3.7.1.1 Reserves and Resources

Up to now 913 copper deposits have been explored in China, with accumulative explored reserves (copper metal, the same below) totaling up to 73,725,000 tons. By the end of 1997 the retained reserves had reached 62,736,000 tons, of which reserves of categories A+B+C amounted to 26,337,000 tons. The distribution of principal deposits, their reserves and utilization are shown in Table 3.7.1 and Fig. 3.7.1 respectively (the numbers of deposits in the table are the same as those in Fig.). According to a prognosis, the reserves, having been explored up to now, only account for 1/4~1/5 of resources forecasted.

3.7.1.2 Characteristics

The distribution of copper deposits in China is both extensive, and relatively concentrated. The copper deposits already identified are distributed in all the provinces, municipalities and autonomous regions of China except Tianjin Municipality. Over 80% of reserves occur in Jiangxi, Tibet, Yunnan, Gansu, Anhui, Inner Mongolia, Shanxi, Hubei and Heilongjiang.

Judging from three economic regions of China the distribution of copper deposits shows a distinct regional difference, and the proportion of reserve distribution among these three large economic zones is as follows (based on the statistics of copper retained reserves by the end of 1998): 8.8% in the eastern coastal region; 48.6% in the central region, and 42.6% in the western region.

In terms of deposit size, copper grade, components, regional distribution, and mining condition, the copper resources of China are characterized by the following features:

1) More medium- and small-sized deposits and less large- and super-large deposits.

The copper deposits with reserves more than 2,500,000 tons are only the Dexing copper field in Jiangxi (Tongchang deposit-5,240,000 tons), Yulong copper deposit in Tibet (6,500,000 tons), Jinchuan copper-nickel deposit in Gansu (3,400,000 tons of copper), and Dongchuan copper field in Yunnan (5,000,000 tons). Among the deposits explored, large and super-large sized ones account for only 3% and medium-sized ones 9%, while small-sized ones account for 88%.

2) More poor ores and less rich ores.

The average grade of copper ores is as low as 0.87% in China, and the copper reserves

Table 3.7.1The principal copper deposits of China

¢Ù There are 72 deposits (onefields) in the Chinese edition of the book , but here only some larger deposits are listed in the English version. The numbering of deposits in Fig. 3.7.1 is the same as in the table.¢Ú According to the "Standards for Classification of Deposits by Size" issued by the National Committee of Mineral Reserves in 1987, copper deposits with reserves over 500,000 tone are classified as large-sized ones, those with 100,000~500,000 tons are medium-sized ones and those with reserves less than 100,000 tons are small-sized ones.

with grade >1% account for about 35.9% of the country's total. Among the large-sized deposits, the reserves with grade > 1% only amount to 13.2% of the total.

3) More deposits of composite ores and less deposits of unitary ores.

Among more than 900 deposits, those of unitary copper ores account for only 21.1%, while the deposits of complex ones amount to 72.9%, having large potential in comprehensive utilization. A number of copper mines recovers a considerable amount of Au, Ag, platinum group elements, In, Ga, Ge, Tl, Re, Se, Te and a large number of S, Pb, Zn, Ni, Co, Bi, As and others in the process of copper concentrate production.

4) More deposits suitable only for underground mining and less deposits for open-cut mining. At present the majority of large- and medium-sized deposits of state-run mines are mined underground, with few deposits suitable for open-cut mining.

The geological features of Chinese copper deposits are as follows:

1) Relatively concentrated metallogenetic epoches. Although copper deposits were formed from the Archaean to the Tertiary in varying degrees, they are mostly occur in the Mesozoic and then in the Meso-Neoproterozoic and Cenozoic. According to the statistics of Wang Zhitian, the proportion of copper reserves of different epoches are 0.6% in the Archaean, 7.8% in the Palaeoproterozoic, 16.5% in the Meso-Neoproterozoic, 3.5% in the early Palaeozoic, 6.2% in the late Palaeozoic, 49.8% in the Mesozoic, and 15.3% in the Cenozoic.

