吉林桦甸张家屯金矿床成因：来自电子探针、流体包裹体测温和原位S−Pb同位素的证据

范明辉; 孙国胜; 潘彦平; 孙九达; 陈凯; 王卓一; 李雪

doi:10.11792/hj20260215

吉林桦甸张家屯金矿床成因：来自电子探针、流体包裹体测温和原位S−Pb同位素的证据

Genesis of Zhangjiatun Gold Deposit in Huadian, Jilin Province: Evidence from electron microprobe, fluid inclusion thermometry, and in-situ S−Pb isotopes

摘要

摘要: 通过对张家屯金矿床金属硫化物电子探针、流体包裹体和黄铁矿原位S−Pb同位素进行测试分析，探讨了成矿流体性质、成矿物质来源及矿床成因。测试结果表明：黄铁矿w（Fe）平均值为46.1 %，w（S）平均值为52.6 %，w（S）/w（Fe）平均值为1.9，δFe−δS图解表现出亏铁亏硫；黄铁矿w（Co）/w（Ni）值均大于1，表明成矿流体以岩浆热液流体为主；w（Fe+S）/w（As）值反映浅成低温热液型金矿床特征。方铅矿w（Pb）平均值为87.0 %，w（S）平均值为13.0 %，w（Pb）/w（S）值大于理论值，富铅亏硫。闪锌矿w（Zn）平均值为59.4 %，w（S）平均值为32.0 %，Fe、Zn呈负相关，Fe与Zn发生类质同象置换；w（Zn）/w（Fe）值为10～100，成矿温度可能在150 ℃～250 ℃。石英中流体包裹体以气液两相包裹体为主，成矿流体呈现低温度（145 ℃～205 ℃）、低盐度（8 %～11 %）及低密度（0.800～0.925 g/cm³），成矿深度在1.80～2.62 km。δ³⁴S值为6.51 ‰～7.16 ‰，显示出岩浆硫的特征；²⁰⁶Pb/²⁰⁴Pb值为16.698～16.866，²⁰⁷Pb/²⁰⁴Pb值为15.500～15.579和²⁰⁸Pb/²⁰⁴Pb值为37.051～37.220，显示与壳源岩浆作用有关。综上所述，认为张家屯金矿床成因类型为浅成低温热液型，与古太平洋板块俯冲后期伸展构造背景下的岩浆活动有关。

Abstract: This study investigated the properties of ore fluids, ore-forming material sources, and the ore genesis of the Zhangjiatun Gold Deposit through the analysis of metal sulfides using electron microprobe, fluid inclusions, and in situ S−Pb isotopes of pyrite. The results indicate that the average weight percentage of w（Fe） in pyrite is 46.1 %, and the average weight percentage of w（S） is 52.6 %, resulting in an average w（S）/w（Fe） ratio of 1.9. The δFe−δS diagram shows a depletion of iron and sulfur. The w（Co）/w（Ni）ratios in pyrite are all greater than 1, suggesting that the ore fluids are primarily magmatic hydrothermal fluids in origin. The w（Fe+S）/w（As） ratio reflects characteristics typical of epithermal gold deposits. The average weight percentage of w（Pb） in galena is 87.0 %, while the average weight percentage of w（S） is 13.0 %. The w（Pb）/w（S） ratio exceeds theoretical values, indicating a lead-rich and sulfur-poor composition. The average weight percentage of w（Zn） in sphalerite is 59.4 %, while the average weight percentage of w（S） is 32.0 %. There is a negative correlation between Fe and Zn, indicating that Fe undergoes isomorphism substitution with Zn. The w（Zn）/w（Fe） ratio ranges from 10 to 100, suggesting that the ore-forming temperature could be 150 ℃−250 ℃. Fluid inclusions in quartz are primarily two-phase （liquid-vapor）, with the ore fluids exhibiting low temperatures （145 ℃−205 ℃）, low salinity （8 %−11 %）, and low density （0.800−0.925 g/cm³）, indicating a mineralization depth of 1.80−2.62 km. The δ³⁴S values range from 6.51 ‰ to 7.16 ‰, exhibiting characteristics consistent with magmatic sulfur. The ²⁰⁶Pb/²⁰⁴Pb ratios range from 16.698 to 16.866, the ²⁰⁷Pb/²⁰⁴Pb ratios from 15.500 to 15.579, and the ²⁰⁸Pb/²⁰⁴Pb ratios from 37.051 to 37.220, indicating relationships with crust-derived magmatic processes. Based on the above findings, it is concluded that the ore genesis of the Zhangjiatun Gold Deposit is characterized as an epithermal type, associated with magmatic activity related to the extensional tectonics of post-subduction of the ancient Pacific Plate.

HTML全文

参考文献(31)

施引文献

资源附件(0)