Geologically, Serra do Mar forms part of a microplate of the same name which is
embedded into the crystalline core of the central segment of the
Ribeira Orogen
(
Mantiqueira Province).
This orogen developped around 600 million years ago
(
Neoproterozoic),
during the so - called Brasiliano / Pan - African orogenic cycle
and results from the closure of the Adamastor Ocean and subsequent
interaction (collision) between the São Francisco Craton and the southwestern part
of the Congo Craton
(see
geology).
It is believed that due to magmatic events during the late
Cretaceous / early Jurassic (80 - 60 Ma), former precambrian faults along Brazil´s
southeastern coastline were reactivated.
Continental rifting at that time led to the uplift of the
Serra do Mar and
Serra da Mantiqueira
mountain ranges while the adjacent oceanic margin (Santos Basin)
was downdropped. Serra do Mar´s magnificent escarpments with difficult access beware
today some of the largest continuous remnants of
submontane and
montane
tropical rainforest
in the state of São Paulo.
