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O estudo das partículas biogênicas dos sedimentos de fundo da Baía de Todos os Santos (BTS) foi realizado com o objetivo de investigar as biofácies como um instrumento de caracterização do ambiente sedimentar da baía. Através da análise... more
O estudo das partículas biogênicas dos sedimentos de fundo da Baía de Todos os Santos (BTS) foi realizado com o objetivo de investigar as biofácies como um instrumento de caracterização do ambiente sedimentar da baía. Através da análise de agrupamento foi possível estabelecer quatro biofácies bem definidas. Estas biofácies permitiram verificar uma transição da composição biogênica do interior da BTS onde, na maioria das vezes, os moluscos predominaram nos sedimentos, em relação à plataforma continental adjacente, onde as algas calcárias passaram a ser o componente principal. Com base nas características composicionais foi possível classificar a maior parte das assembleias biogênicas como parautóctones, ou seja, aquelas que não são transportadas para longe de seu hábitat original. Foi possível constatar que os processos tafonômicos registrados são o reflexo das condições ambientais da baía, um ambiente semi-fechado, apresentando geralmente energia baixa a moderada e uma grande divers...
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O objetivo deste trabalho foi verificar como as familias de Polychaeta, que ocorrem na Laguna Principal do Canal do Parapuca, se relacionam com este ambiente. Foram amostrados 6.236 individuos distribuidos em 18 familias, das quais... more
O objetivo deste trabalho foi verificar como as familias de Polychaeta, que ocorrem na Laguna Principal do Canal do Parapuca, se relacionam com este ambiente. Foram amostrados 6.236 individuos distribuidos em 18 familias, das quais Spionidae e Capitellidae foram as mais abundantes. Nao foi encontrada variabilidade temporal para a densidade total desta taxocenose e ambos os periodos sazonais apresentaram baixo numero de familias constantes, sendo a maioria consumidora de depositos de superficie. A diversidade da area foi considerada moderada. Observou-se que a area de estudo apresenta quatro regioes para cada periodo sazonal, com caracteristicas bioticas e abioticas distintas. Periodo chuvoso – Associacao 1: com elevada abundância de Spionidae e Capitellidae, alem de elevados niveis de MO e CaCO 3 ; Associacao 2: elevada abundância de Spionidae e Capitellidae e valores intermediarios de MO e CaCO 3; Associacao 3: elevados niveis de salinidade e pH e ausencia marcante de grupos oportu...
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This paper presents an environmental vulnerabillity map for the Belmonte and Canavieiras municipalities, southern littoral of Bahia state. During the last two decades economic activity related to silviculture, aquaculture and tourism... more
This paper presents an environmental vulnerabillity map for the Belmonte and Canavieiras municipalities, southern littoral of Bahia state. During the last two decades economic activity related to silviculture, aquaculture and tourism expanded in this region occupying an ever increasing area of lands with varied degrees of vulnerability, thus causing degradation of ecosystems. In this research we derived environmental vulnerability indices though the integration of geological characteristics (age and degree of induration), soils types, terrain slope, and land use and cover. To each of the different features mapped weights were attributed ranging from 1 (least vulnerable) to 5 (most vulnerable). Algebraic manipulation of the different maps was carried out in a Geographic Information System (GIS) environment in a 1:100.000 scale. The final raster product was re-classified into 5 vulnerability classes: low, low to medium, medium, high and very high vulnerability. The very high vulnerabi...
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As Bacias de Camamú e Sul do Recôncavo localizam-se nas proximidades da margem continental passiva do estado daBahia e possuem elevado potencial para a exploração de hidrocarbonetos. Estruturas rúpteis e dúcteis foram estudadas em ambas e... more
As Bacias de Camamú e Sul do Recôncavo localizam-se nas proximidades da margem continental passiva do estado daBahia e possuem elevado potencial para a exploração de hidrocarbonetos. Estruturas rúpteis e dúcteis foram estudadas em ambas e em seus embasamentos e, a partir dessas, foram obtidas a orientação 3D dos tensores principais por métodos de inversão. Esse estudo evidenciou: (i) importante influência de heranças estruturais do embasamento nas suas construções, (ii) inversões locais de orientações de campos de tensão em regime transextensivo, (iii) presença de tensores máximos principais mais antigos verticais, típicos de ambientes extensionais, enquanto que os mais recentes são subhorizontais, típicos de ambientes transextensionais, (iv) presença local de regimes transpressivos, e (v) pelo menos quatro principais padrões de orientação do tensor máximo: um paralelo e outro ortogonal ao comprimento maior das bacias e dois diagonais. Nos últimos casos, os padrões paralelos e ortog...
