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Mesozoic strata in the Canadian Arctic archipelago occur mainly in the Sverdrup basin where the succession is up to 9 km thick. The strata consist of alternating sandstone-dominant units and argillaceous intervals and record 25 regional transgressions and regressions. These resulted from the interplay of sedimentation, tectonics, and eustatic sea level changes. Subaerial unconformities occur on the basin margins and disappear basinward. Most of these unconformities are interpreted to be the product of eustatic sea level fall on the basis of correlation with global sea level charts. However, unconformities of latest Aalenian, late Callovian, Hauterivian, and Coniacian ages are interpreted to be related to tectonic activity and the formation of the Amerasian basin.
Normal faulting and basic dike and sill intrusion occurred in the Sverdrup basin from Middle Jurassic to early Late Cretaceous. The latest Aalenian and late Callovian unconformities probably reflect early rifting events. Hauterivian uplift was widespread and coincides with the final phase of rifting and initiation of sea-floor spreading in the Amerasian basin. Marine onlap across the breakup unconformity began in Barremian time and by Albian much of the Arctic archipelago had been transgressed.
Basalt flows are intercalated with Barremian to Turonian strata in the northeastern Sverdrup basin and represent the cratonward extension of the Alpha-Mendeleyev volcanic ridge, which was active during the opening of the Amerasian basin. Coniacian uplift coincided with the cessation of volcanism in the Sverdrup basin and of sea-floor spreading in the ocean basin to the north.
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