Ore-Forming Fluid and Metallogenesis of the Yinachang Fe-Cu-Au-REE Deposit, Wuding, Yunnan Province, China
详细信息
- 责任者：Hou Lin (State Key Laboratory of Geological Processes and Mineral Resources ; School of Earth Science and Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Ding Jun
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(4)
- 关键词：铁矿 ; iron ores ; 铜矿 ; copper ores ; 金矿 ; gold ores ; 稀土矿床 ; rare earth deposit ; 云南 ; Yunnan Province
- 页码：p.1187-1202
- 图表：illus., 4 tables, 66 refs.
- 分类号：1001
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
The Yinachang Fe-Cu-Au-REE deposit locates in the central of Yunan Province, China, the southern of Kangdian axis, which comprises to the Yangtze block to the SW edge. Fe-REE ores occur as banded and/or disseminated replacements with in the breccia pipes, whereas Cu-Au ores occur predominantly as massive and veinlets within wallrocks and magnetite ores. According to differences in mineral association, ore structure, texture and wallrock alterations, we divide the ore-forming process into three stages: pre-mineralization stage, dominant mineralization stage and post-mineralization stage, and the dominant mineralization stage is comprised by magnetite-REE substage and sulfide-gold substage. Researches in microphysiography, composition and isotope of fluid inclusions suggest that fluids in pre-mineralization stage are high salinity magma, containing alkalic components and volatile phase, which formed in condition of high pressure (150～200MPa) and high temperature (500～600℃). Immiscibility effect happens in these magma, breeding the magmatic hydrothermal (mid-high temperature 170～550℃, mid-high pressure 73～155MPa), which caused the albitization of carbonate, and extract the Fe to the fluid. Replacement between magmatic hydrothermal and carbonaceous wallrock causing the precipitation of Fe and REE in the magnetite-REE substage, and the dehydration of wallrock produced the metamorphic hydrothermal for the aulfide-gold substage. Metamorphic hydrothermal mixed with meteoric water (120～360℃, 31～112MPa), changed the physical and chemical conditions such as pH, Eh, fO2、fS, Cu, Au is no longer stable as clathrate in fluid, but precipitated as sulfide (Cu) and substance (Au). In the stage of post-mineralization, with the depletion of metamorphic hydrothermal, dominant fluid became pure meteoric water with low temperature (95～270℃), low salinity (1.0%～17.9%NaCleqv). The Yinachang Fe-Cu-Au-REE deposit have many similarities with Iron Oxide Copper Gold (IOCG) deposit in geological background, mineral deposit, mineral association, fluid evolution and mineralization process. It could be concluded as a typical IOCG deposits in central Yunnan Province.