Mineralization Age,Fluid Properties and Sources of Ore-Forming Materials for Huajiling Molybdenum Deposit in Helong Area of Yanbian,Jilin Province
The Huajiling molybdenite deposit is a newly discovered molybdenum deposit located in the eastern section of the northern margin of the North China craton.It features an ore body oriented in NNW direction,dipping at 45° to 50°,surrounded by wall rocks of granite porphyry and granodiorite.The ore types include fine veinlet ores and disseminated ores,primarily consisting of molybdenite,magnetite and pyrite,with minor amounts of hematite.The alteration of wall rock involves dolomitization,potassium mineralization,silicification,chloritization,and carbonate mineralization.In order to determine the mineralization age,fluid properties and sources of ore-forming materials,this study conducted molybdenite Re-Os dating,fluid inclusion temperature measurements,and H-O-S-Pb isotope analysis on Huajiling deposit.Results indicate that the Re-Os age of Huajiling molybdenum deposit is(178.0±1.1)Ma,formed in a tectonic environment where the ancient Pacific plate subducted beneath the Eurasian plate.The ore-forming fluid evolved from high temperature,low to medium salinity,and low to medium density to low temperature,low to medium salinity,and medium density.The δ18OH2O values of quartz range from-2.1‰ to 2.6‰,and δDV-SMOW values range from-115.8‰ to-109.7‰,indicating contributions from both magma water and atmospheric precipitation.The w(Re)values of molybdenite range from 19.564 × 10-6 to 23.128 × 10-6,exhibiting a crust-mantle mixed source.The δ34SV-CDT values of pyrite(1.9‰-4.2‰,with an average of 2.7‰)indicate that the sulfur mainly originates from the mantle.Additionally,the 206Pb/204Pb,207Pb/204Pb,208Pb/204Pb values of pyrite range from 17.865-18.279,15.546-15.611,and 38.011-38.486,respectively,further supporting the crust-mantle mixed source hypothesis for ore-forming materials.
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