The North Patagonian Massif covers an area of approximately 100,000 square kilometres (39,000 sq mi).

Compared to neighboring areas, the North Patagonian Massif has thicker continental crust.

[1] The massif consists of a basement formed by Cambro-Ordovician rocks, overlain by the Middle Silurian Sierra Grande Formation.

The Marifil Complex is separated from the Paleozoic sequence by the Enjambre Dikes, dated to the Late Triassic with ages varying between 221 ± 12 and 207 ± 11 Ma.

[3] The Cenozoic cover of the western belt of the massif comprises the Eocene to Oligocene Ventana and Ñirihuau Formations in the north and the Middle to Late Miocene Ñorquincó Formation in the south.