Northern Appalachians: Avalon and Meguma Terranes

Keppie, J. Duncan; Nance, R. Damian; Murphy, J. Brendan; Dostál, J.

doi:10.1007/978-3-642-84153-8_14

Cited by 27 publications

(6 citation statements)

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“…As a result, they are preserved as a collection of suspect terranes in the younger orogenic belts of Europe and North America. Avalonia stretches from New England to southeastern Newfoundland (O'Brien et al 1983;Murphy & Nance 1989Keppie et al 1991) and includes southeastern Ireland (Max & Roddick 1989) and southern Britain (Tucker & Pharoah 1991;Gibbons & Horák 1996). Other periGondwanan terranes occur in the Armorican massif (Cadomia) of northwestern France (Egal et al 1996;Strachan et al 1996), the Iberian peninsula (Quesada 1990;Eguíluz, et al 2000;FernandezSuárez et al 2000), isolated inliers in Germany and the Czech Republic (e.g., Bohemian Massif, Zulauf et al 1999;Linnemann et al 2000), and recently recognized vestiges in the Alpine belt (Neubauer 2002;von Raumer et al 2002).…”

Section: Avalonian and Related Terranesmentioning

confidence: 98%

Late Neoproterozoic and Early Cambrian palaeogeography: models and problems

Pisarevsky

Murphy

Cawood

et al. 2008

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107

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We present two alternative sets of global palaeogeographical reconstructions for the time interval 615-530 Ma using competing high and low-latitude palaeomagnetic data subsets for Laurentia in conjunction with geological data. Both models demonstrate a genetic relationship between the collisional events associated with the assembly of Gondwana and the extensional events related to the opening of the Tornquist Sea, the eastern Iapetus Ocean (600-550 Ma), and the western Iapetus Ocean (after 550 Ma), forming a three-arm rift between Laurentia, Baltica, and Gondwana. The extensional events are probably plume-related, which is indicated in the reconstructions by voluminous mafic magmatism along the margins of palaeo-continents. The low-latitude model requires a single plume event, whereas the high-latitude model needs at least three discrete plumes. Coeval collisions of large continental masses during the assembly of Gondwana, as well as slab pull from subduction zones associated with those collisions, could have caused upper plate extension resulting in the rifted arm that developed into the eastern Iapetus Ocean and Tornquist Sea but retarded development of the western Iapetus Ocean. As a result, the eastern Iapetus Ocean and the Tornquist Sea opened before the western Iapetus Ocean.

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Section: Avalonian and Related Terranesmentioning

confidence: 98%

Late Neoproterozoic and Early Cambrian palaeogeography: models and problems

Pisarevsky

Murphy

Cawood

et al. 2008

Self Cite

107

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“…A particular reconstruction of interest here is that of Hoffman (1991) depicting a proto-Andean orogen fringing the Amazonian craton. This reconstruction has stimulated a longstanding geological debate regarding the interactions of the margins of Amazonia and Laurentia from late Proterozoic to early Paleozoic time (Bond et al, 1984;Kent and Van der Voo, 1990;Hoffman, 1991;Keppie et al, 1991;Keppie, 1993;Dalla Salda et al, 1992a,b;Park 1992;Dalziel et al, 1994 and others). Recently published U-Pb geochronologic data from basement rocks in the central Andes (Chew et al, 2007), confirms the existence of a proto-Andean orogenic system in Peru and Ecuador and its consolidation during the Grenvillian-Sunsas (1.0 Ga) and Famatinian (0.47 Ga) orogenic cycles.…”

Section: Introductionmentioning

confidence: 94%

Northern South America basement tectonics and implications for paleocontinental reconstructions of the Americas

Restrepo-Pace¹,

Cediel²

2010

Journal of South American Earth Sciences

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“…The Meguma terrane records this accretion as a series of deformation events during the late Early Devonian (i.e., Acadian; 410-395 Ma; e.g., Muecke et al 1988;Kontak et al 1998) to the Early Carboniferous (375-350 Ma; e.g., Keppie and Dallmeyer 1995;Archibald et al 2018) time interval. The latter tectonothermal events define the Neoacadian orogeny (van Staal 2007;van Staal et al 2009van Staal et al , 2021 which involved dextral accretion of the Meguma terrane along the composite Laurentian margin (e.g., Keppie et al 1991;Murphy et al 2011;Fig. 2).…”

Section: Geological Settingmentioning

confidence: 99%

The age and origin of the South Mountain Batholith (Nova Scotia, Canada) as constrained by zircon U–Pb geochronology, geochemistry, and O–Hf isotopes

et al. 2022

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The South Mountain Batholith (SMB; Nova Scotia, Canada) is the largest composite batholith exposed in the Appalachians and lies entirely within the most outboard Meguma terrane. In-situ and CA-TIMS U-Pb dating and in-situ isotopes (Lu-Hf, O) and geochemistry for zircon from all phases of the SMB constrain its source as well as its evolution. CA-ID-TIMS for zircon yield emplacement (autocryst) ages indicating a transition from granodiorite (378.7 ± 1.2 to 375.4 ± 0.8 Ma) to leucogranite (375.4 to 371.8 ± 0.8 Ma) over several million years. Furthermore, in situ SHRIMP, LA-MC-ICP-MS, and SIMS analyses of distinct zircon domains reveal: 1) abundant ancient xenocrysts (~420 Ma to 2.2 Ga); 2) antecryst ages ca. 3–15 million years older than SMB emplacement; 3) autocryst δ18O values between +7.3 and +9.1‰ (V-SMOW); 4) similar isotopes, REE signatures, and derived fO2 values among antecrysts and autocrysts; and 5) εHf values from the 371.8 ± 0.8 Ma Davis Lake Pluton (DLP) autocrysts that are higher (+1.74 to +4.38) than the rest of the SMB (-2.99 to +1.68). Collectively, these data suggest a protracted magmatic evolution for the SMB with melt generation and assembly from ~390 to 370 Ma via melting of a metasomatized mantle source followed by contamination, first from the structurally underlying Avalonian terrane and later by metasedimentary wall rocks of the Meguma terrane. The most southwesterly part of the SMB (i.e., DLP) represents a petrogenetically distinct magmatic phase that underwent less overall contamination than the rest of the SMB.

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Northern Appalachians: Avalon and Meguma Terranes

Cited by 27 publications

References 50 publications

Late Neoproterozoic and Early Cambrian palaeogeography: models and problems

Late Neoproterozoic and Early Cambrian palaeogeography: models and problems

Northern South America basement tectonics and implications for paleocontinental reconstructions of the Americas

The age and origin of the South Mountain Batholith (Nova Scotia, Canada) as constrained by zircon U–Pb geochronology, geochemistry, and O–Hf isotopes

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