Lower to Middle Ordovician evolution of peri-Laurentian arc and back-arc complexes in Iapetus: Constraints from the Annieopsquotch Accretionary Tract, Central Newfoundland. | INSTITUT DE PHYSIQUE DU GLOBE DE PARIS

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  Lower to Middle Ordovician evolution of peri-Laurentian arc and back-arc complexes in Iapetus: Constraints from the Annieopsquotch Accretionary Tract, Central Newfoundland.

Type de publication:

Journal Article

Source:

Geol. Soc. Am. Bull., Volume 118, Ticket 3, p.324-342 (2006)

ISBN:

0016-7606

Mots-clés:

accretion, Géosciences marines ; Notre Dame subzone, Sm-Nd isotopes, trace elements, U-Pb geochronology, UMR 7096, whole-rock geochemistry

Résumé:

The Annieopsquotch accretionary tract in Newfoundland is composed of a series of west-dipping structural panels, each containing remnants of ophiolitic and arc-backarc complexes of Laurentian affinity formed during the Ordovician closure of Iapetus. Panels were transferred from an upper-plate to a lower-plate setting during their Middle to Late Ordovician accretion to the Laurentian margin and become progressively younger eastward. Geochronological data indicate a complex and rapid history of generation and accretion of peri-Laurentian suprasubduction zone rocks. The rapid changes in tectonic environments and the complexity of the relationships are analogous to the complex arc-backarc relationships observed in the western Pacific today. The recognition of the peri-Laurentian provenance of these units based on stratigraphy, geochronology, isotopes, and geochemistry defines the position of the Red Indian Line, the fundamental suture zone in the northern Appalachians, but more importantly enables the development of a realistic tectonic model for the Annieopsquotch accretionary tract involving both thrust and sinistral transcurrent displacements.