Abstract The relationship between structure and mineralization of gold ore Sichuan, Shaanxi, Gansu triangle from both the Structural Ore mineralization role and power, the basis of summarizing the zone type gold deposits, genesis, geochemical characteristics of the geology on Three gold mineralization systems in the Sichuan, Shaanxi and Gansu triangles are proposed: (1) gold mineralization system in the South Asian belt of the Western Qinling; (2) metallogenic system of the Motianling fold belt; (3) Northeast Zhuangjin Mineral ore system. The metallogenic series of the gold-forming ore-forming system of the Motianling fold belt was further studied.
Key words: Qinling gold deposit, metallogenic series, ore-forming system, Sichuan, Shaanxi, Gansu area, regional structure, ore-controlling
The geographical areas of Sichuan, Shaanxi and Gansu are generally triangular areas surrounded by Jixian-Luoyang-Kangxian-Wudu (north) and Qixian-Yangpingguan-Qingchuan-Pingwu (southeast). The geotectonic position is at the junction of the Yangtze platform, the Qinling and the Songpan-Ganzi fold belt. The north is connected with the Qinling orogenic belt by the Jixian-Liaoyang-Kangxian-Wudu deep fault, and the south is connected with the Yangtze platform by the Yangpingguan-Jianxian deep fault as a triangle-shaped wedge. Land plot.
According to its structural features, the Sichuan, Shaanxi and Gansu triangles can be divided into four zones by “triangle” and “three sides and one center”. The Jinning Movement, the Caledonian Movement, the Hercynian Movement, the Indo-Chinese Movement, and the Yanshan Movement made the structure extremely complex and distinctive, especially the Caledonian Movement, the Hercynian Movement, and the Indo-Chinese Movement, in which the extrusion-napping- Shearing is an important structuring effect in this area.
North Side (I District): It belongs to the South Asian Belt of the Western Qinling. It is mainly the fold-forming orogeny of the sedimentary caprock (∈-OSDCPTJK), accompanied by the nappe-shear phase, and has certain magmatic activity. The rift of the northern margin of the Early Paleozoic Yangtze plate along the Ningshan-Baihe to the Ziyang-Hongtangba fault, through the Bailong River to the northwestern Sichuan, developed a set of black rock series characterized by siliceous rocks and mudstones; In the Late Paleozoic, the Devonian sediments were the main body, and the sedimentary basin was the fault-depression basin. The sedimentary group was dominated by clastic rocks and carbonate rocks, and the development of flysch in some areas. The Indosinian orogeny was superimposed. The sedimentary facies belt distribution and paleogeographical pattern of the Paleozoic were reconstructed, and a series of tight linear folds were developed near the collision boundary. A series of shear and nappe structures appeared from north to south. The collision stress of the Mesozoic and Cenozoic occurred strongly. The magma activity and slippage are stripped. In the Indosinian collisional orogeny and the Mesozoic and Cenozoic stress return, the Silurian to Devonian hot water jet or hot water activity is the main reason for the formation, migration, enrichment and mineralization of gold-bearing fluids.
Southeast (II): The narrow tectonic belt (Silu sedimentary basin) between the Motianling fold belt and the Yangtze platform. After the formation of the Silurian strata, the magmatism and metamorphism are not very strong, but due to the extrusion-pushing of the two terrane bodies, the parallel Yangpingguan-Jianxian deep fault has produced a series of brittle-ductile shear zones. Deformation-metamorphism is the main reason for gold mineralization.
West Side (Zone III): It belongs to the Songpan-Ganzi fold belt.
