Lagoa Feia Research Articles

Mineralogical and Maturation Considerations of the Coqueiros Formation (Campos Basin, Brazil): Insights from Multi-Technique Analyses of Source Rocks

The Coqueiros Formation, a strategic stratigraphic unit within the Lagoa Feia Group (LFG) in the Campos Basin offshore Brazil, is known for its lacustrine carbonate deposits, which include both organic-rich shales and economically important “coquina” reservoirs. While coquina facies are widely recognized as reservoirs, the source-rock potential of the intercalated shales remains relatively underexplored. This study aims to characterize the mineralogy and thermal maturity of the Coqueiros Formation to assess its potential as a source rock, using a multi-technique approach integrating X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Raman spectroscopy analyses of shale samples from two wells: 3-BP-11-RJS and 6-DEV-18P-RJS. XRD analyses revealed a heterogeneous mineralogy dominated by carbonates (calcite and dolomite) and quartz, with significant contributions from clay minerals and trace minerals such as pyrite and barite. SEM imaging revealed a heterogeneous fabric with grain size, morphology, and porosity variations, reflecting a dynamic lacustrine depositional setting influenced by storm events and fluctuations in terrigenous input. The presence of authigenic minerals, as reported in other studies, such as saddle dolomite, mega-quartz, and various sulfides, provides evidence for hydrothermal alteration, likely related to Late Cretaceous magmatic activity in the Campos Basin. Raman spectroscopy yielded equivalent vitrinite reflectance (Ro%) values consistently exceeding 1.00, ranging from 1.03 to 1.40, indicating that the organic matter in the Coqueiros Formation shales has attained a high thermal maturity level, surpassing the oil window and reaching the condensate wet gas zone. The mineralogical and equivalent maturation data presented herein provide a valuable foundation for future studies, highlighting the complexity and heterogeneity of the Coqueiros Formation and its potential significance as a source rock within the Campos Basin petroleum system.

Tectonic and Stratigraphic Evolution Based on Seismic Sequence Stratigraphy: Central Rift Section of the Campos Basin, Offshore Brazil

The rift section of the Brazilian basins represent the sedimentary record associated with the first stages of Gondwana break-up in the Early Cretaceous phase (Berriasian to Aptian). The rift succession of the Campos Basin constitutes one of the main petroleum systems of Brazil’s marginal basins. This interval contains the main source rock and important reservoirs in the Lagoa Feia Group deposits. The Lagoa Feia Group is characterized by siliciclastic, carbonate and evaporite sediments deposited during the rift and post-rift phases. Despite the economic relevance, little is known in stratigraphic terms regarding this rift interval. To date, most studies of the Lagoa Feia Group have adopted a lithostratigraphic approach, while this study proposes a tectonostratigraphic framework for the deep-rift succession of the Campos Basin (Lagoa Feia Group), using the fundamentals of seismic sequence stratigraphy. This work also aims to establish a methodological and practical procedure for the stratigraphic analysis of rift basins, using seismic data and seismofacies, and focusing on tectonicstratigraphic analysis. The dataset comprised 2D seismic lines, core and lithological logs from exploration wells. Three seismic facies were identified based on reflector patterns and lithologic data from well cores, providing an improved subdivision of the pre-, syn- and post-rift stages. The syn-rift stage was further subdivided based on the geometric patterns of the reflectors. Tectonics was the main controlling factor in the sedimentary succession, and the pattern and geometry of the seismic reflectors of the syn-rift interval in the Campos Basin allowed the identification of three tectonic systems tracts: (i) a Rift Initiation Systems Tract; (ii) a High Tectonic Activity Systems Tract and (iii) a Low Tectonic Activity Systems Tract.

