Labrador Margin 125 Ma) and finished through the Late Cretaceous (

The Labrador water is an extension that is northwestward of North Atlantic Ocean, through the Charlie-Gibbs break zone within the south to Davis Strait when you look at the north (Figure 2), which separates southern Greenland from Labrador. Rifting and breakup of those margins started through 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 substantially with its many years and crustal properties: through the Paleozoic Appalachian Province within the south, through the belated Proterozoic Grenville Province to your Early Proterozoic Makkovik Province, and lastly the Archean Nain Province (Figure 9). A present overview of geophysical properties of those crustal units, according to outcomes through the Lithoprobe ECSOOT system, is provided by Hall et al. (2002).

Figure 9. Maps for the Labrador margin showing (a) total sediment depth ldssingles promo code 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 to your north and closing when you look at the eocene that is late

40 Ma) whenever seafloor spreading ceased. An important change in distributing taken place at

55 Ma when rifting began breaking up Greenland from European countries. During its syn-rift and post-rift period, a tremendous pair of oval-shaped sedimentary basins divided by crustal arches formed along the profoundly subsided crust for the Labrador rack (Figure 9). After the initial syn-rift that is coarse-grained, there clearly was a short span of sediment starvation accompanied by a great deal of 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. Once the cellar proceeded to subside, successive Tertiary sediment perspectives downlap and thicken seaward as the rack attained its current place. 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 were the first to ever consist of a better quantity 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 inside the Upper Cretaceous Bjarni development and Upper Cretaceous to Paleocene Markland Formation matured primarily to form gasoline. Regarding the 31 wells drilled regarding the Labrador margin through the 1970’s and very very early 1980’s, there were six hydrocarbon discoveries of that your biggest had been the Bjarni gas 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. Level area for seismic profile TLS90-1 over the Labrador margin with seismic velocities (in color) from refraction pages. Wells and basement crustal kinds and boundaries as

Clearly, there clearly was notably less recent seismic coverage of this Labrador margin compared to the Newfoundland and Nova Scotian margins.

Nonetheless, 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 whole width regarding 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 over the exact same transect. Mix of these information has allowed a depth that is complete 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 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, a 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, in comparison using the basement that is faulted either part. A prominent sub-basement reflector marks the top of the bigger velocities of this serpentinized mantle. This horizon that is sub-horizontal to your dipping crustal reflectivity to either part. Considering 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 a very asymmetric pattern and lack of quite 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 might undoubtedly be interesting to know if this asymmetry is 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 the continental crust further into the north (Figure 9), however it will not sample the whole change 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 after breakup by serpentinization of mantle (from Chian et al., 1995).

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