Lower to Middle Ordovician evolution of peri-Laurentian arc and backarc complexes in Iapetus: Constraints from the Annieopsquotch accretionary tract, central Newfoundland

Zagorevski, A; Rogers, N; Staal, Cees R. van; McNicoll, V J; Lissenberg, C. Johan; Valverde-Vaquero, Pablo

doi:10.1130/b25775.1

Cited by 67 publications

(107 citation statements)

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“…Isotopic evidence of crustal contamination and zircon inheritance in the outboard peri-Laurentian terranes (e.g. Karabinos et al 1998;Whalen et al 1997;Zagorevski et al 2006;Brem et al 2007;Hibbard et al 2007;van Staal et al 2007;van Staal and Hatcher 2010;Allen et al 2010;Chew et al 2008Chew et al , 2010Skulski et al 2010, Zagorevski and indicate that these isolated blocks subsequently formed the basement to supra-subduction zone magmatism in the outboard arc complexes. Formation of H-blocks and/or large extensional allochthons during hyperextension would remove the necessity of having two discrete rifting events along the Humber margin, resulting in two coeval spreading centres Waldron and van Staal 2001;Burton and Southworth 2010).…”

Section: Formation Of Microcontinentsmentioning

confidence: 99%

“…Dashwoods) along the Newfoundland Humber margin and the Appalachian -Caledonian margin in general (van Staal et al , 2009bChew et al 2010); 3) the markedly variable and spotty preservation of radiogenic age evidence for Taconic-related metamorphism and deformation along strike (Cawood et al 1994;Castonguay et al 2001Castonguay et al , 2010van Staal et al 2009 a, b); and 4) evidence for crustal contamination in felsic rocks of the BVOT and its Early to Middle Ordovician Snooks Arm Group cover ) and other outboard terranes in the peri-Laurentian realm (e.g. Whalen et al 1997;van Staal et al 2007;Zagorevski et al 2006) Thermal Subsidence The highly thinned continental margins of studied OCT zones commonly display significant retardation of thermal subsidence. In addition to the potentially insulating effects of a thick sedimentary blanket and the predicted slow cooling of the upper plate crust during asymmetric extension (Buck et al 1988), anomalous slow cooling and prolonged uplift of a rifted margin may also be related to the structural emplacement of hot mantle under the thinning crust Péron-Pinvidic and Manatschal 2009).…”

Section: Ediacaran Hyperextension Of the Humber Marginmentioning

confidence: 99%

“…Harzburgitic mantle was locally exhumed during the Cretaceous along the Atlantic margin of Newfoundland as a result of hyperextension of the Newfoundland -Iberian sector during opening of the Atlantic Ocean. This harzburgite was interpreted as a slice of supra-subduction zone mantle inherit- (Whalen et al 1997); and Annieopsquotch Accretionary Tract (AAT), Newfoundland (Zagorevski et al 2006). All values are recalculated to 560 Ma (DePaolo 1981).…”

Section: Ediacaran Hyperextension Of the Humber Marginmentioning

confidence: 99%

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Evidence of Late Ediacaran Hyperextension of the Laurentian Iapetan Margin in the Birchy Complex, Baie Verte Peninsula, Northwest Newfoundland: Implications for the Opening of Iapetus, Formation of Peri-Laurentian Microcontinents and Taconic – Grampian Orogenesis