2) Relatively concentrated metallogenetic space distribution. Judging from the copper reserves explored, they are distributed mainly in northeastern Jiangxi, the middle and lower reaches of the Yangtze, the Qilian Mountains and its adjacent areas, the Zhongtiao Mountains, Xichang-central Yunnan, the Sanjiang area, as well as the Nenjiang area of Heilongjiang, eastern Inner Mongolia and so on. The copper reserves explored in these metallogenetic regions and zones account for more than 80% of the country's total.

3) Close relation of metallogenetic evolution with the crust property and the development of geotectonics. The continental crust of China has accreted on the base of several ancient plates. With an old continental block as the core and accretionary fold belts of various times as the edges, it accreted and developed gradually outward, resulting in the development of volcanic-plutonic magmatic rocks, sedimentary series and related large and medium-sized copper deposits progressing towards the plate margins in space, and getting younger and younger in time. Therefore the large and medium-sized copper deposits in China mostly occur in the platform margins, edges of the accretionary fold belts and the intracontinental fault depressions (Wang Zhitian et al., 1994). As the crustal movement in China is characterized by multicyclic evolution, with a variety of sedimentation types and frequent tectonic-magmatic activities, the deposits were reworked and metamorphosed after their formation, resulting in inheritance, superposition and coexistence. Hence there are some composite ore deposits of various origins, accompanied by a number of useful components. Therefore, there are few unique copper deposits, but a lot of paragenetic deposits in China.

4) Formation of large deposits in small igneous rock bodies. Copper (molybdenum) deposits of porphyry type associated with magmatic rocks, copper deposits of skarn type, and copper-nickel deposits of mafic and ultra-mafic rock type in principle are related to small rock bodies in China. For example, the exposure areas of the porphyry bodies related to the Tongchang, Zhushahong and Fujiawu deposits of the super-large Dexing copper field are 0.7 km2, 0.06 km2 and 0.16 km2 respectively; the exposure area of the porphyry body of the large-sized Wunugetushan copper (molybdenum) deposit is 0.5 km2. Some large and medium-sized copper deposits of skarn type are also related to small rock-bodies genetically. For example, the rock-body exposure area of the Tongguanshan deposit (Anhui Prov.) is 1.5km2, that of the Wushan deposit (Jiangxi) is 0.6 km2, and that of the Xinshan copper-tin deposit (Yunnan)-0.32 km2. The metallogenic rock bodies related to copper-nickel sulphide deposits are also small in area. According to the statistics made by Prof. Tang Zhongli the metallogenic bodies related to Chinese copper-nickel sulphide deposits are generally less than 0.1 km2 in area and there are only three metallogenic bodies with exposures reaching 1 km2 in area (Jinchuan deposit in Gansu, Chibaisong deposit in Jilin, and Dapoling deposit in Guangxi). Moreover, small rock-bodies usually have a high rate of ore beatingness. For example, the ore bearingness of the Jinchuan deposit's rock-body is 47%, that of the Kalatongke No. 1 rock-body in Xinjiang is 60%, and that of the Hongqiling rock-body in Jilin is 96%. All these characteristics are quite different from those of the deposits of the same type, or similar deposits abroad.

5) Two big ore-forming series. The large and super-large copper deposits in China can be classified into two big ore-forming series by and large (Pei Rongfu, 1990): (i) Cu-Ni sulfide deposit associated with tectono-magmatic intrusion¡úFe-Cu (Au) deposit of skarn type¡ú Cu (Mo, Au) deposit of porphyry type¡údikelike copper deposit; (ii) massive sulfide Cu-Zn deposit and Cu-Au deposit of volcanic-rock type associated with volcanic eruption-sadimentation¡úCu (Pb Zn) deposit, hosted by sedimentary rocks.

