O ENSAIO DE PIEZOCONE E DE MINICONE NA INVESTIGAÇÃO DO SUBSOLO: ALGUNS EXEMPLOS DE APLICAÇÃO.

O ensaio de penetração do cone elétrico e do piezocone pertence a um grupo de ensaios de campo, cuja utilização vem sendo cada vez mais difundida. Tanto o avanço da eletrônica como a rápida evolução da informática têm proporcionado equipamentos mais apropriados, menores, mais robustos e mais econômicos, permitindo a incorporação de diversos sensores a essa ferramenta de investigação. Isto contribuiu para que esse ensaio se consagrasse para a descrição contínua do perfil geotécnico, a definição do nível de água e para estimativa de parâmetros mecânicos do solo. Neste artigo faz-se uma breve apresentação do piezocone e do minicone elétrico: o primeiro vem sendo utilizado nos últimos anos, especialmente em geotecnia ambiental, e o segundo, na investigação da infra-estrutura de transportes. Apresentam-se e discutem-se exemplos de emprego do piezocone para identificação de regiões do maciço contaminadas e do minicone para detectar a superfície de ruptura de uma seção de um talude de aterro, para avaliar sua estabilidade através de retroanálises. Concluise o trabalho fazendo-se algumas considerações sobre a utilização dessa tecnologia moderna e recente em solos tropicais que ocorrem no Brasil.

Mapeamento geológico - estrutural do astroblema de cerro do Jarau - RS Brasil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Long-term landscape evolution and post-rift reactivation in the southeastern Brazilian passive continental margin: Taubat, basin

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estratigrafia e estrutura do Cerro do Jarau: nova proposta

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Mapeamento geológico-estrutural da Sequência Canto, porção sul do Greenstone Belt do Rio Itapirucu, Bahia

The study area is located in the southern portion of Rio Itapicuru Greenstone Belt, Bahia, where were found rocks that belongs to the Canto Sequence, that comprises felsics and intermediary rocks, beyond metasediments. The studied maps and drill holes help to recognized stratigraphy column that was divided in three mains domains, from the base to the top: andesitics to felsics lavas domain, carbonaceous and metasedimentary domains. The data obtained in mapping and petrography analysis allows classify the area in three deformational phases, Dn, Dn+1, Dn+2. The metamorphism recognized according to the mineralogical associations permitted to classify a progressive regional metamorphism (lower to medium greenchist facies) till biotite zone, falling until chlorite zone due to retrometamorphism. The auriferous mineralizations are mainly related to hydrothermal veins included in the different lithologies, mainly in carbonaceous schists

Geologia de uma área na porção centro leste da folha Cássia (1:50.000), MG

This study aimed the geological characterization at scale 1:50.000 of an area belonging to the southern sector of the Brasilia Belt, located in the western portion of the Passos Nappe, near the town of Cássia, MG. In this region, outcrops rock types belonging to Araxá Group, composed of metasediments associated with metavolcanics which form a tectonometamorphic terrain of great importance for understanding the geological evolution of southeast and midwest regions of Brazil. With the development of work was possible to group the rocks in 10 lithostratigraphic units and had been identified 3 different zones of metamorphism generated during the peak metamorphism. The structural pattern of the area shows that the main foliation has average dip 30 ° NW and mineral lineation parallel to the stretching direction with 290 °. Still, we can conf irm that this inverse gradient metamorphic rocks of the Passos Nappe, described by several authors. Also, were seen lithotypes of economic interest, some already in exploitation, such as clay and sand, and other mineral commodities, which are occurring and can be used: quartz, quartzite, garnet, kyanite, rutile and zircon.

Análise de fácies sedimentares e de paleocorrentes das sequências inferiores do grupo Itararé, Centro-Leste do estado de São Paulo

The Itararé Group is the record of one of the most significant glaciation events of the Gondwana. Of neocarboniferous-eopermian age, this unit has facies associations interpreted as resulted from shallow marine settings with glacial and deglacial water influence. The role of glaciers on the tectonic-sedimentary processes of the Itararé Group is striking, as typical facies such as diamictites, tilites, shales and rhythmites with dropstones are generated, besides the existence of glacially striated and polished surfaces. This work had as main goal to contribute to the geological knowledge of the Itararé Group in the central eastern portion of São Paulo State, using as basis outcrops from Itu, Salto and Porto Feliz, and also pertinent bibliographic data and well profiles located in the surrounding areas. About the stratigraphic framework, genetic association and paleogeography of these deposits, this work concludes that the area studied comprises the basal section of the Itararé Group. The stacking of the facies recognized during the field work begins with the striated and polished surfaces of the basement, described in Salto, superposed by tilites and diamictites with glacial movement features. Over these are the turbidites from Itu, associated with the glacier retreat. The outcrops of Porto Feliz are at the top of this succession, with deposits generated by flows with lateral and vertical variations, sometimes with prevalence of tractive conditions, and sometimes with sediments transported largely by suspension. Paleocurrent measurements show main flow directions towards NW, the same as glacial striae, suggesting the influence of reworking of sediments by the meltwater during deglacial periods

