| Nagengkangqieer silver deposit is the first large-scale independent silver deposit formed by exploration in the East Kunlun metallogenic belt.Breccia is widely distributed in the mining area,which is generally regarded as fault breccia or cryptoexplosive breccia tube structure by predecessors,but no in-depth study has been carried out.However,the structural property,spatial distribution and metallogenic relationship of these breccias have a significant impact on the genetic type of ore deposits and the determination of exploration and reserve increase direction.Based on the previous exploration and research,relying on the project of "special study on ore controlling structure and mineralization characteristics of Nagengkangqieergou silver deposit in Dulan County,Qinghai Province" and "general survey of Nagengkangqieer gou silver polymetallic deposit in Dulan County,Qinghai Province",through the collection of exploration engineering logging data and the identification of light and thin sections,it is considered that the breccia in the mining area is the product of hydrothermal cryptoexplosion structure,and then the cryptoexplosive breccia is analyzed The general characteristics,classification characteristics and spatial distribution characteristics of the rocks are deeply studied,and the cryptoexplosion structural characteristics and formation mechanism of the Nagengkangqieer silver deposit are systematically summarized;the genesis and prospecting direction of the deposit are constrained,and the following achievements are obtained:(1)Hydrothermal cryptoexplosive breccia is widely developed in the mining area.The mineralized breccia is composed of breccia.The ore minerals are mainly natural silver,silver,pyrite,arsenopyrite,etc.gangue minerals are mainly calcite and quartz.At the same time,vein and veinlet disseminated ores are developed in the mining area,which also shows the characteristics of hydrothermal mineralization,which indicates that there is superposition of high-pressure,ultra-high pressure and ordinary fluids.(2)The apparent thickness of the hidden explosion section exposed by the borehole varies from 1-15 m,and the intermittent apparent thickness is 1-157 m,The maximum difference rate of accumulated thickness adjacent difference of adjacent boreholes in different directions is 1-63%,the minimum difference is 0.9-170.7%,and the average difference rate is 0.5-100.1%,It shows that there is no cryptoexplosive breccia belt in any direction,and there is no vertical tube extension cryptoexplosive breccia body.The cryptoexplosive breccia in the mining area constitutes a network vein and vein breccia system with uneven development in all directions.Combined with the study of surface structure in the field,the cryptoexplosion structure in the mining area is a network vein cryptoexplosion structure controlled by the fold related joint and fracture system.(3)The matrix of cryptoexplosive breccia,reflecting the characteristics of highpressure and ultra-high-pressure fluid,can be divided into two types: siliceous and carbonate.The siliceous matrix is subdivided into cryptocrystalline,microcrystalline,fine-grained and mesocrystalline;The carbonate matrix can be divided into cryptocrystalline,fine-grained and mesomorphic structures,which indicates that the high-pressure and ultra-high-pressure fluids that lead to the cryptoexplosion structure in the mining area have multiple types of secondary characteristics.Different types of cryptoexplosive breccia can be seen in the same light sheet,the same sample and the same prospecting project,which can reflect the superposition of different types of explosive high-pressure and ultra-high pressure fluids in different scales.The combination type of cryptoexplosive breccia in the same position is called the internal structure type of cryptoexplosion.There are 5 kinds of Light film,7 kinds of samples and 11 kinds of prospecting engineering,In all the optical films,samples and prospecting projects,the proportion of the visible and the proportion are 2.6%,6.8% and 21.9%,respectively,which shows that there are multiple superimposition of highpressure and ultra-high-pressure fluids in the mining area.(4)The associated hydrothermal veins can be divided into three types: siliceous,carbonate and sulfide.The siliceous hydrothermal veins are subdivided into cryptocrystalline,microcrystalline,fine-grained and mesocrystalline;Carbonate hydrothermal veins can be divided into cryptocrystalline,microcrystalline,fine-grained and mesocrystalline structures;sulfide hydrothermal veins have microcrystalline structure,it is shown that the non explosive ordinary fluid has multi class characteristics,Different types of associated hydrothermal veins can be seen in the same optical film,the same sample and the same exploration project,which can reflect the superposition of different types of non explosive ordinary fluids in different scales.The combination type of associated hydrothermal veins in the same position is called the non hidden explosion type of internal structure.There are 9 kinds of non hidden explosion inner structures,9 kinds of samples and 14 kinds of prospecting engineering,in all the optical films,samples,and prospecting projects,the proportion of common fluid is 7.4%,11.1% and 27.4%,respectively,which shows that there are multiple superposition effects of ordinary fluids in the mining area.(5)Different types of cryptoexplosive breccias and associated hydrothermal veins are found in the same light film,the same sample and the same prospecting project,which can reflect the superposition of different types of explosive high-pressure and ultra-high pressure fluids and non explosive ordinary fluids in different scales.The combination types of the same cryptoexplosive breccias and associated hydrothermal veins are called cryptoexplosion non cryptoexplosion structural types.There are 25 kinds of hidden explosion non hidden explosion structures in the mining area,28 kinds of samples and 32 kinds of exploration engineering.The proportion of hidden explosion non hidden explosion structures in all optical slices,samples and prospecting projects are 23.2%,26.5% and 57.5%,respectively.It shows that there are multiple superposition functions of high-pressure ultra-high pressure fluid and ordinary fluid in the mining area.(6)The superimposition of high pressure ultrahigh pressure fluid and ordinary fluid in the mining area indicates that the Nagengkangqieer silver deposit is a hydrothermal deposit.The hydrothermal activity center is the superimposed area of multiple sub high pressure ultrahigh pressure fluids and ordinary fluids.According to the hydrothermal activity center and its extension direction,this paper infers 4 A-grade metallogenic potential prospective areas,12 B-grade metallogenic potential prospective areas and 12 C-grade metallogenic potential prospective areas. |
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