My first thought is that its somewhere on Venus or Mars but my
Geophysics Book shows the "Boreal Rift" opening between Greenland and Scandavia in the Permian (280-250 Ma). Sinus does apparently mean "Bay"
in the geological context so maybe this is it.
The Yahoo Web Searcher gives the Vastitas Borealis on Mars. This is a wide spread lowland area at 67.5N 180W
Then the web searchers find things like Aroma Borealis (A coffee/tea),
the Aurora Borealis (we know what that is - Northern Lights), various companies with the name something Borealis and various stars.
Sinus Borealis is the ancestral of arctic oceans within the PANGAEA