粤北大宝山多金属矿床成矿流体的He-Ar-Pb-S同位素示踪

大宝山多金属矿床是粤北地区典型的巨厚型及细脉带型矿化的多金属硫化物矿床.层状和脉状黄铁矿的氦氩同位素表明:3He/4He的R/Ra值为0.60～4.13,40Ar/86Ar=327～411,反映该成矿流体是大气饱和水(海水)与地幔流体混合作用的结果.铅和硫同位素都揭示了层状(块状)和脉状矿体可能来自不同时期的成矿流体.其中层状矿体为泥盆纪海底火山喷发沉积作用所致,脉状矿体可能来自燕山期岩浆热液充填叠加形成,古大陆碎屑物质和部分有机质的还原对后期成矿流体具有较大的影响作用.

THE He-Ar-Pb-S ISOTOPE TRACING ON ORE-FORMING FLUID IN DABAO HILL POLYMETALLIC DEPOSIT, NORTH GUANGDONG

Dabaoshan Hill polymetallic deposit is a typical polymetallic sulfide deposit with tremendous thick layered and stringer mineralization.The R/Ra ratio of 3He/4He of the layered and vein-like pyrites are from 0.60-4.13 and 40Ar/36Ar 327411.The isotope compositions are the results of mixture of the saturated meteoric water(seawater) with mantle fluid.The lead and sulfur isotope analysis suggests that the tremendous thick and stringer ore bodies may be formed by fluid of different geologic periods.The mendous thick ore body was formed by sea floor volcanic eruptive sedimentation during the Devonian Period;the stringer ore body by Yanshanian magmatic hydrothermal fluid filling and overprinting.The reduction of old terrigenous detritus and some organic materials has important effect on the late ore fluids.