The center of the "triangle" (zone IV): the fold belt of the Motianling. Simply speaking, it is a proliferating block, from the northern fish hole terrane (the ancient paleo-forms formed by the Archean-Proterozoic crater cleavage, isotopic age 2600 Ma, Wang Xin et al., 2000) and the southern Bikou terrane (Zhongxinyuan ancient proliferating terrane, isotopic age 700~1500 Ma, Wang Xin et al., 2000). In the Neoproterozoic, the ancient North China-Yangtze unified craton began to crack, and there was a rift in this area, accompanied by a basic volcanic eruption, forming the lower part of the Bikou group; the southern part of the Qinling rift in the Neoproterozoic cracking debris-fish hole terrane Drifting southward, colliding with the Bikou hyperplastic terrane, entering the orogenic stage, and invading the basic-ultrabasic rock in the splicing zone, forming the basic-super-basic rock mass around the terrane (Jinning period) The Caledonian movement is mainly for uplift and fold, with inherited magmatic activity; the Hercynian and Indosinian tectonic processes are strong, and the development of medium-acid magmatic activity (granite porphyry, diorite porphyry intrusion); Yanshanian period The main structural effects are extrusion-pushing-shearing and slipping.
2 Gold deposits in Sichuan, Shaanxi and Gansu triangles
According to incomplete statistics, more than 50 rock gold deposits have been discovered in the area, and the accumulated proved reserves are nearly 400 tons. Together with its rich gold deposit, it is called the “Golden Triangle”. In recent years, successive discoveries of new types of large-super large gold deposits such as Dashui, Yangshan, Gansu, Jinlongshan and Dingjialin in Gansu have shown the prospecting potential of huge gold deposits in this area. [next]
According to the surrounding rock environment of gold deposits, there are mainly four types of gold deposits in the Sichuan, Shaanxi and Gansu triangles (Zhou Jiangjun, 1997) (Table 1): 1 gold deposits produced in intrusive rocks; 2 produced in volcanoes - gold deposits in subvolcanic rocks; 3 gold deposits produced in sedimentary rocks; 4 gold deposits produced in tectonic rocks.
Table 1 clearly shows that the large-super large gold deposits are mostly gold deposits produced in sedimentary rocks; they are distributed in the I zone (the South Asian belt of the Western Qinling). There are two main causes, one is the dynamic cause, the other is the hydrothermal fluid of the magma, which has obvious layer control and is closely related to the fold structure; it is produced in the intrusive rock and is produced in the volcanic-subvolcanic rock. The gold deposits are basically distributed in the IV area and are produced along the periphery of the IV area. The northern margin of mineralization is stronger than the southern margin. The ore-forming is closely related to the magmatism of the basement and the basement margin, mainly the magmatic hydrothermal (reform) genesis; The overall size is not as good as that of gold deposits distributed in sedimentary rocks in Area I. The gold deposits produced in the tectonic rocks are only the Dingjialin gold deposit, which is distributed in the II zone. Its metallogenesis is closely related to the extrusion-push-shear-shearing effect, which is a typical dynamic mineralization.

[next]

    3 Dynamic mineralization
Dynamic mineralization refers to the formation of mineral deposits due to tectonic movement (action), deformation and metamorphism of existing rocks (earth matter), and the reorganization or migration of material components to form deposits. It includes three important aspects: 1 mineralization energy: structural (sports) role to provide mineralization energy - mainly kinetic energy, kinetic energy is converted into heat. The tectonic movement produces collision, shearing, and extrusion, which causes the rock (earth matter) in motion to heat up, deform, and deteriorate. The whole system exists in a dynamic thermal system, and the ore-forming material is activated. The conversion of energy is generally the conversion of kinetic energy into heat energy; 2 the source of mineralization: the rock itself is provided with the source of mineralization, and the whole system is a semi-closed system (equal chemical system) - the total composition of the whole system is basically without In and out (or may participate in atmospheric precipitation), only the reorganization or migration of material components leads to local enrichment - mineralization; 3 mineralization sites: large and small structures formed by tectonic action. The tectonic mineralization can be divided into different types according to the nature of the tectonic action. The main findings are the folds (folding) acting on mineralization and shearing. Shearing mineralization is divided into brittle shearing ore-forming, ductile shearing ore-forming and over-type of the two. The most important feature of dynamic mineralization is overall activation and local enrichment.
