Laurentian margin evolution and the Caledonian orogeny—A template for Scotland and East Greenland

Leslie, A. G.; Smith, Martin J.; Soper, Nathaniel J.

doi:10.1130/2008.1202(13)

Cited by 23 publications

(24 citation statements)

References 184 publications

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“…However, available data suggest that rifting progressed from northeast to southwest in present coordinates, being the oldest in Baltica (Bingen et al 1998) and becoming younger in Scotland (e.g. Leslie et al 2008) and the Appalachians (van Staal et al 1998;Burton and Southworth 2010).…”

Section: Resultsmentioning

confidence: 99%

“…Karabinos et al1998;Hibbard et al 2007;van Staal et al 2007;van Staal and Hatcher 2010;Leslie et al 2008;Chew et al 2008Chew et al , 2010Allen et al 2010). Laurentia's Appalachian -Caledonian margin may therefore have been characterised by large, magmapoor, hyperextended segments.…”

Section: Resultsmentioning

confidence: 99%

“…A discontinuous horizon of serpentinite bodies has also been documented in the Easdale Subgroup of central and northeastern Scotland (Garson and Plant 1973). The serpentinite bodies in Ireland and Scotland have been interpreted as seafloor protrusions of serpentinized mantle that were generated in Easdale Subgroup time during a phase of major crustal extension leading to the formation of an OCT (Chew 2001 Leslie et al 2008), they may form a thermally insulating blanket; the underlying crust may therefore heat up and become rheologically weaker during rifting (Reston and Manatschal 2011). Hyperextension and the resultant formation of crustal ribbons, 'hanging wall' (H-) blocks, and extensional crustal allochthons (for definitions and characteristics of these various types of crustal blocks see Péron-Pinvidic and Manatschal 2010) are capable of explaining several puzzling and/or problematic phenomena.…”

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: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Ediacaran Hyperextension Of the Humber Marginmentioning

confidence: 99%

See 1 more Smart Citation

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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“…These are, from youngest to oldest, as follows. 1) Leslie et al (2008) and Prave et al (2009b) correlated the Loch na Cille Boulder Bed (Elles 1934;Prave 1999), which marks the top of the Tayvallich Volcanic Formation in SW Scotland (Pickett, in press), with the Inishowen glacial beds in Donegal (Condon & Prave 2000) and the Macduff Boulder Bed in NE Scotland (Stoker et al 1999). They suggested that these units represent the Gaskier global glacial event (c. 580 Ma).…”

Section: Age Of Volcanismmentioning

confidence: 99%

“…The Crinan Subgroup is characterised by thick sedimentary units and deep water turbiditic facies, which may represent the onset of a rift-to-drift transition (Leslie et al 2008). During this period volcanic activity was relatively low.…”

Section: Crinan and Tayvallich Subgroupsmentioning

confidence: 99%