It covers an area measuring 20,000 square kilometres (7,700 sq mi)[1] and extends north-south from Porto to Lisbon.

[3] The Lusitanian Basin results from the opening of the North Atlantic Ocean due to Mesozoic extension.

Throughout the complete formation of the basin, from the Late Triassic to the Cretaceous, five distinct phases can be defined, with four stages of rifting activity:[1] The most significant faults and salt structures throughout the Lusitanian Basin trend north-northeast, parallel to the elongation of the shoreline.

These faults are a part of in important structural trend within the Estremadura Trough which highlights the Oxfordian extension within the basin.

The thrusting observed is resultant of the basement-attached inversion movements of the pre-existing normal faults during the Miocene.

[1] Resultant of diapirism leading to the formation of salt pillows, the Lusitanian Basin can be divided into seven different sub-basins: The Lusitanian basin Triassic to Cretaceous rocks provided thousands of fossils, from plants, microfossils, invertebrates and vertebrates.

Deposition of Carbonates of the Brenha and Candieros Formations are in shelf, ramp, and sub-marine fan environments and filled the basin during the early and middle Jurassic.

The carbonate shelf environment is still present in the Upper Jurassic—characterized by the Montejunto grainstone and reef facies, Cabacos organic-rich limestone (capped by anhydrite).

In the subsalt petroleum system, there are Paleozoic source rocks and synrift Triassic sandstone reservoirs that are sealed by Dagorda evaporites.