Iguape Formation

Iguape Formation
Stratigraphic range: Paleocene-Pliocene ~
Type	Geological formation
Unit of	Itamambuca Group
Underlies	Sepetiba Formation
Overlies	Santos Fm., Itajaí-Açu Fm., Juréia Fm.
Thickness	up to 2,200 m (7,200 ft)
Lithology
Primary	Calcarenite
Other	Shale, marl, siltstone, conglomerate
Location
Coordinates
Region	Santos Basin, South Atlantic
Country	Brazil
Type section
Named for	Iguape
Location of the Santos Basin

The Iguape Formation (Portuguese: Formacão Iguape) is a geological formation of the Santos Basin offshore of the Brazilian states of Rio de Janeiro, São Paulo, Paraná and Santa Catarina. The calcarenite, shale, siltstone, marl and conglomerate formation dates to the Tertiary period and has a maximum thickness of 2,200 metres (7,200 ft).

Etymology

The formation is named after Iguape, São Paulo.

Description

The Iguape Formation is 1,103 to 2,200 metres (3,619 to 7,218 ft) thick, and consists of bioclastic calcarenites and calcirudites, containing bryozoa, echinoids, corals, foraminifera, fragmented shells, and algae remains. They are interbedded with grey-greenish clays, siltstones, marls and variegated grey fine-to-medium grained conglomerates. These facies are interbedded with and change laterally to the Marambaia Formation. The depositional environment is thought to be a marine carbonate platform, influenced by the arrival of alluvial clastics in the most proximal areas. Biostratigraphic data from planktonic foraminifera, calcareous nannofossils and palynomorphs indicate a Tertiary age. Carbonate production rates of the formation have been estimated at 50 to 55 metres (164 to 180 ft) per million years.

See also

• Campos Basin