Geology and Mineral Chemistry of Gold Mineralization in Mirge‐Naqshineh Occurrence (Saqez,NW Iran): Implications for Transportation and Precipitation of Gold |
| |
| Authors: | Golale ASGHARI Samad ALIPOUR Hossein AZIZI and Hassan MIRNEJAD |
| |
| Institution: | 1 Department of Geology, Urmia University, Urmia, Iran,1 Department of Geology, Urmia University, Urmia, Iran,2 Mining Department, Faculty of Engineering, University of Kurdistan, P.O. Box 416, Sanandaj, Iran and 3 Department of Geology, Faculty of Science, University of Tehran, Tehran, Iran |
| |
| Abstract: | The Mirge-Naqshineh gold district is situated at northwest of Iran with a NW-trending brittle-ductile shear zone. It is hosted by Precambrian meta-sedimentary and meta-volcanic units traversed by mineralized quartz veins. In terms of cross-cutting relationships and sulfide content three types of quartz veins are identified in the region. Among those, parallel to bedding quartz vein (type I) is the main host for gold mineralization. Gold is found in three different forms: 1) submicrometer-size inclusions of gold in arsenian pyrite, 2) as electrum and 3) in the crystal lattice of sulfides (pyrite, galena and chalcopyrite). Six types of pyrite (Py1-Py6) were identified in this ore reserve. Py3 coexists with arsenopyrite and contains the greatest As-Au concentrations. There is a negative correlation between the As and S contents in Py2 and Py3, implying the substitution of sulfur by arsenic. Pyrites and mineralized quartz veins were formed via metamorphic-hydrothermal fluid and reflect the gold-transportation as Au(HS)-2 under reducing and acidic conditions. The gold precipitation mainly controlled by crystallization of arsenian pyrite during fluid/rock interactions and variation of fO2. The volcanic host rock has played an important role in gold concentration, as Py3 in this rock contains inclusion of gold particles, but gold is within the lattice of pyrite in phyllite or other units. |
| |
| Keywords: | gold quartz veins mineral chemistry EPMA Mirge-Naqshineh Iran |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《Acta Geologica Sinica》浏览原始摘要信息 |
| 点击此处可从《Acta Geologica Sinica》下载免费的PDF全文 |
|
