Geologia da área nordeste da Folha Poço da Cruz, Bacia de Jatobá, nordeste do Brasil

Abstract

The Jatobá Basin is located in the south-central portion of Pernambuco state and northern Bahiaand Alagoas, it has an area of approximately 5000 km² in a NE-SW preferred directionand sedimentary record has approximately 3 km. It is a rift basin developed under extensional tectonic events related to the rupture of the Gondwana supercontinent and it marks the northern limit of the aborted Recôncavo-Tucano-Jatobá rift system. The stratigraphic succession in the Campos district,Ibimirim (PE), comprises the Syneclise sequence and Rift Initiation sequence as well as part of the Rift Climax sequence of the basin. Using columnar sections and identifying sedimentary facies, six stratigraphic units were recognized, in addition to the quaternary coverage. The twolower fluvial-marine units are related to the siluro-devonian sedimentary records of the Syneclise sequence, while fluvial-eolic and lacustrine sediments of the upper units mark the Rift Initiation and Rift Climax sequences. The Aliança Formation, discussed in a particular way in this paper, represents the first sedimentary records of the beginning of the Neojurassic rift (Dom João stage). Since it was deposited in a lacustrine system, this formation has highly fossiliferous decimetric carbonate levels arranged in thick pelitic packages, suggesting deposition during times of energy variations within a shallow lake. The detailing of the stratigraphy of these deposits, associated with petrographic and paleontological studies, brings a new understanding of the depositional system that occurred in this environment and the first processes that started the opening of the rift during the Upper Jurassic.