Vegetation and fire variability in the central Cerrados (Brazil) during the Pleistocene-Holocene transition was influenced by oscillations in the SASM boundary belt

This study investigates historical fire regimes and arboreal cover variability in the Brazilian Cerrados, a large Neotropical savanna ecosystem, during the Pleistocene-Holocene transition and early Holocene, and then tests whether the observed variation is linked to South American Summer Monsoon (SASM) variability. We present high-resolution pollen, XRF and charcoal records from Lagoa Feia, located in central Cerrados, and assess how they compare with other pollen records from the surrounding region to investigate regional trends of vegetation and fire regime variability. Our results show that the Pleistocene-Holocene transition was marked by a wet episode, which included moist forest expansion and rising lake levels, that correlates well with increased monsoon activity in a large area of central South America during the same period. This wet episode chronologically coincides with the Younger Dryas cold episode in the northern hemisphere. Our data revealed moisture declines in central Cerrados after 11.2 kyr BP, along with centennial-scale fluctuations from dry to wet conditions throughout the early Holocene period until around 6 kyr BP. These dry/wet oscillations are associated with weakened SASM activity and repeated shifts of its belt position during this time range. Fire activity increased in central Cerrados just after the onset of drier conditions during the early Holocene, and likely contributed to decreased arboreal cover at that time. A trend of increasing moisture in the region was observed after 6 kyr BP. Our study reveals how centennial and millennial-scale changes in monsoon activity influenced arboreal cover, diversity and fire regimes in the central Cerrados.

Lacustrine carbonate platforms: Facies, cycles, and tectonosedimentary models for the presalt Lagoa Feia Group (Lower Cretaceous), Campos Basin, Brazil

Studies of lacustrine carbonate rocks in continental rifts have received huge interest in recent years because of their great economic value in the South Atlantic. However, most existing facies and tectonosedimentary models for carbonate platforms are based on marine carbonate systems, whereas models for nonmarine systems are scarce. The main aim of this paper is to establish such models and to further our understanding of the hydrocarbon-bearing late synrift Lower Cretaceous carbonate successions of the Campos Basin, Brazil. This paper is based on a proximal to distal industrial data set of three-dimensional (3-D) seismic, cores, and well logs from the Coqueiros Formation (Coquina), southern Campos Basin. The dominant carbonate facies in the Coqueiros Formation are mollusk-rich grainstones, rudstones, and floatstones, which form the main reservoir facies. The 3-D seismic interpretations show an oblique extensional rift system, characterized by a series of grabens, half grabens, accommodation zones, and horsts oriented northeast–southwest to north–northeast-south–southwest. Three tectonic domains are recognized based on structural style, stretching factors, and subsidence rates as well as facies and different types of lacustrine carbonate platforms. Proximal rift margin areas are characterized by a series of half grabens with footwall and hanging-wall dip slopes of shallow lacustrine carbonates and fluviodeltaic mixed carbonate and siliciclastic deposits in marginal, hanging-wall basins. Central areas are carbonate rich with platforms established over horst blocks surrounded by deeper-water carbonate facies. Distal areas have the highest amount of stretching and subsidence and accumulate the thickest carbonate successions over a template of buried horsts and grabens. The entire carbonate succession underlies a thick layer of Aptian salt, which forms the seal to this prolific hydrocarbon system.