6) The main metallogenic types. Copper deposits of China are of great economic significance, and mainly the copper deposits of Cu-Ni sulfide type, porphyry type, skarn type, volcanic type, and stratiform type in sedimentary rocks, as well as copper deposits of continental sandstone type in China are exploitable. The reserves of the four former types account for 90% of the country's total. Based on the results of the researches made by Rui Zongyao et al. (1993) and Wang Zhitian et al. (1994), the various types of copper deposits are introduced in order of their significance as follows:

The porphyry type. It is the most important type of copper deposits in China, with the explored reserves of such deposits making up 45.5% of the total. The deposits of this type usually are of great size, with ore bodies occurring in groups and zones and at shallow depths, so they permit open-pit mining. Their ores are easy to dress and are associated with Mo, Au, Ag and a variety of rare and dispersed elements, thus allowing to make overall development and multipurpose application. The Dexing copper (molybdenum) deposit (Jiangxi), the Duobaoshan copper (molybdenum) deposit (Heilongjiang), the Wunugetushan copper (molybdenum) deposit (Inner Mongolia), and the Yulong copper (molybdenum) deposit (eastern Tibet) are typical of this type.

The skarn type. The copper deposits of skarn type in China are quite different from those abroad. The reserves of this type of deposits abroad only occupy a very small proportion, while those in China constitute a large proportion. making up 30% of the country's total. Therefore, such deposits have become one of the important sources of mineral raw materials for China's copper industry. The skarn type is the second major type of copper deposits, only next to the porphyry type in China. Furthermore, deposits of this type are composed mainly of high grade ores and associated with Fe, Pb, Zn, W, Mo, Sn, Au, Ag, as well as rare and dispersed elements, having a great potential in multipurpose application. The Tonglushan deposit (Hubei), the Chenmenshan and Wushan deposits (Jiangxi), the Tongguanshan, Shizishan and Dongguashan deposits (Anhui), and the Shouwangfen deposit (Hebei) are typical of this type.

The volcanic rock type. It is also an important type of copper deposits in China. The explored copper reserves of this type account for 8% of the total, in which the copper reserves of marine volcanic rock type occupy 7%, while those of continental volcanic rock type constitute 1%.

Previously the copper deposits of marine volcanic rock type were traditionally called copper deposits of pyrite type. They are always associated with lead and zinc, as well as abundant gold, silver, cobalt and rare and dispersed elements, suggesting a great potential value of multipurpose utilization. Deposits of this type include the Baiyinchang copper (lead, zinc) field (Gansu) and the Hongtoushan copper-zinc deposit (Liaoning). The recently discovered Zijinshan large copper-gold deposit (Fujian) is typical of the continental volcanic rock type.

The copper-nickel sulphide type. The copper-nickel deposits in mafic and ultramafic rocks are not only the most significant source of nickel resources in China, but also an important type of copper deposits. The copper reserves of this type account for 7.5% of the country's total. The Jinchuan copper-nickel deposit (Gansu), the Hongqiling copper-nickel deposit (Jilin), the Kalatongke copper-nickel deposit (Xinjiang), the Huangshan copper-nickel deposit, and the Limahe copper-nickel deposit (Sichuan) are typical of this type.

The stratiform type in sedimentary rocks. Copper deposits of this type referr to stratiform copper deposit, with sedimentary or sedimentary-metamorphic rocks as their host rocks, which may be completely normal sedimentary formation, or extrusive-sedimentary formation including tuff and volcanic tuffaceous rocks (containing less than 50% of volcanic materials usually). Prof. Tu Guangzhi et al. (1984) classified sedimentary copper deposits of China into two types: ¢Ù sedimentary-metamorphic: for example, the Palaeoproterozoic Henglingguan copper deposit, the Mesoproterozoic Bizigou copper deposit, the Early Paleozoic Liwu copper deposit; and ¢Ú sedimentary-reworked: for example, the Moso (Neo) proterozoic Huogeqi and Dongchuan-Yimen copper deposits and the Cretaceous Dianzhong sandstone copper deposit.

The continental varicolored rock type. The Chinese Ore Deposits names it as continental copper sandstone type. The deposits of this type conventionally are called red bed copper deposits. Now although the explored reserves of this type of deposits are limited, only accounting for 1.5% of the country's total, yet the copper grade is high, ranging between 1.11£¥~1.81%, with silver and selenium associated. The Dayaoliudao copper deposit and the Haojiahe copper deposit (Yunan), and the Chejiang copper deposit (Hunan) are typical of this type.