Study On Geological And Geochemical Characteristics Of Yanzhai Gold Deposit In Danzhai,Guizhou Province

Yanzhai gold deposit in southwestern Guizhou is a medium-sized gold deposit.In this paper,detailed deposit geology,trace elements,rare earth elements and isotopic geochemistry of the deposit have been studied.Based on this,traced the source of mineralization.In addition,the analysis of metallogenic conditions combined with the collected data,Explore the origin of the deposit?This paper mainly draws the following four points of understanding and conclusions:1.Yanzhai gold deposit is located at the northern end of the Sanlu-Danzhai hydrothermal mercury,gold and antimony ore belt,and is located within the main tectonic unit coalescence belt.There are multiple stages of Yanshanian and late-stage structural activities,and the deep fault structure develops.The gold ore bodies are mainly in veins and lenticular in the Cambrian Wuxun Formation,Duliujiang Formation mudstone,carbonaceous mudstone,marl,limestone,and their output is obviously controlled by the structure.The gold grade of ore is low,and the mineral particles are small.It is difficult to see independent gold minerals and no gold is found.Hydrothermal alterations that are closely related to gold mineralization are mainly arsenopyrite,pyrite,stibnite,and silicification.2.According to the interpenetration relationship between veins and the metasomatism of minerals,the ore-forming process of Yanzhai gold deposit was divided into sedimentary diagenesis and tectonic hydrothermal mineralization.The latter is further divided into three stages,namely the quartz-dolomite-pyrite stage,the natural gold-pyrite-toxic sand-quartz stage,and the realgar-cinnamo-quartz calcite stage.3.The analysis of the trace element characteristics of the ore and surrounding rock in the Yanzhai gold deposit shows that the overall distribution curve of the Yanzhai gold deposit has a consistent change trend,indicating that its source is consistent.The trace changes of various trace elements in the host rock of mineralization are relatively large,and the contents of As and Sb are higher than those of similar rocks in the crust by 2-3 orders of magnitude.The elements related to diagenesis,such as Cu,Cr,Co,Ni,Zn,and V,have small changes,and the difference between the highest value and the lowest value is less than one order of magnitude.It shows that under the action of ore-forming hydrothermal fluids,As and Sb elements have undergone strong activation and migration,and Cu,Cr,Co,Ni,Zn,and V elements have almost no active migration.Au mineralization is closely related to As and Sb.4.In the Yanzhai gold mining area,as a sulfur isotope test object,the stibnite mineral closely related to the formation of gold ore is selected,Test results show that there is a sulfur isotope characteristic close to seawater,Indicated that the sulfur in mineralization may be mainly derived from marine formations,The lead isotope test object is stibnite,The characteristics of lead isotopes can be seen in the characteristics of lead source and orogenic belt of the lead source of the Yanzhai gold deposit,and the deep source materials are mixed.Therefore,the characteristics of lead isotope composition in the Yanzhai gold deposit reflect the source characteristics of the metal materials in the deposit.The carbon and oxygen isotope test object is calcite.The ore-forming fluid carbon and oxygen of the Yanzhai gold deposit come from the dissolution of marine carbonate rocks,It shows that dissolution and migration-deposition of carbonate rock as a carrier of metal elements occur during mineralization.5.The Wuwan and Xiongweng faults are the ore-guiding structures in the mining area and are also channels for the upward movement of mineralization materials.Different sources of hydrothermal fluids continuously extract minerals from ore deposits and surrounding rocks,Contains Fe,Ca,S,Si,Hg,Mg,As,Sb and other elements,It migrates along the fault zone under suitable physical and chemical conditions,and it is replaced by metasomatism,filling and replacement in favorable lithological sites.6.Geological and geochemical characteristics of the Yanzhai gold deposit are similar to those of the gold deposits such as Lannigou and Shuiyindong on the Karin-type gold deposits in southwest Guizhou.Therefore,this deposit is also a Carlin-type gold deposit,indicating that Carlin-type gold deposits in the southwest of Guizhou have the possibility of extending eastward,pointing out the direction for regional metallogenic and prospecting evaluation studies.