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TitleProvenance of the incipient passive margin of NW Laurentia (Neoproterozoic): detrital zircon from continental slope and basin floor deposits of the Windermere Supergroup, southern Canadian Cordillera
AuthorHadlari, TORCID logo; Arnott, R W CORCID logo; Matthews, W A; Poulton, T P; Root, K; Madronich, L I
SourceLithosphere vol. 2021, no. 1, 8356327, 2021 p. 1-10, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20210465
PublisherGeological Society of America
Mediapaper; digital; on-line
File formatpdf
ProvinceBritish Columbia; Yukon
AreaAlaska; Idaho; Montana; Washington State; Canada; United States of America
Subjectsgeochronology; sedimentology; tectonics; Science and Technology; Nature and Environment; radiometric dating; uranium lead dating; zircon dates; basins; continental margins; continental slope; tectonic setting; rifting; magmatism; depositional history; sedimentation; provenance; paleodrainage; fault zones; Canadian Cordillera; Laurentian Margin; Windermere Supergroup; Ancestral North America; Rodinia; Windermere Basin; St. Mary-Moyie Fault Zone; Neoproterozoic; Precambrian; Proterozoic
Illustrationsgeoscientific sketch maps; stratigraphic charts; schematic cross-sections; tables; geochronological charts
ProgramGEM2: Geo-mapping for Energy and Minerals Western Arctic-Beaufort-Northern Yukon
Released2021 10 28
AbstractThe origin of the passive margin forming the paleo-Pacific western edge of the ancestral North American continent (Laurentia) constrains the breakup of Rodinia and sets the stage for the Phanerozoic evolution of Laurentia. The Windermere Supergroup in the southern Canadian Cordillera records rift-to-drift sedimentation in the form of a prograding continental margin deposited between ~730 and 570 Ma. New U-Pb detrital zircon analysis from samples of the post-rift deposits shows that the ultimate source area was the shield of NW Laurentia and the near uniformity of age spectra are consistent with a stable continental drainage system. No western sediment source area was detected. Detrital zircon from postrift continental slope deposits are a proxy for ca. 676-656 Ma igneous activity in the Windermere basin, likely related to continental breakup, and set a maximum depositional age for slope deposits on the eastern side of the basin at 652±9 Ma. These results are consistent with previous interpretations. The St. Mary-Moyie fault zone near the Canada-U.S. border was most likely a major transform boundary separating a rifted continental margin to the north from intracratonic rift basins to the south, resolving north-south variations along western Laurentia in the late Neoproterozoic at approximately 650-600 Ma. For Rodinia reconstructions, the conjugate margin to the southern Canadian Cordillera would have a record of rifting between ~730 and 650 Ma followed by passive margin sedimentation.
Summary(Plain Language Summary, not published)
This is a tectonic summary that discusses the birth of the northern Pacific Ocean. The paper summarizes the initial stage of breakup and continental drift for the western margin of North America during the Neoproterozoic, particularly as it relates to western Canada and rocks in the mountainous regions of the Yukon.

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