新矿化带和11个新矿体,金品位大于3g/t的矿体共有14个。1987年经钻探施工,3个钻孔浅部都见到金矿体,深部见到高品位铜矿体。1988年确定了矿区属含金的铜矿带,上部为氧化带金矿,下部为原生带含金铜矿,认为是与火山-次火山岩有关的热液矿床,决定铜金并举的工作方案。经钻探、坑探,控制铜矿化长度大于700m,宽200~500m,同年12月闽西地质大队编制了《福建省上杭紫金山铜矿区地质普查总体设计》。1989年,紫金山金铜矿普查以北西矿段为重点,全年施工钻探1995m/18孔和部分坑探工程,初步控制铜矿(化)带长700m,宽300~800m,垂深550m,预测铜储量可达到大型矿床规模。1990年施工钻探19310m/27孔,坑探800m,初步圈出41个铜矿体,单个矿体厚5~15m,最厚43.62m,矿石平均含铜0.6%~1.5%。通过进一步详查工作,铜矿达到大型规模,金矿达到中型规模,并进行了矿石可选性试验, 选矿性能良好,铜精矿品位24.79%,回收率87.26%。现该区已列入国家铜矿重点勘查项目之一,1993年北西矿段进行对口勘探,作为矿山设计、建矿的依据。

紫金山大型铜金矿床的发现与成功的勘查,不仅给我国沿海地区发展有色金属工业提供了大型铜矿资源基地,而且也给在陆相火山岩地区寻找、勘查大型铜金矿开阔了新思路,提供了新经验,意义十分重大。  

2.矿床地质特征 

(1)地质概况紫金山矿床位于闽西南晚古生代拗陷之西南,云霄-上杭北西向深断裂带与宣和北东向复式背斜交汇处,上杭北西向的白垩纪火山-沉积盆地的北东缘。矿区地层主要分布于外围地区,矿区范围内仅有白垩系火山-沉积岩零星分布。燕山期岩浆岩占据矿区中部。区内断裂构造发育。

(2)岩浆岩与成矿 紫金山矿床的形成,与燕山晚期中酸性次火山岩及火山机构有密切关系。主要铜矿体产于火山机构外侧,沿北西向裂隙贯入到燕山早期花岗岩中,受隐爆角砾岩和英安玢岩带所控制。矿区燕山期岩浆岩类为复式岩体呈北东向展布,长约8km,宽4km。由燕山早、晚两个不同构造岩浆旋回的多次侵入体组成。复式岩体主体为燕山早期侵入体,由似斑状中粗粒二长花岗岩(143Ma)、中粒二长花岗岩(157Ma)和细粒花岗岩组成。燕山晚期岩体为花岗闪长岩类(102.2Ma),主要分布于北东部,呈小岩株、岩枝和岩脉产出。

矿区火山活动强烈,已发现有紫金山、二庙沟和赤水三个火山机构(图3.7.8)。火山机构受北东和北西向断裂交汇结点控制。矿区中部紫金山主峰东南侧火山机构即位于北东向小金沟断裂和北西向紫金山断裂带的交汇部位。火山机构北西和南东侧发育大量的脉状次英安玢岩和隐爆角砾岩,形成长1800m、宽800m的次英安玢岩-角砾岩带,总体呈北西-南东走向,倾向北东,倾角中等至缓。与矿区主要铜金矿化带分布基本一致,控制了铜金矿带的展布。次英安玢岩和隐爆角砾岩相对集中发育地段是铜金矿化主要地段。矿体多为脉状产出。

(3)围岩蚀变矿区热液蚀变强烈,达数平方公里,垂深可达千米,具有“面型”和“线型”多期蚀变叠加特点,呈现硅化、迪开石化、明矾石化、绢云母化和黄铁矿化等一套低温热液蚀变类型。垂直分带较明显,深部主要为石英-绢云母带,中部为石英-明矾石-迪开石带,上部为硅化帽。

