Tectonic evolution of the Ubarana area, offshore portion of the Potiguar Basin

Abstract

Loeated at the eastemmost tip of Brazil, the Potiguar Basin is an intraeontinental rift formed at the interseetion of the Equatorial and East Brazilian Margins. Seismie and well data were used to develop an evolutionary model for the offshore portion of this basin, near the Ubarana oil field. The rift was formed in the Early Cretaceours (Neocomian), in response to WNW-ESE regional extension. Inthe studied area a transfer zone (the Ubarana Transfer Zone) was reeognized, whieh aeeommodated a polarity reversal of the rift fau/ts. The Potiguar Basin was subjeeted to further teetonie aetivity during the Middle Campanian, in the post-rift stage, when transtensional stresses, aeting on the former Ubarana Transfer Zone, ereated the Ubarana Transeurrent Zone, generating folds and strike-slip faults with small right-Iateral displaeement. During the Tertiary, the Potiguar Basin was subjeeted to E-W eompressional stresses, when long wavelength folds were generated with N-S trending axes.