The Annieopsquotch ophiolite belt of southwest Newfoundland: Geology and tectonic significance

Dunning, G. R.; Chorlton, L. B.

doi:10.1130/0016-7606(1985)96<1466:taobos>2.0.co;2

Cited by 24 publications

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“…Variation within a single body may be due to contamination and/or fractionation during ascent and emplace ment. Dunning and Chorlton (1985) found evidence of signifi cant crustal contamination in plutons of the Central Gneiss Terrane, and Fox and van Berkel (1988) deduced that circulation of hydrous fluids altered the composition of ultramafic rocks. Whalen and Currie (1984) found magma mixing to be a major process in the Topsails Terrane to the north.…”

Section: Discussionmentioning

confidence: 99%

“…Ultramafic rocks of ophiolitic affinities occur in narrow (<500 m) sinuous strips bounded by high strain zones (Fox and van Berkel, 1988). Middle Ordovician radiometric ages have been obtained from both gneisses and granitoid intrusions (Stevens et ah, 1982;Dunning and Chorlton, 1985). North of the Little Grand Lake fault, undeformed early Silurian A-type granites intruded plutons of Ordovician age (Whalen et al, 1987) and little metamorphosed Ordovician volcano-sedimentary suites of ophiolitic affinity.…”

Section: Geological Settingmentioning

confidence: 99%

“…1). The gneisses and granitoid rocks gave middle Ordovician radiometric ages (Stevens et al, 1982;Dunning and Chorlton, 1985). Dunning eta/.…”

Section: Introductionmentioning

confidence: 99%

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Geochemistry of post-tectonic mafic intrusions in the Central Gneiss Terrane of southwestern Newfoundland

Currie

Berkel

1989

atgeol

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South of Grand Lake, mafic igneous complexes of proven or probable Silurian age intruded quartzofeldspathic gneisses that had been deformed and raised to granulite facies inmid-Ordovician time. The mafic igneous complexes consist of gabbroic units, which locally exhibit igneous layering and contain ultramafic cumulate pods, that grade to and are cut by finer-grained hornblende gabbro. Compositions more felsic than diorite exhibit intrusive to co-mingling relationships with more mafic rocks. Chemical data for possible liquid-derived rocks exhibit characteristics suggesting derivation from diverse mantle sources, followed by varying combinations of fractionation, contamination, mixing and metasomatism by hydrous fluids during ascent and emplacement. The post-tectonic emplacement of the plutons suggests stabilisation of the Central Gneiss Terrane by late Ordovician or Silurian time, when the adjacent terrane to the southeast (Meelpaeg Terrane) was still undergoing deformation and granitic plutonism.Au sud de Grand Lake, des complexes ignes mafiques, dont l'age estassurementouprobablement silurien, firent intrusion dans des gneiss quartzofeldspathiques qui avaient ete deformes et avaient atteintle facies des granulites au milieu de l 'Ordovicien. Les complexes ignds mafiques sont constitues d 'unites gabbroi'ques (montrant localement un aspect rubanne et contenant des lentilles de cumulats ultramafiques) passant graduellement a un gabbro a hornblende moins grenu qui les recoupe aussi. Les compositions plus felsiques que la diorite sont en relation d'intrusion ou de melange avec les roches plus mafiques. Les donnees chimiques concemant des roches possiblement derivees du liquide montrent des caracteres suggerant une derivation a partir de diverses sources mantelliques, suivie d'une combinaison variee de fractionnement, contamination, melange et metasomatisme par des fluides aqueux durant 1'ascension et l'emplacement. L'emplacement post-tectonique des plutons suggere une stabilisation de la laniere Central Gneiss Terrane avant l 'Ordovicien tardif ou le Silurien, au moment oil la laniere adjacente au sud-est (la Laniere de Meelpaeg) subissait encore une deformation et un plutonisme granitique.[Traduit par le journal]

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Section: Discussionmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

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Geochemistry of post-tectonic mafic intrusions in the Central Gneiss Terrane of southwestern Newfoundland

Currie

Berkel

1989

atgeol

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“…Herd and Dunning (1979) as signed a Precambrian age to granulite-grade metamorphism of the Cormacks Lake complex, van Berkel and Currie (1988) argued that units could be correlated across the Long Range Fault and that much of the protolith could be Precambrian, although strongly reworked during the Paleozoic. Dunning and Chorlton (1985) suggested that the oldest rocks were lower Ordovician ophiolites. Dunning (1987) demonstrated that the pervasive tonalite to granite suite is of mid-Ordovician age (456 Ma), but the age of the granulite-facies metamorphism could be older.…”