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Abstract The Sao Francisco River is the fourth longest river in South America and one of the most regulated. Severe coastal erosion has affected the delta shoreline since 1985, leading to the complete destruction of Cabeco village between... more
Abstract The Sao Francisco River is the fourth longest river in South America and one of the most regulated. Severe coastal erosion has affected the delta shoreline since 1985, leading to the complete destruction of Cabeco village between 1997 and 1999. In this study, we mapped and radiocarbon dated the beach ridge sets occurring on the delta plain and performed a detailed analysis of the delta shoreline changes since 1960. During the Holocene, the delta plain construction was punctuated and took place during episodes of higher river discharges coincident with Bond events 4, 2 and 1 and periods of higher precipitation in the river basin, as reconstructed by δ18O measurements in cave speleothems. The last major episode of delta construction apparently ended at approximately 1.0 ka cal. BP. Since that time, riverine sediment input has been just sufficient to maintain the shoreline. A comparison of historical maps and aerial photographs showed that from 1853 to 1960, the shoreline at the river mouth remained in approximately the same position. A decrease in rainfall in combination with river regulation, particularly after 1985, triggered extensive erosion at the delta shoreline. This erosion was not caused by sediment retention behind the major dams but instead resulted from changes in the backwater/drawdown effects deriving from river regulation. Shoreline erosion mostly affected the river mouth. The mobilized sediments caused progradation of the downdrift shoreline. Updrift of the river mouth, the shoreline remained stable, as it had already reached an equilibrium orientation in which the net longshore transport was zero.
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The continental shelf off Salvador city faces the third largest metropolitan area of Brazil. It is also the narrowest shelf (8 km wide) in the entire Brazilian continental margin. The continental shelf off Salvador city (CCS) is... more
The continental shelf off Salvador city faces the third largest metropolitan area of Brazil. It is also the narrowest shelf (8 km wide) in the entire Brazilian continental margin. The continental shelf off Salvador city (CCS) is characterized by an uneven topography with high and low regions usually oriented obliquely to the shoreline. The circulation is tide and wind-driven. The bathymetric highs are made up of Mesozoic–Cenozoic rocks covered by a thin veneer of bioclastic gravels and sands, whereas at the intervening areas fine-grained sediments accumulate. Integration of previously collected biophysical data allowed the individualization of five geohabitats (channel, hard bottom, littoral sands, muddy bottom, and sand bank). The shelf area is used for domestic waste outfalls, disposal of dredged sediments from major port facilities of the Todos os Santos Bay, artisanal fisheries, and dive tourism. It also has archeological importance due to the presence of several shipwrecks. Bec...
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Previous studies on the mollusks from Brazilian underwater canyons have addressed the record and description of new species of aplacophorans, bivalves, scaphopods and/or gastropods (Leal... more
Previous studies on the mollusks from Brazilian underwater canyons have addressed the record and description of new species of aplacophorans, bivalves, scaphopods and/or gastropods (Leal & Simone 2000; Absalão 2010; Corrêa et al. 2014). Leal & Simone (2000) described a new bathyal gastropod of the family Pseudococculinidae collected from the continental slope and Doce River Canyon (960 m) off the state of Espírito Santo (southeastern Brazil). Absalão (2010) reported a number of species of gastropods, bivalves and scaphopods from Campos Basin off the state of Rio de Janeiro (southeastern Brazil). It is likely that some of these species reported by Absalão (2010) were collected from underwater canyons in the northern portion of the Campos Basin. Corrêa et al. (2014) recorded two species of aplacophorans of the genus Falcidens Salvini-Plawen, 1968 obtained from the continental slope and underwater canyons of Campos Basin. Certainly more species of mollusks were studied from Brazilian underwater canyons, but not duly mentioned in publications (i.e., the region of canyons may have been referred to as the continental slope or deep sea).
