Dongchuan copper mine is located in the western edge of Yangtze plate, the eastern edge of the middle section of Kangdian axis-Dongchuan massive uplift, surrounded by faults on the east, south and west, and connected to the Kunyang Group in Huili in the north. The metallogenic belt belongs to Kangdian iron-copper-vanadium-titanium-tin-nickel-rare earth-chrysotile asbestos metallogenic sub-belt.
1. Brief description of mine geology
(1) stratum
The geological structure of the mining area is complex, and the exposed strata from new to old are: Quaternary (Q), Upper Sinian Doushantuo Formation (Zd), Dayingpan Formation (Pt2kn2h), Heishan Formation (Pt2kn2l), Luoxue Formation (Pt2kn2y) and Paleoproterozoic Xiaoliukou Formation (PT2kn2Y).
(2) Structure
Dongchuan copper mine area belongs to a trapezoidal faulted basin at the eastern end of Huili-Dongchuan aulacogen in Kunyang Rift, surrounded by boundary faults-Matang fault, Puduhe fault and Baojiu fault Xiaojiang He fault. There are also two groups of main faults in the mining area, north-south and east-west Among them, the north-south fault zone and the east-west Tangdan-Lanniping fault, Huangshuiqing-Xintang fault and Sishu-Mianshan fault are characterized by growth faults or multiple activities in the later period, which further decompose the Dongchuan fault basin into some semi-graben sedimentary depressions.
(3) Magmatic rocks
Magmatic activity in the mining area is strong and lasts for a long time, and the peak of activity is mainly in the human period and the late Jinning period. Volcanic rocks dominated in the Republic of China and intrusive rocks dominated in the late Jinning period. Volcanic rocks are mainly spilite porphyry series, followed by basalt, and trachyte can be seen locally. Pyroclastic rocks include volcanic breccia, tuff and sedimentary tuff. The intrusive rocks are mainly gabbro, diabase and a small amount of albite diorite and albite porphyry. Volcanic rocks and pyroclastic rocks are mainly distributed at the bottom of Yin Min Formation, followed by Xiaoliukou Formation and Heishan Formation. Intrusive rocks mainly intrude along the subsidence fault zone and the transverse and longitudinal faults on both sides, and are produced in the form of dykes and dikes.
2. A brief description of the characteristics of the deposit
(1) ore body characteristics
The deposits in Dongchuan ore field can be divided into two ore belts: the artificial snow belt in the north, with a total length of 28 kilometers; ; In the southeast, the Xintang-Tangdan Lanniping ore belt (hereinafter referred to as Tangxin ore belt) extends intermittently 17km. The main deposit types are Dongchuan copper mine, rare copper-bearing magnetite mine, Lanniping copper mine, Taoyuan copper mine and the newly discovered Xiaoliukou and Boka gold mines. Ore bodies are mainly layered and quasi-layered, showing the characteristics of syngenetic ore. In addition, some ore bodies are veined, lenticular and irregular, with obvious post-generation ore characteristics.
Yinmin copper deposit: located in the middle of the western arc fold belt, located in the west wing of the anticline and the west side of the fault zone. Geological exploration has found 20 ore bodies. There are three main ore bodies, which are layered and quasi-layered. The ore body strike is 340 ~ 355, inclined to the southwest, and the dip angle is 55 ~ 80. Among them, a main ore body is 1725m long and over 400m deep, with a true thickness of1.21~12.60m, an average thickness of 5.04m and an average copper grade of 1.04%. The strike extension of the other main ore body is more than 1000m, the extension depth is more than 560m, the true thickness of the ore body is 2.50 ~ 25.80 m, the average thickness is11.0/.09%, and the average copper grade is 1.09%.
Lanniping copper mine: located in the western section of Huangcaoling arc fold belt in the south, between Diaostair fault and Lanniping reverse fault, 2 1 ore body was found in geological exploration. There are three main ore bodies, which are layered and quasi-layered. The overall strike of the ore body is 63 and the dip angle is 57 ~ 60. The ore body is 200m long, with controlled vertical depths of 37 1 m,199m and 240m respectively, and average thicknesses of1.40m,1.57m and 6.35m respectively.
The specimen was collected from Baixila mine section in Lanniping mining area. The main ore bodies are LL3 and LV4, and their characteristics are summarized as follows:
The control length of LL3 orebody is 200m, the dip angle is 438m, the thickness is 1.0 ~ 1.80m, and the average thickness is1.40m.: The copper grade is 0.44% ~ 0.9 1%, and the average grade is 0.76%. The ore body is layered and lenticular along the bed, with a strike of 63 and a dip angle of 57 to the northwest. The ore-bearing strata are located in the first member of Luoxue Formation, and the ore-bearing rocks are grayish white siliceous and sandy argillaceous dolomite.
LV4 orebody has a controlled length of 380m, a dip angle of 233m, a thickness of 3.75 ~ 15.00m and an average thickness of 9.38m The average grade of copper is 1.76%. The ore body is layered with strike of 56, dip angle of 326 and dip angle of 64.
(2) Ore type and structure
There are three main ore types in the mining area: sulfide ore, oxide ore and mixed ore. Mainly copper, accompanied by iron, gold, silver and other beneficial components. Ore structure includes crystal lattice, droplets, images, leaves, clastic structure, particles, metasomatic residues and so on. The ore structure is characterized by sedimentation, which mainly includes layered, rhythmic banded, granular disseminated, horsetail-shaped, layered, bamboo-leaf-shaped, oolitic, corrugated and oblique bedding. The ores in the transformation area are massive, breccia-like, folded, reticulated and veined, and the ores in the oxidation zone are hard shell-like and grape-like.
Specimen name sandstone-type copper oreNo. DB027 Stratigraphic Age Mesoproterozoic
Atlas of large ore specimens from typical mines in China
The ore specimen was collected from Baixila section of Lanniping mining area in Dongchuan. The surface of the sample is grayish yellow-white, with recrystallization structure and block structure. Ore minerals include chalcocite, bornite, chalcopyrite, pyrite, malachite and so on. Gangue minerals are mainly dolomite and quartz. The grade of copper is 0.62%
Genetic types of Dongchuan copper deposit in Kunming City, Yunnan Province; Origin of marine sedimentary metamorphism and transformation