Opening Iapetus: Constraints from the Laurentian margin in Newfoundland

• Main Authors: Cawood, Peter Anthony, McCausland, P J A, Dunning, G R
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2001
• Subjects: Appalachian-Caledonian; paleogeography; paleomagnetism; Precordillera; tectonics; U-Pb; U-PB ZIRCON; CATOCTIN VOLCANIC PROVINCE; APPALACHIAN BLUE-RIDGE; POLAR WANDER PATH; LONG-RANGE DIKES; WESTERN NEWFOUNDLAND; ARGENTINE PRECORDILLERA; NORTH-AMERICA; NEOPROTEROZOIC BREAKUP; OUACHITA EMBAYMENT; Argentine; Skinner Cove; Newfoundland
• Online Access: https://risweb.st-andrews.ac.uk/portal/en/researchoutput/opening-iapetus-constraints-from-the-laurentian-margin-in-newfoundland(321925b5-8185-44c3-972e-2a7bb9a97930).html; http://www.scopus.com/inward/record.url?scp=0035314361&partnerID=8YFLogxK

Late Neoproterozoic to Early Cambrian geologic, geochronologic, and paleomagnetic data from along the Iapetus margin of Laurentia may be reconciled,within a multistage rift history that involved an initial separation of Laurentia from the west Gondwana cratons ca. 570 Ma, followed by rifting of a further block or blocks from Laurentia ca 540-535 Ma into an already open Iapetus Ocean to establish the main passive-margin sequence in the Appalachians. Paleomagnetic data suggest that Laurentia rifted from Amazonia-Rio de la Plata cratons and began its northward movement ca. 570 Ma to produce a wide Iapetus Ocean by 550 Ma. Geologic data from the Newfoundland segment of the Laurentian margin provide evidence for a rift-drift transition ca. 540-535 Ma, as constrained by the youngest rift-related magmatism at 550.5 (+3)/(-2) Ma (U/Pb zircon) for the Skinner Cove Formation and 555 (+3)/(-5) Ma for the Lady Slipper pluton, and a late Early Cambrian age of ca, 525-520 Ma for the oldest drift-related sedimentation. Rifting between the Laurentia and the west Gondwana cratons was probably distributed among multiple rift systems that fostered the production of a number of terranes (such as the Argentine Precordillera, Oaxacan) as well as the Iapetus Ocean. Development of Laurentian-derived Iapetan terranes during the final breakout of Laurentia from Rodinia may have been facilitated by preexisting 760-700 Ma rift weaknesses and apparently rapidly changing plate vectors during latest Neoproterozoic time.