浙江璜山金矿床同位素地球化学研究

ISOTOPE GEOCHEMICAL STUDY ON THE HUANGSHAN GOLD DEPOSIT, ZHEJIANG

本文根据最新获得的两组矿石和含矿石英中流体包裹体的Ｒｂ－Ｓｒ等时线年龄数据和初始锶同位素组成及２１个新测定的矿石、石英及围岩（石英闪长岩）的铅同位素组成，讨论了璜山金矿床的成矿时代、矿床成因及物质来源等问题。 矿石及成矿流体包裹体的年龄分别为３５８±２２Ｍａ和３９６．９±３４．５Ｍａ，表明成矿时代为海西期，与该地区韧性剪切带形成时代（３２５～３９９Ｍａ）一致。初始锶同位素比值低，在０．７０４０～０．７０４２范围内，落在玄武岩（地幔锶）区内，且铅同位素具低μ值特征，落在岛弧铅与地幔铅演化曲线之间，说明成矿溶液及成矿物质均来自上地幔或下地壳源区，同时，矿石铅同位素组成与围岩（幔源型石英闪长岩）铅同位素一致，表明二者在来源上关系密切。

Based on Rb-Sr isochron ages and Sr, Pb isotope data of the ore and fluid inclusion in the quartz veins from the Huangshan gold deposit, this paper deals with such problems as metallo- genic time, ore genesis and source. The authors determined metallogenic time of gold by means ores and fluid inclusion Rb-Sr isochrons. Two isochron ages have been obtained for auriferous quartz veins of the gold deposit: 358±22Ma, (87Sr/86Sr)i=0. 70421±0.00001 and 396.±34.5Ma, (87Sr/86Sr)i=0. 70404± 0.00001 age data are consistent with the ages (330-399Ma) of formation for Huangshan ductile shear zone. It is considered that the mineralization of the Huangshan gold deposit is related the Variscan mylonitization of this region. Most of the lead isotope data in Huangshan deposit fall between the orogenic zone (arc) lead evolution curve and mantle lead evolution curve (Doe and Zartman, 1979), suggesting that the lead(and gold) has derived mainly from the upper mantle or lower crust. The lead isotopic compo- sition for the ore and fluid inclusion in quartz is similar to that in the quartz diorite, indicating that the soruce of the mineralizing materials related to the host quartz diorite, which belongs to plutonic primary gold-bearing formation (Zhu Ping, Wan Naiyu, 1994). Sr isotopic composition of Huangshan gold deposit also indicates that the ore-forming solution and mineralizing materials derived from mantle source region.