1.Laminar control characteristics of mineralization in China's rock gold deposits
1) Most rock gold deposits are produced in a particular ore-bearing formation in a certain geotectonic environment. The deposits (points) are densely distributed and distributed in groups, and their extension is consistent with the overall occurrence of the formation.
2) The gold abundance of mineralized surrounding rock is often several times to several tens of times greater than the abundance value of similar rocks in the crust.
3) The isotopic combination characteristics of most gold ore bodies and surrounding rocks are basically similar. For example, in the Wenyu gold deposit in the Xiaoqinling area of ​​Henan Province, the ore isotope δ34S is 1.35‰, the sulfur isotope δ34S of the Yangzhaitun ore is 1.55‰, the gold hole ore δ34S is -3.58‰, and the δ34S of the two mining areas is 3.39‰. It shows that ore sulfur is similar to formation sulfur. This shows that the ore-bearing layer is often the source layer.
4) The strata produced by China's rock gold deposits are dominated by Taiguyu, followed by gold deposits in Yuanguyu, Paleozoic and Mesozoic, but the degree of development varies. There are metamorphic rocks, sedimentary rocks and igneous rocks in the mineralized surrounding rocks, and their mineralization conditions are different. The current layer control of its main mineralized areas is summarized as follows:
(1) Gold deposits in the North China Platform Gold deposits (points) are concentrated in the edge of the plate and the uplift of the basement tectonic layer, and are mainly produced in the mid-deep metamorphic rocks of the Taiguyu crystalline basement.
1 The gold deposits in the Yanshan gold deposit area are concentrated in the Shanhaiguan and Miyun uplift areas, and the ore-bearing rock formation is the Tailan Yuqian West Group Malangyu Formation. This group has a strong mixed lithification effect. The rock layer contains gold abundance of 0.7 to 0.83 × 10-6, which is 25 to 200 times higher than that of similar rocks. There are 115 gold deposits (points) known in the area, and 109 of them are produced in this rock formation.
2 More than 80% of the gold deposits (points) in the dense area of ​​Jianping-Beipiao Gold Mine in western Liaoning are concentrated in the Jianping uplift area. The ore-bearing rock stratum is the slanted amphibolite and the oblique long-horned gneiss of the Jiantai Group Xiaotazigou Formation.
3 The Jiapigou gold ore gold deposit is mainly produced in the hornbeam slant gneiss, the black cloud slant gneiss, the slanted amphibolite and the amphibolite in the lower part of the Sandaogou Formation of the Yu'anshan Group in Taikoo. The gold abundance value of the surrounding rock averages 41.5×10-9. According to the study of 320 sulfur isotopes, the ore sulfur δ34S averaged 5.6 ‰; the surrounding rock sulfur δ34S was 2.1‰. The two are similar and the sulfur source is the same.
4 Xiaoqinling gold ore field: The surrounding rock of the gold deposit is the lower group of the Taihua Group. The rock types are the oblique long-horned gneiss, the black cloud slant gneiss and the oblique amphibolite. The gold abundance value of the rock formation is 1.24×10-9 on average. The average δ34S of the gold mine is 2.71‰, which is nearly equal and has a close twin relationship.
The surrounding rock of each area is restored to the base-medium volcanic rock by the original rock. The rock is dark green, also known as the green rock system. This gold-bearing construction is the original source layer of the gold mines in the area. It is not only the source layer of metamorphic hydrothermal gold deposits, but also an important source layer of other types of gold deposits in this area.
(2) The gold deposits in the Jiangnan Gulu gold deposit metallogenic belt are mainly distributed in the Xuefeng uplift of the Jiangnan ancient land and the two areas of the Mufushan uplift. Its gold deposit (dot) in 95% yield Proterozoic Lengjiaxi group and Banxi tuff containing sericite slate, sandy slate, which is a primary argillaceous rock, tuff clastics . There may be volcanic sedimentary rocks locally. The gold abundance value of the rock formation is 0.0012-0.03 g/t, the ore δ34S is 2.85‰, and the surrounding rock δ34S is 7.9‰.
