Jatoba Basin Research Articles

The geometry, sedimentary filling and depth estimate of the Mirandiba Basin, Pernambuco, Brazil: new insights about the depositional regional gap of rift phases in the interior basins

The Mirandiba Basin has a well-defined stratigraphic sequence and its sedimentation may be directly correlated with the Jatoba Basin and some other interior basins. The sedimentation began in intracratonic conditions with a Paleozoic sequence (Tacaratu/Inaja Formations), which acted as a substrate without any genetic relationship with the basin. The fluvial Tacaratu Formation emerges beyond the limits of this basin, where a remnant core named here as Poco do Ico was found wrapped around the basement to the west of the basin. Subsequently, there was a deposition in a shallow marine environment of the Inaja Formation (Devonian) formed by the intercalation of clay/siltstones and sandstones with ichnofossils. Pre-rift sedimentation occurs over the Paleozoic sequence, characterized in the basin by the lacustrine sediments of the Alianca Formation, represented by the intercalation of shales and calcarenites with desiccation cracks and fossil fragments. In spite of depositional gap described between the local Aratu and Alagoas Stages, the presence of Salvador Formation close to the north border fault may represent a rare rift phase record in the interior basins. The post-rift sequence is represented by the Marizal Formation, deposited during the Aptian. This formation is distinguished by the intercalation of fine sandstone, siltstone and conglomerate deposited in an alluvial fan environment. The pre-rift, rift and post-rift sedimentation are embedded in the depocenter of the basin, where the main NE-SWgraben stands out. A gravity survey was carried out, which obtained a negative, asymmetric Bouguer anomaly, with gradients added to the northwest, suggesting the existence of a half-graben. The result of the gravity 3D model indicates the existence of a main depocenter in the NE-SW direction with depths of up to 400 meters. These geophysical results support the tubular well location drilled 410 m in depth that was used in this work to better characterize the basin. The joint interpretation of gravity, aeromagnetic and structural data suggest that the half-graben framework of the basin developed by the evolution of a pull-apart extension system. The structural system that gave rise to the Mirandiba Basin has the maximum compression tensioner oriented to NE-SW and the distention to NW-SE. It has a depth of around 400 meters and the depressions formed by tectonic events were filled by Post-Tacaratu sedimentation.

CARACTERIZAÇÃO GEOLÓGICA E ESTRATIGRÁFICA DA REGIÃO A NORTE DE INAJÁ (PE), BACIA DE JATOBÁ, NORDESTE DO BRASIL

Neste trabalho são apresentados os resultados do mapeamento geológico na escala 1:50.000 de uma área de 100 km2 na Bacia de Jatobá, ao norte do município de Inajá, interior do estado de Pernambuco, Nordeste do Brasil. As unidades estratigráficas possuem grande similaridade litológica, demandando a realização de estudos detalhados para sua distinção. As análises petrográficas permitiram o acompanhamento das transições litológicas e granulométricas dos sistemas deposicionais que configuram as fases sinéclise, início e clímax de rifte. Os estudos bioestratigráficos possibilitaram a identificação de seis biozonas de ostracodes para a bacia estudada: RT-001 (Formação Aliança), RT-003 (Formação Candeias) e RT-004 a RT-007 (Grupo Ilhas), determinando o posicionamento biocronoestratigráfico das unidades com base em ostracodes não-marinhos nos andares Dom João (Tithoniano), Rio da Serra (Berriasiano-Hauteriviano), Aratu (Hauteriviano-Eobarremiano) e Buracica (Barremiano). Os dados obtidos resultaram na atualização da carta estratigráfica da Bacia de Jatobá.

Paleolimnological reconstruction of a marginal area of Jurassic Capianga Lake, Jatobá Basin, northeast Brazil

