Metallogenic Distinction of Mercury in China
Metallogenic Distinction of China’s mercury deposits are as follows:
1) The deposits are relatively concentrated in time and space. Most of the known mercury deposits (or occurrences) in China belong to late Mesozoic time. Of the mercury deposits listed in the Notes to the Metallogenic Map of Endogenetic Metallic Deposits in China (1987), 91% are metallogenically of Yanshanian age; and mercury mineralization of Himalayan age can also be found in western Yunnan, Tibet and Taiwan. In spatial distribution, there can be distinguished four major metallogenic regions or belts: the upper Yangtze, the Kunlun-Qinling, the Sanjiang and the South China. The upper Yangtze is the most important mercury metallogenic region in the country, of which the known mercury deposits are distributed mainly in the west-central part of the Yangtze paraplatform, i.e. in southeastern Sichuan, western Hunan, and central, northeastern and southwestern Guizhou. It is the metallogenic region with most abundant explored mercury reserve (accounting for over 75% of the country’s total).
2) The mercury metallogeny occurs mainly in platform region. China’s mercury deposits are located at the favorable junction between two global mercury metallogenic belts (circum-Pacific and Mediterranean). They can be found both in platform and geosyncline regions, but occurring mainly in platform region. The country’s known superlarge and many large mercury deposits are primarily distributed in the Yangtze paraplatform and concentrated in the border area of Guizhou, Hunan and Sichuan. Stratigraphically, the deposits, except one or two, occur in the Middle and Lower Cambrian and have a regional stratabound characteristic. They are large in size, mostly zonal or layered in shape, and contain the aggregate explored reserve accounting for over 80% of the country’s total. In addition, they are densely distributed and occur in swarms or clusters.
3) Host rocks of China’s mercury deposits are chiefly sedimentary, and very few are magmatic and metamorphic. According to He Lixian et al. (1989), the mercury deposits (occurrences) in sedimentary rocks make up 97% of the country’s total, and 91% of their explored reserves occur in carbonate rocks. Only 3% of the country’s mercury deposits are in various types of magmatic and metamorphic rocks. Most of the deposits (occurrences) of China are distant from magmatic rocks and exhibit no metallogenic relationship with magmatism.As the professional manufacturer of complete sets of mining machinery, such as cone crushers,cement mill, Henan Hongxing is always doing the best in products and service.
4) On the basis of their ore-bearing sequences (formations), China’s mercury deposits can be divided into three types: carbonate, clastic and magmatic (He Lixian et al., 1989). An ore-bearing sequence is a reliable geological body with clear indicators. It not only reflects the geological background, metallogenic setting and ore-forming mode, but also facilitates the search for mercury deposits. Basic characteristics of the three types of mercury deposit are described below:
The carbonate type is most important in China. The aggregate explored mercury reserve of deposits of this type occupies more than 90% of the total of deposits of all the types. All of the superlarge mercury deposits in the country, such as the Wanshan ore field and the Shuiyinchang deposit in Guizhou, the Yangshikeng deposit in Sichuan and the Gongguan deposit in Shaanxi, belong to this type. Deposits of this type, located predominantly on the Yangtze platform, are markedly stratabound and controlled chiefly by anticline. Most of their orebodies (ore-bearing bodies) occur in layers along the beds, with some being vein-like or in other shapes.
Deposits of the clastic type are distributed mainly in the middle segment of the Kunlun-Qinling geosynclinal fold belt and the southern segment of the Yunnan-Tibet geosynclinal fold belt. Their basic characteristics are as follows: The mercury deposits (or occurrences) are all of a certain polymetallic metallogenic region (or belt) and commonly associated with other metals, forming Hg-dominant Hg-W deposits (e.g. the Muhei Hg deposit in Qinghai) and Hg-Cu deposits (e.g. the Wenshuihe Hg deposit in Yunnan); near them there are intense magmatic activities and usually small intrusions of various kinds; the ore-bearing sequence is often intercalated with volcanic sediment, has a high content of Hg, and thus is most probably the direct source of the mineralizing material.
Deposits of the magmatic type are very few in number and small in size. Some mercury deposits (occurrences) occur in granitoids and are distributed mainly in the northeast of the country (e.g. the Yingfenggou mercury deposit in Dunhua, Jilin Province), while others occur in basic intrusive dikes and their adjacent country rocks (e.g. a deposit in the Baoshan-Shidian mercury belt in western Yunnan).
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