326 BRAZIL Neocomian to Early Aptian rift-stage deposits consist of basalts and continental siliciclastics, deposited in depocentres controlled by normal faulting in alluvial, fluvial, deltaic, and lacustrine environments The Aptian transitional proto-oceanic supersequence, characterized by low subsidence rates, marks the incursion of marine waters into the basin system, and comprises coastal to shallow-marine carbonates and mudstones and thick evaporites (Figures 16 and 17) Salt was deposited in the central segment of the eastern margin (from the Santos to the SergipeAlagoas basins; Figure 11) in an evaporative basin created by a volcanic barrier, the Walvis–Sa˜ o Paulo Ridge (Figure 18) The first-order drift package comprises an Albian– Cenomanian retrogradational transgressive supersequence, a Cenomanian–Turonian maximum flooding interval, and a Late Cretaceous–Holocene progradational regressive supersequence Whereas the transgressive supersequence is mostly carbonate, the regressive supersequence comprises unconformitybounded third-order depositional sequences of turbidite-prone lowstand systems tracts and siliciclastic or, subordinately, mixed-carbonate transgressive highstand systems tracts (Figure 17) Salt tectonics (deformational structures in response to gravity driving motion of salt layers) controlled the sediment bypass and the main depocentres, as well as the architecture of the drift package (Figure 16) The Campos Basin in the southern segment of the eastern margin (Figure 11) contains approximately 85% of the recoverable hydrocarbon reserves in Brazil, forming together with the adjacent Santos and Espirito Santo basins the most prolific oil province of Brazil Equatorial margin basins The Brazilian equatorial margin evolved in four tectonosedimentary stages (Figures 19, 20 and 21): Neocomian interior rift; Aptian transtensional rift; Albian wrench; and Cenomanian– Holocene drift with wrench reactivations Figure 21 Schematic geological sections through the Brazilian equatorial margin (A) Barreirinhas and (B) Poriguar offshore basins Modified from the Brazilian Petroleum Agency (Ageˆncia National Petroleo, ANP) home page at www.anp.gov.br