The Paranapanema block is a coherent block of

lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the portion of the upper mantle that behaves elastically on time scales of up to thousands of years ...

located in southeastern South America spanning roughly the same area as the

Paraná Basin The Paraná Basin ( pt, Bacia do Paraná, es, Cuenca del Paraná) is a large cratonic sedimentary basin situated in the central-eastern part of South America. About 75% of its areal distribution occurs in Brazil, from Mato Grosso to Rio Grande ...

. The existence of a tectonically stable zone beneath the Paraná Basin was first suggested in 1975. Despite difficulties in accessing the buried Paranapanema block it is inferred it must be composed mostly of

orthogneiss Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures an ...

and that it existed before the

Brasiliano orogeny Brasiliano orogeny or Brasiliano cycle ( pt, Orogênese Brasiliana and ''Ciclo Brasiliano'') refers to a series of orogenies of Neoproterozoic age exposed chiefly in Brazil but also in other parts of South America. The Brasiliano orogeny is a regi ...

Description

Paranapanema is a triangular block surrounded by structures of the Neoproterozoic Brasiliano orogeny. The northwestern edge faces the Paraguai Belt, probably the remains of an

island arc Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle alo ...

from the Brazilides Ocean. On the northeast edge are the southern end of the Brasilia Belt and the Arenópolis magmatic arc. To the south and southeast are the Apiaí and São Roque belts. During the Carboniferous, Paranapanema was covered by sediments and during the Early Cretaceous, the Paraná-Etendeka

large igneous province A large igneous province (LIP) is an extremely large accumulation of igneous rocks, including intrusive (sills, dikes) and extrusive (lava flows, tephra deposits), arising when magma travels through the crust towards the surface. The formation ...

added a layer of flood basalts before the South America-Africa breakup.

References

Bibliography

* * Cratons Geology of South America Geology of Argentina Geology of Brazil Geology of Paraguay Precambrian South America Historical tectonic plates {{geology-stub