Shirov Slav?

I have a question about two lines of Slav defences which converge:

Slav proper 1 d4 d5 2 c4 c6 3 Nf3 Nf6 4 Nc3 dxc4 5 a4 then 5...e6

Noteboom 1 d4 d4 2 c4 c6 3 Nf3 e6 4 Nc3 dxc4 5 a4 then 5...Nf6

Shirov has played this.  Can you give more information on this opening?

People won't let you play the Noteboom since they will avoid it with 4.Qc2...

And if you try playing it with the QGD move order, they will play Marshall Gambit

The Slav proper on the other hand is a nice choice. White has 2 options after Bf5: Ne5 and e3. In the Ne5 line, Black has the bishop sac line, the real mine line with e5 and the Nb6 line.

If Black wants, he can also castle queenside in the Slav and go for a sharper game.

Sorry if I wasn't clear.  I was asking from the white side.  This position is where the two lines which I gave converge.  Can you give information about this opening?

white plays a4 because he wants to stop black from playing b5 to protect his c4 pawn.

kasparov has played a gambit which e4.  with the idea being e5, Ng5, and Qh5

if black plays e6 with the bishop still on c8 then he generally will play c5 to equalize