Authors / CoAuthors
Bastrakov, E.N. | Skirrow, R.G. | Davidson, G.J.
Abstract
The available geological data suggest two stages of hydrothermal activity at a number of sub-economic iron-oxide copper-gold systems of the Olympic Dam region of the Olympic Cu-Au province of the eastern margin of the Gawler Craton. They contain high- (>400?C), and moderate- to low-(200 to 300C?) temperature Fe-oxide rich hydrothermal alteration. The mineral assemblages are CAM: calcsilicate - alkali feldspar ? magnetite ? Fe-Cu sulphides, and HSCC: hematite-sericite-chlorite-carbonate ? Fe-Cu sulphides ? U, REE minerals ([Skirrow, 2002 #563; Skirrow et al., this volume). The bulk of the sub-economic Cu-Au mineralisation is associated with HSCC stage. Microanalytical results by PIXE, however, demonstrate that significant amount of copper (>500 ppm) has been transported by early-stage high-temperature fluids. These fluids were recorded as extremely concentrated fluid inclusions with multiple solid phases, compared to relatively simple liquid-vapour inclusions of the HSCC stage. Sulfur isotopes demonstrate that sulphur in these system was be derived either from magmatic rocks by relatively oxidised fluids (?34Ssulfides from ?5 to 2?), or from crustal sedimentary rocks (?34Ssulfides from 5 to 10?). Oxygen and hydrogen isotopes suggest ?metamorphic? rather then ortho-magmatic origin of the HSCC fluids. These observations can be reconciled with a two-stage model where pre-existing geochemical trap of hydrothermal magnetite (? sub-economic copper-gold mineralisation) is flushed by oxidised brine of sedimentary or metamorphic origin. The reduction of this brine due to magnetite to hematite conversion results in precipitation of copper and gold.
Product Type
nonGeographicDataset
eCat Id
61811
Contact for the resource
Custodian
Point of contact
Cnr Jerrabomberra Ave and Hindmarsh Dr GPO Box 378
Canberra
ACT
2601
Australia
Keywords
-
- External PublicationScientific Journal Paper
- ( Theme )
-
- economic geology
- ( Theme )
-
- metallogenesis
- ( Theme )
-
- mineral exploration
-
- AU-SA
- Australian and New Zealand Standard Research Classification (ANZSRC)
-
- Earth Sciences
-
- Published_Internal
Publication Date
2005-01-20T00:00:00
Creation Date
Security Constraints
Legal Constraints
Status
Purpose
Maintenance Information
unknown
Topic Category
geoscientificInformation
Series Information
Lineage
Unknown
Parent Information
Extents
[-31.8, -30.0, 136.8, 137.2]
Reference System
Spatial Resolution
Service Information
Associations
Downloads and Links
Source Information
Source data not available.