Tectonic-stratigraphic subdivisions of central Newfoundland

Williams, Harold; Colman-sadd, SP; Swinden, H S

doi:10.4095/122425

Cited by 93 publications

(70 citation statements)

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“…Whereas the Notre Dame belt contains a sparse Lower to lower Middle Ordovician North American conodont fauna that evolved on or near Laurentia, the Exploits belt and the Gander zone to the southeast contain an approximately coeval Celtic brachiopod fauna thought to have evolved far to the south, on islands within Iapetus or on Avalon itself in Early Paleozoic time (Neuman, 1984;Harper et al, 1996). The boundary of rock assemblages containing these contrasting faunas passes through Red Indian Lake (Williams et al, 1988, Fig. 1) and is named the Red Indian line (RIL).…”

Section: A Search For the Red Indian Line In New Englandmentioning

confidence: 99%

“…On the basis of faunal and other geologic contrasts, Williams et al (1988) divided the Dunnage zone of Newfoundland into two sharply separated subzones termed the Notre Dame subzone on the northwest, and the Exploits subzone on the southeast. Whereas the Notre Dame belt contains a sparse Lower to lower Middle Ordovician North American conodont fauna that evolved on or near Laurentia, the Exploits belt and the Gander zone to the southeast contain an approximately coeval Celtic brachiopod fauna thought to have evolved far to the south, on islands within Iapetus or on Avalon itself in Early Paleozoic time (Neuman, 1984;Harper et al, 1996).…”

Section: A Search For the Red Indian Line In New Englandmentioning

confidence: 99%

“…1, T1 + T2), broadly correlated to the Notre Dame arc of Newfoundland (Williams et al, 1988). This occurred shortly before closure of Iapetus at $460 Ma.…”

Section: Introductionmentioning

confidence: 99%

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Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England

Moench¹,

Aleinikoff²

2003

Physics and Chemistry of the Earth, Parts A/B/C

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The Ammonoosuc sequence is defined by the Middle Ordovician Ammonoosuc Volcanics near Littleton, NH, the type area, northeast to Milan, NH, and Oquossoc, ME; it also includes black slate of the Partridge Formation (C. bicornis--zone graptolites, $457 Ma). Related metamorphosed intrusives are the tonalitic Joslin Turn pluton (469 AE 2 Ma), the Cambridge Black granitic pluton (468 AE 3 Ma), and gabbro, tonalite (467 AE 4 Ma), and sheeted diabase of the Chickwolnepy intrusions. These intrusives cut lowermost Ammonoosuc (therefore >469 Ma). Probable uppermost Ammonoosuc is dated at 465 AE 6 and 461 AE 8 Ma. Successively below the Ammonoosuc are the Dead River and Hurricane Mountain Formations (flysch and melange), and the Jim Pond Formation (484 AE 5 Ma) and Boil Mountain Complex (both ophiolite), which are structurally underlain by the Neoproterozoic(?) Chain Lakes massif.The Quimby sequence is defined by the Lower Silurian(?) to Upper Ordovician Quimby Formation, composed of bimodal volcanics (443 AE 4 Ma) and sulfidic shale and graywacke that lie conformably to unconformably above the Ammmonoosuc Volcanics and Partridge Formation. Also in the Quimby sequence are several granitic to sparsely gabbroic plutons of the Highlandcroft (441-452 Ma) and Oliverian (435-456 Ma) Plutonic Suites, which intrude the Dead River, Ammonoouc and Partridge, but not the Quimby Formation.Based on faunal, paleolatitude, and isotopic data, the Ammonoosuc sequence and its correlatives and underlying sequences formed off the southern Laurentian margin, but northwest of the principal Iapetan suture, or Red Indian line. The Boil MountainJim Pond-Hurricane Mountain sequence was ramped northwestward over the Chain Lakes massif at $475 Ma, on the basal Boil Mountain surface. This obduction probably occurred slightly before obduction on the Baie Vert-Brompton surface (BBL), farther NW, over the Laurentian margin, and was followed by Dead River flysch sedimentation, which ended with the abrupt onset of Ammonoosuc-sequence arc magmatism at $470 Ma. Ammonoosuc eruptions probably ended at $460 Ma, when Iapetus closed along the Red Indian line.During a following magmatic hiatus of $3-5 m.y., now represented by portions of the Partridge Formation that overlie the Ammonoosuc Volcanics, subduction polarity reversed, and subduction resumed below the northwest-dipping Brunswick subduction complex (BSC) of New Brunswick, Canada. Quimby-sequence magmatism ($456-435 Ma) on the newly accreted Laurentian margin occurred above the BSC, whose footwall is now buried to the southeast by mainly Silurian clastic sediments of the MerrimackFredericton trough, deposited in the ''Fredericton Sea''. In Silurian to Early Devonian time, the NW-dipping BSC footwall was paired with a SE-dipping subduction zone that produced arc magmas of the Coastal Volcanic belt, built on the composite Avalon and adjacent peri-Avalonian terranes. Orogen-normal extension produced by rapid rollback of both subduction zones narrowed the Fredericton Sea, produced the Central Maine and Connecti...

