The Ribeira Orogen (21°S - 26°S)
corresponds to the central segment of the
Mantiqueira Province.
It was formed towards the end of the neoproterozoic Brasiliano / Pan - African cycle
(prior to the opening of the South Atlantic) as part of the evolution of
Western Gondwana
(see
geology).
It can be divided in a
southern,
central and
northern
part.
This ancient mountain chain resulted from the closure of the Adamastor Ocean
by convergence of the
São Francisco
/ Congo (SFC) and (in part) Rio de la Plata (RP) cratons such as several smaller terranes
(Apiaí (A), Curitiba (C) or Juiz de Fora (JF)).
Similar to its northern neighbour, the
Araçuaí - Orogen, nowadays only
the precambrian basement (partly covered by sediments) and a variety of granitic intrusions (plutons)
have remained.
