who composed its soundtrack?
Vidler
Blackrock (film)
Vidler said a lot of time was spent sifting through hundred of CDs "trying to find stuff that was not only appropriate for the film but would also be appealing to the audiences and hopefully, you know, would be released around the same time as the film, which isn't as easy as it sounds!" 
what is the theme of the film blackrock? Australian masculinity, mateship, violence and sexuality.
wiki:20660045
Blackrock (film) [SEP] Soundtrack
The soundtrack to the film was released on 28 April 1997 on Mercury Records Australia. Vidler said a lot of time was spent sifting through hundred of CDs "trying to find stuff that was not only appropriate for the film but would also be appealing to the audiences and hopefully, you know, would be released around the same time as the film, which isn't as easy as it sounds!" Jonathan Lewis from "AllMusic" gave the album four and a half out of five stars, concluding that it was "A fine collection of songs that, given the diversity of artists featured, is surprisingly cohesive as an album."