Geological And Geochemical Characteristics And Genesis Of The Yawan Antimony Deposit In Gansu Province

The West Qinling region is an important metallogenic belt in the central orogenic belt,which is ideal for metallogenic geological conditions.Ya Wan antimony deposit is located in Xihe County,Gansu Province and belongs to the east-west tectonic belt of the West Qinling Mountains.Study on the genesis and background of the deposit can not only enrich the metallogenic theory of antimony deposits in China,but also provide theoretical basis for the same type of antimony deposits.This paper makes a detailed understanding of the geological structure activities in the area under the precondition of the previous geological data of the West Qinling region,deeply discusses the geological evolution process in the area,and makes a study on its mineralization.The metallogenic periods are divided in this paper.The ore-forming stage of the Yawan antimony deposit is divided into three stages:sedimentary diagenesis,medium-low-temperature hydrothermal transformation and epoxidation,and the intermediate-low-temperature hydrothermal transformation stage can be divided into two stages according to the ore output form and microscopic observation of mineral assemblage relationship:the first stage is ore-bearing hydrothermal mainly metasomatism,filling,formation of disseminated ore,the main minerals are stibnite and pyrite,a small amount of white iron ore;In the second stage,the ore-bearing residual liquid is filled in the structural fissures of the original ore and developed into ore-bearing quartz and calcite veins.The study further determined the genesis type of the deposit by analyzing its geochemical characteristics.According to the sulfur isotope?³⁴S data,the sulfur in the deposit is mainly affected by sedimentation and magmatism,indicating that the sulfur is basically derived from the strata.Data characteristics of lead isotopes vary relatively small,and radioactive lead is relatively enriched,indicating that the source area is rich in ²³⁸ U?²³²Th,indicating that the ore-forming material sources such as lead in the Yawan antimony deposit have high maturity and stable upper crust characteristic source area.The results show that the hydrothermal metallogenic system of the Yawan antimony deposit is reductive,medium-low temperature and low salinity.Through the above research,it is considered that the Yawan antimony deposit is a sedimentary-medium-low-temperature hydrothermal modified deposit.In the process of metallogenic material formation,early weathering and denudation play a role in enrichment,and the intermediate metallogenic minerals undergo hydrothermal transfer and activation in magmatic and tectonic activities,and precipitate and form antimony deposits in favorable tectonic positions.