水岩体系Eh-pH法在层间氧化带铀成矿预测研究中的应用OA

Sandstone-type uranium deposits of interlayer oxidation zones are important types of in-situ leachable uranium deposits.Accurate division of oxidation zone,transition zone and reduction zone is of great significance for uranium metallogenic prediction.Based on the principle of water-rock interaction,this paper systematically expounds the basic principle,characteristics and determination method of the Eh-pH for water-rock system.The profile ZK6 in Juyanhai depression was used to quantitatively determine the redox environment characteristics of the ore-bearing layer through Eh-pH tests of water-rock system and chemical composition analysis of leachate on drill core samples.The research results showed that the Eh value ranges of the oxidation zone,redox transition zone and reduction zone in the Kuquangou formation(N2k)were 78～111 mV,－27～60 mV and －311～－280 mV respectively;the Eh value range of the reduction zone in the Wulansuhai formation(K2 w)was－457～－316 mV.According to the critical Eh value for uranium precipitation calculated by the PHREEQC program,the determined reduction zone of the Kuquangou formation and the redox transition zone to reduction zone of the Wulansuhai formation were both located in the uranium precipitation area,and the redox environment was conducive to uranium metallogenesis.The study indicates that the significant decrease of Eh value of sandstone groundwater along the groundwater flow direction can be used as an important indicator for determining the location of uranium orebodies.The Eh-pH method of water-rock system has the advantages of low cost,large amount of data and no restriction by exploration stages,which can provide an effective technical means for the metallogenic prediction and target area screen for sandstone-type uranium deposits of interlayer oxidation zones.The research proves that the Eh-pH method of water-rock system has good applicability in the uranium metallogenic prediction of sandstone-type uranium deposits in interlayer oxidation zones.