摘要
华集岭钼矿床位于华北克拉通北缘东段,是近年来新发现的钼矿床.该矿床中矿体呈NNW向展布,倾向西,倾角为45°～50°,主要赋存在花岗斑岩及花岗闪长岩中.矿石类型主要有细脉状和浸染状两种,矿石矿物以辉钼矿、磁铁矿和黄铁矿为主,少量赤铁矿和钼华,发育云英岩化、钾化、硅化、绿泥石化和碳酸盐化等围岩蚀变.为了确定成矿时代、成矿流体特征及成矿物质来源,本文对华集岭钼矿床中的辉钼矿进行了 Re-Os测年、流体包裹体测温和H-O-S-Pb同位素分析.结果显示:华集岭钼矿床中辉钼矿Re-Os年龄为(178.0±1.1)Ma,处于古太平洋板块向欧亚板块俯冲的构造环境.成矿流体由早期的高温、中低盐度、中低密度向晚期的中低温、中低盐度、中等密度演化.石英的δ18OH2O值为-2.1‰～2.6‰,δDV-SMOW值为-115.8‰～-109.7‰,成矿流体显示岩浆水与大气降水混合的特征;辉钼矿w(Re)值为19.564× 10-6～23.128×10-6,成矿物质具有壳幔混合的特征;黄铁矿的δ34 SV-CDT值为1.9‰～4.2‰,均值为2.7‰,表明硫主要来自幔源;黄铁矿的206 Pb/204 Pb、207 Pb/204 Pb、208 Pb/204 Pb值分别为17.865～18.279、15.546～15.611、38.011～38.486,进一步表明成矿物质具有壳幔混合的特征.
Abstract
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.
维普
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