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Page 1. SEA-LEVEL HISTORY AND QUATERNARY EVOLUTION OF RIVER MOUTH-ASSOCIATED BEACH-RIDGE PLAINS ALONG THE EAST-SOUTHEAST BRAZILIAN COAST: A SUMMARY JOSE M. L. DOMINGUEZ' Universidade ...
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A zona costeira de Caravelas, situada no extremo sul da Bahia, apresenta ricos ecossistemas terrestres e aquáticos, incluindo o complexo recifal dos Abrolhos, considerado o mais importante do Atlântico Sul Ocidental. Visando contribuir... more
A zona costeira de Caravelas, situada no extremo sul da Bahia, apresenta ricos ecossistemas terrestres e aquáticos, incluindo o complexo recifal dos Abrolhos, considerado o mais importante do Atlântico Sul Ocidental. Visando contribuir para a manutenção da qualidade ambiental desta região, confeccionou-se um mapa geológico-geomorfológico onde foi possível a individualização das seguintes unidades: Tabuleiros, Terraços Arenosos Internos, Terraços Argilosos, Terraços Arenosos Externos, Brejos, Planícies de Maré/ Manguezais e Praias. As características destas unidades e os processos ativos limitam ou condicionam o uso e a ocupação humana, sendo desta forma de importância relevante para o planejamento ambiental. GEOLOGIC-GEOMORPHOLOGICAL INFORMATIONS AS SUBSIDIES FOR ENVIRONMENTAL ANALYSIS: THE EXAMPLE OF CARAVELAS COASTAL PLAIN − BAHIA Extended The coastal zone of Caravelas, located in the Southern part of Bahia State (figure 1), contains diverse and productive ecological systems, incl...
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This paper shows that the location of the shoreface bank reefs along the northeastern and eastern coasts of Brazil, in a first order approximation, seem to be controlled by the deficit of sediment in the coastal system. The sediment... more
This paper shows that the location of the shoreface bank reefs along the northeastern and eastern coasts of Brazil, in a first order approximation, seem to be controlled by the deficit of sediment in the coastal system. The sediment transport pattern defined by a numerical modeling of wave refraction diagrams, representing circa 2000 km of the northeastern and eastern coasts of Brazil, permitted the regional-scale reproduction of several drift cells of net longshore sediment transport. Those drift cells can reasonably explain the coastal sections that present sediment surplus or sediment deficit, which correspond, respectively, to regions where there is deposition and erosion or little/no deposition of sand. The sediment deficit allows the exposure and maintenance of rocky substrates to be free of sediment, a favorable condition for the fixation and development of coral larvae.
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By using the mean directions of the wave-fronts approaching the Brazilian northeastern coastal stretch comprised between the localities of Real river (Sergipe State) and Galinhos (Rio Grande do Norte State) - coincident with those of the... more
By using the mean directions of the wave-fronts approaching the Brazilian northeastern coastal stretch comprised between the localities of Real river (Sergipe State) and Galinhos (Rio Grande do Norte State) - coincident with those of the main winds occurring in the area - and their periods, we have defined a wave climate model based on the construction of refraction diagrams. The resulting model of sediment transport, as obtained by numerical modelling from the refraction diagrams, taking into consideration the angle of approach and waves heights along the 10-m isobath, was capable of reproducing the patterns of sediment dispersion provided by geomorphic indicators of the longshore drift. All this coastal region, approximately 900 km in length, is characterized by a significant divergence zone in the direction of net longshore drift of sediments, the potential intensity of which increases considerably in value, in almost its entire length, continuously toward downdrift, which might ...
