Adirondack-Appalachian crustal structure: The COCORP Northeast Traverse

Brown, L. D.; Ando, Clifford; Klemperer, S. L.; Oliver, Jack; Kaufman, S.; Czuchra, B. L.; Tj, Walsh; Isachsen, Yngvar W.

doi:10.1130/0016-7606(1983)94<1173:acstcn>2.0.co;2

Cited by 58 publications

(30 citation statements)

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“…The concept of a major allochthon in the Newfoundland Central Mobile Belt is consistent with long established ideas in the Scandinavian Caledonides (Tornebohm 1888(Tornebohm , 1896Asklund 1938) and with more recent geophysical work in the Appalachians (Cook et al 1979;Ando et al 1983). It is also in agreement with work in Newfoundland by Karlstrom et al (1982).…”

Section: Resultssupporting

confidence: 83%

“…These have come to be regarded, Consortium for Continental Reflection Profiling (COCORP) respectively, as the eastern edge of the ancient North American and SociCtC quCbCcoise d'initiative petrolibre (SOQUIP) seiscontinent, the remnants of the Iapetus Ocean, and the western mic profiling (Cook et al 1979(Cook et al , 1981Cook 1983; al. edge of a continent that lay to the east of Iapetus and that Ando et al 1983;St.-Julien et al 1983) has provided collided with North ~m e r i c~. More recently, with the advent of the "suspect terrane" concept (Coney et al 1980), some authors have suggested that the orogenic belt did not result from a simple collision, but instead was put together piecemeal by a series of accretionary events, many of which may have involved major strike-slip faulting (Zen 1981(Zen , 1983Hatcher 1982, 1983).…”

Section: Introductionmentioning

confidence: 99%

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A tectonic window in central Newfoundland? Geological evidence that the Appalachian Dunnage Zone may be allochthonous

Colman-Sadd¹,

Swinden²

1984

Can. J. Earth Sci.

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In the Through Hill area of central Newfoundland, mafic to ultramafic complexes, which preserve varying amounts of ophiolite stratigraphy, mark the trace of a major fault zone that outcrops in a roughly elliptical pattern. The major, northeasttrending axis is about 60 km and the shorter axis is about 30 km in length. The most complete ophiolite stratigraphy is preserved in the Coy Pond and Pipestone Pond complexes, which have steep dips and face east and west, respectively, outwards from the centre of the ellipse.The ophiolitic rocks are bounded on the outside by rocks typical of the Dunnage Zone of central Newfoundland, principally Lower to Middle Ordovician volcanic and volcaniclastic rocks interpreted to be of island-arc affinity (Davidsville, Victoria Lake, and Baie d'Espoir groups, Cold Spring Pond Formation) and Upper Ordovician to Silurian clastic sediments (Botwood Group). The volcano-sedimentary sequences are interpreted to have been deposited on the ophiolite conformably, but the contacts are not exposed. Both ophiolite and volcano-sedimentary sequences have similar structural and metamorphic histories, exhibiting one principal deformation and the formation of folds with subhorizontal axes, local development of secondgeneration folds and associated cleavage, and an intervening period of metamorphism in the greenschist facies.The elliptical area enclosed by the ophiolite belt is referred to as the Mount Cormack Terrane, and is underlain by variably metamorphosed shale, quartz-rich sandstone, quartzo-feldspathic to amphibolitic gneisses, and granite. A limestone occurrence contains shelly fossils of Early to Middle Ordovician age. An early deformation formed folds with steep axes, and subsequent metamorphism resulted in a progression from greenschist facies to upper amphibolite facies, with the production of migmatite and granodiorite.The preferred interpretation of the geology is that the elliptical Mount Cormack Terrane is exposed as a window through an overlying allochthon composed of ophiolitic and volcano-sedimentary rocks of the Dunnage Zone. The emplacement of the allochthon probably postdated deposition of the Silurian Botwood Group. Paleontologic, lithologic, and structural considerations suggest that the sediments of the Mount Cormack Terrane were deposited at the eastern margin of Iapetus and are perhaps correlatives of rocks exposed in the Gander Zone. This implies that the Dunnage Zone has been thrust, probably in an eastwards direction, on a scale comparable with the allochthons mapped in the Scandinavian Caledonides and proposed for the Appalachians of Quebec and the United States. Dans la region de Through Hill du centre de Terre-Neuve, les complexes mafiques et ultramafiques, dans lesquels sont consemees des sequences ophiolitiques en diverses proportions, marquent la trace d'une zone de faible majeure qui affleure avec un motif plus ou moins elliptique. Le grand axe est orient6 nord-est et s'allonge sur 60 km et le petit axe a une longueur d'environ 30 km. La coupe stratigraphique la plu...

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Section: Resultssupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

A tectonic window in central Newfoundland? Geological evidence that the Appalachian Dunnage Zone may be allochthonous

Colman-Sadd¹,

Swinden²

1984

Can. J. Earth Sci.