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Section: A Search For the Red Indian Line In New Englandmentioning

confidence: 99%

Section: A Search For the Red Indian Line In New Englandmentioning

confidence: 99%

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Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England

Moench¹,

Aleinikoff²

2003

Physics and Chemistry of the Earth, Parts A/B/C

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“…1) straddles the boundary between the Humber Zone, the remnant of the ancient continental margin of Laurentia (referred to as Humber margin from here on), and the diverse ophiolitic complexes and cover rocks of the BVOT of the Notre Dame Subzone (western Dunnage Zone; Williams et al 1988), which mainly represent periLaurentian arc systems and related environments. The BVOT is interpreted to represent the vestiges of a relatively narrow seaway (Taconic seaway of Hibbard et al 2007) that developed between Laurentia proper and isolated ribbon-like zones of continental crust of Laurentian affinity, collectively forming the Dashwoods microcontinent (Waldron and van Staal 2001;van Staal et al 2013).…”

Section: Tectonostratigraphic Settingmentioning

confidence: 99%

Taconic Metamorphism Preserved in the Baie Verte Peninsula, Newfoundland Appalachians: Geochronological Evidence for Ophiolite Obduction and Subduction and Exhumation of the Leading Edge of the Laurentian (Humber) Margin During Closure of the Taconic Seaway

Castonguay

Staal

Joyce

et al. 2014

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The Baie Verte Peninsula, western Newfoundland Appalachians, preserves evidence for Early to Mid Ordovician closure of the Taconic seaway, which led to obduction of the Baie Verte oceanic tract (BVOT) ophiolites onto the Laurentian (Humber) margin and Taconic orogenesis. The scarcity of Taconic radiometric ages (and predominance of Silurian (Salinic) data) from the Humber margin rocks (down-going plate) has been problematic, calling into question the intensity and existence of Taconic collisional orogenesis. 40Ar/39Ar and in situ U–Pb geochronology was undertaken on metamorphosed units from the Laurentian basement (Mesoproterozoic East Pond Metamorphic Suite), from the ca. 560 Ma Birchy Complex forming the leading edge of the Humber margin, and from the ca. 490 Ma ophiolitic rocks of the BVOT (Advocate Complex) in order to address this question. Our results confirm evidence of Taconic metamorphism along the Humber margin and at the base of the ophiolites. Ages obtained from the structural base of the Advocate Complex (481–465 Ma) are interpreted to reflect the timing of accretion and internal thickening of the ophiolite, whereas data from the underlying Birchy Complex (467–461 Ma) record the underthrusting and exhumation of the leading edge of the Humber margin along a subduction channel, penecontemporaneously with final obduction of the BVOT. A concordant ca. 465 Ma zircon age and REE data obtained from retrogressed eclogite of the East Pond Metamorphic Suite suggest that the parautochthonous Humber margin was locally subducted to eclogite-facies conditions during the Taconic collision and partly exhumed to amphibolite-facies conditions prior to a strong Silurian (Salinic) tectonometamorphic overprint.SOMMAIRELa péninsule de Baie Verte dans les Appalaches de l’ouest de Terre-Neuve a conservé des indices de la fermeture du bras de mer taconique, qui a mené à l’obduction des ophiolites de la bande océanique de Baie Verte (BOBV) sur la marge laurentienne (Humber) et à l’orogénèse taconique. La rareté des âges radiométriques taconiques (et la prédominance des données siluriennes (saliniques)) provenant des roches de la marge de Humber (i.e. la plaque subductée) a été problématique, mettant en question l’intensité et l’existence de la collision orogénique taconique. De la géochronologie 40Ar/39Ar et U–Pb in situ a été réalisée sur des unités métamorphisés provenant du socle laurentien (la Suite Métamorphique d’East Pond d’âge Mésoprotérozoïque), du Complexe de Birchy daté à ca. 560 Ma formant la partie frontale de la marge de Humber, and des roches ophiolitiques de la BOBV (Complexe d’Advocate) datée à ca. 490 Ma afin de confronter ce questionnement. Nos résultats confirment les indices de métamorphisme taconique le long de la marge de Humber et à la base des ophiolites. Les âges obtenus à la base structurale du Complexe d’Advocate (481–465 Ma) sont interprétés comme reflétant la période d’accrétion et d’épaississement interne de l’ophiolite, tandis que les données du Complexe de Birchy sous-jacent (467–461 Ma) enregistrent le sous-charriage et l’exhumation de la partie frontale de la marge de Humber au sein d’un chenal de subduction, de façon pénécontemporaine à l’obduction finale de la BOBV. Un âge concordant de ca. 465 Ma d’un zircon et les données de terres rares provenant d’une éclogite rétromorphosée de la suite métamorphique d’East Pond suggèrent que la marge de Humber parautochtone a été localement subductée à des conditions du faciès éclogitique durant la collision taconique et partiellement exhumée à des conditions du faciès des amphibolites précédant la forte surimposition tectonométamorphique silurienne (salinique).