(4)矿带矿体矿区铜矿带中铜矿体主要赋存于650m高程以下的原生带中,为隐伏矿体。矿带主要由一系列密集的脉状铜矿体组成。已初步圈定铜矿体41个,总体走向320°,倾向北东,倾角20~50°,有上陡下缓的趋势。紫金山矿床系指矿区西北矿段的铜金矿体,并依据次火山岩脉和隐爆角砾岩带的发育程度划分出三个铜金矿带。由南往北,由下往上,为0号矿带、Ⅰ号矿带、Ⅱ号矿带。

0号矿带:位于矿区北西向脉状隐爆角砾岩和第二次次英安玢岩密集带1号矿带下盘,已圈出17矿体。矿化带厚度100~280m,延深约500~600m,最大深度达900m,矿化围岩主要为蚀变花岗岩。铜储量占全区的43.58%。

I号矿带:主要分布于次英安玢岩和脉状隐爆角砾岩密集带内。已控制矿带长约600m,宽500m,矿化带厚度200~260m,延深470~750m,最大延深达800m。带内有11个矿体。矿体的围岩主要为隐爆角砾岩、蚀变花岗岩,其次为次英安玢岩。矿带铜储量占全区的48.88%,是铜矿主要矿化带。

Ⅱ号矿带:位于Ⅰ号矿带上盘。该带规模较小,控制程度低,埋藏较浅。矿化带厚度在300m以上,延深尚不清楚。已控制有13个矿体。矿化围岩主要为蚀变花岗岩,其次为隐爆角砾岩,其铜储量占全区的7.5%。

金矿体主要分布在I号矿化带,赋存在650m高程以上的氧化带中,金矿体一般厚几十厘米到几米,延长几十到百余米,延深几十至200余m,没有天然矿体界限,呈脉状,部分呈扁豆状、透镜状,金品位一般3~5g/t,最高达30.24g/t。矿带中发现金工业矿体数十个。

(5)矿石类型铜矿石基本为原生硫化物矿石,以黄铁矿、蓝辉铜矿-辉铜矿为主,其次为硫砷铜矿、铜蓝,少量的斑铜矿和微量的黄铜矿、黝铜矿、砷黝铜矿、硫锗铜矿、硫铜锗矿、 锡黝铜矿等。铜矿物及黄铁矿呈脉状或浸染状,充填交代隐爆角砾岩及蚀变次英安玢岩和蚀变花岗岩中。金矿石为氧化矿石,主要为褐铁矿、针铁矿、赤铁矿等,局部见有少量黄铁矿、自然金、方铅矿、斑铜矿、蓝辉铜矿、硅孔雀石、自然铜等。

(6)矿床类型如上所述,紫金山铜金矿床与火山构造、次火山岩-英安玢岩及隐爆角砾岩带密切相关,铜金矿化的成矿作用相当于燕山晚期,铜金矿化与蚀变作用,发生在本区最发育的次火山岩及隐爆作用之后的火山热液作用。故成因类型划归为燕山晚期陆相火山岩次火山岩-隐爆角砾岩期后热液脉状矿床。金矿的最后定型则在表生成矿期的次生富集成矿作用下,形成铁帽型金矿。

(八)云南东川铜矿田

东川铜矿位于云南省东川市境内,由落雪、汤丹、因民、滥泥坪、石将军、白锡腊、新塘等大中型和一些小型铜矿床组成东川铜矿田。其范围东起小江,西至普渡河,南抵雪岭、北达金沙江,面积660km2。

东川铜矿田经过40多年来的地质勘查工作,共发现、勘查铜矿床、矿点148个。其中,详细勘探40个、初步勘探16个、普查38个、概查54个。探获大型铜矿床2个(汤丹、落雪),中型铜矿床5个(石将军-萝卜地、面山、大英稠、滥泥坪、新塘),小型矿床36个。共累计探明铜储量391.4万t,近年来通过成矿预测研究和勘查,预测东川矿田铜储量包括已探获的铜储量可达到500万t以上

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