The Labrador water is really an extension that is northwestward of North Atlantic Ocean, through the Charlie-Gibbs break zone into the south to Davis Strait when you look at the north (Figure 2), which separates southern Greenland from Labrador. Rifting and breakup of the margins started through the Early Cretaceous (
85 Ma) predicated on borehole information (Balkwill 1990). Volcanics of Cretaceous and early Tertiary age onlap the rift structures and synrift sediments. A final period of intense volcanism in the Paleocene in the region of Davis Strait
60 Ma) is linked to the North Atlantic Magmatic Province (Gill et al., 1999). Unlike the Newfoundland and Nova Scotia margins towards the south, the pre-existing continental crust differs significantly in its many years and crustal properties: through the Paleozoic Appalachian Province within the south, through the belated Proterozoic Grenville Province into the Early Proterozoic Makkovik Province, and lastly the Archean Nain Province (Figure 9). A review that is recent of properties among these crustal devices, predicated on outcomes through the Lithoprobe ECSOOT system, is written by Hall et al. (2002).
Figure 9. Maps for the Labrador margin showing (a) total sediment depth and (b) free-air gravity. Sedimentary basins and terranes that are continental
Following rifting, subsequent seafloor distributing into the Labrador water is documented by magnetic lineations (Roest and Srivastava, 1989), beginning first into the south through the belated Cretaceous (
70-80 Ma), then propagating towards the north and closing within the belated Eocene (
40 Ma) when seafloor spreading ceased. A change that is major distributing taken place at
55 Ma when rifting began breaking up Greenland from Europe. An immense set of oval-shaped sedimentary basins separated by crustal arches formed along the deeply subsided crust of the Labrador shelf (Figure 9) during its syn-rift and post-rift period. After the initial coarse-grained syn-rift deposits, there clearly was a short span of sediment starvation followed closely by a wide range of clastic sediment influx throughout the Late Cretaceous and Tertiary. This generated a major seaward progradation of sediment on the rift-age grabens and ridges. Once the cellar proceeded to diminish, successive Tertiary sediment perspectives downlap and seaward that is thicken the shelf attained its current place. In contrast, the Southwest Greenland rack is slim and contains skilled little if any subsidence south of 63°N (Rolle, 1985). Thermal types of borehole information through the Labrador margin had been the first to ever add a larger number of lithospheric versus crustal stretching (Royden and Keen, 1980) so that you can explain its bigger post-rift versus syn-rift subsidence history.
During subsidence regarding the Labrador margin, terrigenous supply stones in the Upper Cretaceous Bjarni development and Upper Cretaceous to Paleocene Markland development matured mainly to create gasoline. Regarding the 31 wells drilled regarding the Labrador margin through the 1970’s and very very early 1980’s, there have been six hydrocarbon discoveries of that the biggest had been the Bjarni gas pool (Bell and Campbell, 1990). Hydrocarbon reservoirs for those discoveries are formed in structural traps of Lower and Upper Cretaceous fluvial sandstone overlying cellar horst obstructs.
Figure 10. Depth area for seismic profile TLS90-1 throughout secret social security benefits the Labrador margin with seismic velocities (in color) from refraction profiles. Wells and basement types that are crustal boundaries as
Clearly, there clearly was significantly less recent coverage that is seismic of Labrador margin compared to the Newfoundland and Nova Scotian margins.
Nevertheless, due to the restricted width associated with Labrador water and seafloor that is relatively simple history, just one local profile ended up being shot that spans the entire width associated with the basin and its particular conjugate margins (Keen et al., 1994). In addition, a few split but coordinated refraction pages had been shot along and throughout the transect that is same. Mixture of these data has allowed an entire level part to be produced from seafloor to mantle throughout the whole basin (Chian et al., 1995; Louden et al., 1996). The part throughout the Labrador margin is shown in Figure 10. Of specific note could be the interpretation of a broad zone of thinned crust that is continental the exterior rack and slope, which contrasts with past interpretations of oceanic crust ( e.g. Balkwill et al., 1990). Further seaward, an area of high velocity reduced crust, interpreted as partially serpentinized mantle, separates the zones of thinned crust that is continentallandward) and oceanic crust (seaward). Cellar over the area of serpentinized mantle is reasonably flat, in comparison utilizing the faulted cellar to either part. A prominent sub-basement reflector marks the top the larger velocities regarding the mantle that is serpentinized. This sub-horizontal horizon contrasts towards the dipping crustal reflectivity to either part. According to this profile and an identical one throughout the Southwest Greenland margin, a balanced reconstruction that is crustal of two conjugate margins during the point of breakup is shown in Figure 11 (Chian et al., 1995). This suggests that a very asymmetric pattern and lack of a lot of mantle melt will need to have resulted late through the rifting process, in comparison to predictions from pure-shear models (Louden and Chian, 1999). It could undoubtedly be interesting to know if this asymmetry is just a typical function among these margins. A refraction that is subsequent 92-5 (Hall et al., 2002) shows an even more abrupt initial thinning of this continental crust further to your north (Figure 9), nonetheless it will not sample the whole change in to the oceanic basin.
Figure 11. Feasible situation for asymmetric crustal breakup of Labrador-Greenland block that is continental on balanced crustal cross-sections from velocity models. Crustal sections removed during reconstruction (yellow and red) are thought to own created breakup that is following serpentinization of mantle (from Chian et al., 1995).