The Labrador water is a northwestward expansion associated with the North Atlantic Ocean, through the Charlie-Gibbs break area into the south to Davis Strait into the north (Figure 2), which separates southern Greenland from Labrador. Rifting and breakup among these margins started through the Early Cretaceous (
85 Ma) considering borehole information (Balkwill 1990). Volcanics of Cretaceous and early Tertiary age onlap the rift structures and synrift sediments. In the order of Davis Strait, one last amount of intense volcanism into the Paleocene (
60 Ma) is linked to the North Atlantic Magmatic Province (Gill et al., 1999). The pre-existing continental crust varies substantially in its ages and crustal properties: from the Paleozoic Appalachian Province in the south, through the Late Proterozoic Grenville Province to the Early Proterozoic Makkovik Province, and finally the Archean Nain Province (Figure 9) unlike the Newfoundland and Nova Scotia margins to the south. A review that is recent of properties among these crustal devices, according to results from the Lithoprobe ECSOOT system, is distributed 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 continental terranes are
Following rifting, subsequent seafloor distributing within the Labrador water is documented by magnetic lineations (Roest and Srivastava, 1989), beginning first when you look at the south throughout the belated Cretaceous (
70-80 Ma), then propagating into military cupid app the north and closing when you look at the eocene that is late
40 Ma) whenever seafloor spreading ceased. A significant improvement in distributing happened at
55 Ma when rifting began Greenland that is separating from. During its syn-rift and post-rift period, an enormous group of oval-shaped sedimentary basins divided by crustal arches formed along the profoundly subsided crust for the Labrador shelf (Figure 9). Following initial syn-rift that is coarse-grained, there is a brief period of sediment starvation followed closely by a wide range of clastic sediment influx through the belated Cretaceous and Tertiary. This resulted in a seaward that is major of sediment throughout the rift-age grabens and ridges. Since the basement proceeded to subside, successive Tertiary sediment perspectives downlap and seaward that is thicken the rack attained its current place. In contrast, the Southwest Greenland shelf is slim and it has experienced little if any subsidence south of 63°N (Rolle, 1985). Thermal types of borehole information through the Labrador margin had been the first ever to add a better number of lithospheric versus crustal stretching (Royden and Keen, 1980) to be able to explain its larger post-rift versus syn-rift subsidence history.
During subsidence associated with Labrador margin, terrigenous source stones inside the Upper Cretaceous Bjarni development and Upper Cretaceous to Paleocene Markland development matured mainly to make gasoline. Associated with the 31 wells drilled on the Labrador margin through the 1970’s and very very very early 1980’s, there have been six hydrocarbon discoveries of that your biggest ended up being the Bjarni fuel pool (Bell and Campbell, 1990). Hydrocarbon reservoirs of these discoveries are created in structural traps of Lower and Upper Cretaceous fluvial sandstone overlying cellar horst obstructs.
Figure 10. Depth area for seismic profile TLS90-1 throughout the Labrador margin with seismic velocities (in color) from refraction pages. Wells and basement crustal kinds and boundaries as
Demonstrably, there is certainly notably less recent seismic coverage of this Labrador margin compared to the Newfoundland and Nova Scotian margins.
But, due to the restricted width associated with the Labrador water and seafloor that is relatively simple history, an individual local profile ended up being shot that spans the whole width for the basin as well as its 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 information has permitted an entire level area to be produced from seafloor to mantle throughout the whole basin (Chian et al., 1995; Louden et al., 1996). The area over the Labrador margin is shown in Figure 10. Of specific note could be the interpretation of an extensive zone of thinned continental crust beneath the exterior rack and slope, which contrasts with previous interpretations of oceanic crust ( ag 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 continental crust (landward) and oceanic crust (seaward). Cellar over the area of serpentinized mantle is reasonably flat, on the other hand because of the faulted cellar to either part. A prominent sub-basement reflector marks the top the bigger velocities regarding the mantle that is serpentinized. This sub-horizontal horizon contrasts towards the dipping crustal reflectivity to either part. Predicated on this profile and an identical one over the Southwest Greenland margin, a balanced crustal reconstruction regarding the two conjugate margins during the point of breakup is shown in Figure 11 (Chian et al., 1995). This means that that an extremely asymmetric pattern and lack of a lot of mantle melt should have resulted later through the rifting process, as opposed to predictions from pure-shear models (Louden and Chian, 1999). It might definitely be interesting to know if this asymmetry is just a typical function of those margins. A refraction that is subsequent 92-5 (Hall et al., 2002) suggests an even more abrupt initial thinning regarding the continental crust further towards the north (Figure 9), nonetheless it will not sample the whole change to the oceanic basin.
Figure 11. Available situation for asymmetric crustal breakup of Labrador-Greenland continental block based on balanced crustal cross-sections from velocity models. Crustal sections eliminated during reconstruction (yellow and red) are assumed to own created after breakup by serpentinization of mantle (from Chian et al., 1995).