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Geological Travel

Brasiliano - Pan African Cycle

Brazil Tours / Trekking – The Neoproterozoic Brasiliano - Pan African cycle (850 - 500 Ma) describes the assembly of West Gondwana from the break - up of supercontinent Rodinia / Pannotia to the closure of all oceanic basins, over a series of subduction and collisional events up to its final fusion / agglutination.

At the end of this orogenic cycle, a large continuous landmass was formed, comprising the protoypes of South America (the so-called South American Platform) and Africa prior to the opening of the South Atlantic.

During the divergent stage of this cycle, Rodinia break - up into different pieces which drifted away from each other. The open spaces inbetween these fragments were filled with oceans. One of those fragments, the São Francisco - Congo craton (descendant of 2 Ga supercontinent Atlantica) was surrounded by the Pharusian - Borborema Ocean to the north, the Goianides Ocean to the southwest and the Adamastor Ocean to the southeast.

During the convergent stage of this cycle, subduction gave rise to magmatic arc suites and was followed by arc - continent and continent - continent collisions which resulted in the closure of these oceans and the docking / amalgation of a number of tectonic blocks and orogenic belts to the border of the craton. The Atlantic Shield was formed.

For descriptive purposes, the orogenic belts around the São Francisco - Congo craton (on the Brazilian side) were divided into 3 geotectonic provinces: Borborema (Northeast), Tocantins (Centraleast) and Mantiqueira Province (East - Southeast). The Mantiqueira Province is composed of the orogens: Araçuaí in the north Ribeira (northern, central and southern segment) in the center and the Dom Feliciano orogen in the south.

The Neoproterozoic geological evolution of the Atlantic Rainforest / (Mata Atlântica) region in southern Bahia / Espírito Santo (Discovery Coast), Rio de Janeiro and São Paulo / Paraná (South-East Reserves) is recorded in the crystalline core and mobile fold belts of the Araçuaí and Ribeira orogen.

In the course of the Brasiliano / Pan - African orogeny, granitic magmatism in the coastal crystalline core of these two orogens took place. Molten rock (magma) intruded into the Earth's crust, where it slowly cooled, solified and crystallized, forming ingeous rock. As this happened below the surface, these rocks are called intrusive or plutonic rocks (e.g. granite). As the orogeny continued, high - pressure and high temperature metamorphism altered the granite into metamorphic rock (e.g. gneiss).

Over time, the topographic surface expression (volcanoes) of the Brasiliano / Pan - African orogens eroded away and only the deep roots of the mountains remained as a series of belts of igneous and metamorphic rock that outcrop in Southeast and South Brazil. Some of the most famous granite and gneiss outcrops are the Marumbi massif in Paraná, the Cantareira batholith in the State of São Paulo, the Sugarloaf Mountain (Pão de Açucar) and Corcovado in Rio de Janeiro / Tijuca National Park or the rock formations related to the Serra dos Órgãos – Geotravel & tours / Brazil.