- 责任者：Chi Guoxiang (Department of Geology ; University of Regina ; Regina S4S 0A2 ; Saskatchewan ; Canada) ; Jayanta Guha
- 刊名：Earth Science Frontiers
- 出版年：2011
- 卷期：18(5)
- 关键词：金矿 ; gold ores ; 显微构造 ; ultrastructure ; 成矿流体 ; ore-forming fluids ; 加拿大 ; Canada
- 页码：p.43-54
- 图表：6 illus., 39 refs.
- 分类号：1001
- issnNo：ISSN1005-2321
- isbnNo：CN11-3370/P
The Donalda gold deposit in the southern part of the Archean Abitibi greenstone belt consists mainly of a subhorizontal gold-quartz vein perpendicular to subvertical shear zones. The 0.3~0.5 m thick vein is characterized by vein-parallel banding structures indicating multiple episodes of fracture opening and mineral precipitation. Measurement of the c-axis of primary growth quartz indicates that quartz preferentially grew perpendicular to the fracture, suggesting open space filling and/or extensional nature of the fracture. Measurement of the orientations of microfractures, veinlets and fluid-inclusion planes (FIPs) crosscutting primary growth quartz indicates that the vein minerals were subject to a vertical maximum principal stress (σ 1), which is inconsistent with the subhorizontal σ 1 inferred from the regional stress field with N-S shortening. This apparent discrepancy is explained by invoking episodic fluid pressure fluctuation between supralithostatic and hydrostatic regimes accompanied by episodic opening and closing of the subhorizontal fracture.