Re-sedimented deposits in the rift section of the Campos Basin

An integrated petrologic-sedimentologic-stratigraphic-seismic study of the Lagoa Feia Group, rift section of the Campos Basin, has shown that rift sedimentation was dominantly intrabasinal (carbonate and stevensitic deposits), with siliciclastic deposits restricted to the proximity of graben border faults. The bivalve bioclastic rudstones (“coquinas”) that constitute the rift reservoirs show commonly limited abrasion of the bioclasts, and were deposited both on basement highs and lows throughout the rift section. Although in situ deposits of stevensite ooids and peloids occur dominantly at the base of the succession, these particles are ubiquitous to the entire rift section, mixed in variable proportion with siliciclastic and carbonate sediments. The environmental conditions required for the formation of stevensite and the growth of bivalves are mutually exclusive, as stevensite forms only at pH greater than 10, while bivalves cannot tolerate pH greater than 9. The common mixture of well-rounded basaltic rock fragments with angular, granitic-gneissic rock fragments and feldspars in the sandstones and conglomerates indicates recycling of epiclastic deposits from the early rift section, combined with first-cycle contribution from the plutonic basement. The studied cores show no evidence of subaerial exposure, and there is a lack of bioturbation, suggesting harsh environmental conditions. The rift deposits are dominantly massive or faintly-laminated, with diffuse facies boundaries. Structures indicative of unidirectional or oscillatory flow are subordinate. Integration of seismic, sedimentologic and petrographic evidence indicates that the Campos Basin rift section is formed mostly by re-sedimented gravitational deposits. The onset of the rift sedimentation occurred in synformal depressions, where bivalve banks or stevensite ooids were formed in shallow lacustrine environments under variable alkalinity conditions. With the development of half-grabens and concentration of the tectonic activity along the border faults, recurrent tectonic events promoted the mixing and gravitational re-deposition of stevensitic, clastic and bioclastic sediments in deeper, fault-bounded troughs. Large-scale units, hundreds of meters thick, were generated by major tectonic events, whereas compositional variations in the scale of meters were possibly a product of lake-level climatic fluctuations. Thus, due to syn-rift and mainly to post-rift erosion (the Neo-Aptian unconformity), the preserved rift section of the Lagoa Feia Group comprises mostly sediments deposited in the central troughs of the half-graben structures. Marginal sediments were extensively eroded and re-sedimented as gravity-driven mixed deposits. This new model, constructed form the integration of seismic, stratigraphic, sedimentologic and petrologic data, diverges substantially from the presently accepted model for the sedimentation of the rift section, opening new possibilities for the exploration of Campos Basin, as well as of similar settings, as in the adjacent Santos Basin.

Deposition, diagenesis and reservoir potential of non-carbonate sedimentary rocks from the rift section of Campos Basin, Brazil

A new petrographical study was performed on the rift section of the Lagoa Feia Group, Lower Cretaceous of the Campos Basin, eastern Brazilian margin. The primary constituents of the analysed rocks are siliciclastic and volcaniclastic grains, stevensite ooids and peloids, and bioclasts of bivalves and ostracods. This study focused on the clastic, stevensitic and hybrid rocks, as previous studies were limited to the bioclastic rudstones and grainstones that constitute the producing reservoirs. The rift sedimentation was mostly intrabasinal, with extrabasinal contribution concentrated close to half-graben border faults. The mixture of rounded volcanic fragments with angular quartz, feldspars and plutonic fragments in the sandstones and conglomerates indicates recycling of early rift epiclastic deposits, combined with first-cycle sediments eroded from uplifted plutonic basement blocks. Stevensitic ooids and peloids, formed in shallow, alkaline lacustrine environments, were mixed throughout the rift section with bivalve and ostracod bioclasts, and with the clastic sediments. Gravitational redeposition was promoted by intense and recurrent tectonism along the rift margins. The main diagenetic processes in clastic sandstones and conglomerates and hybrid arenites are cementation and grain replacement by smectite, zeolites, calcite and dolomite, mechanical compaction and dissolution of feldspars, volcanic fragments and bioclasts. Stevensitic arenites experienced early cementation and replacement of ooids and peloids by quartz, calcite and dolomite, or intense compaction of stevensitic grains in uncemented areas. Volcaniclastic sandstones and conglomerates with smectite rims, remnant intergranular porosity and grain dissolution may constitute fair hydrocarbon reservoirs. Stevensitic and hybrid arenites with dissolution of stevensite grains, bioclasts and calcite cement may also constitute reservoirs, although with potential quality limited by the poor connection of their pore systems. An understanding of the controls on the depositional and diagenetic evolution of the dominantly intrabasinal, gravitationally redeposited, rift succession will contribute to new exploration strategies for the Campos Basin.

Redescription of Hisonotus notatus Eigenmann & Eigenmann, 1889 (Loricariidae: Hypoptopomatinae), the type species of the genus, and description of a new species from coastal drainages of southeastern Brazil

ABSTRACT Our analyses showed that the type series of Hisonotus notatus , type species of the genus, is mixed, composed by two different species. Based on that, we redescribe H. notatus with the designation of a lectotype, restricting the species to rio São João drainage and other small coastal drainages running to the Baía de Guanabara and to the Baía de Sepetiba in Rio de Janeiro State. We also describe a new species of Hisonotus from drainages of the rio Paraíba do Sul, Lagoa Feia, rio Macaé, and coastal rivers of Espírito Santo State, from rio Itabapoana to rio Doce basin. These two species are sister-taxa and can be distinguished by the number of plates in the mid-dorsal series.