Pleated (folding) action The ore system refers to tectonic movement (action) to cause the rock to wrinkle (fold). During the process of rock fold (folding), the structure of the activated material (which can be called tectonic thermal fluid) is due to the "potential difference" ( Mainly the pressure difference), from the high potential (high pressure) zone to the low (low pressure) zone to the enrichment, mineralization or mineralization. Since the low pressure zone of the pleats (folds) is mainly the collapse of the core of the folds (folds), the interlaminar slippage of the folds (folds), and the pleats (they are all free spaces), mineralization often occurs at these locations.
Shearing ore-forming system refers to tectonic movement (action) to cause shear deformation of rock. In the process of shear deformation, along with the fine granulation of rock, the structure of activated matter (which can be called tectonic thermal fluid) is due to The effect of the potential difference (mainly the pressure difference) is transferred from the high-potential (high-pressure) zone to the low-potential (low-pressure) zone until enrichment, mineralization or mineralization occurs. The low potential (low pressure) zone of brittle shear is mainly free space such as shear crack, while the low potential (low pressure) zone of ductile shear is mainly the weak strain zone of strong strain zone (non-free space). The undeformed rock does not form the above-mentioned free or non-free space, so the low-pressure (low-pressure) zone of the shearing action exists only in the strong deformation zone, and the mineralization associated therewith only occurs in these parts.
This region is typical of gold JINLONGSHAN fold (fold) effect of the mineralization, mine (vein) form pleats along one for the gold-quartz core portion anticline split distribution - calcite veins and surrounding rock sides CLEAVED The feather is not continuous; the other is the mineralized surrounding rock formed along the anticline north wing interlaminar slip plane (distributed along the interface of D3n and C1y strata). Gold deposits such as Qingmuchuan, Yuquanba and Bahai are typical brittle-ductile shearing mineralization, and Dingjialin gold deposit is a typical ductile-brittle shearing mineralization.
4 Gold deposit metallogenic system in Sichuan, Shaanxi and Gansu triangles
The endogenous gold deposits in the Sichuan, Shaanxi and Gansu triangles are either produced in the vicinity of the “triangle” center or on the “edge” of the strip, but the different types of deposits have significant differences in the types, scales and genesis of the deposits. That is, the special tectonic position and specific tectonic division determine the unique tectonic action and mineralization-metallogenic system. From the viewpoint of tectonic-diagenesis-mineralization (翟裕生, 1999), according to the tectonic dynamics system of gold deposits in the Sichuan, Shaanxi and Gansu triangles, the area can be divided into three gold mineralization systems: 1 West Qinling Gold mineralization system in South Asia; 2 gold mineralization system in the Motianling fold belt; 3 metallogenic system in the northeastern gold deposit.
The gold mineralization system of the South Asia Belt in the Western Qinling Mountains includes large-super large gold deposits such as Jinlongshan, Yangshan, Dashui and Lalma, as well as large gold deposits such as Shuangwang and Baguamiao, which are equivalent to the gold deposits in the South Asian Belt of the Western Qinling Mountains. Mineral belt. The common feature is that the gold mineralization has a certain layer control. The ore-forming power is derived from the Qinling orogen and its related extrusion-push-shear tectonics and related magmatism. Caledon-Haixi - Indosin - Yanshan - Himalayan period has mineralization. The ore-forming materials of the Jinlongshan and Lalma gold deposits are mainly from the surrounding rocks, while the ore-forming materials of the Yangshan and Dashui gold deposits are from the surrounding rocks and magmatic rocks. The reasons for the differences between the deposits are the location, mode, nature, strength, age of the tectonics, composition of sedimentary rocks, sedimentary facies, sedimentary basins, sedimentary ages, composition of magmatic rocks, mode of magmatism, intensity, age, and period. Different. [next]
