Study On Geological Characteristics And Genesis Of Delebuqin Gold Deposit In Inner Mongolia

The Delebqin Au-deposit,lied in Inner Mongolia,is a recently discovered gold deposit in the southearn part of the Greate Khingan Mountains.Up to now,the proved Au metalamount is?3 tons(not yet controlled),which is the representative Au-deposit mainly dominated by Au and associated with Ag discovered in the Xilin Haote-Xilin Gol metallogenic belt in the southern part of Greater Khingan Mountains.Au mineralization occurs mainly as disseminated,veinlet-disseminated and massive in the volcanic-sedimentary units and forms vein orebodies,which is also closely related to the Mesozoic tectonic-magmatic rocks in spatial distribution.In this paper,based on field geological survey and deochemical characteristics of ore deposits,This study focuses on the Au-mineralization in the Delabuqin deposit.This paper provides an account of new geological,mineralogical,geochemical date of magmatic rocks and ore system.On this basis,this paper also describes and classifies the different mineralization types and wall-rock alteration.this paper also presents new geochronological date,(LA-ICP-MS U/Pb zircon ages).Based on the previous studies,this study aims mainly at:describing and dividing the rock units in the ore district;and reporting chronological constraints on the metallogenesis.Delebqin Au-deposit is located in the southeast of Central Asian orogenic belt(CAOB),and the southearn part of Greate Khingan Mountains.The main host-rock of the ore-bodiesis Mid-Jurassic altered andesite.The ore-bodies is mainly controlld by the E-W trending strike faults.The strike length of the mineralization zone is>3000m,with a maximum length of 300m.The ore-bodies are essentially quartz veinsand occurs in altered rock.The main metallic minerals in ores are pyrite,chalcopyrite,galena,et.The main gangue mineral is quartz,chlorite,epidote,kaolin,and calcite.The main alterations are sericization,silicification,chloritization,kaolinization,carbonation and pyritization,which are usually superimposed.The Au-bearing minerals are mainly pyrite and sphalerite?In this study,andesite in the Delebqin mining area were datedby Zircon LA-ICP-MS U-Pb dating.The ²⁰⁶Pb/²³⁸U age range of the 15 measurement points was 173.9?176.5Ma,and the weighted average age was 175.1±1.8 Ma,which represented the formation age of the ore body surrounding rock.In addition,the ²⁰⁶Pb/²³⁸U ages of the other two survey points are relatively high,with point 3 being 588.49m A and Point 11 being 303.8 Ma.These two zircons should be considered as zircons to be captured,which represents the ages of zircons captured from the surrounding rocks during the emplacement of the rock mass.Through fluid inclusion experiments,the complex morphology of the inclusion in quartz vein samples in Delebchin Au-deposit was observed,and the gas-liquid ratio of the inclusion was measured between 20%and 60%,with an average of 25%.The homogenization temperature of the fluid inclusions ranged between 167?and194?,with an average temperature of 174?;and it show a low salinity of 5.1-9.3wt%with an average salinity of7.6wt%.The H-O isotopes of the deposit were measured.In the D-18OH₂O isotopes diagram,the Delebuqin gold deposit were all placed between the meteoric line and magmatic water,and they were concentrated,belonging to the category of meteoric origin fluid,indicating that the ore-forming fluid came from the mixed water of meteoric and magmatic water,and was dominated by a large amount of meteoric water.The Delebuqin Au deposit is therefore interpreted as a low-temperature,deposit and the mineralization was deposited from a mixed source during a phase,probably during fluid mixing and boiling.The structural evolution of the Great Khingan Range is largely controlled by multi-stage and complex geological events including subduction and closure of Paleo-Asian Ocean in the Paleozoic,and The Mid-Jurassic magmatism in the Delebuqin district are related to subduction of the Mongolia–Okhotsk Ocean and subduction of the Paleo-Pacific Ocean Plate,respectively,and it is controlled by this joint mechanism.The ore-forming type of the delebuqin gold deposit is determined as a epithermal epithermal deposit.According to the model of this type of deposit,it is proposed that delebchin gold deposit belongs to the same metallogenic system as the nearby Mauden porphyry copper polymetallic deposit,which is helpful for further targeted prospecting around the deposit.