brasil geologia ecoturismo geoturismo turismo geológico Pré - Cambriano brasil geología geoturismo turismo geológico Precambrico brasilien geologie reise reisen urlaub Präkambrium

Geology of Brazil

Precambrian (4,5 Ga - 542 Ma)

Geological Travel / Brazil – The Precambrian describes the time - span from the formation of earth about 4,5 billion years (Ga) ago to the evolution of abundant macroscopic hard - shelled fossils, which marked the beginning of the Cambrian, about 542 million years (Ma) ago. It is divided into the eons Hadean (4,5 - 3,8 Ga), Arquean (3,8 - 2,5 Ga) and Proterozoic (2,5 Ga - 542 Ma).

At the end of this age, the prototypes of South America (the South American Platform) and Africa were formed. At the end of the Brasiliano - Pan African orogenic cycle both constitute the western part of supercontinent Gondwana.

During the Precambrian, the first primeval life - forms, so - called stromatolites were formed. These microorganisms were responsible for the atmosphere's oxygen which they created by photosynthesis out of the sunlight. The oldest fossilized stromatolites (3,5 Ga) were found recently in the Warrawoona Group, in Australia. In 1944, Collenia itapevensis, the first South American fossil of proven Precambrian age, was found in the carbonatic rocks of the Itaioca Group at Serra de Paranapiacaba (São Paulo State) – Ecotravel & Tours / Brazil.