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“…These zones represent the margins of the Ordovician Iapetus Ocean and its remnants. The CMB may be further subdivided into the Dunnage Zone, consisting of the Exploits and Notre Dame Subzones, and the Gander Zone [1], but for the purpose of this study we will use the term CMB (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Early Silurian paleolatitude for central Newfoundland from paleomagnetism of the Wigwam Formation: Discussion

Pluijm¹,

Voo²,

Potts³

et al. 1993

Can. J. Earth Sci.

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Ancient remanences are retained by the Early Silurian (429 + 6/-5 Ma) mafic volcamcs of the Sprmgdale Caldera (five sites) and the overlying red beds (seven sites) Dual polarity magnetizations are obtained by thermal demagnehzation of samples from the red beds, whereas single polarity d~rectlons are observed m the volcamcs High unblockmg temperatures indicate hematite as the remanence carrier m both the volcamcs and sedxments These h~gh-temperature, characteristic remanences are easily ~solated and pass both the tilt and conglomerate tests, they are likely to be of primary Silurian age Characteristic dechnatlons are predominantly northerly and northeasterly, and md~cate s~gmficant structural rotahons on a local scale When the results of the red beds and the voleamcs are combined they show characteristic mchnatlons that are shallower than those of the correlative Botwood Group (ca 36 ° vs 43 °) but not nearly as shallow as those reported from the King George IV Lake area (0 5 °) Mean mchnatlons obtained from the Sprmgdale red beds are, however, slgmficantly shallower than those of the Sprmgdale volcanlcs The same difference can be seen m other previous Silurmn paleomagnehc studies of central Newfoundland We infer that an mcllnat~on error affects the red bed magnetizations of the Sprmgdale Group, Botwood Group (Wigwam Formation) and rocks of the King George IV Lake area Therefore, the results from Sdurlan red beds should not be used to determine paleolahtudes for central Newfoundland The mean paleolatltude of the Sprlngdale Group volcamcs is 30 ° The mean paleolatltudes for both the Sprlngdale volcanlcs and Botwood volcamcs (Lawrenceton Formation) are md~stmgmshable w~thm paleomagnetlc error hm~ts from the predicted paleolatltude of Newfoundland on the northeast-trending North American margin Thus, no detectable post-Silurian displacement ts shown by the volcamcs of the Sprmgdale Group with respect to cratomc North America.

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Tectonic-stratigraphic subdivisions of central Newfoundland

Cited by 93 publications

References 0 publications

Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England

Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England

Taconic Metamorphism Preserved in the Baie Verte Peninsula, Newfoundland Appalachians: Geochronological Evidence for Ophiolite Obduction and Subduction and Exhumation of the Leading Edge of the Laurentian (Humber) Margin During Closure of the Taconic Seaway

Early Silurian paleolatitude for central Newfoundland from paleomagnetism of the Wigwam Formation: Discussion

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