Evolução complexa de um meio-gráben: seção rifte da Bacia de Campos baseada em análise sismoestratigráfica

A seção rifte da Bacia de Campos é composta pela porção basal a intermediária do Grupo Lagoa Feia, e inclui a principal rocha geradora da bacia, e rochas reservatório carbonáticas. A interpretação e o mapeamento sistemático de linhas sísmicas 2D em uma área chave da bacia onde ocorrem dois meio-grábens, integradas com dados de perfis litológicos de poço, e a construção de uma carta cronoestratigráfica, permitiram elaborar um modelo evolutivo para a fase inicial da bacia. Assim, foram definidas dez unidades sismoestratigráficas, superfícies limítrofes chave e três sismofácies, que representam os principais grupos litológicos da seção rifte: depósitos de falha de borda, depósitos ressedimentados de grãos finos e depósitos ressedimentados de grãos grossos. A estratigrafia da Bacia de Campos foi subdividida em tratos de sistema tectônico, que refletem sua evolução tectonoestratigráfica. O trato de sistema de início de rifte apresenta tectônica bem distribuída. O trato de sistema de alta atividade tectônica é marcado pela significativa movimentação das falhas de borda; e o trato de sistemas de baixa atividade tectônica é caracterizado por um processo de fault restriction. A análise de cada etapa evolutiva levou à proposição de um modelo tectonoestratigráfico. Inicialmente os sedimentos sin-rifte foram depositados em uma depressão sinformal sem a presença de falhas de borda. Com o contínuo rifteamento e aumento da atividade tectônica, a deformação concentrou-se nas falhas principais, resultando na formação de dois meio-grábens bem estruturados com bordas de falha bem definidas. Essa fase foi seguida por uma fase de movimentação incipiente das falhas de borda até cessar o rifteamento, resultando em um preenchimento complexo e interdependente entre as diferentes calhas da bacia durante seu desenvolvimento.

Pre-salt microbialites from the Campos Basin (offshore Brazil): image log facies, facies model and cyclicity in lacustrine carbonates

Abstract This study uses a borehole image log, supported by limited sidewall-core samples, and conventional wireline logs to erect facies and stratigraphic models for the Aptian pre-salt microbial carbonates (Macabu Formation (Fm)) of the southern Campos Basin, Brazil. This supports the widely held view that these reservoirs are very significant, unusual, partly microbial, and lacustrine in origin. This single-well study penetrates 220 m of microbialite facies from the pre-salt Lagoa Feia Group non-marine carbonates. Continuous borehole images, available sidewall-core data, and gamma-ray and sonic wireline logs are used to identify and characterize borehole image facies. These facies are interpreted to have formed in four lacustrine depositional environments: deep subaqueous, intermediate subaqueous, shallow subaqueous and subaerial. The borehole image facies commonly show shallowing-upward facies trends topped by emergent surfaces. Such trends are interpreted as metre-scale, high-frequency cycles that are grouped into lower order depositional sequences interpreted from the gamma-ray log. A Fischer plot of the high-frequency cycle suggests that the entire Macabu Fm is represented by a decrease in the accommodation space followed by increase in the accommodation space; consistent with this suggestion are trends in δ 18 O values from an adjacent well that indicate an initial trend of increased evaporation followed by increased freshwater inflow (lighter δ 18 O and thicker cycles).

