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 145–130 million years ago during the breakup of Gondwana. It has a total area of about 115,000 square kilometres (44,000 sq mi), with the onshore portion small at only 500 square kilometres (190 sq mi).