(3) The gold deposits in the Nanling gold deposit metallogenic area are mainly distributed in the Dayaoshan trough anticline and the Yunkai uplift area. According to statistics, about 74% of the gold deposits (points) in the Guangdong and Guangdong provinces are concentrated in the Cambrian area of ​​the area. It is in the rock formation of the Eight Villages. The Cambrian in the area is constructed as a set of geologic-type flysch clastic rocks, with multi-layered carbonaceous shale and carbonaceous sandstones with a carbon content of up to 10%. The surrounding rocks of the gold deposit are mainly siliceous rocks, carbonaceous shale and carbonaceous clastic rocks.
The rock layer contains gold abundance values. According to the chemical spectrum analysis of Nanjing University, the average carbonaceous shale is 32.5×10-9; the argillaceous sandstone is 4.4×10-9. According to the analysis of Guangxi Metallurgical Company, the sandstone is 80×10-9, and the carbonaceous shale is as high as 130×10-9, which is obviously higher than the Clark value of gold.
In the mining areas such as Taohua, Gupao and Yunling, the ore sulfur δ34S ranged from -0.9‰ to +6.4‰ and 1.05‰～8.2‰, showing the properties of shell sulfur. The lead isotope age of the Peach Blossom Mine is 729-785 Ma, which is older than the Cambrian and Caledonian granites . Therefore, it is believed that the ore-forming materials in this area are from deep, and also from the Cambrian gold-bearing ore source layer.
The northern part of the area is adjacent to Jiangnan Ancient Land. Its basement is Yuanguyu Lengjiaxi Group and Banxi Group. This ancient gold-bearing stratum can provide a source of gold for the upper Cambrian of the area.
2. Construction control of gold mineralization
(1) Geotectonic pattern and spatial distribution of gold deposits China's gold deposits are obviously controlled by the regional geotectonic pattern. Although each area has gold mineralization distribution, it is extremely unbalanced and has its own characteristics, so it can be roughly divided into five. Gold mineralization domain.
1) North China-type gold mineralization area is the oldest platform in China. It is the Anshan group, the Jianping group, the single tower group, the Weiping group and the Taihua group. A set of metamorphic volcanic-sedimentary rocks with deep metamorphism and strong mixed lithification is a good trough phase. Among them, the abundance of basal volcanic rocks is generally high, which is the original source layer and the main source of gold in this area.
This area is the main gold mine distribution area in China. According to statistics, the number of gold deposits (points) accounts for more than 85% of the national total. Gold reserves account for 78% of the country's total reserves of rock gold. Gold deposits are mainly distributed in the edge of the platform and in the basement block uplift in the platform. The area mainly consists of regional metamorphic hydrothermal action, granitization and Yanshan magmatism, and the formation of ore deposits is a prominent feature. It is an excellent trough phase. The distribution of gold deposits is mainly metamorphic hydrothermal type and granitized hydrothermal type, followed by magmatic hydrothermal type and volcanic-subvolcanic hydrothermal gold deposit. The ore-bearing surrounding rock is the source layer and belongs to the near-source type. The ore-forming era was mainly the Paleoproterozoic and Mesozoic. There is great potential for prospecting.
2) The Yangtze-type gold mineralization domain has not formed a platform in the Neo-Proterozoic. The basement rock system is exposed to the edge of the platform. For example, the Kunyang Group on the axis of the western edge of Kangxi; the Lengjiaxi Group and the Banxi Group on the southeastern edge. The base inside the platform is exposed only at individual locations and is small in size. Such as the Huangling anticline of the Quling group. The basement is composed of argillaceous slate and metamorphic rocks. The original rock is a muddy tuffaceous clastic rock with a relatively low degree of metamorphism. The gold deposits in the area are mainly distributed in the uplift belt at the edge of the platform. The Xuefeng paleo-uplift on the southeastern margin of the platform and the gold deposits in the Mufushan uplift are more concentrated. The number of rock gold deposits (points) in the whole area accounts for 16% of the country. Reserves accounted for 7.8% of the national total. The area mainly consists of the regional metamorphic hydrothermal action of the Yangtze fold basement and the Paleozoic caprock dissolution by underground hot water. The type of gold deposit is mainly metamorphic hydrothermal fluid, followed by magmatic hydrothermal type and underground hot water deep filtration type gold deposit. The ore-bearing surrounding rocks are muddy tuffaceous clastic rocks and carbonates, and the ore-forming age is the Proterozoic and Mesozoic. The ore-forming material is derived from the surrounding rock or the lower basement structural layer.
