论文摘要
Traditionally, the value of δS34（ΣS） can be used to infer the S source of the ore-forming hydrothermal fluid. In most case, δS34（ΣS） is represented by peak value of sulfur isotope data of metal sulfide, however if metals precipitate at medium（or high） oxygen fugacity and pH conditions, this method will be imprecise. The constructing of the log?O2-pH diagram of δS34 contours with the stability fields of significant minerals and the log?S2-T diagram can effectively calculate value of δS34（ΣS）, explain the transformation of sulfur isotope data in different mineralization stage and restore the physico-chemical conditions of mineralization process. The Weilasituo Zn-Cu-Ag deposit is a typical hydrothermal vein deposit in the south of the Great Hinggan Range, which was hosted in the Hercynian quartz diorite and Paleozoic gneiss. The mineralization sequence was divided into four stages: stage 1, quartz-pyrite-arsenopyrite（generally most abundant minerals listed first）; stage 2, quartzsphalerite-chalcopyrite-pyrite-pyrrhotite; stage 3, quartz-calcitegalena-chalcopyrite-pyrite; stage 4, quartz-poor sulphide. The δS34 values of the stage 2 and 3 metal minerals, from-1.6 to 2 and from-4.4 to 1.7, respectively. The δS34（H2S） which can be calculated from the δS34 values of metal minerals, range from-1.7 to 1.9 in the stage 2 and from-4.7 to 1.4 in the stage 3. Based on thermodynamic Model, the pH range from 5.2 to 7.7 and the log?O2 range from-40.8 to-35.8 in the stage 2, and the pH range from 5.8 to 7.7 and the log?O2 range from-37.5 to-34.8 in the stage 3. And δS34（ΣS） is more accurately estimated to be-2 which represents the sulfur is sourced from magma. Obviously, an significant factor affecting the mineral precipitation in Weilasituo deposit is the transition from low to high oxygen fugacity, while the p H may remain in a stable range. The accompanying trend is the conversion of low sulphur fugacity（log ?S2≈-12） to medium sulphur fugacity（log ?S2≈-10）. These changes in the ore-forming environment are considered to be the key to the decline of the δS34（H2S）. Here, a distinct transition of physico-chemical conditions were recognized and Thermodynamic modeling, one of the most significant method are showed.
论文目录
文章来源
类型: 国际会议
作者: MA Wanli,WANG Keyong,YANG He
来源: 第九届世界华人地质科学研讨会 2019-06-01
年度: 2019
分类: 基础科学,工程科技Ⅰ辑
专业: 地质学,矿业工程
单位: College of Earth Sciences, Jilin University
分类号: P618.2
DOI: 10.26914/c.cnkihy.2019.028511
页码: 414
总页数: 1
文件大小: 229k
下载量: 3