Geological Characteristics And Genesis Of The Lead-zinc Polymetallic Deposit In North Of Kaerqueka,Qinghai Province

The lead-zinc polymetallic deposit in north of Kaerqueka is part of the Bekalike-Xiangride Proterozoic paleocontinental block?Grade III?in the western part of the Dongkunlun Qimantage metallogenic belt,ekalike-Xiangride Gold,lead and zinc?copper,rare,rare earth?metallogenic belts?III12?.In the study area,the northwest-western tectonic development,multi-period reciprocating and pulsating inheritance develop magmatism,and it has superior ore-forming geological conditions.The Kaerqueka North crypto-breccia does not have vertical zoning characteristics:according to field observations,the breccia is mainly homologous plaque-like feldspar breccia,a small amount of heterogeneous breccia,and the cement is chlorite.,sericite and rock powder,the breccia is sharp and angular,without any rounding,indicating that it has no displacement.The composition of the breccia in the north of the Kaerqueka breccia is basically the same,and the characteristics of the bristles can be combined,and the plane length and depth are not much different.These features are significantly different from the apparent vertical zoning of the blasting breccia tube,and the vertical depth is much larger than the plane length.These characteristics indicate that the North of Kaerqueka cryptoexplosive breccia is more in line with the characteristics of hydrothermal breccia.It is considered to be a porphyritic monzonitic granite according to the composition of the breccia and the composition of the deep plaque-like monzonitic granite.The product of the hydrothermal cryptoexplosion at the top of the body belongs to the hydrothermal breccia and is named as the hydrothermal breccia shell produced at the top of the rock mass.The lead-zinc polymetallic ore in the study area mainly exists in the cryptoexplosive breccia shell.The mineralization and enrichment of the rock crust is relatively high,and it has the characteristics of full-shell mineralization of surface and deep cryptoexplosive breccia.The type of mineralization varies greatly in the vertical direction.The upper part is the vein-like and disseminated shape of the crypto-explosive breccia,and the lower part is star-shaped and fine-veined.Zn is a series of elements,Cu is mainly concentrated in the lower part of the rock crust,and Pb and Zn are enriched in the upper part of the crust.Through the zircon U-Pb dating,it is determined that the formation age of the breccia shell is 439 Ma,which is basically the same as that of the surrounding rock-like monzonitic granite?448 Ma?.Combined with the geochemical characteristics of the plaque-like monzonitic granite and the study mineralization of the predecessors,it was determined to form in the original Tethys subduction and collision reduction stage.It is concluded that the formation of lead-zinc polymetallic deposits is closely related to the collision of the original Tethys subduction.The fluid inclusion temperature measurement shows that the ore-forming fluids in the Karzaka North Lead-Zinc Mine have high temperature and low salinity characteristics.The gas phase composition of the fluid inclusions is mainly H2O vapor and CO2.The H and O isotope test results show that the ore-forming fluid is mainly magmatic water with a little atmospheric water added.The distribution of sulfide sulfur isotope composition in the study area is concentrated,indicating that the sulfide sulfur source precipitated in the ore-forming hydrothermal fluid is single.The?³⁴ S value changes around zero,indicating that the sulfur in the ore-forming fluid originates from the deep magma.According to the comprehensive analysis,the deposit type is cryptoexplosive breccia shell-type lead-zinc polymetallic ore.