Research Interests: Geology, Physics, Multidisciplinary, Transport, Littoral, and 3 moreSediment, Modelisation, and Quaternaire
This paper presents a numerical modeling estimation of the sediment dispersion patterns caused by waves inciding through four distinct coastline contours of the delta plain of the Doce River during the Late Holocene. For this, a wave... more
This paper presents a numerical modeling estimation of the sediment dispersion patterns caused by waves inciding through four distinct coastline contours of the delta plain of the Doce River during the Late Holocene. For this, a wave climate model based on the construction of wave refraction diagrams, as a function of current boundary conditions, was defined and was assumed to be valid for the four coastlines. The numerical modeling was carried out on basis of the refraction diagrams, taking into account the angle of approximation and the wave height along the coastline. The results are shown to be comparable with existing data regarding the directions of net longshore drift of sediments estimated from the integration of sediment cores, interpretation of aerial photographs and C14 datings. This fact apparently suggests that, on average, current boundary conditions appear to have remained with the same general characteristics since 5600 cal yr BP to the present. The used approach may...
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During the geological mapping of the Salvador city the conglomerates outcropping at Mont Serrat were studied. This outcrop is located near the escarpment of the Salvador fault, which marks the boundary between the Salvador high and the... more
During the geological mapping of the Salvador city the conglomerates outcropping at Mont Serrat were studied. This outcrop is located near the escarpment of the Salvador fault, which marks the boundary between the Salvador high and the Recôncavo basin. These conglomerates belong to the Salvador formation, and they provide useful information concerning the major rock types at the source áreas and the deposicional environments. The Salvador high is comprised of ortho and para-derived rocks intensely deformed and metamorphosed in the granulite and amphibolite facies, together with mafic dikes and sienogranites emplaced in a more recent time. The sedimentary structures and channel geometry indicate the action of a variety of depositional and transport processes including traction, grain flows and debris flows. Sediments accumulated in fan deltas prograding into the tectonic lake of the Recôncavo basin from the Salvador fault. The dominant sediment transport direction was towards southwe...
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Using numerical modeling, this work estimates sediment dispersion patterns caused by the incidence of waves in five distinct coastline contours of the Jequitinhonha River delta plain during the Late Holocene. For this study, a wave cliate... more
Using numerical modeling, this work estimates sediment dispersion patterns caused by the incidence of waves in five distinct coastline contours of the Jequitinhonha River delta plain during the Late Holocene. For this study, a wave cliate odel based on the construction of ave refraction diagras relative to the current boundary conditions as defined and assumed to be valid for the five coastlines. Numerical modeling from the refraction diagrams was carried out considering the angle of incidence and wave height along the coastline. This work has allowed us to reproduce past and current patterns of net longshore sediment drift defined by a conceptual model developed from the integration of sediment cores, aerial photograph interpretation, C14 datings and geomorphic indicators of longshore drift. These results show that, on average, current wave conditions in the east-northeastern Brazilian region seem to have remained characteristically the same from approximately 5100 years BP until t...
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... 1999 Flexure as a Tectonic Control on the Large Scale Geomorphic Characteristics of the Eastern Brazil Coastal Zone Abilio Carlos da Silva Pinto Bittencourtt, Jos6 Maria Landim Dominguezt, and Naomi Ussamit tLaborat6rio ...
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Research Interests: Geology()
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The study of the dynamic processes in coastal environments is very important, since these processes determine the evolution of these environments. This work aims to contribute to an assessment of the marine and sedimentary dynamics in the... more
The study of the dynamic processes in coastal environments is very important, since these processes determine the evolution of these environments. This work aims to contribute to an assessment of the marine and sedimentary dynamics in the coastal line of the city of Aracaju, through the application of the Coastal Modeling System (SMC), a tool that includes a set of methodologies and numerical models that allow studying the processes and quantify the variations that the coast suffers as a consequence of natural events and / or human interference. The methodological procedure consisted in the propagation of waves, currents and sediment transport using the MOPLA module of the SMC. Two main wave systems, from east-southeast (ESE) and Southeast (SE), operate in the area investigated. The most frequent waves are those with significant height between 1.0 and 1.5 m, and peak period around 5 and 8 s in 30.84% of the cases. In most of the coastline, the mean positive mean transport Northeast-...
