The Tectonic, Magmatic and Mineralization History of the Sudbury Structure

The Sudbury Structure consists of three major components: 1) the Sudbury Basin; 2) the Sudbury Igneous Complex which surrounds the basin as an elliptical collar; and 3) an outer zone of shatter-coned and intensely brecciated footwall rocks. Although the Sudbury Event which formed the structure may be unique, the area has, in fact, been shaped by a series of tectonic, magmatic and mineralization events which can be considered in terms of two Wilson cycles of continental extension and closure. The first cycle, from 2500 to 1700 Ma, included the following events: doming (uplift of Levack Gneiss Complex); NE-SW extension (Matachewan dikes); N-S to NW-SE rifting (faults, mafic intrusions, sedimentation, and Ni-Cu-PGE and U mineralization); NW-SE extension (Nipissing diabase, and Ni-Cu-PGE, Ag, Co mineralization); and NW-SE and NE-SW closure (Penokean Orogeny, 1900 to 1700 Ma) with superimposed meteorite impact (1850 Ma, Ni-Cu- PGE, Zn-Cu-Pb deposits). The second cycle, from 1700 to 1000 Ma, included: N-S extension (alkali metasomatism, Au); N-S extension (hornblende diabase dikes along the Murray fault set); NNESSW extension (olivine diabase dikes); NE-SW extension (Fecunis Lake fault set); and NW-SE closure (Grenvillian Orogeny).
The rich and diverse Ni-Cu-PGE and subordinate Zn-Pb-Cu and Au mineralization of the Sudbury region is related to endogenic and impact-triggered crustal extension and magmatism. The Sudbury Structure apparently was the site of a triple junction or hot-spot. The Sudbury ores, although located within an impact structure, are analogous in terms of age and tectonic setting to Ni-Cu-PGE and Zn-Pb-Cu ores elsewhere in the world. Meteorite impact accentuated on-going ore forming processes and magmatism at Sudbury.
Keywords: Mineralization, Sudbury structure, Tectonic events, Magmatic events
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Summary: A consistency-driven pairwise comparisons method for mineral potential assessment is presented, using a simplified case of volcanic-associated massive sulfide type deposits as an example. Geological, geochemical, and geophysical criteria are considered on two levels: local and regional. The local geological criteria are subdivided into stratigraphy, lithology, alteration and/or mineralization, and structure. The concept of geomerit index and a procedure for computing this index are introduced...
Publication: Exploration & Mining Geology
Author(s): WALDEMAR W. KOCZKODAJ: Centre in Mining and Mineral Exploration Research Laurentian University, Sudbury, Ontario, Canada P3E 2C6; WILLIAM O. MACKASEY: WOM Associates, 140 Crater Crescent, Sudbury, Ontario, P3E 5Y8
Keywords: Mineralogy, Geological criteria, Geochemical criteria, Geophysical criteria
Issue: 1
Volume: 6
Year: 1997
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Summary: Measurement of natural radioactivity has been used in both a qualitative and a quantitative way in mineral exploration, particularly in the search for uranium. In the last five years, the Kernfysisch Versneller Instituut (KVI) and British Geological Survey (BGS) have designed, built and tested a new detector system that greatly improves quantitative applications in mineral exploration, especially on the seafloor and in the nearshore zone. The new system is an enhancement of an earlier BGS...
Publication: Exploration & Mining Geology
Author(s): D.G. JONES, P.D. ROBERTS: British Geological Survey, Keyworth, Nottingham NG12 5GG, United Kingdom; A. ROZENDAAL, W.G. MACDONALD: Department of Geology, University of Stellenbosch, P.O. Box X01, Matieland 7602, Stellenbosch, South Africa
Keywords: Radioactivity, KVI, BSG, Mineral exploration, Mineral Processing, Heavy-mineral concentration, On-line quality control
Issue: 1
Volume: 6
Year: 1997
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Summary: The Navan zinc-lead ore deposit (70 million tonnes) is hosted principally (97%) by the Meath Formation (Lower Carboniferous, Courceyan, Navan Group), comprising a lower, mainly carbonate mudstone unit, the Stackallan Member, and an upper grainstone-dominated unit. The Stackallan Member, about 60 m thick, comprises about 35 peritidal cycles including an oolitic grainstone interval. Grainstones forming the upper part of the formation, about 150 m thick, comprise at least six shallowing-upward...
Publication: Exploration & Mining Geology
Author(s): GIANCARLO RIZZI and C.J.R. BRAITHWAITE Department of Geology and Applied Geology
University of Glasgow, G12 8QQ, Scotland
Keywords: Navan zinc-lead ore deposit, Meath Formation, Mudstone, Upper grainstone-dominated unit
Issue: 1
Volume: 6
Year: 1997
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Summary: The Amazon region is characterized by the development of deep chemical weathering represented by widespread lateritic covers and soils. Two distinct periods of laterite formation can be distinguished: mature laterites from the Eocene-Oligocene (and locally from the end of the Cretaceous), and immature laterites from the Pleistocene. The older laterites occur on plateau landscapes, and the younger ones on widespread hilly to flat lowlands. Both types show complete or truncated profiles,...
Publication: Exploration & Mining Geology
Author(s): MARCONDES LIMA COSTA: Geosciences Center, Federal University of Pará, C.P. 1611 66075-110, Belém-PA, Brazil.
Keywords: Amazon Region, Laterite formation, Mineral deposits.
Issue: 1
Volume: 6
Year: 1997
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