[1][2][3][4] It comprises two outcropping sections called the Dufek Massif and the Forrestal Range that are thought to be connected beneath the Sallee Snowfield.
The Dufek intrusion is associated with large volumes of Jurassic tholeiitic magmatism associated with the breakup of Gondwana.
Stratigraphy within the intrusion includes the 1.8 km thick Dufek Massif section and associated nanataks.
This massif section is composed of the 230 m thick Walker Anorthosite, with laminated plagioclase cumulates, overlain by the Aughenbaugh Gabbro.
This gabbro consists of laminated plagioclase with and the augite-pigeonite pyroxene cumulus.