Litofácies e relações estratigráficas da formação Aquidauana no nordeste da Bacia do Paraná - São Sebastião do Paraíso (MG)

The Aquidauana Formation is characterized by sandstones of variable granulation, mudstones and diamectites abundant in clay, typical colors like brick red (vermelho tijolo) of glacial, fluvial and lacustrine origin. It’s chronostratigraphic equivalent to the Itarará group from the Neo Carboniferous age, that under the exploratory view, such units represent important intervals in the basin, occurring together with them minerals as well as energy resources as petroleum, underground water and coal – what requires a great paleogeography and stratigraphy knowledge for its exploration. By gathering information from the columnar sections of the area, it was possible to characterize the sedimentary facies, the stacking pattern as well as the association. It was also made an attempt of stratigraphic correlation, which showed great difficulties since glacial environments present a great lateral discontinuity of the facies besides the complex relationship process of formation. As a result, it was obtained 8 sedimentary facies, the lateral and vertical relations and genesis process. It is proposed that the sedimentary environment in the study area is the fluvio glacial, characterized by alluvial systems formed by defrosted water which transport the sediments that are deposited in plains in front of the glacier (distal outwash). Petrographic thin section analysis showed that the transportation process was ineffective. The grains present punctual to lobular contacts, characterizing good porosity and permeability to the rock, varying these qualities according to more or less existence of matrix. The presence of Iron Oxide deposited between the recrystallization border and feldspathic mineral indicates that this rock has possibly presented a primary rubefaction, intensified by alkaline fluid percolation

Evolução da tectônica rúptil no nordeste do Brasil baseada na termocronologia por traço de fissão em apatita

Results of apatite fission tracks from twelve samples collected across a Borborema Province transect, northeastern Brazil, revealed two major paleothermal events: a cooling event occurred between Albian and late Cenomanian (110 - 80 Ma) and a second cooling event starting on early Paleocene (66 Ma). Given the wide expression of the studied area (sampling trend along four brazilian states) a correlation between the distribution of fission track data and the current geological / geomorphological scenario was made possible, considering the area’s tectono - stratigraphic past and its thermochronologic evolution until now. The fact that the employed thermochronologic tool relates to a relatively shallow geothermometer, substancially information for understanding the behavior of basement brittle tectonic was achieved. These data were used to analyze faults origin and reactivation, associated with sedimentary basins evolution in the context of South America - Africa continental breakup.

Geologia das coquinas-reservatório do Campo de Pampo, Bacia de Campos

The Pampo oil field is located in the southwest of the trend Badejo-Linguado-Pampo in an accumulation of single - mixed trap: structural-stratigraphic-diagenetic. Its main reservoir is a coquina shell of bivalves (the lowest) in the Lagoa Feia Group. During the rift phase, the Badejo-Linguado-Pampo trend´s accumulations evolve according to three tectono-stratigraphic cycles. The first two cycles are formed by siliciclastic rocks with fining up sequences and carbonates coquinas bivalves. The youngest cycle related to Alagoas age is a transgressive event represented by the presence of an evaporitic layer in the top (anhydrite). This study aims to characterize the reservoir Coqueiros Formation based on the analysis of 2D and 3D seismic data and well data-correlation profiles. The structural map of the top of coquinas reservoir indicates a curvilinear contour of Pampo Fault as described on the literature. This fault was interpreted on seismic data as a basement´s high, and it doesn´t show influence on the horizons above the top of Lagoa Feia Group. The Pampo fault is responsible for the division of the field into two blocks: the hanginwall in the West and the footwall to the East. This division is well marked on the reservoir´s isopach map where a greater thickness of reservoir is observed on the lower block. In the Southeast extreme of Badejo-Linguado-Pampo trend, on Pampo Field, the thick siliciclastic´s interval ends laterally to the basement, and its lower´s cycle forms a wedge, as consequence the carbonate-coquina overlaps directly the basement. Another implication of the higher and distal position of Pampo field is that the third cycle is absent, truncated by the unconformity pre-Macaé Group (Albian)