Oil source rocks at the mesozoic and cenozoic continental margins: Communication 1. Oil source rocks at continental margins in the Triassic-Jurassic and Neocomian-Aptian

The presence of rocks capable of generating hydrocarbons (HC) in the section of sedimentaryrock basins is an essential criterion for their qualification as structures with oil and gas pools. Although organic matter (OM) is always present as dissemination in genetically different sediments, it is believed that rocks enriched with OM of the sapropel series (2 to 3% Corg) can generate a significant amount of liquid HC. However, rock sequences with the Corg ranging from 3–5 to 15–20% are considered oil source formations. The rock section of large petroliferous basins usually includes one or two source sequences, which generated liquid and gaseous HCs after submergence to high temperature and pressures zones. In the basin confined to the Arctic slope of Alaska, one of the main producers of liquid HC is represented by the Upper Triassic clays and limestones of the Shublik Formation. In the Barents Sea and North Sea basins, such rocks are represented by the Spekk Formation and the Kimmeridge Clay, respectively; in the West Siberian basin, by the Bazhenovo Formation; in the Persian Gulf, by the Fahlian, Sargelu, and Garau formations; in basins of the Caribbean region, by marls and clayey limestones of the La Luna Formation. In perioceanic basins of the South Atlantic, the major source sequences are represented by the Neocomian and Barremian clays and marls. The source rocks are identified as the Lagoa Feia Formation in the Campos and Santos basins. They are cognized as the Black Marlstone or Bukomazi Formation in the Lower Congo, Kwanzaa-Cameroon, and Angola basins.

Tectonic subsidence history and source-rock maturation in the Campos Basin, Brazil

The Campos Basin is a petroleum-productive, marginal sag basin along the Brazilian margin. It contains a stratigraphic sequence recording lithospheric extension and rift tectonics developing to a fully evolved post-break-up setting. We present a combined approach using subsidence analysis and basin history inversion models to make predictions on source-rock maturation. The classical uniform stretching model does not account for the observed tectonic subsidence , and so we consider the thermal and subsidence implications of incorporating different events of magmatic underplating. The post-rift is characterized by one major phase of post-rift thermal subsidence: changes in sediment supply and load, as well as halokinetic movements, cause deviations from normal thermal subsidence and relaxation. The dimensions of these events have been examined and quantified. Our best-fit forward model is tested against measured borehole temperature (BHT) data. Results show a systematic overestimation of present-day temperatures in the shallow-water wells. Including the effects of hydrothermal convection by raising the conductivity of the top part of the stratigraphic sequence results in an almost perfect fit between predicted and measured BHTs in the shallow-water wells. Based on these forward models, we predict that the lacustrine shales of the syn-rift Lagoa Feia Fm. could be mature to generate oil and/or gas over a larger area than previously expected. Furthermore, our results suggest that the early post-rift Macaé Fm. is locally mature to generate oil, and that the middle/late post-rift Carapebus/Ubatuba Fm. shales are likely to generate oil as well, if organic-rich facies are indeed present. In light of the most recent pre- and post-salt discoveries made near established oil fields in the Campos Basin, our results support the idea that many more such accumulations may be found.

Propostas de indicadores ambientais na gestão de recursos hídricos na comunidade de Ponta Grossa dos Fidalgos, Lagoa Feia – RJ: utilização do Modelo Força Motriz/Pressão-Situação-Impacto-Resposta

Selecting alternatives that work as a potential aid to the decision-making process between government and civil society, as well as the effective dialogue between these stakeholders is one of the most important tasks for a rational and conscious use of natural resources. The importance of this work is, to structure a methodology that aims to provide the understanding of the Lagoa Feia flood perimeter, aiming at the demarcation of Protected Areas along it and solution for the conflicts generated by the use of its margins, as well as the preservation of environmental quality and landscape. Thus the data and parameters obtained with this study can be used for the decisionmaking process.

Variações sazonais e conflito no povoado pesqueiro de Ponta Grossa dos Fidalgos, Rio de Janeiro

Ponta Grossa dos Fidalgos is a small fishing village located on the north shore of Lagoa Feia, in the state of Rio de Janeiro. This article aims to present how the people from this village organize their daily activities from crossing three calendars fishing. A careful reflection shows conflicts about the seasonal regulations of fishing activities and how fishermen and public officials are positioned on them.

