The existence of a Parnaíba block was hypothesized from geophysical evidence, petrography, geochronology of the basement rocks,[3] and from collisional tectonic models.

[9] To the west, the Araguaia suture zone represents the final Neoproterozoic collision between the Amazonian craton and the Parnaíba block and, to the east, the Transbrasiliano Lineament marks the border with the Borborema Province.

The sedimentary rocks vary greatly throughout the stratigraphy of the basin and depsostional enciroment changes, and includes shale, siltstone, mudstone, sandstone, conglomerate, breccia, limestone, and more.

Most of the magmatic rocks are sub-alkaline tholeiitic basalts, and occur as dykes and sills mainly within the Silurian to Carboniferous and as magmatic flows in the Jurassic and, less commonly, in the Cretaceous[13] Balsas megasequence Caninde megaseqeuence Serra Grande megasequence The Parnaíba basin is located above a complex basement comprising several Archaean and Proterozoic terranes that stabilized during the Brasiliano orogeny.

[11] The Riachão I sequence is a thin, banded package of high-amplitude reflections that extend across most of the basin area and define a broad arch.

An intense erosional event took place after the deposition of the Riachão basin sequences that ultimately created a profound pre-Silurian unconformity.

[23] The underlying subsidence appears largely continuous throughout the basin's history, there are minor deviations associated with regional disconformities.

These variations in subsidence can be interpreted as brief uplift events from epeirogenic movement caused by changing patterns of dynamic topography.