The gold ore-forming system of the Motianling fold belt is equivalent to the surrounding area of ​​the fish-hole terrane and the Bikou terrane. It consists of gold deposits such as Qichanggou, Donggouba, Jianchaling and Lijiagou. It is produced in the northern belt) and gold deposits such as Bahai, Yuquanba and Qingmuchuan (basically small, produced in the southern belt). It is divided into two metallogenic series: 1勉 slightly suture zone gold ore metallogenic series: controlled by the slightly suture zone, the ore-forming materials are derived from volcanic-subvolcanic rocks (铧厂沟, 东沟坝) and basic-super Basic rock (Jianchaling, Lijiagou); 2 Yangpingguan fault gold deposit metallogenic series: is a typical dynamic diagenesis-metallogenic series; the ore-forming power is mainly from the south of the fish hole and the blue mouth Nappe (or the drift of the Yangtze platform to the north). Contains 2 metallogenic belts and 2 types of gold deposits. 1 Qingmuchuan-Yuquanba-Bahai gold ore belt: containing gold deposits such as Qingmuchuan, Yuquanba and Bahai, which are typical brittle-ductile shearing ore-forming, mainly composed of tectonic-type gold deposits, mainly ore-forming materials. It is derived from the middle-basic volcanic rocks of Bikou Group. The ore body and mineralization are continuous and the gold color is high. 2 Dingjialin-Yupingping Gold Belt: Contains gold deposits such as Dingjialin and Sunping, which are typical ductile and brittle shearing mineralization. It is mainly composed of quartz vein type gold deposits. The ore-forming materials are mainly derived from the Silurian Huangping Formation stratum (dark fine clastic rocks). The ore body and mineralization are discontinuous and the gold color is low. The gold deposit metallogenic system of the Dongzhai gold deposit is located on the west side of the “triangle”. It is controlled by the Songpan-Ganzi fold belt and is structurally different from the former three gold mineralization systems. Large gold deposits such as bridges are produced.
5 Conclusion
(1) The Sichuan, Shaanxi, and Gansu triangles can be divided into four structural sections by “triangle” and “three sides and one center”. The controlled (mineral) ore structure is the boundary fault zone of each structural division and the shear zone and fold structure associated with it. Most of the conditional beds are controlled by the fold structure;
(2) Whether it is the South Asian Belt of the Western Qinling Mountains or the Motianling fold belt, the dynamic mineralization associated with collisional orogeny plays an important role. The Jinlongshan gold deposit is a fold-forming tectonics, the Dingjialin gold deposit is a ductile-brittle shearing mineralization, and the Bahai and Yuquanba gold deposits are ductile shearing mineralization, which are all kinetic energy mineralization.
(3) The Sichuan, Shaanxi and Gansu triangles are divided into three gold mineralization systems. Among them, there are two metallogenic series in the metallogenic system of the Motianling fold belt gold deposit: 1 Jinluo suture zone gold ore metallogenic series, It is controlled by the suture zone and is related to the basement fault and igneous activity. It is a gold ore-forming series in the Yangpingguan fault zone. It is a dynamic mineralization associated with shearing.
(4) In the internal dynamic geological action of the chemical system, the tectonic action (motion) can provide labor and manufacturing space (site) for mineralization; and can complete mineralization independently.
References Wang Xin, Wang Ruiting, He Ying. 2000. Associated gold in Jianchaling and Jinchuan superlarge nickel deposits and their comparative analysis. Northwestern Geology, 21(1): 38~44.
Zhou Yanjun. 1997. On the classification of gold deposits. Gold Geology.
Gold Command of the Chinese People's Armed Police Force. 1997. Fine Dip-dyed Gold Deposit Geology of Jinlong Mountain, Shaanxi Province. Beijing: Seismological Press. 149~151.
Yan Shenghao, Wang Anjian, Gao Lan, et al. 2000. Geological characteristics and genesis of the Dashui gold deposit. Deposit geology, 19(2).
Bai Zhong. 1996. Discussion on the genesis of the Huangchanggou gold deposit in Shaanxi. Minerals and Geology, 10(52): 108~113.
Ren Wenqing. Zhou Dingwu. 1999. Structural magmatism formed by the Jianchaling gold, nickel and iron deposits. Northwest Geology, 32(2): 19~24.
Gao Hangxiao. 1999. Study on the source of ore-forming materials in the Lijiagou gold deposit. Non-ferrous metal minerals and exploration, 8(2): 86~91.
Yan Yusheng. 1999. On the metallogenic system. The frontier of geosciences, 6(1): 13~26.

Bubble mailer

Dongguan Sun Pak Packing Product Ltd. , https://www.dgsunpak.com