3) The South China-type gold mineralization area belongs to the South China-Southeast Asia plate, located in the South China fold system section of the south of the Yangtze platform. This is a Caledonian trough fold system, and the fold basement tectonic layer is composed of the Sinian-Siluid system. For the construction of flysch, it is a shallow trough, and the degree of metamorphism is shallow. The main characteristics of the Early Paleozoic fold basement are regional metamorphism, hydrothermal action and the ore-forming mineralization of the Caledonian and Yanshanian magmatism. Gold deposits are mainly distributed in Dayaoshan and Yunkai uplift areas. Gold deposits (points) account for 13.3% of the national total, and reserves account for 4.7% of the total national gold. The gold mine type of Guixi is a carbonate quartz calcite vein type; the junction of Guangdong and Guangxi is a metamorphic hydrothermal type and a magmatic hydrothermal type. The mineralized surrounding rocks are Cambrian carbonaceous clastic rocks, Carboniferous carbonate rocks and medium-acid intrusive rocks. The ore-forming materials are from the deep tectonic layers. The metallogenic age is mainly the Caledonian period, followed by the Yanshanian period.
4) The Pacific type gold mineralization area is affected by the subduction of the Pacific plate in the eastern part of China, forming a large-scale mid-Cenozoic continental plate marginal active belt. Its outstanding feature is that the Mesozoic NE-trending structure is extremely developed. The other is the formation of a huge Mesozoic volcanic belt. It faces the Heilongjiang River in the north and the south beach in the south, with a length of more than 3,000 km and a width of 300 to 800 km. Volcanic rocks range from medium to acidic, with acidic rocks.
A variety of endogenous deposits are often formed with intrusion and eruption activities. China's volcanic-subvolcanic hydrothermal gold deposits are mainly produced in this zone. Such as unity ditch, ditch Nailin, Chiwei ditch, Mount Holyoke, copper wells, two Qi ditch, Babaoshan gold deposit, in addition, still distributed magmatic hydrothermal type gold deposits. The former is mainly produced at the edge of the Mesozoic fault basin and is controlled by a certain fault structure.
5) Tianshan-Xing'an type gold mineralization area The area is located in the Paleozoic trough between the Siberian plate and the Tarim-Zhongchao plate, which is a huge east-west curved Haixi fold belt. The Haixi period magmatic rocks in this area are widely distributed and the near-East-West fault structure is developed.
The area is famous for its rich gold. Rock gold is only distributed in the east and west Junggar, Tianshan and Jiamusi uplift areas. Gold mineralization is mainly characterized by the activity of the granite in the Hercynian and Yanshanian periods. The gold deposits (points) in the region account for 7% of the country, and the reserves account for 3% of the total national gold. The northwestern part of the area is dominated by magmatic hydrothermal type, the metallogenic age is mainly in the Hercynian period, and the northeast is dominated by subvolcanic-volcanic hydrothermal type, followed by metamorphic hydrothermal gold deposit. The metallogenic age is mainly the Yanshanian period, followed by the Hercynian period.
In summary, you can clearly see:
1 Different geotectonic units have different characteristics of gold mineralization and gold mineralization, each with its own characteristics.
2 China's gold mines are mainly distributed in the eastern region and are mainly distributed in the ancient Sino-Korean plate.
3 The gold deposits in the eastern part of China are obviously controlled. The ore-forming materials are mainly from the source layer of the ancient basement; the rock control and deep fault control of the western gold deposit are more obvious, and the main source of ore-forming materials is the basic-ultrabasic rock.
4 China's volcanic-subvolcanic hydrothermal gold deposits are mainly distributed in the continental marginal active belt of the Mesozoic in the east.