A new species of Trichomycterus (Siluriformes: Trichomycteridae) from lagoa Feia drainage, southeastern Brazil

Trichomycterus caipora, new species, is described from rio Macabu basin, lagoa Feia drainage, serra de Macaé, southeastern Brazil. The new species is distinguished from its congeners from southern and southeastern Brazil by the combination of: the presence of nine pectoral-fin rays, caudal fin emarginated and high number of opercular and interorpecular odontodes. Ecological notes are presented and putative phylogenetic relationships and characters shared with congeners are discussed.

ブラジルカンポス堆積盆地の石油システム評価

The Campos Basin, offshore Brazil, is a typical passive margin basin in the western South Atlantic, and the most prolific basin with about forty producing fields including deep-water giant fields. The Campos Basin is currently responsible for more than 80% of Brazilian oil production.The hydrocarbon accumulations are distributed throughout the stratigraphic column of the basin from Neocomian to Miocene. The most important oil accumulations in the basin are associated with deep-water fans distributed in the stratigraphic column from Cenomanian to Miocene. Almost all the hydrocarbon accumulations discovered to date are sourced mainly from Barremian to early Aptian lacustrine shales of the Lagoa Feia Formation in the pre-salt sequence. The oil pooled in the post-salt sequence migrated through a system associated with pre-salt normal faults, “salt windows” in the Aptian evaporite, listric faults and regional unconformities.The play fairway map was made based on considering the basement and the salt development, the fault distributions and the kitchen area. This map presented that the Campos Basin was divided into five structural zones. These zones could be closely related to the hydrocarbon potential. It was evaluated that the eastern part of Zone I and Zone IIa along the present day shelf edge provided more favorable condition for the hydrocarbon accumulation than other zones. The oil of Marlim Sul field is trapped in the blanket turbidites that pinch out toward the northwest landward. The thick mud deposits derived from the muddy turbidites was considered to be the important factor for establishing the stratigraphic trap.

ABSTRACT: Lagoa Feia of Brasil's Campos Basin: Observations on Source Potential and Quality

ABSTRACT: Lagoa Feia of Brasil's Campos Basin: Observations on Source Potential and Quality

Lake-type controls on petroleum source rock potential in nonmarine basins

Based on numerous empirical observations of lacustrine basin strata, we propose a three-fold classification of lacustrine facies associations that accounts for the most important features of lacustrine petroleum source rocks and provides a predictive framework for exploration in nonmarine basins where lacustrine facies are incompletely delineated. (1) The fluvial-lacustrine facies association is characterized by freshwater lacustrine mudstones interbedded with fluvial-deltaic deposits, commonly including coal. Shoreline progradation dominates basin fill, resulting in the stacking of indistinctly expressed cycles up to 10 m thick. In map view, the deposits may be regionally widespread but laterally discontinuous and contain strong facies contrasts. Transported terrestrial organic matter contributes to mixed type I-III kerogens that generate waxy oil (type I kerogen is hydrogen rich and oil prone; type III kerogen is hydrogen poor and mainly gas prone). The Luman Tongue of the Green River Formation (Wyoming) and the Honyanchi Formation (Junggar basin, China) provide examples of this facies association, which is also present in the Songliao basin of northeastern China, the Central Sumatra basin, and the Cretaceous Doba/Doseo basins in west-central Africa. (2) The fluctuating profundal facies association represents a combination of progradational and aggradational basin fill and includes some of the world's richest source rocks. Deposits are regionally extensive in map view, having relatively homogenous source facies containing oil-prone, type I kerogen. Examples include the Laney Member of the Green River Formation (Wyoming), the Lucaogou Formation (Junggar basin, China), the Bucomazi Formation (offshore west Africa), and the Lagoa Feia Formation (Campos basin, Brazil). (3) The evaporative facies association represents dominantly aggradational fill related to desiccation cycles in saline to hypersaline lakes and may include evaporite and eolianite deposits. Sublittoral organic-rich mudstone facies are relatively thin but may be (Begin page 1034) quite rich and widespread. The highest organic enrichment coincides with the deepest lake stages. Low input of land plant organic matter results in minimal lateral contrasts in organic content. In some cases a distinctive type I-S (sulfur-rich) kerogen may generate oil at thermal maturities as low as 0.45% vitrinite reflectance equivalent. Examples include the Wilkins Peak Member of the Green River Formation (Wyoming), the Jingjingzigou Formation (Junggar basin, China), the Jianghan and Qaidam basins (China), and the Blanca Lila Formation (Argentina).

