Mesozoic tectonic events in the North Atlantic and Arctic: stratigraphic response in an adjacent rift-flank basin (Sverdrup Basin, Arctic Canada)

The Sverdrup Basin (Arctic Canada) lies outside the North Atlantic and Arctic rift systems, but on the flanks of both. During Mesozoic time, rivers draining these rift flanks entered the basin at several points around the basin margin. Consequently, the changing pattern of Mesozoic sedimentation in the basin provides a sensitive, independent record of tectonic events in the adjacent rifts. The constraints provided on three Triassic-Jurassic events in the northern North Atlantic rift system are considered.

Evidence exists for an important Early Triassic rifting event in several parts of the northern North Atlantic rift system, but lack of data and poor biostratigraphic control means that the exact timing and regional significance are unclear. The advance and subsequent retreat of Early Triassic deltas into marine shelf environments along the eastern and southwestern margins of the Sverdrup Basin is compatible with regionally important tectonism that rejuvenated river systems draining the rift flanks. Marine faunas provide good biostratigraphic control: tectonism probably began around the Permo-Triassic boundary, peaked during Early Triassic (Nammalian) time and waned by the onset of Mid-Triassic time.

A poorly constrained tectonic event affected the northern North Atlantic rift system around the Triassic-Jurassic boundary. During the same interval, a vast deltaic system built out into the eastern Sverdrup Basin, again implying that regionally significant tectonism controlled the rejuvenation of river systems. Regional uplift centres developed in the northern North Atlantic region during ?Pliensbachian to Aalenian time, prior to the onset of rifting in Mid-Jurassic time. A reduction of sediment supply to the eastern Sverdrup Basin during this interval is interpreted to reflect modification to drainage patterns caused by uplift in the adjacent North Greenland region. A coeval increase in sediment input to the East Greenland margin of the northern North Atlantic rift system may reflect capture of the drainage network formerly entering the eastern Sverdrup Basin.