Staal

Chew

Zagorevski

et al. 2013

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The Birchy Complex of the Baie Verte Peninsula, northwestern Newfoundland, comprises an assemblage of mafic schist, ultramafic rocks, and metasedimentary rocks that are structurally sandwiched between overlying ca. 490 Ma ophiolite massifs of the Baie Verte oceanic tract and underlying metasedimentary rocks of the Fleur de Lys Supergroup of the Appalachian Humber margin. Birchy Complex gabbro yielded a Late Ediacaran U–Pb zircon ID–TIMS age of 558.3 ± 0.7 Ma, whereas gabbro and an intermediate tuffaceous schist yielded LA–ICPMS concordia zircon ages of 564 ± 7.5 Ma and 556 ± 4 Ma, respectively. These ages overlap the last phase of rift-related magmatism observed along the Humber margin of the northern Appalachians (565–550 Ma). The associated ultramafic rocks were exhumed by the Late Ediacaran and shed detritus into the interleaved sedimentary rocks. Psammite in the overlying Flat Point Formation yielded a detrital zircon population typical of the Laurentian Humber margin in the northern Appalachians. Age relationships and characteristics of the Birchy Complex and adjacent Rattling Brook Group suggest that the ultramafic rocks represent slices of continental lithospheric mantle exhumed onto the seafloor shortly before or coeval with magmatic accretion of mid-ocean ridge basalt-like mafic rocks. Hence, they represent the remnants of an ocean – continent transition zone formed during hyperextension of the Humber margin prior to establishment of a mid-ocean ridge farther outboard in the Iapetus Ocean. We propose that microcontinents such as Dashwoods and the Rattling Brook Group formed as a hanging wall block and an extensional crustal allochthon, respectively, analogous to the isolation of the Briançonnais block during the opening of the Alpine Ligurian–Piemonte and Valais oceanic seaways.SOMMAIRELe complexe de Birchy de la péninsule de Baie Verte, dans le nord-ouest de Terre-Neuve, est constitué d’un assemblage de schistes mafiques, de roches ultramafiques et de métasédiments qui sont coincés entre des massifs ophiolitiques d’ascendance océanique de la Baie Verte au-dessus, et des métasédiments du Supergroupe de Fleur de Lys de la marge de Humber des Appalaches en-dessous. Le complexe de gabbro de Birchy a donné une datation U-Pb sur zircon ID-TIMS correspondant à la fin de l’Édiacarien, soit 558,3 ± 0,7 Ma, alors qu’un gabbro et un schiste tufacé intermédiaire montrent une datation LA-ICP-MS Concordia sur zircon de 564 ± 7,5 Ma et 556 ± 4 Ma, respectivement. Ces datations chevauchent la dernière phase de magmatisme de rift observée le long de la marge Humber des Appalaches du Nord (565-550 Ma). Les roches ultramafiques associées ont été exhumées vers la fin de l’Édiacarien et leurs débris ont été imbriqués dans des roches sédimentaires. Les psammites de la Formation de Flat Point susjacente ont donné une population de zircons détritiques typique de la marge laurentienne de Humber des Appalaches du Nord. Les relations chronologiques et les caractéristiques du complexe de Birchy et du groupe de Rattling Brook adjacent, permettent de penser que ces roches ultramafiques pourraient être des écailles de manteau lithosphérique continental qui auraient été exhumées sur le plancher océanique peu avant ou en même temps que l’accrétion magmatique de roches mafiques basaltiques de type dorsale médio-océanique. Par conséquent, elles seraient des vestiges d’une zone de transition océan-continent formée au cours de l’hyper-extension de la marge de Humber avant l’apparition d’une dorsale médio-océanique plus loin au large dans l’océan Iapétus. Nous proposons que des microcontinents comme de Dashwoods et du groupe de Rattling Brook ont constitués respectivement un bloc de toit et un allochtone crustal d’extension, de la même manière que le bloc Briançonnais a été isolé lors de l’ouverture des bras océaniques alpins de Ligurie-Piémont et de Valais.

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Section: Formation Of Microcontinentsmentioning

confidence: 99%

Section: Ediacaran Hyperextension Of the Humber Marginmentioning

confidence: 99%

Section: Ediacaran Hyperextension Of the Humber Marginmentioning

confidence: 99%

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Evidence of Late Ediacaran Hyperextension of the Laurentian Iapetan Margin in the Birchy Complex, Baie Verte Peninsula, Northwest Newfoundland: Implications for the Opening of Iapetus, Formation of Peri-Laurentian Microcontinents and Taconic – Grampian Orogenesis

