Opening Iapetus: Constraints from the Laurentian margin in Newfoundland

Peter Anthony Cawood, P J A McCausland, G R Dunning

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404 Citations (Scopus)

Abstract

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.

Original languageEnglish
Pages (from-to)443-453
Number of pages11
JournalGeological Society of America Bulletin
Volume113
Issue number4
Publication statusPublished - Apr 2001

Keywords

  • 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

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