New multi-channel seismic reflection data from Northwater Bay, Nares Strait: Indications for pull-apart Tectonics

Report of the project:

• Marine geophysical investigations in the Nares Strait between Ellesmere and North-West Greenland

Stacked seismic section of line NARES 01-24. The section extends from the Thule Super Group south of Northumberland Island into the Kiatak Basin. The basin is bounded to the cast by a major fault. Source: BGR

New multi-fold marine seismic reflection data acquired as part of the 2001 Nares Strait Geoscientific Cruise totals 1201 km. Marine reflection seismic acquisition parameters were varied due to operating limitations in high arctic waters and standard marine data processing was performed resulting in stacked and partly migrated profiles located in Hall Basin, Kennedy Channel. Northwater Bay and one profile in Kane Basin offshore Cape Lawrence.

Here we only deal with the results from Northwater Bay north of the deep water Baffin Bay. These data totals 778 km and comprises a relatively high quality irregular grid covering about 17000 km². An additional 750 km covering 8000 km², of lesser quality 1970s industry marine seismic data were available in paper copy form and have been tied to the western part of the new data. Our interpretation suggests the presence of several fault-bounded NW-SE trending rift basins containing at least 4 km of sediments subdivided into at least four stratigraphic sequences. Differing axes of stratigraphic thickening and recognized unconformities imply several episodes of tectonic adjustment related to the opening of Baffin Bay. A N-S trending basin following approximately the 76 degree of longitude, is characterized by flower structures on all four lines crossing the basin. These may well indicate the trace of the Wegener strike-slip transform Fault. There is a direct continuation to similar structures described along the Carey Basin further south. To the north, the basin trends towards the west side of the narrow Smith Sound, where heavy pack ice prevented the collection of seismic data.

Schematic structural map for the Northern Baffin Bay derived from new multi-channel seismic data. Source: BGR

Incorporation of the results from the geological mapping onshore around the investigated area indicates that several kilometres of imaged older strata can be interpreted as stratified successions of the Meso-Proterozoic Thule Super Group.