The Labrador water is an extension that is northwestward of North Atlantic Ocean, through the Charlie-Gibbs break area when you look at the south to Davis Strait into the north (Figure 2), which separates southern Greenland from Labrador. Rifting and breakup of the margins started through the Early Cretaceous (
85 Ma) centered on borehole onenightfriend com review 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 of the crustal devices, centered 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 continental terranes are
Following rifting, subsequent seafloor distributing in the Labrador water is documented by magnetic lineations (Roest and Srivastava, 1989), beginning first into the south throughout the belated Cretaceous (
70-80 Ma), then propagating to your north and closing into the eocene that is late
40 Ma) whenever seafloor spreading ceased. A change that is major distributing happened at
55 Ma when rifting began Greenland that is separating from. 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. Following initial syn-rift that is coarse-grained, there was clearly a brief period of sediment starvation accompanied by a lot 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 cellar proceeded to diminish, successive Tertiary sediment perspectives downlap and seaward that is thicken the shelf attained its current place. In comparison, the Southwest Greenland rack is slim and it has skilled 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 larger number of lithospheric versus crustal stretching (Royden and Keen, 1980) to be able to explain its bigger post-rift versus syn-rift subsidence history.
During subsidence associated with the Labrador margin, terrigenous supply stones in the Upper Cretaceous Bjarni development and Upper Cretaceous to Paleocene Markland Formation matured mainly to make 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 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 sandstone that is fluvial cellar horst obstructs.
Figure 10. Depth area for seismic profile TLS90-1 over the Labrador margin with seismic velocities (in color) from refraction pages. Wells and basement types that are crustal boundaries as
Demonstrably, there was significantly 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 water and easy seafloor distributing history, an individual local profile had been shot that spans the entire width associated with 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 over the transect that is same. Mix of these information has permitted an entire level area to be manufactured 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 particular note may be the interpretation of an extensive zone of thinned crust that is continental the external 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 continental crust (landward) and oceanic crust (seaward). Cellar over the area of serpentinized mantle is reasonably flat, in comparison with all the basement that is faulted either part. A prominent sub-basement reflector marks the top the greater velocities for the mantle that is serpentinized. This sub-horizontal horizon contrasts into the dipping crustal reflectivity to either side. Centered on this profile and an equivalent one throughout the Southwest Greenland margin, a well-balanced crustal reconstruction regarding the 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 later through the rifting process, contrary to predictions from pure-shear models (Louden and Chian, 1999). It could undoubtedly be interesting to know if this asymmetry is really a typical function among these margins. A subsequent refraction profile 92-5 (Hall et al., 2002) suggests a far more abrupt initial thinning regarding the continental crust further into the 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 continental block based on balanced crustal cross-sections from velocity models. Crustal sections eliminated during reconstruction (yellow and red) are thought to possess formed breakup that is following serpentinization of mantle (from Chian et al., 1995).