Development of the continental margins of the Labrador Sea: a review

Abstract

The Labrador Sea is a small oceanic basin that developed when the North American and Greenland plates separated. An initial period of stretching in Early Cretaceous time formed sedimentary basins now preserved under the continental shelves and around the margins of the oceanic crust. The basins subsided thermally during Late Cretaceous time and a second episode of tectonism took place during latest Cretaceous and early Paleocene time, before the onset of sea-floor spreading in mid-Paleocene time. Around the northern Labrador Sea, Davis Strait and in southern Baffin Bay, voluminous picrites and basalts were erupted at and shortly after the commencement of sea-floor spreading. Volcanism occurred again in early Eocene time at the same time as sea-floor spreading commenced in the northern North Atlantic. Farther southeast, along the Labrador and southern West Greenland margins, oceanic crust is separated from continental crust by highly stretched but non-magmatic transition zones which developed before sea-floor spreading. A complex transform zone, which developed during sea-floor spreading in late Paleocene and early Eocene time, separates continental and oceanic crust along the Baffin Island margin. The Greenland and Labrador ocean-continent transitions are asymmetric across the only available conjugate cross-sections. However, a cross-section through the Labrador margin farther north resembles the Greenland cross-section in the conjugate pair more than it does the Labrador cross-section of this pair. Consideration of the geological history of the area suggests that the non-magmatic transition zones may have formed by slow extension of a few millimetres per year through a period of 53 Ma during Cretaceous and early Paleocene time.

Tectonic variation and structural evolution of the West Greenland continental margin

“…The Early Cretaceous rifting event is evidenced by deposition of clastic sediments in half grabens and graben basins, such as the Kitsissut and Appat sequences (Chalmers and Pulvertaft, 2001). Sedimentary facies within this area includes alluvial fan, fluvial, fan-delta, deltaic and shallow lacustrine sandstones and mudstones of the Kome and Atane Formations from Nuussuaq basin (Balkwill et al, 1990;Chalmers and Pulvertaft, 2001;Dam et al, 2000).…”

“…Sedimentary facies within this area includes alluvial fan, fluvial, fan-delta, deltaic and shallow lacustrine sandstones and mudstones of the Kome and Atane Formations from Nuussuaq basin (Balkwill et al, 1990;Chalmers and Pulvertaft, 2001;Dam et al, 2000).…”

“…The Kangeq seismic sequences in West Greenland basin were probably deposited into a thermally subsiding basin (Chalmers et al, 1993;Chalmers and Pulvertaft 2001). The oldest Mesozoic sediments in the Baffin Bay region are Aptian to…”

“…An unconformity is present between the Cretaceous and early Paleocene mudstones (Nøhr-Hansen and Dam, 1997). Early Palaeocene mudstones were deposited above the Kangeq Formation (Chalmers and Pulvertaft 2001).…”

“…The aim of this study is to consider the lateral variability of a single margin. We chose the West Greenland Cretaceous and early Tertiary periods (Balkwill et al, 1990;Chalmers, 1991Chalmers, , 2000Chalmers, , 2012Chalmers and Pulvertaft, 2001;Chalmers et al, 1993;Nielsen et al, 2002;Roest and Srivastava, 1989;Rowley and Lottes, 1988;Schenk, 2011).…”