So to kick things off for the inspiration of creating these cavernous, ice infested spaces I looked through concepts that other people have created.
Lubos de Gerardo Surzin was the first person I came across who has created digital art for Lucasfilm. The two images that stood out to me was the matte painting - Canyon of Iced Ships
And the second image - Ice Cave Base and Landscape Valley
Check out more of Surzin's work at CG Society
thePoet showing marvelous work on conceptart.org caught my attention with the ice cave image found here - thePoet sketchbook
Andrew Kim's work for the game Uncharted 2 also caught my eye with the game being set in icey caves partly. Check out the gallery for his inspiring concepts - Andrew Kim's Gallery