河南汝阳老代仗沟铅锌矿床成因研究

Genesis of the Laodaizhanggou Pb-Zn deposit,Ruyang County,Henan Province

本文结合前人的研究成果,利用地质年代学、同位素及流体包裹体特征分析方法,总结了老代仗沟铅锌矿床的硫、铅、氢、氧、碳同位素地球化学特征。老代仗沟铅锌矿床的铅同位素显示铅来自地幔;δ^(34)S变化范围6.2‰~12.2‰,平均8.61‰,具有多源性;石英中的δD值为-91.9‰~-81‰,δ^(18)O_(H_(2)O)值为-7.5‰~9.3‰,说明岩浆水和大气降水同时参与了该矿床的成矿过程;方解石碳同位素δ^(13)CPDB值为-4.5‰,δ^(18)O_(SMOW)值为8.4‰,显示了地幔来源的特征。结合铷锶同位素等时线年龄(126±13)Ma及该矿床的流体包裹体显示的中-高温、低盐度的含CO2的K^(+)-Na^(+)-Ca^(2+)-Cl^(-)-SO_(4)^(2-)体系特征,笔者认为老代仗沟铅锌矿床为燕山晚期成矿的中-高温岩浆热液充填交代型铅锌矿床。该研究对汝阳南部地区同类型铅锌矿床的寻找具参考价值。

Based on the previous research results,this paper summarizes the geochemical characteristics of the sulfur isotope,lead isotope,hydrogen and oxygen isotope and carbon isotope in the Laodaizhanggou Pb-Zn deposit through geochronology,isotope and fluid inclusion characteristics analysis method.The lead isotope of Laodaizhanggou Pb-Zn deposit shows that the lead cames from the mantle.The δ^(34)S varied from 6.2‰~12.2‰with the average of 8.61‰,which had the characteristics of multiple sources.The δD of quartz range from-91.9‰~-81‰and the δ^(18)O_(H_(2)O) of quartz range from-7.5‰~9.3‰,which shows that the magmatic water and meteoric water participate in the different metallogenic stage of the deposit.Theδ^(13)CPDB and δ^(18)O_(SMOW) values in the calcite is-4.5‰and 8.4‰respectively,which show the characteristics of mantle source.Combining with the Rb-Sr isochron age of(126±13)Ma and the features of the ore-fluid with moderate-high temperature,low salinity,CO_(2)-riched in the K^(+)-Na^(+)-Ca^(2+)-Cl^(-)-SO_(4)^(2-)system,this paper presents that Laodaizhanggou Pb-Zn deposit is a high-middle temperature magmatic hydrothermal filling metasomatic deposit formed during the Late Yanshanian period.This study has a certain reference value for the exploration of the same type of lead-zinc deposits in the south of Ruyang.