The Frade Group is 4,000 metres (13,000 ft) thick and includes three formations: Santos, Itajaí-Açu and Juréia.
They predominantly comprise turbidites.

Santos Formation
The Santos Formation is 1,275 metres (4,183 ft) thick and consists of reddish lithic conglomerates and sandstones, interbedded with grey shales and reddish clays.
These facies are interbedded and change laterally into the Itajai-Açu and Juréia Formations.
The sedimentary environment is thought to be transitional continental to marginal marine, ranging from alluvial to braided rivers and deltas.
Biostratigraphic data indicate a Late Cretaceous age (Cenomanian-Maastrichtian).

Itajaí-Açu Formation
The Itajaí-Açu Formation is 1,545 metres (5,069 ft) thick and comprises a thick interval of dark grey clayey rocks, interbedded with the clastics of the Santos and Juréia Formations.
Within this formation, the Ilhabela Member includes the turbiditic sandstones occurring along the section.
The sedimentary environment is thought to be marine talus to open basin.
Biostratigraphic data from palynomorphs, calcareous nanofossils and planktonic foraminifera indicate a Late Cretaceous age (Cenomanian-Maastrichtian).

Juréia Formation
The Juréia Formation is 952 metres (3,123 ft) thick and includes a succession of clastics between the coarse facies of the Santos Formation in the west and the fine-grained clastics of the Itajai-Açu Formation in the east.
The formation is characterized by dark grey to greenish and brown shales, dark grey siltstones, fine-very fine sandstones and light ochre calcisilts.
The depositional environment is thought to be of a marine platform setting.
The age based on palynomorphs and calcareous nanofossils is Late Cretaceous (Santonian-Maastrichtian).
Two new ostracod species were identified in the drilling cuttings of wells drilled into the Santonian-Campanian section, ?
Afrocytheridea cretacea and Pelecocythere dinglei.
The Frade Group is 4,000 metres (13,000 ft) thick and includes three formations: Santos, Itajaí-Açu and Juréia. They predominantly comprise turbidites.
Santos Formation
The Santos Formation is 1,275 metres (4,183 ft) thick and consists of reddish lithic conglomerates and sandstones, interbedded with grey shales and reddish clays. These facies are interbedded and change laterally into the Itajai-Açu and Juréia Formations. The sedimentary environment is thought to be transitional continental to marginal marine, ranging from alluvial to braided rivers and deltas. Biostratigraphic data indicate a Late Cretaceous age (Cenomanian-Maastrichtian).
Itajaí-Açu Formation
The Itajaí-Açu Formation is 1,545 metres (5,069 ft) thick and comprises a thick interval of dark grey clayey rocks, interbedded with the clastics of the Santos and Juréia Formations. Within this formation, the Ilhabela Member includes the turbiditic sandstones occurring along the section. The sedimentary environment is thought to be marine talus to open basin. Biostratigraphic data from palynomorphs, calcareous nanofossils and planktonic foraminifera indicate a Late Cretaceous age (Cenomanian-Maastrichtian).
Juréia Formation
The Juréia Formation is 952 metres (3,123 ft) thick and includes a succession of clastics between the coarse facies of the Santos Formation in the west and the fine-grained clastics of the Itajai-Açu Formation in the east. The formation is characterized by dark grey to greenish and brown shales, dark grey siltstones, fine-very fine sandstones and light ochre calcisilts. The depositional environment is thought to be of a marine platform setting. The age based on palynomorphs and calcareous nanofossils is Late Cretaceous (Santonian-Maastrichtian). Two new ostracod species were identified in the drilling cuttings of wells drilled into the Santonian-Campanian section, ?Afrocytheridea cretacea and Pelecocythere dinglei.
Santos Basin