The Northeastward Termination of the Appalachian Orogen

Williams, Harold; Kennedy, Michael J.; Neale, E R W

doi:10.1007/978-1-4684-3033-2_4

Cited by 36 publications

(13 citation statements)

References 38 publications

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“…The Gander and Avalon Zones (Williams et al 1974) mark the southeastern side of the Appalachian system in Newfoundland. The Avalon Zone (Avalon Platform of Kay and Colbert 1965) is characterized by Precambrian volcanic and flyschoid rocks, which exhibit varying degrees of low-grade metamorphism and deformation.…”

Section: Introductionmentioning

confidence: 99%

The Gander–Avalon Zone boundary in southeastern Newfoundland

Blackwood¹,

O'Driscoll²

1976

Can. J. Earth Sci.

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The Dover Fault, characterized by a 300–500 m wide mylonite zone, separates the Gander and Avalon Zones in northeastern Newfoundland and formed in association with the Precambrian regional deformation that overprints these zones. In southern Newfoundland, foliated granitic rocks of the Gander Zone are separated from non-foliated granites and clastic sedimentary and volcanic rocks (Connaigre Bay Group) of the Avalon Zone by a 50–100 m wide breccia zone called the Hermitage Bay Fault. Relationships along the Hermitage Bay Fault suggest that it is an Acadian structure that modifies the original Precambrian mylonite zone.

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Section: Introductionmentioning

confidence: 99%

The Gander–Avalon Zone boundary in southeastern Newfoundland

Blackwood¹,

O'Driscoll²

1976

Can. J. Earth Sci.

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“…The Appalachian Dunnage zone is characterized by Cambrian to Silurian oceanic volcanic, hypabyssal, and epiclastic rocks, widely interpreted to comprise vestiges of the Iapetus ocean, which separated the Laurentian and Gondwanan continents during the early Paleozoic (Wilson, 1966;Bird and Dewey, 1970;Harland and Gayer, 1972;Williams et al, 1974;Williams, 1979). Early models for the plate tectonic evolution of the Dunnage zone involved Cambrian to Early Ordovician opening of Iapetus, recorded by ophiolites, followed by Early to Middle Ordovician closing of the ocean, recorded by thick volcanic and/or epiclastic sequences.…”

Section: Introductionmentioning

confidence: 99%

Magmatic and tectonic evolution of the Cambrian-Ordovician Laurentian margin of Iapetus: Geochemical and isotopic constraints from the Notre Dame Subzone, Newfoundland

Swinden¹,

Jenner²,

Szybinski³

1997

The Nature of Magmatism in the Appalachian Orogen

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Late Cambrian to Early Ordovician volcanic and hypabyssal rocks in the NotreDame subzone, Newfoundland Appalachians, are generally considered to have formed in a series of island arcs and back arc basins on the Laurentian side of Iapetus. Our compilation of new geochemical and Nd isotopic data provides a more detailed look at the nature of magmatism in these environments than has heretofore been possible. Nd isotopic data constrain the nature of the magma sources for the various volcanic episodes and, in particular, allow us to track the early Paleozoic interaction of mantle and continental lithosphere at the Laurentian margin. New and published geochronological data permit us to assign a time sequence to the various events that we recognize.Geochemical data show that volcanic rocks in the Notre Dame subzone can be divided into several groups, most of which have well-documented analogs in modern plate environments. In nonarc environments, tholeiitic rocks with characteristics of N-MORB (normal mid-ocean basalt ridge) and E-MORB (enriched-MORB) are present, as are tholeiitic and alkalic basalts with characteristics of oceanic island basalts. The geochemical and isotopic data indicate derivation from time-integrated depleted mantle sources. We interpret these to have formed in ensimatic back arc basins.Arc volcanic rocks include island arc tholeiites, transitional island arc tholeiites, calc-alkalic basalt and/or andesite, boninites, and felsic volcanics. Geochemical and Nd isotopic data indicate that the tholeiitic rocks were derived from time integrated LREE-(light rare earth element-) depleted mantle sources contaminated by subducted, hydrous oceanic lithospheric and continentally derived sediments. Calc-alkalic rocks and associated felsic volcanic rocks have Nd isotopic compositions that indicate the direct involvement of continental lithosphere in their petrogenesis.Integration of geochemical, geological, and geochronological evidence suggests the following sequence of events: (1

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“…and it has high initial Srs7/Sra6 ratios (Bell and Blenkinsop 1975), all features that distinguish it from the other granitoid plutons, which underlie about 25% of Newfoundland. The St. Lawrence pluton occurs on the Burin Peninsula, on the southwestern flank of the Avalon Zone of the Canadian Appalachian Structural Province (Williams et al 1974;Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Geology and geochemistry of the St. Lawrence peralkaline granite and associated fluorite deposits, southeast Newfoundland

Teng¹,

Strong²

1976

Can. J. Earth Sci.

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The southern part of the Burin Peninsula of southeast Newfoundland is marked by extensive Carboniferous granite magmatism, intruding Late Precambrian to Middle Cambrian volcanic and sedimentary rocks. The St. Lawrence pluton, representative of this Carboniferous magmatism, ranges from equigranular to porphyritic in texture, displays much evidence of gas brecciation, and contains no pegmatites or schlieren, all features of high-level intrusion. The bulk chemistry corresponds to cotectic compositions in the synthetic Q–Ab–Or–H2O system for 500 bar [Formula: see text], likewise suggesting shallow levels of intrusion and crystallization. The granite is alkaline to peralkaline and of commenditic affinity, with agpaitic indices around 1 and modal aegirine and riebeckite. Its chemical affinity with less silicic alkaline granites of the same age in southeast Newfoundland suggests an origin by differentiation of such granites. A high initial Sr87/Sr86 ratio of 0.722 suggests substantial interaction with or derivation from continental crust. The St. Lawrence fluorite deposits occur as veins confined to and derived from the granite during the final stages of cooling.

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The Northeastward Termination of the Appalachian Orogen

Cited by 36 publications

References 38 publications

The Gander–Avalon Zone boundary in southeastern Newfoundland

The Gander–Avalon Zone boundary in southeastern Newfoundland

Magmatic and tectonic evolution of the Cambrian-Ordovician Laurentian margin of Iapetus: Geochemical and isotopic constraints from the Notre Dame Subzone, Newfoundland

Geology and geochemistry of the St. Lawrence peralkaline granite and associated fluorite deposits, southeast Newfoundland

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