Variations morphologiques des coulées méta-ultra-mafiques komatiïtiques du sillon Archéen de La Motte-Vassan, Abitibi-Est, Québec

Imreh, L.

doi:10.1016/0301-9268(80)90021-2

Cited by 5 publications

(1 citation statement)

References 13 publications

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“…It is, however, strikingly similar to the shallow water environments of island arcs, some back-arc basins, and environments deduced using similar criteria in some greenstone belts (cf. De Rosen-Spence et al 1980;Imreh 1980;Jackson 1980;Okada 1980;Tarney & Windley 1981;Bluck 1982).…”

Section: Environment Of Volcanismmentioning

confidence: 99%

Nature, affinities and significance of metavolcanic rocks in the Outokumpu assemblage, eastern Finland

Park¹

1984

Bull Geol Soc Finland

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The rock association of serpentinite-chrome-silicate skarn-dolomitequartz rock-black schist in the Outokumpu region, in which polymetallic sulphide ore deposits occur, has been compared to an ophiolite. However, despite evidence that the orebodies have a sea-floor exhalative origin, volcanogenic rocks have only been described recently. Evidence is now presented that, in the Losomäki district, the volcanogenic rocks include pillow lavas, vesicular lava, agglomerate and tuff with autoclastic breccia. These original features indicative of a volcanogenic derivation are restricted to low strain enclaves in amphibole-chlorite (± garnet) schists, amphibole-epidote schists, zoisite-amphibole (+ chlorite) rocks and hornblende-plagioclase-quartz rocks, previously mapped as »skarn». These banded amphibolites and greenschists show evidence of repeated deformation and recrystallisation under P-T conditions pertaining successively to amphibolite and greenschist facies conditions, and grade into rocks retaining distinctive volcanogenic features. At Losomäki they constitute about 30 % of the outcrop of the serpentinite-skarn-dolomite-quartz rock-black schist assemblage, referred to as the Outokumpu assemblage. Comparable rocks occur in the same assemblage elsewhere in the Outokumpu region. Even though original volcanogenic features survive, complete metamorphic reconstitution means that the original compositions have to be deduced. Possible pseudomorphs after skeletal olivine (?spinifex) occur in some pillow cores, suggesting komatiitic affinities. Whole-rock chemistry indicates extensive alteration before the first metamorphic reconstitution; leaching of alkalis, iron, nickel, cobalt, chromium and base metals is implied, presumably in a marine environment. Some trace element ratios appear to remain well constrained, particularly Ti:Zr, Zr:Y and Ti:Y. On discriminant function diagrams affinities are suggested with primitive tholeiites of island arcs or back-arc basins; other features suggest similarities to the komatiite-tholeiite association of Archaean greenstone belts. The environment of eruption, as indicated by the relict morphology and field relations of the pillow lavas and related volcanoclastic deposits, appears to have been under shallow water on the seafloor. The geochemical parameters suggest that the tectonic setting was in an island-arc or back-arc basin and not on the deep ocean floor.

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Section: Environment Of Volcanismmentioning

confidence: 99%

Nature, affinities and significance of metavolcanic rocks in the Outokumpu assemblage, eastern Finland

Park¹

1984

Bull Geol Soc Finland

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Paleogeographic and Paleotectonic Evolution of a Basement-Controlled Archean Supracrustal Sequence, Chibougamau-Caopatina, Quebec

Mueller¹,

Chown²,

Sharma³

et al. 1989

The Journal of Geology

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Geology and Mineral Deposits of the Superior Province of the Canadian Shield

Card¹,

Poulsen²

1998

Geology of the Precambrian Superior and Grenville Provinces and Precambrian Fossils in North America

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It has been the custom of the Geological Survey of Canada (GSC) to periodically publish a summary account of the geology and economic mineral deposits of Canada. Such ‘Geology and Economic Minerals of Canada’ volumes were published in 1909, 1926, 1946, 1957, and 1970. During the 1980s, in lieu of a sixth edition, the GSC embarked on the production of a series of more comprehensive ‘Geology of Canada’ volumes as part of the Geological Society of America (GSA) Decade of North American Geology (DNAG) series. Much of the material for this review of the geology and economic minerals of Superior Province was prepared as part of the DNAG initiative but, due to revised operational requirements, the integration of the geological and metallogenic aspects arose much later. In this integrated review, we place particular emphasis on advances that have taken place in the 25 years since the last summaries of this kind (Stockwell et al., 1970; Lang et al., 1970; Goodwin, 1972). The Archean Superior Craton forms the core of the North American continent (Fig. 2.1) and is surrounded and truncated on all sides by Proterozoic orogens, the collisional zones along which the elements of the Precambrian Canadian Shield were amalgamated (Hoffman, 1988, 1989). The Superior Province (Fig. 2.2) is the 2 × 106 km2 region of this craton which is free of significant post-Archean cover rocks and deformation. The rocks of Superior Province are of mainly Meso- and Neoarchean age and have been significantly affected by post-Archean deformation only along

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Variations morphologiques des coulées méta-ultra-mafiques komatiïtiques du sillon Archéen de La Motte-Vassan, Abitibi-Est, Québec

Cited by 5 publications

References 13 publications

Nature, affinities and significance of metavolcanic rocks in the Outokumpu assemblage, eastern Finland

Nature, affinities and significance of metavolcanic rocks in the Outokumpu assemblage, eastern Finland

Paleogeographic and Paleotectonic Evolution of a Basement-Controlled Archean Supracrustal Sequence, Chibougamau-Caopatina, Quebec

Geology and Mineral Deposits of the Superior Province of the Canadian Shield

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