The Alianca Formation, within the Brazilian Reconcavo–Tucano–Jatoba Rift System, is a succession of Late Jurassic sedimentary rocks that record the maximum flooding surface of shallow Capianga Lake in the Afro-Brazilian Depression, Gondwana. Several aulacogens and drift-marginal Mesozoic basins of eastern Brazil and western Africa recorded the great extensional event that occurred during the early stage of Gondwana break-up. Lithologic, petrographic, micropaleontological and geochemical analyses of lacustrine carbonates collected near the city of Ibimirim, Pernambuco State, were carried out to establish the paleolimnological evolution of a marginal area of Capianga Lake, in the Jatoba Basin. The ostracode fauna, obtained from grainstone and calcareous quartzarenite, is constituted by Theriosynoecum pricei, Theriosynoecum uninodosa, Theriosynoecum quadrinodosum, Reconcavona? jatobaensis and Alicenula? spp. Carbon and oxygen stable isotopes in bulk rock, Theriosynoecum pricei and Alicenula? spp. were measured. Theriosynoecum pricei displays the most negative δ13C values, between − 2.1 and − 1.3‰. The δ13C values obtained from Alicenula? spp. and bulk rock were also negative. The δ18O values for Theriosynoecum pricei range from − 10.1 to + 4.1‰. Alicenula? spp. show δ18O values between − 4.6 and + 5.8‰. The bioclastic character of the carbonates and the presence of cross-bedding and ripple marks suggest deposition in a low-energy, low-gradient, ramp-type littoral zone of a shallow, balanced-fill lake. The ostracode association, characteristic of permanent, alkaline, freshwater bodies, corresponds to the Theriosynoecum pricei ostracode biozone, which is of Tithonian age. The lithofacies, along with covariation of δ13C and δ18O, and large δ18O fluctuations, suggest that this marginal area of Capianga Lake was characterized by stable hydrological conditions in a closed basin. The δ13C values display a slightly narrower range, suggesting oligotrophic to slightly mesotrophic conditions, and holomixis in this marginal area of Capianga Lake.

A history of basin inversion, scarp retreat and shallow denudation: The Araripe basin as a keystone for understanding long-term landscape evolution in NE Brazil

At the border between the states of Ceará and Pernambuco (northeast Brazil), the Chapada do Araripe is a high plateau (800–1000ma.s.l.) formed by a slab of Cenomanian fluvial sandstone. This caprock is underlain by lacustrine or marine Albian layers and older rift deposits. During the Cretaceous, the Araripe basin lay at a palaeoelevation close to sea-level. Through a presentation and discussion of original field and cartographic data we analyse the mechanisms of topographic inversion in this sedimentary basin in relation to local or regional crustal upwarp. The contrast between the plateau — a weakly dissected structural surface — and the surrounding lowlands is explained through a study of the erosional scarps — cuesta-like landforms and their outliers — that fringe the Chapada. No evidence of local tectonic inversion is found. River incision, spring sapping, landslides and other forms of mass movement are listed as efficient processes of topographic inversion and scarp retreat, the rates and patterns of which appear to be controlled by lithological contrasts and conditions of exhumation of the basement. Geometric relationships with regional stepped surfaces (e.g., the low-elevation Sertaneja Surface), exhumed palaeosurfaces and regional drainage systems are analysed. Our estimation of the amplitude of denudation and topographic inversion (0.6–0.7km) differs significantly from apatite fission-track-derived estimates reported in recent literature, which would imply burial by considerable thicknesses of younger sediments followed by 1.5km or more of post-rift denudation — not just in the study area, but also in the Tucano–Jatoba basin to the south. The exhumation and reworking of surrounding basement surfaces probably began during the early Cenozoic, as shown to the northwest of the Chapada by the presence of widespread laterites of probable Palaeogene age. A second stage of topographic inversion occurred during the Oligocene or later. This would correspond to the major stages of river incision, partial planation and basin inversion.

Deep structure of a stretched lithosphere: Magnetotelluric imaging of the southeastern Borborema province, NE Brazil

Abstract Magnetotelluric data were collected at 25 stations along a NNW–SSE linear profile deployed perpendicularly to the main structures in the southeastern portion of the Borborema province, northeast Brazil. The geotectonic scenario is characterized by a broad range of tectomagmatic events including periods of compressive tectonism associated with amalgamation of lithospheric blocks during the Brasiliano orogeny in the Late Neoproterozoic, superimposed by extensional events related to the continental break-up and plate drift that led to the formation of the southern Atlantic Ocean in the Early Cretaceous. Strike analysis and distortion decomposition show that most of the data are two-dimensional (2D) but sensitive to distant off-profile structures. Data fit an ENE regional geoelectric strike direction, consistent with the geological and tectonic setup. A joint 2D inversion of the TE and TM modes defined by this strike direction was undertaken and the obtained model exhibits signatures of the different tectonic events in the area. The model suggests that the SE Borborema province is electrically separated into two parts. The first, comprising the southern domain of the province (Sergipano belt and Pernambuco–Alagoas block), has a highly heterogeneous crust and an anomalously conductive upper mantle. The second, comprising the transversal domain of the province (Alto Moxoto terrain), displays crust and upper mantle predominantly homogeneous and resistive. A deep Neoproterozoic lithospheric shear zone (Pernambuco lineament) marks the limit between the two contrasting domains. Also, the region where the Jatoba basin is located in the southern domain presents a striking conductor at upper- to mid-crustal depths beneath the basin. These results correlate well with seismic refraction data that indicate thicker crust for the transversal domain than for the southern domain, with the thinnest crust coinciding with the location of the Jatoba basin. The data support the conclusion that the lithosphere of the southern domain of the Borborema province was significantly stretched in the Cretaceous during the opening of the South Atlantic Ocean, allowing refertilization of depleted upper mantle with incompatible elements from enriched deeper mantle material and reactivation of older crustal fabrics. The conductivity increase below the Jatoba basin is associated with ionic conduction in a currently reactivated fracture zone filled with high salinity fluid. Apparently, the Alto Moxoto terrain worked as a region of higher resistance to stretching, causing the crustal thinning and geoelectric effects to be concentrated to the south of the Pernambuco lineament.

