Abstract: Based on the evolution of the tectonic plate and pregeography，the passive continental margin basins on the east
coasts of Brazil experienced three prototype phases. Berremian intracontinental rift megasequence in lower cretaceous，comprising
lacustrine sediments overlying Neocomian basalts，Aptian intercontinental rift basin，in which the laqoon transitional
megasequence deposited，including two sedimentary units：the lower，mostly composed by carbonate and the upper represented
by halite，and the drift phase，passive continental margin basin from Albian until the present-day，deposited with the marine
megasequence. The Lower Cretaceous lacustrine calcareous black shale is the main source rocks of the giant oil and gas fields.
The reservoirs include two sects：lower laqoon carbonatea nd upper，Tertiary and Cretaceous turbidites. The carbonate reservoirs
is sealed by halite，while the turbidites are preserved by marine shale. The lower Cretaceous lacustrine source rocks starts
to generate the oil and gas from Eocene-Miocene formed“double insurance”type models of giant oil and gas fields. If no
salt windows existing，hydrocarbons migrated vertically along faults and are trapped mainly in the pre-salt carbonates. If salt
windows exiting，hydrocarbons are accumulated in Upper Cretaceous-Tertiary turbidites which are packaged by marine facies
shale .

Key words: East coast of Brazil, passive continental margin basins, prototype basin, giant gas fields, model of hydrocarbonsaccumulation