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“…Similar reflectivity patterns were observed in France (Bois et al 1986) and around Great Britain (Matthews and Cheadle 1986). Although the nature of this highly reflective zone is unknown, many papers speculate about the origin of the lower crustal reflectivity: Meissner (1973) and McKenzie (1984) favour multiple intrusions into the lower crust; Brown, Ando, Klemperer, Oliver, Kaufman, Czuchra, Walsh and Isachsen (1983) explain the reflections by metasediments guided to lower crustal levels along prominent faults; Matthews (1986) considers fluid-filled cracks, and the BIRPS group designed an experiment (the WAM line) to test whether the reflections are created by flow under the influence of stress systems as proposed by Phinney and Jurdy (1979).…”

Section: Introductionsupporting

confidence: 66%

CRUSTAL REFLECTIVITY PATTERN AND ITS RELATION TO GEOLOGICAL PROVINCES¹

Trappe¹,

Wever²,

Meißner³

1988

Geophysical Prospecting

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TRAPPE, H., WEVER, TH. and MEISSNER, R. 1988. Crustal reflectivity pattern and its relation to geological provinces. Geophysical Prospecting 36,265-281.The statistical treatment of deep seismic reflections from several different geological units has resulted in different reflectivity histograms. Reflectivity in old and cold shields differs significantly from that in younger, warmer areas. In the shields reflectivity is generally poor and concentrated in the upper crust whilst Caledonian and Variscan areas show strong reflecting lamellae in their lower crust. Also the length of the reflecting elements varies with age and heat flow. The lower crust in young areas is a zone of a strong viscosity minimum as derived from model studies with a temperature dependent rheology. The subhorizontal reflecting lamellae in the lower crust are considered to have been created in a large-scale hightemperature, low-viscosity ordering process whose remnants are still preserved today. Localscale differences of reflectivity histograms define certain subprovinces which can be distinguished by their specific patterns.

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“…4) (Ando et al 1983, 1984) and the Minist6re de l'Energie et des Richesses Naturelles du Qu6bec (MERQ) profile in Quebec (Fig. 4, profile R5) (LaRoche 1983, St Julien et al 1983).…”

Section: Near-vertical Seismic Reflection Resultsunclassified

“…The subscript a indicates unpublished data. Sources of information are as follows: R1, Nelson et al 1982, Lillie et al 1983R2, Cook et al 1979R2, Cook et al , 1981R2, Cook et al , 1983R2a, J. Oliver & L. Brown 1984, personal communication;R3, Clarke et al 1978, Harris et al 1981, Costain et al 1984R3a, Phinney et al 1984;R4, Brown et al 1983, Ando et al 1983, 1984R5, Seguin 1982, St Julien et al 1983, LaRoche 1983R5a, Green & Berry 1984;R6, Smythe etal. 1982, Brewer & Smythe 1984R7, Brewer eta[.…”

mentioning

confidence: 99%

Crustal and upper mantle structure of the Appalachian-Caledonide orogen from seismic results

Cook

Matthews

Jacob

1988

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S U M M A R Y : The Appalachian-Caledonide orogen extending from the southeastern USA to northeastern Canada and Britain now has more crustal-scale seismic reflection profiles recorded across it than any other orogen in the world. From SW to NE these include the COCORP Ouachita traverse, the COCORP southern Appalachian traverse, the COCORP northern Appalachian traverse, the BIRPS Western Isles-North Channel (WINCH) offshore profile, the BIRPS Moine-Outer Isles Seismic Traverse (MOIST) profile and the BIRPS SW Approaches Traverse (SWAT) profile. In addition there are several seismic profiles in the eastern USA and Canada with data to mid-crustal (15-20 km) depth within the crystalline 'core' of the Appalachians. In eastern N America, where the Caledonian (Taconian) deformation is overprinted by Acadian and Alleghanian deformation, the seismic reflection data clearly indicate large-scale (several hundred kilometres) cratonward thrusting of shelf, off-shelf and basinal facies sediments and metasediments. The eastern limit of undeformed Precambrian (Grenville) basement is probably represented by a zone of E-dipping reflectors which, in New England, can be correlated with surface exposures of faults and metasediments. Two profiles offshore from Scotland cross the Caledonide orogenic front. The BIRPS MOIST profile indicates that the Moine thrust zone is also characterized by E-dipping reflectors which extend to mid-crustal depths. In contrast with the data from the Appalachians, the BIRPS MOIST, WINCH and SWAT data show remarkably continuous reflections from the crust-mantle transition, as identified on seismic refraction data both across strike (LISPB) and along strike (ICSSP and CSSP). The Moho is at a depth of about 30 km throughout much of Britain and is commonly overlain by a thick (4-5 s travel time or about 12-15 kin) layered lower crust at depths between 15 and 30 km. In some areas the data offshore from Scotland show deep reflections which extend into the mantle. Additionally, many of the profiles in eastern N America and Britain provide strong evidence that late normal faults (Mesozoic) may be reactivated older compressional structures (Caledonian and Variscan in Britain; Alleghanian in the southern Appalachians).

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Adirondack-Appalachian crustal structure: The COCORP Northeast Traverse

Cited by 58 publications

References 0 publications

A tectonic window in central Newfoundland? Geological evidence that the Appalachian Dunnage Zone may be allochthonous

A tectonic window in central Newfoundland? Geological evidence that the Appalachian Dunnage Zone may be allochthonous

CRUSTAL REFLECTIVITY PATTERN AND ITS RELATION TO GEOLOGICAL PROVINCES¹

Crustal and upper mantle structure of the Appalachian-Caledonide orogen from seismic results

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Adirondack-Appalachian crustal structure: The COCORP Northeast Traverse

Cited by 58 publications

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A tectonic window in central Newfoundland? Geological evidence that the Appalachian Dunnage Zone may be allochthonous

A tectonic window in central Newfoundland? Geological evidence that the Appalachian Dunnage Zone may be allochthonous

CRUSTAL REFLECTIVITY PATTERN AND ITS RELATION TO GEOLOGICAL PROVINCES1

Crustal and upper mantle structure of the Appalachian-Caledonide orogen from seismic results

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CRUSTAL REFLECTIVITY PATTERN AND ITS RELATION TO GEOLOGICAL PROVINCES¹