Baffin Bay Composite Tectono-Sedimentary Element

Abstract

Abstract Baffin Bay formed as a result of continental extension during the Cretaceous, which was followed by seafloor spreading and associated plate drift during the early to middle Cenozoic. The formation of an oceanic basin in the central part of Baffin Bay may have begun from about 62 Ma in tandem with the Labrador Sea opening, but the early spreading phase is controversial. Plate-kinematic models suggest that from Late Paleocene the direction of seafloor spreading changed to north–south, generating strike-slip movements along the transform lineaments, e.g. the Ungava Fault Zone and the Bower Fracture Zone, and structural complexity along the margins of Baffin Bay. The Baffin Bay Composite Tectono-Sedimentary Element (CTSE) represents a 3–7-km-thick Cenozoic sedimentary and volcanic succession that was deposited over oceanic and rifted continental crust since active seafloor spreading began. The CTSE is subdivided into 5 seismic mega-units that have been identified and mapped using a regional seismic grid tied to wells and core sites. Thick clastic wedges of likely Late Paleocene to Early Oligocene age (mega-units E and D2) were deposited within basins floored by newly formed oceanic crust, transitional crust, volcanic extrusives and former continental rift basins undergoing subsidence. The middle–late Cenozoic is characterized by fluvial–deltaic sedimentary systems, hemipelagic strata and aggradational sediment bodies deposited under the influence of ocean currents (mega-units D1, C and B). The late Pliocene to Pleistocene interval (mega-unit A) displays major shelf margin progradation associated with ice-sheet advance–retreat cycles resulting in the accumulation of trough-mouth fans and mass-wasting deposits in the oceanic basin. The Baffin Bay CTSE has not produced discoveries, although a hydrocarbon potential may be associated with Paleocene source rocks. Recent data have improved the geological understanding of Baffin Bay, yet large data and knowledge gaps remain.