Avalonian perspectives on Neoproterozoic paleogeography: Evidence from Sm-Nd isotope geochemistry and detrital zircon geochronology in SE New England, USA

Thompson, Margaret D.; Barr, Sandra M.; Grunow, Anne M.

doi:10.1130/b30529.1

Cited by 54 publications

(33 citation statements)

References 108 publications

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“…Davies et al 1985;Thorogood 1990). Although older model ages that require a contribution from an ancient crustal source have also been recognized in the Welsh Borderlands and New England (Schofield et al 2010;Thompson et al 2012), the bulk of the Nd isotopic data strongly suggest that the T DM model ages are characteristic of Avalonia. This includes data from complexes that predate the main phase of arc magmatism (630-570 Ma), suggesting that the model ages record a genuine tectonothermal event in the terrane's early history rather than the mixing of juvenile Neoproterozoic-Paleozoic and ancient crustal magmas (cf.…”

Section: Introductionmentioning

confidence: 98%

“…730 Ma and 630-570 Ma) to Devonian igneous rocks with Sm/Nd ratios typical of intracrustal melts, show similar initial ε Nd values that range between -1.6 and +6.0 (e.g. Barr and Hegner 1992;Doig et al 1993;Kerr et al 1995;Murphy et al 1996aMurphy et al , b, 2000Samson et al 2000;Thompson et al 2012), suggesting the involvement of relatively juvenile basement Murphy 1994, 1996;Murphy and Nance 2002). ε Nd growth lines typically yield overlapping depleted mantle (T DM ) model ages in the interval 0.8-1.3 Ga in the northern Appalachians and 1.0-1.3 Ga in southern Britain (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Also common among Avalonian detrital zircon populations are Mesoproterozoic ages (e.g. Keppie et al 1998;Thompson and Bowring 2000;Murphy et al 2004b, c;Barr et al 2012;Thompson et al 2012), which have been used to position the terrane during the Neoproterozoic/Cambrian in the proximity of Amazonia, the age provinces of which they broadly match (e.g. Nance et al 2008).…”

Section: Introductionmentioning

confidence: 99%

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Does the Meguma Terrane Extend into SW England?

Nance

Neace

Braid

et al. 2015

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Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Does the Meguma Terrane Extend into SW England?

Nance

Neace

Braid

et al. 2015

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“…Although several sub-terranes exist, the two larger terranes or domains that are interpreted to extend southwest through New England are Ganderia and Avalonia (Hibbard et al 2006; Thompson et al 1996Thompson et al , 2012Aleinikoff et al 2007;Walsh et al 2007). Ganderia is a Late Neoproterozoic to Early Cambrian arc and subsequent passive margin terrane that rifted from Gondwana at about 505 Ma (e.g., .…”

Section: Introductionmentioning

confidence: 99%

The Appledore Island pluton of the Rye Complex, coastal New Hampshire and Maine, USA: geochronological and chemical evidence for the affinity of an enigmatic terrane

Dorais

Bothner

Buchwaldt

2014

atgeol

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The Rye Complex of coastal New Hampshire and Maine is a peri-Gondwanan terrrane that up to now had an uncertain origin. An offshore portion of the complex, Appledore Island of the Isles of Shoals, hosts a mainly dioritic intrusion that yielded an U-Pb zircon age of 361.09 ± 0.14 Ma, allowing comparison of its geochemical characteristics with mafic rocks of similar age across the northern Appalachian orogen. The Appledore Island diorite has similar major, trace, and isotopic compositions as continental rift tholeiite in the Narragansett Basin in southern New England and in the Maritimes Basin of Canada. These intraplate volcanic rocks range from 375 to 330 Ma, bracketing the age of the Appledore Island diorite. Their intraplate tectonic setting reflects regional extension during the Late Devonian to Early Carboniferous which produced successor basins after the Acadian orogeny. The geochemical and age similarities of the Appledore Island diorite and the mafic rocks of the successor basins suggest that the Rye Complex is a basement fragment of a successor basin block. Further evidence of the identity of the Rye Complex is provided by the isotopic composition of intermingled, comagmatic granitic rocks associated with the Appledore Island diorite. The granite has a Ganderian isotopic signature, suggesting that the Rye Complex is a Ganderian basement block that was transposed by movement along the Norumbega Fault System to its position adjacent to the Merrimack Trough of New Hampshire and Maine.

