Characteristics of Ore-Forming Fluid and Mineralization Process of the Yangla Copper Deposit, Yunnan
详细信息
- 责任者：Chen Siyao (State Key Laboratory of Geological Processes and Mineral Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Gu Xuexiang
- 刊名：Earth Science Frontiers
- 出版年：2013
- 卷期：20(1)
- 关键词：铜矿 ; copper ores ; 成矿流体 ; ore-forming fluids ; 云南 ; Yunnan Province
- 页码：p.82-91
- 图表：illus., 2 tables, 42 refs.
- 分类号：1001
- issnNo：ISSN1005-2321
- isbnNo：CN11-3370/P
摘要
The Yangla copper deposit is located in the middle part of the Jinshajiang belt.It was formed by the westward subduction of the Jinshajiang oceanic basin and collisional orogeny during the Mid-Late Triassic.Ore bodies are typically layered or bedded and controlled by interlayer fracture zones in the wall rocks.Based on the study of fluid inclusions,the present paper is to discuss characteristics and evolution of ore-forming fluids and to evaluate the relationship between fluid immiscibility and mineralization.According to the petrographic study,various types of fluid inclusions including predominant vapor or liquid-rich aqueous inclusions and daughter minerals-bearing multiphase inclusions,and subordinately mono-phase liquid and organic vapor inclusions,are present in anhydrous skarn stage(Ⅰ),hydrous skarn-magnetite stage(Ⅱ),quartz-sulfide stage(Ⅲ) and calcite-sulfide stage(Ⅳ).Daughter minerals-bearing multiphase inclusions are abundant in garnet(Ⅰ),epidote(Ⅱ) and especially in quartz(Ⅲ).Ore-forming fluids of stageⅠandⅡhave high homogenization temperatures(413-593 ℃ and 336-498 ℃,respectively) and high salinities(19.1%-49.7% NaCl eq and 15.7%-53.3% NaCl eq,respectively).StageⅢore-forming fluid has a wide homogenization temperature range(148-398℃) and is characterized by existence of both high-salinity(35.5%-65.3% NaCl eq) and lowsalinity(2.1%-9.6% NaCl eq) end members.StageⅣ ore-forming fluid is characterized by low temperature(132-179℃) and low salinity(3.4%-10.4% NaCl eq).Based on the characteristics of fluid inclusions together with geological features,fluid immiscibility(boiling) is suggested to be the main mechanism for metal precipitations in this deposit.
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