Revision of silurian and devonian strata of Brazil

Abstract The Silurian and Devonian stratigraphy of Brazil has been revised and refined with the help of available data on shelly fossils, spores, graptolites and chitinozoans. The Silurian sedimentation can be divided into four depositional cycles: (1) early ‐ middle Llandovery, (2) late Llandovery‐earliest Wenlock, (3) late Wenlock‐early Ludlow, and (4) late Ludlow‐earliest Pridoli. All four cycles are present in the Amazonas, Parnaiba and probably Jatoba basins, whereas only the two youngest occur in the Solimoes Basin. The oldest cycle constitutes the Silurian beds of the Parana Basin. Glaciations occurred in the Amazonas, Parnaiba and Jatoba basins during middle and late Llandovery. Early Lochkovian beds are widespread in all of these basins, while late Lochkovian‐Pragian beds are known only from the Parana Basin. The chitinozoan faunas in the Silurian‐lower Lochkovian show a striking similarity to those from Florida and north Gondwana. Emsian beds are absent in the Solimoes and Jatoba basins, but pre...

The Onshore Northeast Brazilian Rift Basins: An Early Neocomian Aborted Rift System: ABSTRACT

Early Cretaceous rift basins of northeastern Brazil illustrate key three-dimensional geometries of intracontinental rift systems, controlled mainly by the basement structures. These basins were formed and then abandoned during the early extension associated with the north-south-propagating separation of South America and Africa. During the early Neocomian, extensional deformation jumped from the easternmost basins (group 1: Sergipe Alagoas and Gabon basins; group 2: Reconcavo, Tucano, and Jatoba basins) to the west, forming a series of northeast-trending intracratonic basins (group 3: Araripe, Rio do Peixe, Iguatu, Malhada Vermelha, Lima Campos, and Potiguar basins). The intracratonic basins of groups 2 and 3 consist of asymmetric half-grabens separated by basement highs, transfer faults, and/or accommodation zones. These basins are typically a few tens of kilometers wide and trend northeast-southwest, roughly perpendicular to the main extension direction during the early Neocomian. Preexisting upper crustal weakness zones, like the dominantly northeast-southwest-trending shear zones of the Brazilian orogeny, controlled the development of intracrustal listric normal faults. Internal transverse structures such as transfer faults (Reconcavo basin and onshore Potiguar basin) and accommodation zones (onshore Potiguar basin and Araripe basin) were also controlled by the local basement structural framework. Transverse megafaults and lithostructural associations controlled the three main riftmore » trends. The megashear zones of Pernanbuco (Brazil)-Ngaundere (Africa) apparently behaved like a huge accommodation zone, balancing extensional deformation along the Reconcavo-Jatoba/Sergipe Alagoas-Gabon trends with simultaneous extension along the Araripe-Potiguar trend. The Sergipe Alagoas-Gabon trend and the Potiguar basin represent the site of continued evolution into a marginal open basin following early Neocomian deformation.« less

A NEW APPROACH TO THE GEOLOGICAL CONFIGURATION OF THE LOWER CRETACEOUS TUCANO AND JATOBÁ BASINS, NORTHEASTERN BRAZIL

Until recently, the Lower Cretaceous Reconcavo-Tucano-Jatoba Rift was interpreted as being a system of basins connected since the beginning of rifting and filled by a fluvio-deltaic-lacustrine system which prograded from north to south. In this work, based on field observations, gravity data, new models for the evolution of continental rifts, and comparison with the East African rifts, the basins are interpreted as a series of half-grabens with disconnected depocenters, and which evolved separately. The isolation was effected by transfer faults - the Itapicuru and Vaza-Barris faults - which cut the rift in a NW-SE direction and are, principally the Vaza-Barris fault, controlled by basement anisotropy. According to this model, the majority of drilled wells were located on stable platforms, without suitable conditions to generate hydrocarbons, and thus the Tucano and Jatoba basins are not adequately explored.