Staal

Chew

Zagorevski

et al. 2013

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“…Subsequent detailed investigations of the AAT, focusing on the differences and/or changes in tectonic setting and structure over time between different areas, implied a greater complexity, as each one of these slivers, in essence, was shown to constitute a discrete terrane (Fig. 1;Bostock 1988;Zagorevski et al 2006Zagorevski et al , 2010aZagorevski and Rogers 2009).…”

Section: Introductionmentioning

confidence: 99%

From Large Zones to Small Terranes to Detailed Reconstruction of an Early to Middle Ordovician Arc–Backarc System Preserved Along the Iapetus Suture Zone: A Legacy of Hank Williams

Zagorevski

McNicoll

Staal

et al. 2015

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“…Because first order latitudinal differences in the evolution of the orogen have been recognized (Sinha et al 1996;Sinha and McLelland 1999;Loewy et al 2003;Tohver et al 2004;Hibbard et al 2007Hibbard et al , 2010Fisher et al 2010;McLelland et al 2010;Hibbard and Karabinos 2014), identifying the timing and style of the main Iapetan suture zone in the southern Appalachians is important to further our understanding of the Iapetan cycle along the entire length of the orogen, rather than only in the Canadian Appalachians (e.g. Williams et al 1988;Zagorevski et al 2006Zagorevski et al , 2007aZagorevski and van Staal 2011).…”

Section: Introductionmentioning

confidence: 99%

Detrital Zircon Geochronology Across the Chopawamsic Fault, Western Piedmont of North-Central Virginia: Implications for the Main Iapetan Suture in the Southern Appalachian Orogen

