Mumford & Sons is heading for a massive week.

The rock quartet’s new album “Babel” is on course to sell as much as 600,000 copies by the end of the tracking week on Sunday, Sept. 30 — so say industry sources. The set, released yesterday (Sept. 25), will easily debut atop the Billboard 200 next week, giving the band its first chart-topper.

The new Billboard 200 chart’s top 10 will be revealed on the morning of Wednesday, Oct. 3.

“Babel’s” forecasted sales should give the band the biggest debut week this year, surpassing Justin Bieber’s “Believe” launch with 374,000 according to Nielsen SoundScan. Mumford & Sons will also tally the largest sales frame for any rock album (debut or otherwise) since AC/DC’s “Black Ice” stormed in with 784,000 at No. 1 on the Nov. 8, 2008 chart.

Further, “Babel,” released on Gentlemen of the Road through Glassnote Records, will nab the largest sales week ever for RED Distribution and the first No. 1 for Glassnote. RED — which is Sony’s indie distribution arm — saw its previous highest week when Bone Thugs-N-Harmony’s 1997 album “The Art of War” (Ruthless/Relativity) sell 394,000 in its debut at No. 1.

“Babel’s” digital sales are through the roof, according to sources. It will likely lock in the second-largest sales week ever for a digital album, as it could sell more than 400,000 downloads. The biggest digital week ever for a set belongs to Lady Gaga’s “Born This Way,” which moved 662,000 downloads in its first week. (A chunk of that figure was driven by Amazon MP3’s sale pricing of the set at 99-cents for two days during release week.)

“Babel” is Mumford & Sons’ second studio album, and follows 2010’s “Sigh No More.” The latter has sold 2.5 million in the U.S. according to SoundScan and peaked at No. 2 on the Billboard 200. The new album’s lead single, “I Will Wait,” is bulleted at No. 2 — its so far peak — on the Alternative Songs chart. The tune debuted and peaked at No. 23 on the Billboard Hot 100 in August.

Mumford & Sons wasn’t the only major act to drop a new album yesterday, as Green Day, No Doubt and Lupe Fiasco all issued their latest releases. At the present, it looks as if Green Day’s “Uno!” will bow in the No. 2 slot with perhaps 150,000 or so, while No Doubt’s “Push and Shove” is headed for No. 3 with 125,000. Fiasco’s “Food and Liquor II” is aiming for the No. 4 position with perhaps 100,000. [Billboard.biz]