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“…One area of Avalonia that remains poorly understood is the part of the southeastern New England (SENE) Avalon (Thompson et al 2010(Thompson et al , 2012 on which the Pennsylvanian Narragansett Basin lies. The SENE Avalon block is separated from the Putnam-Nashoba terrane to the west by the Bloody Bluff, Lake Char, and Honey Hill fault zones (Fig.…”

Section: Introductionmentioning

confidence: 99%

Alleghanian deformation of Cambrian metasedimentary rocks on Avalonia in south-central Rhode Island, USA

Carter¹,

Mosher²

2013

atgeol

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Lower greenschist-facies metasedimentary rocks of the Middle Cambrian Conanicut Group occur in and around Beavertail State Park, Rhode Island. Detailed structural mapping (1:1000-scale) and petrology of these rocks indicate an early fold generation (F 1 ) and axial planar metamorphic foliation (S 1 ). F 1 is folded by a more prominent, E-verging, NNE-to NNW-trending, non-coaxial fold generation (F 2 ) and an associated pressure solution-enhanced crenulation cleavage (S 2 ). A third map-scale fold generation is inferred from NNE-trending broad folding of F 2 and S 2 . N-S extension resulted in boudins that deformed S 2 on a scale of 1-10 m, whereas late planar quartz veins indicate NW-SE extension. All structures are cross cut by faults striking N-to NE-and ENEto ESE that show dominantly normal motion with minor sinistral or dextral components. Kink bands associated with faulting trend NNE to ENE with WNW to NNW side up. The vertical Beaverhead shear zone juxtaposes the Cambrian rocks with Pennsylvanian rocks of the Narragansett Basin, and deflects S 2 in a dextral sense, consistent with motion recorded elsewhere.The Cambrian rocks record the same deformation and metamorphism as the adjacent Narragansett Basin rocks. No evidence was found for pre-Alleghanian deformation or for northwest-or north-directed thrusting and accretion of a Meguma-like terrane during the Alleghanian orogeny. If the Beaverhead shear zone was a preexisting terrane boundary within Avalonia, both the Cambrian and Pennsylvanian Narragansett Basin sediments were deposited after terrane accretion. AbStRACt RÉSUMÉDes roches profondes métasédimentaires du faciès des schistes verts, que l' on retrouve dans le groupe Conanicut du Cambrien moyen, sont présentes dans le Beavertail State Park, au Rhode Island, et dans les environs. Une cartographie structurale détaillée (à l' échelle 1:1 000) et la pétrologie de ces roches indiquent la formation précoce d'un pli (F 1 ) et une foliation métamorphique (S 1 ) de plan axial. Le F 1 est causé par la formation d'un pli (F 2 ) non coaxial plus dominant, à vergence est et d' orientation NNE-NNO ainsi que par une schistosité de crénulation (S 2 ) amplifiée en raison d'une dissolution par pression connexe. La formation d'un troisième pli à l' échelle cartographique est provoquée par un vaste plissement du F 2 et de la S 2 d' orientation NNE. Une extension N-S a produit des boudins qui déforment la S 2 sur l' échelle de 1 à 10 m, tandis que des veines de quartz planes formées ultérieurement indiquent une extension NO-SE. Toutes les structures sont traversées par des failles orientées N-NE et ENE-ESE montrant un mouvement normal dominant accompagné de composantes senestres et dextres peu importantes. Les bandes froissées associées à ces failles sont orientées NNE-ENE et présentent une tangente verticale ONO-NNO. Dans la zone de cisaillement verticale de Beaverhead, les roches du Cambrien sont juxtaposées aux roches de la Pennsylvanie du bassin Narragansett, et la S 2 dévie en un mouvement dextre, ce qui concorde...

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Avalonian perspectives on Neoproterozoic paleogeography: Evidence from Sm-Nd isotope geochemistry and detrital zircon geochronology in SE New England, USA

Cited by 54 publications

References 108 publications

Does the Meguma Terrane Extend into SW England?

Does the Meguma Terrane Extend into SW England?

The Appledore Island pluton of the Rye Complex, coastal New Hampshire and Maine, USA: geochronological and chemical evidence for the affinity of an enigmatic terrane

Alleghanian deformation of Cambrian metasedimentary rocks on Avalonia in south-central Rhode Island, USA

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