The oldest rocks that are part of the Vishnu Basement Rocks is the Elves Chasm pluton. It consists of metamorphosed mafic (hornblende-biotite tonalite) and intermediate-composition plutonic rocks (quartz diorite). Within it, there are tabular amphibolite bodies that might be dikes, that have been dated at about 1.84 billion years ago. It is regarded to be an older granodioritic pluton that was exposed by erosion prior to being buried by the original volcanic and submarine sedimentary rocks of the Granite Gorge Metamorphic Suite. The Elves Chasm pluton is likely part of the basement rocks on which the original volcanic rocks and sediments of the Granite Gorge Metamorphic Suite were deposited.