The Labrador water is an extension that is northwestward of North Atlantic Ocean, through the Charlie-Gibbs break area within 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. In the near order of Davis Strait, your final amount of intense volcanism within 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 program, 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 into the Labrador water is documented by magnetic lineations (Roest and Srivastava, 1989), beginning first when you look at the south through the belated Cretaceous (
70-80 Ma), then propagating to your north and closing into the belated Eocene (
40 Ma) whenever seafloor spreading ceased. A change that is major distributing taken place at
55 Ma when rifting began splitting Greenland from European countries. 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 is 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 on the rift-age grabens and ridges. Because the basement proceeded to subside, successive Tertiary sediment perspectives downlap and seaward that is thicken the rack attained its current position. In contrast, the Southwest Greenland rack is slim and has now 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 better amount 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 Labrador margin, terrigenous supply stones inside the Upper Cretaceous Bjarni development and Upper Cretaceous to Paleocene Markland development matured mainly to create gasoline. Associated with the 31 wells drilled in 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 formed in structural traps of Lower and Upper Cretaceous fluvial sandstone overlying basement 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 types that are crustal boundaries as
Demonstrably, there was not as recent coverage that is seismic of Labrador margin compared to the Newfoundland and Nova Scotian margins.
Nonetheless, because of the restricted width associated with Labrador water and not at all hard seafloor distributing history, an individual regional profile ended up being shot that spans the whole width associated with the basin and its particular conjugate margins (Keen et al., 1994). In addition, several split but coordinated refraction pages had been shot along and over the exact same transect. Mixture of these data has permitted a whole level part to be manufactured from seafloor to mantle over the whole basin (Chian et al., 1995; Louden et al., 1996). The part over the Labrador margin is shown in Figure 10. Of particular note may be the interpretation romance tales dating site of a broad zone of thinned crust that is continental the external rack and slope, which contrasts with previous 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). Basement over the area of serpentinized mantle is reasonably flat, on the other hand aided by the basement that is faulted either part. A prominent sub-basement reflector marks the top the greater velocities of this serpentinized mantle. This horizon that is sub-horizontal to your dipping crustal reflectivity to either part. Predicated on this profile and an equivalent one throughout the Southwest Greenland margin, a well-balanced reconstruction that is crustal of two conjugate margins in the point of breakup is shown in Figure 11 (Chian et al., 1995). This suggests that an extremely asymmetric pattern and absence of a lot of mantle melt should have resulted late through the rifting process, as opposed to predictions from pure-shear models (Louden and Chian, 1999). It could undoubtedly be interesting to know if this asymmetry is just a feature that is common of margins. A refraction that is subsequent 92-5 (Hall et al., 2002) suggests a far more abrupt initial thinning associated with continental crust further towards the north (Figure 9), however it doesn’t sample the whole change 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 own formed breakup that is following serpentinization of mantle (from Chian et al., 1995).