Cracks in my floor ... HELP

Hey all ... I've been posting a lot lately, but I have a major concern and I really need an expert eye on this. I have a massive crack that goes from wall to wall in my basement that I was going to seal. Attachment 44752 (http://www.doityourself.com/forum/attachments/basements-attics-crawl-spaces/44752-cracks-my-floor-help-long-crack.jpg) From the internet I knew I had to widen the edges before installing a sealant. However, as soon as I started chiseling it, I realized two things: 1. it was much deeper than I realized and 2. There's some exposed plastic line running along the crack. Attachment 44753 (http://www.doityourself.com/forum/attachments/basements-attics-crawl-spaces/44753-cracks-my-floor-help-opened-crack-2-.jpg) As I examined this further, I found that there's a thinner crack in my basement, running perpendicular to it, that goes the other length of my basement: