The Iguape Formation ( pt, 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
Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...
,
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...
,
marl
Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae.
Marl makes up the lower part o ...
and
conglomerate
Conglomerate or conglomeration may refer to:
* Conglomerate (company)
* Conglomerate (geology)
* Conglomerate (mathematics)
In popular culture:
* The Conglomerate (American group), a production crew and musical group founded by Busta Rhymes
** Co ...
formation dates to the
Tertiary period and has a maximum thickness of .
Etymology
The formation is named after
Iguape, São Paulo.
Description
The Iguape Formation is thick,
[Kiang Chang et al., 2008, p.32] and consists of
bioclast
Bioclasts are skeletal fossil fragments of once living marine or land organisms that are found in sedimentary rocks laid down in a marine environment—especially limestone varieties around the globe. some of which take on distinct textures and col ...
ic
calcarenites and calcirudites, containing
bryozoa,
echinoids,
corals,
foraminifera, fragmented shells, and
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
remains. They are interbedded with grey-greenish clays,
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980, p ...
s,
marl
Marl is an earthy material rich in carbonate minerals, clays, and silt. When hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae.
Marl makes up the lower part o ...
s and variegated grey fine-to-medium grained
conglomerates. These facies are interbedded with and change laterally to the
Marambaia Formation
The Marambaia Formation ( pt, Formacão Marambaia) is a geological formation of the Santos Basin offshore of the Brazilian states of Rio de Janeiro, São Paulo, Paraná and Santa Catarina. The predominantly shale and marl formation dates to ...
. 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
Calcareous nannofossils are a class of tiny (less than 30 microns in diameter) microfossils that are similar to coccoliths deposited by the modern-day coccolithophores. The nannofossils are a convenient source of geochronological data due to the ...
and
palynomorphs indicate a Tertiary age.
[Clemente, 2013, p.24] Carbonate production rates of the formation have been estimated at per million years.
[Contreras, 2011, p.107]
See also
*
Campos Basin
The Campos Basin is one of 12 coastal sedimentary basins of Brazil. It spans both onshore and offshore parts of the South Atlantic with the onshore part located near Rio de Janeiro. The basin originated in Neocomian stage of the Cretaceous period ...
References
Bibliography
*
*
* {{cite LSA , last=Kiang Chang , first=Hung , last2=Assine , first2=Mario Luis , last3=Santos Corrêa , first3=Fernando , last4=Setsuo Tinen , first4=Julio , last5=Campane Vidal , first5=Alexandre , last6=Koike , first6=Luzia , year=2008 , title=Sistemas petrolíferos e modelos de acumulação de hidrocarbonetos na Bacia de Santos , url=http://geomuseu.ist.utl.pt/GSP2012/GSP2009/Casos%20de%20estudo%20SP/GSP%20Bacia%20Santos.pdf , journal=
Revista Brasileira de Geociências , volume=38 , pages=29–46 , accessdate=2017-09-04
Geologic formations of Brazil
Santos Basin
Neogene Brazil
Paleogene Brazil
Neogene System of South America
Paleogene System of South America
Limestone formations
Sandstone formations
Siltstone formations
Shale formations
Marl formations
Conglomerate formations
Alluvial deposits
Shallow marine deposits
Formations
Formations
Formations
Formations
Tupi–Guarani languages