On the Origin of Some Birds Collected by George Such, and the Type Localities of Several Forms

In early part of 19th century, George Such (17981879), an English medical doctor and member of Linnean Society of London, collected and described some birds from eastem (Foster 1888, Wynne 1966). During his stay in Brazil, Such was in contact with William Swainson and Nicholas Vigors, of prominent ornithologists of that time. In articles published in Zoological Journal of London in 1825, Such described genus Gubernetes and 11 species of birds, but only Ardea fasciata (= Tigrisoma fasciatum, Fasciated Tiger-Heron) and Thamnophilus leachii (= Mackenziaena leachii, Large-tailed Antshrike) have been maintained (see Appendix for complete list). geographic origin of material collected by Such is established in following section of one of above-mentioned articles (Such 1825a): The situation to which I allude is that broad mountainous belt which forms skirt of table land of Brazil, at that part, where it rises from low of to elevated surface of Province of Geraes. plains of Goaytacazes were well known as territory of indigenous (or similar spelling), which included lowland from Macae to Itabapoana (dominated by Lagoa Feia), and mouth of Paraiba do near Vila de Sao Salvador dos dos in northern de state (Ayres de Casal 1817, Wied 1940). dos Goytacazes is still major population center of this region, and for at least past 100 years it has been known simply as Campos (Moreira Pinto 1894). In Such's day, region to north and west of (where land rises toward Gerais) was virtually uninhabited (Moreira Pinto 1894, Such 1825a) and must have been very difficult of access. There existed to west of Campos, Caminho do Paraiba, which led to present-day S6o Fidelis and doubtfully as far west as Santo Antonio de Padua, and Caminho Campista do Muriae, which linked with Itaperuna (Lamego 1963: map p. 24). Both roads were entirely within state of de Janeiro, and they followed river valleys of same names at elevations of less than 200 m. Before about 1833, only links between states of de and were probably through Petr6polis and Cantagalo (Lamego 1963). Thus, Such's locality of collection may be narrowly defined as upland region that lies just west of plain upon which is situated, and well within borders of state of de Such also collected three other valid species that were described by others. type localities for most of these species have been controversial and always in some doubt. We discuss each of them below. Fasciated Tiger-Heron (Tigrisoma fasciatum) (Such 1825).-Citing his correspondence with E. Eisenmann, Pinto (1964) considered fasciatum a species distinct from T. lineatum (Rufescent Tiger-Heron) and arbitrarily proposed Rio Grande do Sul as type locality. In his work on tiger-herons in Argentina, Eisenmann (1965) clarified specific status of fasciatum and, citing Such (1825a), established provenance of type as the mountainous region of state of de above low of Goyatacazes (= of Campos, fide 0. Pinto). Although Pinto (1978) maintained Grande do as type locality for fasciatum and did not admit de in distribution of species, Eisenmann's (1965) view is now universally accepted. Pale-browed Treehunter (Cichlocolaptes leucophrus) (Jardine and Selby 1830).-This furnariid was described from material collected by Such, and type locality Minas Gerais was proposed, with reservations, by Hellmayr (1915) and followed by Pinto (1938). Peters (1951) left type locality as Brazil and did not include in range of species. More recently, Pinto (1978) designated type locality as leste de Gerais (i.e. eastern Gerais), confusing George Such with Schuch Capanema, who was a famous Brazilian scientist born in in 1824 (Sacramento Blake 1895). There are no published specimens of C. leucophrus from Gerais, although species has been found in that state recently (Mattos et al.1993). Large-tailed Antshrike (Mackenziaena leachii) (Such 1825).-Cory and Hellmayr (1924) were fairly specific in their designation of type locality for this species as vicinity of (= Campos), Prov. de Janeiro. This designation has not been challenged and is an important factor in delimiting type locality of other forms under question (see below). Eastern Slaty Antshrike (Thamnophilus [punctatus] ambiguus) Swainson 1825.-Cory and Hellmayr (1924) stated we have to consider of Campos, on confines of states and de Janeiro as type locality, although recognizing that Swainson based his description on two birds brought to England from Geraes by Dr. Such. Pinto (1978) further defined type locality as near in

