A refraction seismic transect from Greenland to Ellesmere Island, Canada: The crustal structure in Southern Nares Strait

Thomas Funck, H. Ruth Jackson, Sonya A. Dehler, Ian D. Reid

Publikation: Bidrag til tidsskriftArtikelForskningpeer review


A refraction and wide-angle reflection seismic study was carried out in southern Nares Strait (northernmost Baffin Bay) on a 378 km long profile running from Pituffik/Thule Air Base on Greenland into Makinson
Inlet on Ellesmere Island, Canada. Eight ocean bottom seismometers and eight land stations were deployed to record the airgun shots along the line. A crustal
velocity model was developed by forward and inverse modeling techniques. The Proterozoic Thule Basin can be correlated across Nares Strait as a continuous structure with a total thickness of 4-5 km. The basin is divided into three units. The upper unit has velocities of 4.5-5.0 km s-1 and a Poisson’s ratio (σ) of 0.30, indicating a high content of carbonates. The middle unit is characterized by high velocities (6.1 km s-1) and a Poisson’s ratio of 0.28. This unit is interpreted to correlate with the basaltic sills found in the Cape Combermere formation. The lower unit is a low-velocity zone and, hence, its velocities are
unconstrained. The underlying crust is divided into three layers, upper crust (6.0-6.2 km s-1 , σ = 0.25), middle crust (6.1-6.3 km s-1, σ = 0.26) and lower
crust (6.7-6.9 km s-1, σ = 0.26). These properties are consistent with a granitic/gneissic composition in the upper/middle crust and with granulites in the lower crust. Moho depth on either side of Nares Strait is 36 km, with some shallowing to 33 km in a 100 km wide zone. The Moho shallowing is related to local uplift at the Carey Islands just to the south of the line based on correlation with the gravity data. With only minor lateral changes of crustal velocities and Moho depth across southern Nares Strait, the eastern
Archean/Proterozoic part of Ellesmere Island appears to be part of the same plate as Greenland with Thule Basin as intracratonic feature. No structures consistent with a strike-slip boundary could be resolved in southern Nares Strait.
Sider (fra-til)97-112
Antal sider16
Udgave nummer1-3
StatusUdgivet - 2006
Udgivet eksterntJa


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