RESUMO O estudo hidrodinâmico do trecho litorâneo entre Cumbuco e Matões, costa NW do Estado do Ceará, foi realizado tomando como base um método empírico que utiliza o processo gráfico de confecção de diagrama de refração, associado a... more
RESUMO O estudo hidrodinâmico do trecho litorâneo entre Cumbuco e Matões, costa NW do Estado do Ceará, foi realizado tomando como base um método empírico que utiliza o processo gráfico de confecção de diagrama de refração, associado a trabalhos de campo ...
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Abstract. The integration of methods for calculating soil loss caused by water erosion using a geoprocessing system is important to enable investigations of soil erosion over large areas. Geographic information system (GIS)-based... more
Abstract. The integration of methods for calculating soil loss caused by water erosion using a geoprocessing system is important to enable investigations of soil erosion over large areas. Geographic information system (GIS)-based procedures have been used in soil erosion studies; however in most cases it is difficult to integrate the functionality in a single system to compute all soil loss factors. We developed a system able to combine all factors of the Universal Soil Loss Equation (USLE) with the computer functionality of a GIS. The GISus-M provides tools to compute the topographic (LS-factor) and cover and management (C-factor) from methods using remote sensing data. The other factors necessary to use the USLE, including soil erodibility, rainfall erosivity, and conservation practices, are also integrated in this tool. We describe in detail the GISus-M system and show its application in the RibeirA£o do Salto sub-basin. From our new system, it is possible to work with different types of databases, making the GIS-procedure developed here a useful tool for researchers and decision makers to use spatial data and different methods to create future scenarios of soil erosion risk.
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New pollen data from a core at Lagoa do Caçó, Maranhão state, Brazil (2°58′S 43°25′W; 120 m elevation), show higher frequencies ofPodocarpusat the end of the Pleistocene than today. The increase inPodocarpus, which follows the successive... more
New pollen data from a core at Lagoa do Caçó, Maranhão state, Brazil (2°58′S 43°25′W; 120 m elevation), show higher frequencies ofPodocarpusat the end of the Pleistocene than today. The increase inPodocarpus, which follows the successive increase of various pioneer species such asDidymopanax, Melastomataceae/Combretaceae, andCecropia, implies a progressive late-glacial increase of moist and cool climatic conditions. A comparable increase inPodocarpusis found in other lowland records in Amazonia. A review of published pollen data from Amazonia suggests that the moisture source was from the southeast. By contrast, present-day moisture comes from the tropical Atlantic and from the Amazon basin, with its convective precipitation. The likely cause for the southeastern moisture source between ca. 15,000 and 14,500 cal yr B.P. was enhanced polar (Antarctic) advection that reached low latitudes and maintained year-round the meteorological equator in its austral-winter position at northern l...
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Sedimentological studies including seismic profiles, mineralogy and organic geochemistry on two cores from the center and margin of Caçó Lake, Maranhão State, northern Brazil, revealed variable climatic and environmental conditions during... more
Sedimentological studies including seismic profiles, mineralogy and organic geochemistry on two cores from the center and margin of Caçó Lake, Maranhão State, northern Brazil, revealed variable climatic and environmental conditions during the last 21 cal kyr BP. Between 21 ...
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An evolutionary model is proposed for the Caravelas strandplain. The model encompasses integration of: (i) mapping of Quaternary deposits, (ii) cartography of beach-ridge alignments and their truncations, (iii) relative sea-level history,... more
An evolutionary model is proposed for the Caravelas strandplain. The model encompasses integration of: (i) mapping of Quaternary deposits, (ii) cartography of beach-ridge alignments and their truncations, (iii) relative sea-level history, (iv) development history of the Abrolhos coral reefs, (v) vibra-coring and (vi) C14 dating of Quaternary deposits. Seven major evolutionary stages were identified. These stages show that the strandplain has had its Quaternary evolution strongly controlled by relative sea-level changes. In addition, the development of the Abrolhos coral reefs has also played an important role in dispersion and accumulation of sediments along the coastline, causing localized inversion in longshore sediment transport.
