Metallogenesis and ore-forming time of the Changtuxili Mn-Ag-Pb-Zn deposit in Inner Mongolia:Evidence from C-O-S isotopes and U-Pb geochronology  

作　　者：Kuo Zhang Ruo-Shi Jin Feng-Yue Sun Bi-Le Li Peng He Yue-Long Zhang Shuo Guo Tian-Fu Zhang 

机构地区：[1]College of Earth Sciences,Jilin University,Changchun,130061,China [2]Tianjin Center,China Geological Survey,Tianjin,300170,China [3]North China Center for Geoscience Innovation,Tianjin,300170,China [4]Qiqihar Branch,Heilongjiang Institute of Geological Survey and Research,Qiqihar,150036,China

出　　处：《Geoscience Frontiers》2020年第4期1369-1380,共12页地学前缘（英文版）

基　　金：This study was funded in part by the China Geological Survey(Grant Nos.DD20190075 and DD20160041).

摘　　要：This paper reports new geochronological(U-Pb) and isotope(C,O,and S) data to investigate the timing of mineralization and mode of ore genesis for the recently discovered Changtuxili Mn-Ag-Pb-Zn deposit,located on the western slopes of the southern Great Hinggan Range in NE China.The mineralization is hosted by intermediate-acidic lavas and pyroclastic rocks of the Baiyingaolao Formation.Three stages of mineralization are identified:quartz-pyrite(Stage I),galena-sphalerite-tetrahedrite-rhodochrosite(Stage II),and quartz-pyrite(Stage Ⅲ).δ13C and δ18O values for carbonate from the ore vary from-8.51‰ to-4.96‰ and 3.97‰ to 15.90‰,respectively,which are indicative of a low-temperature alteration environment.δ34SV-CDT values of sulfides range from-1.77‰ to 4.16‰ and show a trend of equilibrium fractionation(δ34SPy>δ34SSp>δ34SGn).These features indicate that pyrite,sphalerite,and galena precipitated during the period of mineralization.The alteration mineral assemblage and isotope data indicate that the weakly acidic to weakly alkaline ore-forming fluid was derived largely from meteoric water and the ore-forming elements C and S originated from magma.During the mineralization,a geochemical barrier was formed by changes in the pH of the ore-forming fluid,leading to the precipitation of rhodochrosite.On the basis of the mineralization characteristics,new isotope data,and comparison with adjacent deposits,we propose that the Changtuxili Mn-Ag-Pb-Zn deposit is an intermediate-to lowsulfidation epithermal deposit whose formation was controlled by fractures and variability in the pH of the oreforming fluid.The surrounding volcanic rocks yield zircon U-Pb ages of 160-146 Ma(Late Jurassic),indicating that the mineralization is younger than 146 Ma.

关 键 词：Inner Mongolia Changtuxili Mn-Ag-Pb-Zn deposit C-O-S isotope geochemistry Zircon U-Pb age Intermediate-to low-sulfidation epithermal deposit 

分 类 号：P618.2[天文地球—矿床学]