Estudo do reservatório de coquinas do grupo Lagoa Feia (Eocretáceo) na acumulação de Linguado, sudoeste da Bacia de Campos

The Linguado Field is located in the extreme southwest portion of Campos Basin. It’s associated with Structural Badejo High and can be divided in two groups of faults: one manly formed by antithetic faults, with NW-SE direction, continuous to Badejo Fault, and another identified by N-S faults. Besides these faults had affected the basement and the stratification of basin, these systems also had contributed to coquina permoporosity development, that show 80% of recoverable oil volume of the field. The carbonate marine sequence, Albian age, it was deposited under the salt. This forms structures as like as pillows and raft as a result of the halocinese. Structurally the Linguado Field coquina has monoclinal direction with east dip, it’s cut by faults with slip up to 50 meters. In addition to structural control, stratigraphy and diagenesis also were important to carbonate trap oil. The identification of recoverable oil levels in the low phase of the coquina from Lagoa Feia Group was done by well data. The seismic 2D and 3D, with the well data, was used to structural interpretation to regional scale either to reservoir scale.

Evolução tectônica do Trend Badejo-Linguado-Pampo, bacia de Campos (RJ)

The regional geological work for the oil industry, in order to find potential areas for hydrocarbon exploration and understand the geological parameters responsible for the formation of the deposit are known importance. This work fits into that scenario, with regional research with the aid of wells and 2D and 3D seismic sold by DBEP (Database Exploration and Production). Were also used as GeoGraphix software package Landmarks modules Prizm and SeisWork 2D and 3D, and the Surfer 8 and ArcGIS 9.2 with the infrastructure provided by the 05 PRH - ANP with LSGI (Laboratory of Seismic and Geological Interpretation) located at UNESP -- Campus de Rio Claro. The work focuses on study the trend of oil-Badejo-Linguado-Pampo, producing fields since the beginning of offshore holdings. The Campos Basin is now known as the offshore basin of the country more productive, and the high structural Badejo is a structure of great importance in the basin presents itself as largely responsible for the conditioning of hydrocarbon fields Pampo, Linguado and Badejo. Therefore this work also aims to increase knowledge of the region in terms of tectonic and stratigraphic characterize the geometry of the structures associated with this major regional structure. For this we used structural contour maps of the main chrono-horizons, and Isopach maps for the purpose of better understanding the tectono-sedimentary evolution of the Campos Basin locally.

A formação Serra Alta, Permiano, no centro-leste do Estado de São Paulo, Bacia do Paraná, Brasil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise estratigráfica em depósitos lacustres maastrichtianos da Formação Yacoraite (Bacia de Salta - Argentina): definição e rastreabilidade de sequências de alta resolução

Pós-graduação em Geologia Regional - IGCE

Sucessão estratigráfica e tratos de sistemas do Membro Romualdo, porção leste da Bacia do Araripe, nordeste do Brasil

Located in northeastern Brazil, the evolution of Araripe Basin has been associated with the fragmentation of Gondwana and opening of the South Atlantic. The Santana Formation belongs to the post-rift sequence of the basin and is characterized by the presence of laminated limestones in the lower portion (Mb. Crato), evaporite (Ipubi) and siliciclastics (Mb. Romualdo). For better understanding of the Romualdo's stratigraphy, depositional environments and tract of systems, a stratigraphic analysis was made with representative columnar sections of the unit. Sedimentary facies have been described in detail, as well as paleocurrents measured at different stratigraphic levels. It was found that the contact of Mb. Romualdo with the carbonate-evaporite section (Mbs. Crato and Ipubi) is a unconformity, evidenced by residual lags and thin layers of conglomerates above the contact. Above the conglomeratic levels predominate fine sandstones / medium interlayered with calciferous green shales. The percentage of shales increases towards the top, featuring retrogradational stacking culminating in layers of coquinas, excellent stratigraphic mark in the basin. Thin layers of coquins of gastropods comprising equinoids, located on the shale section, present in three sections marine deposits are associated with surfaces ravine. The upper section is characterized by recurrent facies of green shales, sandstones intercalated with sandstones progressively become more frequent towards the top of the unit, featuring the regressive part of the cycle. The sandstones present cross-stratification, often with mud clasts and clay layers in the foresets, and beddings of flaser type and wavy in heterolitic facies, suggesting the action of tidal currents. Paleocurrents measured in the sandstones show gaps with opposite flow directions outlining bipolar standards, which reinforce the interpretation of shallow marine environment influenced by tides during the sedimentation...