The Labrador water is just an extension that is northwestward of North Atlantic Ocean, through the Charlie-Gibbs break zone within the south to Davis Strait into the north (Figure 2), which separates southern Greenland from Labrador. Rifting and breakup among these margins started during the Early Cretaceous (
85 Ma) centered 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 from 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 with its many years and crustal properties: through the Paleozoic Appalachian Province into the south, through the belated Proterozoic Grenville Province to your Early Proterozoic Makkovik Province, last but not least the Archean Nain Province (Figure 9). A present post on geophysical properties of those crustal devices, according to results through the Lithoprobe ECSOOT program, is provided by Hall et al. (2002).
Figure 9. Maps for the Labrador margin showing (a) total sediment thickness and (b) free-air gravity. Sedimentary basins and continental terranes are
Following rifting, subsequent seafloor distributing in the Labrador water is documented by magnetic lineations (Roest and Srivastava, 1989), beginning first when you look at the south through the Late Cretaceous (
70-80 Ma), then propagating into the north and closing within the eocene that is late
40 Ma) whenever seafloor spreading ceased. A change that is major distributing taken place at
55 Ma when rifting began isolating Greenland from European countries. During its syn-rift and post-rift period, an enormous pair of oval-shaped sedimentary basins divided by crustal arches formed along the profoundly subsided crust for the Labrador shelf (Figure 9). After the initial syn-rift that is coarse-grained, there was clearly a short span of sediment starvation accompanied by a massive amount clastic sediment influx through the belated Cretaceous and Tertiary. This resulted in a major seaward progradation of sediment within the rift-age grabens and ridges. While the cellar proceeded to diminish, successive Tertiary sediment perspectives downlap and seaward that is thicken the rack attained its present place. In comparison, the Southwest Greenland rack is slim and contains skilled minimal 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) so that you can explain its bigger post-rift versus syn-rift subsidence history.
During subsidence for the Labrador margin, terrigenous supply stones in the Upper Cretaceous Bjarni development and Upper Cretaceous to Paleocene Markland development matured mainly to make gasoline. Regarding the 31 wells drilled in the Labrador margin through the 1970’s and very early 1980’s, there were six hydrocarbon discoveries of that the biggest had been the Bjarni fuel pool (Bell and Campbell, 1990). Hydrocarbon reservoirs for those 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
Clearly, there was a lot less recent coverage that is seismic of Labrador margin compared to the Newfoundland and Nova Scotian margins.
Nonetheless, due to the restricted width of this Labrador Sea and simple and easy seafloor distributing history, an individual local profile had been shot that spans the entire width of this basin as well as its conjugate margins (Keen et al., 1994). In addition, a few split but coordinated refraction profiles had been shot along and throughout the transect that is same. Mix of these information has permitted a total depth part to be produced from seafloor to mantle over 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 may 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 ( 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 crust that is continentallandward) and oceanic crust (seaward). Cellar over the area of serpentinized mantle is reasonably flat, in comparison using the basement that is faulted either part. A prominent sub-basement reflector marks the top of the bigger velocities associated with mantle that is serpentinized. This horizon that is sub-horizontal into 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 an extremely asymmetric pattern and lack of a lot of mantle melt will need to have resulted later through the rifting process, as opposed to predictions from pure-shear models (Louden and Chian, 1999). It could truly be interesting to know if this asymmetry is really a feature that is common of 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 doesn’t 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 eliminated during reconstruction (yellow and red) are thought to possess created following breakup by serpentinization of mantle (from Chian et al Trans dating apps., 1995).