(2) Control of gold deposits by regional structure 1 Most of the main metallogenic belts in China's gold deposits are distributed on the edge of ancient plates, and the ancient island-shaped uplift zones of the suture boundary, such as the Yinshan-Yanshan metallogenic belt and the Qinling-Dabie mountain metallogenic belt, respectively Controlled by the uplift boundary of the northern and southern margins of the North China Plate. 2 The uplifting zone such as the platform anticline and the groove anticline in the plate controls the distribution of the secondary metallogenic belt (zone) or the mineralized concentration zone. For example, the Jianping uplift area of ​​the North China plate, the Shanhaiguan uplift, the Jiaodong uplift, and the Wufengjia uplift are all concentrated areas of gold deposits. 3 The ancient basement of the Sino-Korean plate developed two major fault zones, the east-west and the north-east, and the large gold deposits were usually found near the intersection. For example, the obvious north latitude 40° fault zone and the 42° fault zone intersect with the NE trending fault, which controls the distribution of several important large gold deposits and shows a certain equidistant distribution. 4 Large gold deposits are produced in the lateral secondary fractures of large faults, and the distance from large faults is generally 2-8 km. Most of the large gold deposits are located in the narrow section of the shaft with a strongly compressed anticline or inverted anticline. For example, the large gold deposits such as Wenyu, Yangzhaiyu and Jindongyu in the Xiaoqinling ore field are distributed in the shaft of the old Yalong inverted tilting anticline. Wulong Gold Mine is located in the shaft of the Wulong anticline.
(3) The granitic magmatic rocks control the gold deposits. The spatial distribution of gold deposits is often associated with granite intrusions, and some deposits of gold ore bodies are directly produced in rock masses or contact belts. This phenomenon indicates that gold deposits There is active participation in magmatic rock activity during the mineralization process.
According to the study of modern petrology, granites are divided into two categories according to their causes, the source type and the crust remelting type. However, many data indicate that the granites most closely related to gold are mainly products of remelting and regenerating of basement metamorphic rocks. China, Shandong, Liaoning, Jilin, Guangdong and other provinces have such gold deposits.
The gold metallogenic belt is accompanied by the intersection of deep and large faults controlling various mineralizations and various magmatic rocks, indicating that the gold matter below the crust participates in mineralization, in the ultrabasic rocks Ni, Co, Pt The gold content in the etc. is high and forms an independent gold ore body. In line with this, gold deposits such as Yunnan Mojiang Gold Mine, Qinghai Xiaosong Tree South Ditch and Xinjiang Tori are accompanied by ultra-basic rock mass and have obvious birth. Relationship is a convincing example. The same conclusions have been drawn from the study of isotopes in gold-bearing sulfides.
According to the actual data, the relationship between gold mineralization and significant magmatic rocks three times, first Caledonian granite, mainly in the Eastern Trough Area Hua Nan Jiali, lithology porphyritic granodiorite and granitic porphyry Quartz porphyry, etc. For example, the average content of the Daning rock mass—the biotite diorite and the plaque granodiorite—is 9×10-9 and 3.7×10-9, respectively. The Longshui and Zhanggongling gold deposits are formed in the contact zone between the rock mass and the Cambrian stratum. Second, the Hercynian magmatic rocks are mainly distributed in the Hercynian fold belts in the northwest and northeast of China. Most of the ore-controlled ore deposits are derived from rocky bases, rock strains and rock branches in the mid-late and late granitic granitic rocks, granodiorite and monzonitic granites. According to statistics, more than 50 gold deposits (points) have been discovered in the area, most of which are produced in or near the rock mass. The third is the structural magmatism of the Yanshanian period. Many endogenous gold mines in China are closely related to this activity, especially in the eastern region. For example, the reserves of gold mines belonging to this type in the western Liaoning region account for 22% of the total amount of the province. The Yan'er Cliff, Baizhangzi, Jinchangyu and Sanjiazi in the Yanshan area are related to the Yanshanian medium-acid small intrusion, Henan Xiaoqinlingjin The northern part of the ore field is exposed from the west to the east: Huashan Rock Mass, Wenyu Rock Mass, and Niangniang Rock Mass. They are all Yanshanian products. The rock mass contains gold and is found in gold deposits in local areas.
The above facts can be summarized and the following conclusions can be drawn:
1) The composition of the stratum basement has a great influence on the mineralization of gold deposits, and is the material basis for the formation, evolution and inheritance of deposits. Its ancient Archean green rock series is the initial mineral source of gold mineralization and the main ore-bearing layer of gold deposits.
2) The comprehensive geological function of structure and magmatism is an indispensable condition for gold mineralization.
CNC Aluminum Parts,CNC Aluminum Machining,CNC Machining Aluminum,CNC Machined Aluminum Parts
Grand Nakamura Mechanical and Electrical (Suzhou) Co., Ltd. , https://www.gns-mp.com