Estudo Paleoambiental Preliminar Do Cretáceo Da Bacia Potiguar

Abstract

lntcgration c f micropaleontologieal information , based mainly on the study of foraminifers and palynomorph s from seven wells, led to the reeognition of th e paleoenvironm ental development of the Potíguar Basin from the Alagoas to the Maastriehtian. Seventeen bioestrat lgraphlcal zones and one subzone have been recognized. Seven episodes-four tr ansgressive and three regressive-could be dete cted between the Early-Middle Albian to th e Maastriehtian , and have been regarded as result from relative global fluctuatíons of the Cretaeeous sea level. A distinctive hiatu s of Late Albian age may be inferred from the absenee of diagnostie index fossils. Fine grained clastic sediments deposited duríng the Late Cenomanian and the Early Turonian show evidence of anoxia. This is assumed to be synchronous with similar events detected elsewhere in many Cretaeeous basins (including some in Braail). Carbo natie cycles have been found to oeeur in the Early-Mlddle Albian, Early-Middle Cenomanian, Turonian and ConiacianjSanto nian, each of th em being represent ed by shallow neritie palcoecological units wíth distinetive mierofaunal assemblages: Early-Middle Albian-Favuse/la spp., calcispherulíds association ; Ear1y-Middle Cenomanian-Trocholína spp. association ; Turonian-marine ostracods-gastropcd s-worrn tubes association ; Santonian-Buliminidae-8iphogenerínoídes spp.-Dinogy mn ium spp.•Deflandrea spp. association.

Gravity and magnetic joint modeling of the Potiguar Rift Basin (NE Brazil): Basement control during Neocomian extension and deformation

“…During the Aptian, the extensional efforts jumped eastwards, leaving an aborted continental rift system in NE Brazil. A subsequent thermal subsidence occurred, allowing the deposition of a transitional unit (Alagamar Formation) that was covered with siliciclastic (Açu Formation) and carbonate (Jandaíra Formation) drift sequences (Tibana and Terra, 1981;Viviers and Regali, 1987;Bertani et al, 1990). The boundary between the siliciclastic and carbonate sequences is well recorded in the local topography (SDS/CDS in Fig.…”

Stratigraphic evolution from the early Albian to late Campanian of the Potiguar Basin, Northeast Brazil: An approach in seismic scale

“…The Potiguar Basin's biostratigraphic zonation is based on the integration of different data types, including palynomorphs, foraminifera and nanofossils, and on the correlation with other sections of the Atlantic Margin, which facilitates the interpretation of transgressive/regressive events and depositional hiatus (Beurlen, ; Regaliet al, ; Viviers & Beurlen, ). Regali and Gonzaga () defined a biostratigraphic palynological framework specific for the Potiguar Basin, which was later updated and has been used frequently by other studies as an age reference (Córdoba, ; Gil, ; Lana, ; Viviers & Regali, ). The Aptian Age is represented by Palynozone 270 (P‐270), which is useful for the interpretation of post‐rift deposits of the Alagamar Formation.…”

“…However, even after such efforts, the Potiguar Basin does not have a complete chronostratigraphic framework for the early Albian to late Campanian interval, the most important interval currently in terms of oil production. Depositional sequences in this interval, as described in the most recent Potiguar Basin stratigraphic chart (Pessoa Neto et al, ), are based on depositional hiatuses defined in biostratigraphic studies (Beurlen, ; Regali & Gonzaga, ; RegaliUesugui & Santos, ; Viviers & Beurlen, ; Viviers & Regali, ), in which systems tracts are not defined and the relationship with lithostratigraphic units is not well‐understood. Lithostratigraphic units are still used in seismic interpretations and regional correlations, typically resulting in horizons, maps and geological models that are not representative of the temporal and spatial relations of production zones.…”

Stratigraphic analysis of the marine cretaceous in the eastern margin of Portiguar Basin

“…), and fme/medium grained with Bouma sequence eo-Turonian: their limestones and shales show a gradation from lagoonallshallowneritic in Macau High area to deep neritic/bathyal in Ubarana area. These latter environrnents are represented by a fauna of hedbergelliform planktonic foraminifers and absence of benthic forms (Zone Whiteinella brittonensis , Viviers & Regali 1987), attesting an anaerobic bottom that can be correlated with an anoxic event of same age in the Atlantic region. The isopach map of sequence V, together with the paleoenvironrnental map of Santonian ( Fig.…”