Re: thanks Barry...
There's a problem with this paper which I have had the chance to read in full.
If there were a brine layer, or even interconnected slush, then the minimal residual topography of the northern plains and its large impact basins would have been totally erased.
Furthermore, what he says about currents is total nonsense. They would decay in seconds to minutes without a large energy source to maintain them, and he doesn't discuss any such source...