Heilongjiang Institute of Geophysical and Geochemical Exploration
三合屯金矿床位于黑龙江省嫩江县境内，矿体赋存于晚三叠世花岗质糜棱岩中，靠近下白垩统光华组火山岩与晚三叠世花岗质糜棱岩接触带附近。为探讨成矿流体的来源，对矿石样品S、Pb、H、O同位素和惰性气体He、Ar同位素组成进行了系统研究，稳定同位素结果表明：硫化物的δ34Ｓ在-4.4‰～4.9‰之间，与陨石硫的δ34Ｓ值接近，反映为深源地幔岩浆硫；黄铁矿Pb同位素的206Pb/204Pb=17.284～18.290， 207Pb/204Pb=15.505～15.561， 208Pb/204Pb=37.656～38.116；石英中的206Pb/204Pb=18.206～18.449， 207Pb/204Pb=15.526～15.652， 208Pb/204Pb=38.050～38.648，成矿物质主要来自壳幔混源；H、O 同位素石英的δDV-SMOW 值为-77.5‰～ -96.3‰，δ18OV-SMOW 为7.4‰～11.6‰，δ18OH2O 为-0.2‰～4.8‰，反映成矿流体主要来自大气降水并有岩浆水参与；黄铁矿流体包裹体的3He/4He比值为l.19～1.54R/Ra，高于地壳的3He/4He比值数十～百余倍，但明显低于地幔流体的3He/4He比值；40Ar/36Ar=608.5～922.6，高于地壳流体（40Ar/36Ar＞295.5）氩的同位素组成；40Ar*/4He比值0.14～1.56，平均值0.95，其中SHT19样品数据40Ar*/4He （0.14）接近地壳40Ar*/4He（0.2）流体，其它样品40Ar*/4He （0.88～1.56）远高于地幔（0.33～0.56）流体，说明成矿流体可能以大气降水为主，又有地壳及深源地幔流体的加入。综合区域矿床成矿时代，显示三合屯金矿床为早白垩世晚期，成矿物质来源与早白垩世光华期火岩浆活动密切相关。
Sanhetun gold deposit is located in Nenjiang County, Heilongjiang Province. The ore body occurs in the late Triassic granitic mylonite, near the contact zone between the volcanic rocks of the lower Cretaceous Guanghua Formation and the late Triassic granitic mylonite. In order to discuss the source of ore-forming fluid, this work systematically studied the S, Pb, H, O isotopes and inert gas He, Ar isotopic compositions in different minerals collected. Stable isotope results show that: δ34S is between -4.4‰~4.9 ‰，which is similar to meteorite sulfur δ34S value,reflects the contribution of sulfur from deep magma; 206Pb/204Pb of Pyrite =17.284-18~180290，207Pb/204Pb=15.505~15.561,208Pb/204Pb=37.656~38.116; 206Pb/204Pb of Quartz=18.206~ 18.449,207Pb/204Pb=15.526~15.652,208Pb/204Pb=38.050~38.648, which indicates that the ore-forming material mainly comes from mantle; H, O isotopes of Quartz δ DV-SMOW value is - 77.5 ‰~- 96.3 ‰, δ 18OV-SMOW is 7.4 ‰~11.6 ‰, δ18OH2O is - 0.2 ‰~4.8 ‰, which reflects that the ore-forming fluid mainly comes from atmospheric precipitation, and some magmatic water also participates; The 3He/4He ratio of Pyrite fluid inclusions is 1.19～1.54R/Ra, tens to more than hundreds times higher than the 3He/4He ratio of the crust, but obviously lower than the 3He/4He ratio of mantle fluid; 40Ar/36Ar=608.5～922.6, higher than the 40Ar/36Ar composition of crustal fluid (40Ar/36Ar＞295.5);The 40Ar*/4He ratio is 0.14～1.56, with an average value of 0.95. The 40Ar*/4He (0.14) of SHT19 sample data is close to the 40Ar*/4He (0.2) fluid of the crust, and the 40Ar */4He (0.88～1.56) of other samples is much higher than the mantle (0.33～0.56) fluid, indicating that the ore-forming fluid may be mainly meteoric water, but also the crust and deep mantle fluid. According to the regional metallogenic epoch, the Sanhetun gold deposit was formed in the late Early Cretaceous, and the source of ore-forming materials was closely related to the magmatic activity in the Guanghua period of the Early Cretaceous.