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The Todos os Santos Bay, located on northeastern Brazil, is the second largest coastal bay in the country, after São Marcos Bay. The three main drainage basins convey an average of 120 m³/s of freshwater towards the bay, the majority of... more
The Todos os Santos Bay, located on northeastern Brazil, is the second largest coastal bay in the country, after São Marcos Bay. The three main drainage basins convey an average of 120 m³/s of freshwater towards the bay, the majority of it, however, held by a dam in Paraguaçu River since 1985. The original average freshwater inflow was two orders of magnitude smaller than the estimated tidal discharge through the main bay entrance, and the oceanographic characteristics of the bay, as indicated by bay salinity measurements, are clearly marine. The tides are semi-diurnal, and are amplified up the bay by a factor of 1.5. Shallow water constituents become more important as the tide propagates along Paraguaçu Channel and Paraguaçu River, where they generate time asymmetries that change between spring and neap tides. Currents in the bay are mainly bi-directional, and are stronger during the ebbing tide in most of the bay. Offshore, relatively strong tidal currents appear to be felt in a r...
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This research work, which sought to comprise the coastal locations of Flexeiras, Baleia, Paracuru e Jericoacoara, Northwest Ceara State, aimed at assessing the migration process of dunes, taking into account their morphological features,... more
This research work, which sought to comprise the coastal locations of Flexeiras, Baleia, Paracuru e Jericoacoara, Northwest Ceara State, aimed at assessing the migration process of dunes, taking into account their morphological features, dimensions and volume, in addition to gauging the influence of rainfall over their dynamics. The estimation of dune migration rates was based on direct, in situ, and indirect, by means of sattelite imaging, measurements of the distances between their dune tracks. The size and volume of dunes were obtained through topographical surveying and remote sensing. The comparison between such data and rainfall at the time of their formation showed there to occur a good inverse correlation between volume and main size features, and their respective migration speed, emphasizing the outstanding role of climate on the development and displacement of eolian dunes in Northwest Ceara State.
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Knowledge of benthic marine communities is ecologically and economically important. The objective of this study was to map epibenthic marine habitats of the northeastern portion of the Todos os Santos Bay (TSB). High-resolution satellite... more
Knowledge of benthic marine communities is ecologically and economically important. The objective of this study was to map epibenthic marine habitats of the northeastern portion of the Todos os Santos Bay (TSB). High-resolution satellite images available from Google Earth Pro were used to map optically different seafloor and intertidal areas. The integration of these images with available previously published biophysical data, such as nautical charts, surface sediment maps, and shallow seismic records allowed the individualization of different underwater/coastal habitats from which 145 sampling stations were selected for analysis of epibenthic communities. To evaluate the biological communities a photoquadrat 0.25 m² square was used in all sampling stations. A Van Veen grab was used to sample sediments from unconsolidated substrate areas. The analysis of epibenthic data yielded statistically different biological communities among most of the habitats initially identified. By combini...
Research Interests: Geology()
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Research Interests: Geology()
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Les auteurs présentent une étude des variations du niveau relatif de la mer au cours du Quaternaire supérieur sur la côte orientale du Brésil, de l'Etat Alagoas à celui de Santa Catarina. Ils s'appuient sur des données... more
Les auteurs présentent une étude des variations du niveau relatif de la mer au cours du Quaternaire supérieur sur la côte orientale du Brésil, de l'Etat Alagoas à celui de Santa Catarina. Ils s'appuient sur des données géologiques, biologiques et préhistoriques. Les variations qui se sont produites au cours du dernier millénaire ont joué un role très important dans la formation des plaines côtières brésiliennes. Plus généralement, celles du Quaternaire supérieur ont caractérisé la mise en place des plaines deltaïques des fleuves de cette partie de côte. Leur modèle évolutif diffère de ceux proposés par la littérature.