Alguns parâmetros utilizados na avaliação hidrogeoquímica de um campo petrolífero na Bacia de Campos (RJ): estudos preliminares

The study of the formation water is receiving a great importance, as a tool in the studies of migration, weathering and accumulation of hidrocarbons. The present study is based on the interpretation of chemical and isotopic data of formation water belonging to Lagoa Feia and the Macae Formations of the Campos Basin oil field. The purpose of mecanisms for evolution and genetic classification of formation water, that was intended in the recent study, determined theirs sources and hydrogeological environments in question. Finnaly, these basic facts were related with the possibility, or not, of accumulation of hydrocarbons. The sample from Campo X point towards existence of "stagnated environments" with low circulation of water, inclined for accumulation of hydrocarbons, shuting out sample 4 (four), belong to Lagoa Feia Formation, is described how indued in the hydrodinamic circulation zone. The strong point of dolomitization and water reaction with clay minerals shows an influence of the meteoric diagenetic environments, proving that before the establishment of estagnated condition observed, probably the water of Campo X received a strong meteoric influence. The waters studied are resulted of one mixture of waters from different brines among these waters originated by evaporation are included. It's possible, because high brines of Lagoa Feia Formation could have some vulcanic contribution.

Petroleum geology of the Campos Basin, offshore Brazil

Abstract The Campos Basin, offshore Brazil, is the most prolific basin in the western South Atlantic, with more than thirty hydrocarbon accumulations currently accounting for about 60% of Brazilian oil production. Intensive drilling and seismic, gravity and magnetic data have contributed to the recognition of four tectono-stratigraphic units related to the rifting and break-up of Pangea. The lowest sequence consists of Neocomian clastics deposited on basalt dated at 120–130 Ma, and reflects the fault-controlled subsidence associated with the stretching that preceded the emplacement of oceanic crust. The Aptian proto-oceanic stage is characterized by a sequence of evaporitic rocks that have undergone intense diapiric activity in deep water. An open-marine environment begins with a thick sequence of Albian/Cenomanian limestones, locally with clastic input, which grades upwards and basinwards into deep water marls and shales. This section is structurally associated with detached listric normal faults that sole out on the Aptian evaporites. Finally, the marine Upper Cretaceous to Recent clastic section is characterized by a more quiescent phase of thermal subsidence, with some residual halokinetic activity that increases in intensity towards deeper waters. The hydrocarbon accumulations are distributed throughout the stratigraphic column of the basin from Neocomian to Miocene. The reservoirs range from fractured basalts and porous bioclastic limestone (coquinas) in the Lagoa Feia Formation, to limestones and sandstones in the Macaé Formation, and sandstones in the Campos Formation. Detailed geochemical analyses undertaken on cutting, core and oil samples show that almost all the hydrocarbon accumulations discovered to date are sourced mainly from lacustrine calcareous black shales deposited in a closed Upper Neocomian lake system, having saline to hypersaline waters of alkaline affinities. The extreme anoxic conditions in this lacustrine environment resulted in the deposition of fine, well laminated organic-rich (TOC up to 9%) calcareous black shales, with high-quality organic matter composed almost entirely of low-sulphur type-I kerogen, originating from lipid-rich algal and bacterially-derived material. The excellent hydrocarbon source potential of these sediments, combined with the appropriate thermal history, produced the necessary conditions to yield low-density oil (around 30° API) characterized by a low sulphur content (around 0.30%), and significant quantities of alkanes (up to 70%). Diagnostic features in the biological markers from this depositional environment include: low concentration of steranes, presence of β-carotane, gammacerane and 28,30-bisnorhopane, very high concentrations of hopanes and high relative abundances of tricyclic terpanes up to C 34 .