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TitleDual provenance signatures of the Triassic northern Laurentian margin from detrital-zircon U-Pb and Hf-isotope analysis of Triassic-Jurassic strata in the Sverdrup Basin
AuthorMidwinter, D; Hadlari, T; Davis, W J; Dewing, K; Arnott, R W C
SourceLithosphere 2016, 16 pages, (Open Access)
LinksCircum-Arctic Lithosphere Evolution (CALE)
Alt SeriesEarth Sciences Sector, Contribution Series 20160017
Alt SeriesCircum-Arctic Lithosphere Evolution (CALE) Contribution
PublisherGeological Society of America
Mediapaper; on-line; digital
File formatpdf
ProvinceNunavut; Northwest Territories
NTS39B; 39C; 39F; 39G; 49; 58B; 58C; 58F; 58G; 59; 68; 69; 78; 79; 88; 89; 98; 99; 340A; 340B; 340C; 340D; 340E; 340F; 560A; 560B; 560C; 560D; 560E; 560F
AreaArctic Ocean; Canadian Arctic Archipelago; Ellesmere Island; Axel Heiberg Island; Melville Island; Prince Patrickk Island
Lat/Long WENS-130.0000 -70.0000 83.0000 72.0000
Subjectsgeochronology; tectonics; provenance; radiometric dating; uranium lead dating; isotopic studies; hafnium; detrital minerals; zircon dates; source rocks; tectonic evolution; tectonic setting; tectonic interpretations; rifting; plate margins; magmatism; paleogeography; basin evolution; Sverdrup Basin; Laurentia; Amerasia Basin; Bjorne Formation; Heiberg Formation; Romulus Member; Heiberg Group; King Christian Formation; Pat Bay Formation; Yukon Tanana Terrane; siliciclastic sedimentary successions; Phanerozoic; Mesozoic; Cretaceous; Jurassic; Triassic; Paleozoic; Permian; Carboniferous
Illustrationsgeological sketch maps; stratigraphic columns; stratigraphic charts; graphs; plots
ProgramWestern Arctic, High Arctic LIP, GEM2: Geo-mapping for Energy and Minerals
ProgramPolar Continental Shelf Program
Released2016 05 20
AbstractThe tectonic setting of northern Laurentia prior to the opening of the Arctic Ocean is the subject of numerous tectonic models. By better understanding the provenance of detrital zircon in the Canadian Arctic prior to rifting, both the prerift tectonic setting and timing of rifting can be better elucidated. In the Sverdrup Basin, two distinct provenance assemblages are identified from new detrital-zircon U-Pb data from Lower Triassic to Lower Jurassic strata in combination with previously published detrital-zircon data. The first assemblage comprises an age spectrum identical to that of the Devonian clastic wedge in the Canadian Arctic and is termed the recycled source. In contrast, the second assemblage is dominated by a broad spectrum of near syndepositional Permian-Triassic ages derived from north of the basin and is termed the active margin source. Triassic strata of Yukon and Arctic Alaska exhibit a similar dual provenance signature, whereas in northeastern Russia, Chukotka contains only the active margin source. Complementary hafnium isotopic data on Permian-Triassic zircon have eHf values that are consistent with the common evolved crustal signature of the Devonian clastic wedge detrital-zircon grains and Neoproterozoic-Paleozoic basement rocks in the Arctic Alaska-Chukotka microcontinent. Furthermore, newly identified volcanic ash beds throughout the Triassic section from the northern part of the Sverdrup Basin, along with abundant Permian-Triassic detrital zircon, suggest a protracted history of magmatism to the north of the basin. We interpret that these zircons were sourced from a magmatically active region to the north of the Sverdrup Basin, and in the context of a rotational model for opening of Amerasia Basin, this was probably part of a convergent margin fringing northern Laurentia from the northern Cordillera along the outboard edge of Arctic Alaska and Chukotka terranes. In Early Jurassic strata, Permian-Triassic zircons decrease substantially, implying the diminution of the active margin as a sediment source as initial rifting isolated the Permian-Triassic source from the Sverdrup Basin.
Summary(Plain Language Summary, not published)
This contribution redefines the tectonic setting of the Sverdrup Basin during the Triassic, prior to opening of the Arctic Ocean. In addition to analysis of U-Pb isotopes to establish the origin of sand grains within Triassic rocks our key observation during 2015 GEM2 fieldwork of volcanic ash beds allows for the interpretation of a much more dynamic tectonic setting than previously thought. Ash beds have never been described from the Triassic part of the Sverdrup Basin before now.