Hughes

Hibbard

Pollock

et al. 2014

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The Chopawamsic fault potentially represents the main Iapetan suture, previously unidentified in the southern extent of the Appalachian orogen. The fault trends through the north-central portion of the western Piedmont of Virginia and separates the composite metaclastic Potomac terrane, commonly interpreted to be of Laurentian affinity, from the Chopawamsic terrane, the remains of a Middle Ordovician volcanic arc of uncertain crustal affinity. To gain insight on the first-order orogenic significance of the Chopawamsic fault, we report the results of LA–ICP–MS U–Pb analyses of 1,289 detrital zircons from 13 metasedimentary rock samples collected from both sides of the fault. The near exclusivity of Middle Ordovician zircon grains (ca. 470 – 460 Ma) in four sampled metasedimentary rocks of the Chopawamsic Formation likely represents the detrital recycling of syndepositional Chopawamsic volcanic rocks. A subset of Cambrian and older grains hint at one or more additional, older sources. Samples from the Potomac terrane include mostly Mesoproterozoic zircon grains and these results are consistent with previous interpretations that the metaclastic rocks are Laurentian-derived. The youngest zircons (ca. 550 – 500 Ma) and the age of cross-cutting plutons indicate that at least some parts of the Potomac terrane are Late Cambrian – Early Ordovician. The results imply temporally discrete and geographically isolated sedimentary systems during deposition of sedimentary rocks in the Chopawamsic and Potomac terranes. Metasedimentary rocks near Storck, Virginia, previously identified as a successor basin, contain detrital zircon populations that indicate they are actually peri-Gondwanan derived metasedimentary rocks unrelated to a successor basin system; their geographic position between the Laurentian-derived Potomac terrane and the Chopawamsic terrane suggests a peri-Gondwanan affinity for the Chopawamsic arc and geographic separation of the Chopawamsic and Potomac terranes in the Middle Ordovician. Consequently, we tentatively support the hypothesis that the Chopawamsic fault system represents the main Iapetan suture in the southern Appalachian orogen. Most detrital zircons from samples of the Arvonia successor basin crystallized in the Ordovician—Silurian or Mesoproterozoic. These data suggest that the Arvonia basin was deposited in the latest Ordovician to Early Silurian only after the Late Ordovician accretion of the Chopawamsic arc to Laurentia. SOMMAIRELa faille de Chopawamsic représente peut-être la principale suture japétienne, non-reconnue dans prolongement sud de l’orogène des Appalaches. La faille traverse la portion nord du centre du piedmont ouest de Virginie et sépare le terrane métaclastique de Potomac, d’affinité laurentienne pensait-on, du terrane de Chopawamsic, vestige d’un arc volcanique de l’Ordovicien moyen d’affinité crustale incertain. Afin de mettre en lumière la signification orogénique première de la faille de Chopawamsic, nous présentons les résultats d’analyses U-Pb par ICP–MS par AL sur 1 289 zircons détritiques provenant de 13 échantillons de roches métasédimentaires prélevés de chaque côté de la faille. L’existence quasi-exclusive de grains de zircon de l’Ordovicien moyen (env. 470 – 460 Ma) dans quatre roches métasédimentaires de la Formation de Chopawamsic représente vraisemblablement le recyclage détritique des roches volcaniques synsédimentaires de Chopawamsic. Un sous-ensemble de grains cambriens et plus anciens, évoque l’existence d’une ou plusieurs sources plus anciennes additionnelles. Les échantillons du terrane de Potomac renferment principalement des grains de zircon du Mésoprotérozoïque, ce qui correspond avec les interprétations antérieures voulant que les roches métaclastiques soient d’origine laurentienne. Les zircons les plus jeunes (env. 550 – 500 Ma) ainsi que l’âge des plutons qui recoupe l’encaissant indiquent qu’au moins certaines parties du terrane de Potomac sont de la fin du Cambrien ou du début de l’Ordovicien. Les résultats impliquent l’existence de systèmes sédimentaires distincts au cours du temps, et isolés géographiquement durant le dépôt des roches sédimentaires dans les terranes de Chopawamsic et de Potomac. Les roches métasédimentaires près de Storck en Virginie, jadis interprétées comme bassin successeur, renferment des populations de zircons détritiques qui indiquent qu’ils proviennent en fait de roches métasédimentaires péri-gondwaniennes sans rapport avec un système de bassin successeur; leur localisation géographique entre le terrane de Potomac issu des Laurentides et le terrane de Chopawamsic porte à penser que l’arc de Chopawamsic est d’affinité péri-gondwanienne, et que les terranes de Chopawamsic et de Potomac à l’Ordovicien moyen étaient séparés géographiquement. En conséquence il nous semble justifié de proposer que le système de faille de Chopawamsic représente la principale suture japétienne dans le sud de l’orogène des Appalaches. La plupart des zircons détritiques des échantillons du bassin successeur d’Arvonia ont cristallisés entre l’Ordovicien et le Silurien ou au Mésoprotérozoïque. Ces données suggèrent que le bassin d’Arvonia s’est rempli de la fin entre l’Ordovicien et le début du Silurien, seulement après l’accrétion de l’arc de Chopawamsic à la Laurentie, à la fin de l’Ordovicien.

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Lower to Middle Ordovician evolution of peri-Laurentian arc and backarc complexes in Iapetus: Constraints from the Annieopsquotch accretionary tract, central Newfoundland

Cited by 67 publications

References 31 publications

Evidence of Late Ediacaran Hyperextension of the Laurentian Iapetan Margin in the Birchy Complex, Baie Verte Peninsula, Northwest Newfoundland: Implications for the Opening of Iapetus, Formation of Peri-Laurentian Microcontinents and Taconic – Grampian Orogenesis

Evidence of Late Ediacaran Hyperextension of the Laurentian Iapetan Margin in the Birchy Complex, Baie Verte Peninsula, Northwest Newfoundland: Implications for the Opening of Iapetus, Formation of Peri-Laurentian Microcontinents and Taconic – Grampian Orogenesis

From Large Zones to Small Terranes to Detailed Reconstruction of an Early to Middle Ordovician Arc–Backarc System Preserved Along the Iapetus Suture Zone: A Legacy of Hank Williams

Detrital Zircon Geochronology Across the Chopawamsic Fault, Western Piedmont of North-Central Virginia: Implications for the Main Iapetan Suture in the Southern Appalachian Orogen

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