Role of Fault Rejuvenation in Hydrocarbon Accumulation and Structural Evolution of Reconcavo Basin, Northeastern Brazil

From a geometric analysis of the fault pattern in the Reconcavo basin, Brazil, supported by a reinterpretation of the early opening history of the South Atlantic Ocean, it is inferred that the basin formed as a result of Valanginian (Early Cretaceous) motion on a major N40°E-striking left-lateral transform fault located offshore between Salvador and Recife. This left-lateral motion was due to the location of the Valanginian pole of South American-African plate rotation within northern Brazil, at 2.5°S, 45.0°W, rather than farther north as interpreted previously. Left-lateral movement along the inferred transform created three fault sets: (1) a predominant set striking N30°E ± 20° (1^sgr); and two lesser developed sets striking (2) N13°W ± 6° and (3) N37°W ± 12° (1^sgr). Sets (1) and (3) are interpreted, respectively, as Riedel and conjugate Riedel shears (with an extensional component) to the N40°E-trending left-lateral transform fault. Set (2) formed as an extensional fault system. Intersections of these three sets subdivide the basin into triangular and diamond-shaped blocks. The Reconcavo basin continues northward in northeastern Brazil into the Tucano and Jatoba basins. These basins collectively form a north-south-trending, mega half-graben within continental crust. Geohistory curves for Early Cretaceous units in the Reconcavo basin indicate that the syn-tectonic Valanginian shales of the lacustrine Candeias Formation began to generate hydrocarbons during the earliest subsequent deposition of the Ilhas Formation (?Hauterivian). Because diamond-shaped structural traps had formed earlier during the Valanginian, hydrocarbons generated in the Candeias Formation are believed to have then migrated into the Sergi Formation (?Upper Jurassic) reservoir units in structurally juxtaposed fault blocks. During Barremian to Aptian time, deposition of fluvial, lacustrine, and alluvial sediments of the Ilhas and Sao Sebastiao Formations occurred. Rejuvenation as normal faults of earlier formed strike-slip and normal faults occurred in the latest Aptian (106 Ma) when the pole of South American-African plate rotations jumped to 41.3°N, 43.8°W. This pole jump caused extension along the previously formed transform margin between Salvador and Recife and the abandonment of rifting in the Reconcavo basin. Rejuvenated faults tapped earlier filled Sergi Formation reservoirs, which then leaked earlier reservoired hydrocarbons up these fault planes into higher reservoirs in the Ilhas and Sao Sebastiao Formations. This structural history thus explains the frequency distribution and orientation of faults in the basin, Sergi Formation production from corners of diamond-shaped fault blocks, and production from stratigraphically and structurally higher reservoirs (Ilhas and Sao Sebastiao Formations) in rollover folds and stratigraphic traps charged by second-phase faulting.

OCORRÊNCIA DE PALINOMORFOS EM SEDIMENTOS PALEOZÓICOS DA BACIA DE JATOBÁ (PERNAMBUCO)

The palynological analysis of Paleozoic sediments of 2-IMst-l-PE (Ibimirim-Pernambuco, Jatoba Basin) well, yielded microfossils such Ancyrospora cf. ancyrea, Hystricosporites corystus, Maranhites brasiliensis, Reticulatisporites spp., Hymenozonotriletes lepidophytus, Knoxisporites spp and Tholisporites sp. This association characterize the Upper Devonian (Strunian) and Lower Carboniferous (Tournaisian/Visean) to the interval studied. On the Devonian sediments of Ibimirim well, were found a great amount of the genus Maranhites and Tasmanites which are normally associated with reducing conditions and sediments rich on radioative elements like uranium and radium. The Devonian microfossils forms characterize marine conditions; on the Carboniferous section there are not evidences of the depositional environment. The paper presents illustrations of the sporomorphs acompanied by correlation with Carboniferous and Devonian sediments from the Mac Mahon Basin (Algerian Sahara) and comparison with the Devonian from the Parana Basin.