Section: Central Gneiss Subzonementioning

confidence: 99%

“…Metasedimentary rocks justeastof the Long Range Fault have recrystallised to coarse (>2 mm) granoblastic fabrics difficult to distinguish from granitoid plutons (van Berkel and Currie, 1988) and may also have reached granulite facies. The Central Gneiss Subzone contains thin (<500 m) strips of ophiolite bounded by high strain zones (Fox and van Berkel, 1988), as well as larger sheets of ophiolite (Brown, 1977) intruded by the tonalite-granite complex (Dunning and Chorlton, 1985). All rocks exhibit a late, greenschist or lower grade metamorphic overprint.…”

Section: Introductionmentioning

confidence: 99%

Age of high-grade gneisses south of Grand Lake, Newfoundland

Currie

Breeman

Hunt

et al. 1992

atgeol

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Crystalline rocks of the Steel Mountain Subzone of the Humber Zone in southwest Newfoundland give an age for granulite-grade metamorphism of 1498+9/-8 Ma, similar to ages from the Long Range inlier and northwestern Cape Breton Island. Peralkaline leucogranite was emplaced at 608 ± 4 Ma. The emplacement of anorthosite-gabbro complexes and amphibolite-grade metamorphism took place between these dates. The southern part of the Dunnage Zone (Central Gneiss Subzone), in contact with the Steel Mountain Subzone at the Long Range Fault, lacks Precambrian crystalline rocks, but was intruded by charnockitic plutons and metamorphosed to granulite facies at 460 ± 10 Ma. This subzone was exhumed before 435 Ma. In the Meelpaeg Subzone of the Gander Zone, which is in contact with the Central Gneiss Subzone along the Victoria River Fault, the oldest intrusive component of a granoblastic migmatitic gneiss was emplaced at 418 ± 4 Ma.These data demonstrate that both the Long Range and Victoria River faults form major tectonic boundaries. Subzones appear to have been thrust westward in Silurian or later time.Les roches cristallines de la sous-zone du mont Steel, dans la zone de Humber du sud-ouest de Terre-Neuve, ont donne des ages de 1498+9/-8 Ma pour le metamorphisme de haut grade, similaires a ceux de la boutonniere de Long Range et du nord de l 'lle-du-Cap-Breton. Un leucogranite peralcalin s'est mis en place a 608 ± 4 Ma. L'intrusion des complexes a anorthosite-gabbro et le metamorphisme au facies amphibolite se sont produits entre ces deux 6venements. La partie sud de la zone de Dunnage (sous-zone de gneiss centrale), en contact avec la sous-zone du mont Steel a la faille de Long Range, ne contient pas de roches cristallines precambriennes mais a ete recoup6e par des plutons charnockitiques et a6te metamorphisee au facies granulite a 460± lOMa. Cette sous-zone aeteexhum6e avant 435 Ma. Dans la sous-zone Mulpaeg de la zone de Gander, qui est mise en contact avec la sous-zone de gneiss centrale par la faille de la riviere Victoria, la phase intrusive la plus ancienne d 'un gneiss migmatitique et granoblastique s 'est mise en place a 418 ± 4 Ma.Ces donnees demontrent que les failles de Long Range et de la riviere Victoria sont des frontieres tectoniques majeures. Les sous-zones semblent avoir subi un chevauchement vers l 'ouest au plus tard au Silurien.[Traduit par le journal]

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The Record of Ordovician Arc–Arc and Arc–Continent Collisions in the Canadian Appalachians During the Closure of Iapetus

Zagorevski

Staal

2011

Frontiers in Earth Sciences

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The Annieopsquotch ophiolite belt of southwest Newfoundland: Geology and tectonic significance

Cited by 24 publications

References 0 publications

Geochemistry of post-tectonic mafic intrusions in the Central Gneiss Terrane of southwestern Newfoundland

Geochemistry of post-tectonic mafic intrusions in the Central Gneiss Terrane of southwestern Newfoundland

Age of high-grade gneisses south of Grand Lake, Newfoundland

The Record of Ordovician Arc–Arc and Arc–Continent Collisions in the Canadian Appalachians During the Closure of Iapetus

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