Navegando por Assunto "Geologia estratigráfica"

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Análise faciológica e aspectos estruturais da formação Águas Claras, região central da Serra dos Carajás-PA
(Universidade Federal do Pará, 1995-01-31) NOGUEIRA, Afonso César Rodrigues; TRUCKENBRODT, Werner Hermann Walter; http://lattes.cnpq.br/5463384509941553
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Análise morfoestratigráfica do estuário do Rio Marapanim - NE do Pará
(Universidade Federal do Pará, 1998-12-20) SILVA, Cléa Araújo da; EL-ROBRINI, Maâmar; http://lattes.cnpq.br/5707365981163429
The estuary of Marapanim River is developed on tertiary-quaternary sediments of Barreiras and Pós-Barreiras Formation. It is inserted on "Littoral of Rias" of Pará northeast, which from High Pleistocene was submitted to marine transgression that drowned coastal paleolines and, in the maximum of Holocene Transgression, reached the coastal plateau. This portion of coast is strongly influenced by dynamic macrotides (5,3m) and salt wedge with mear salinity of 8%0 (high tide — Marudazinho) and 3%0 (low tide — Marapanim). So that, on outer funnel (Marudá) the salinity is 35°/00, representing no influente of mouth river discharge. Geomorphology of the area is subdivided in three morphologic domains: (1) Coastal Plain, constituted by strand plain, paleodune, coastal dune, salt marsh, tidal flat (sand flat and mangrove swamp), recurved spit, lake and palco tidal creek; (2) Estuarine Plain, constituted by estuarine channel (subdivided in estuarine funnel segment, sinuous meandering segment, cuspidate meandering segment and upstream channel), tidal creek and floodplain (salt marsh and fresh water marsh) and; (3) Alluvial Plain constituted by meandering channel (chute cutoff), channel deposits (channel lag deposits), overbank deposits (natural levee, crevasse-splay deposits and floodplain) and channel-fill deposits. Fourteen morphostratigraphic units was identified: floodplain, levee, chute cutoff, fresh water marsh, mudflat, channel bar, point bar, strand plain, paleodune, coastal dune, recurved spit, sand flat and salt marsh. Six stratigraphic facies are also present: point bar sand and mud, marine sands, estuarine sand and mud, estuarine muds, fluvial sands and motled sand. Stratigraphical analysis permitted recognize stratigraphic sequences: Basal Marine Transgressive (Si) with fluvial, salt marsh and shoreface environments; Marine Regressive (S2) with fluvial, fresh water marsh, tidal flat, salt marsh and strand plain environments and; Recent Marine Transgressive (S3) with estuarine (channel bar and point bar) and littoral environments (recurved spit, strand plain and coastal dune). Geological evolution of the estuary of Marapanim River is associated with sea levei oscillations that occurred during progradation and regressive cycles on Later Holocene, which in the maximum of the Holocenic Transgression eroded the highland (coastal plateau). In stillstand sea levei conditions occurred marine regressive and mud flat progradation over marine sand deposits. In present time, sand sheets are deposited over mud ilat providing partia! filling in the mouth of estuary by sand bars.
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Aplicação dos métodos geofísicos elétrico e eletromagnético na determinação de unidades sedimentares costeiras tropicais em Bragança, Nordeste do Pará
(Universidade Federal do Pará, 2002-02-25) SILVA, Regina Célia dos Santos; LUIZ, José Gouvêa; http://lattes.cnpq.br/8676530374310847
This thesis shows the application of geophysical methodology on several deposition environments of the Planície Costeira Bragantina (Bragantina Coastal Plain), which are being studied in the Mangrove Dynamics and Management (MADAM) Project. The aim of the work was to test geophysics on coastal deposition environment to help the geological understanding of the recent stratigraphic evolution of the Bragantina Coastal Plain. Geophysical measurements were carried out on several morpho-stratigraphic geological units using: (a) the conventional dc resistivity method, through Schlumberger vertical sounding, and (b) the slingram horizontal loop electromagnetic method, with measurements taken for eight frequencies. Vertical electric soundings allowed to know the resistivity distribution in subsurface. The resistivity models could be correlated to geology, but the results were not satisfactory for the depth of investigation as a result of the environment high condutivity. The electromagmetic method was easier and quicker to apply than the resistivity method. Electromagnetic data were analized in profiles and in electromagnetic soudings. The data allowed to stablish geological contacts and geophysical signatures for the coastal deposits of the area.
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Aspectos lito-estruturais e evolução crustal da região centro-oeste de Goiás
(Universidade Federal do Pará, 1985-11-13) COSTA, João Batista Sena; VILLAS, Raimundo Netuno Nobre; http://lattes.cnpq.br/1406458719432983; HASUI, Yociteru; http://lattes.cnpq.br/3392176511494801
The study area is bounded by the cities Paraíso do Norte, Gurupi, and Dianópolis in north-central Goiás State. The area contains diverse lithostratigraphic units and various generations of structures related to distinct thermo-tectonic events. Based on the distribution and the petrographic and structural characteristics of the ancient rock assemblage, four litho-structural domains were defined and attributed to the Archean. Domain "1" includes the region of Almas-Dianópolis and is interpreted as part of granite-greenstone terrane. It includes a group of tonalitic gneisses with associated supracrustal rocks (Goiano Complex), a sequence of metavolcanic rocks and metasediments (Riachão do Ouro Group), and various tonalite bodies (Serra do Boqueirão Suite) intruded into the earlier units. The evolution of the domain includes three principal deformational events: a) Formation of the amphibolites and/or biotite gneisses and granitoids characterized by sub-vertical banding oriented N10ºE and accompanied by mineralogical changes under conditions of amphibolite facies; b) deposition of the Riachão do Ouro Group, followed by isoclinal folding oriented N10°E and consequent transformation to greenschist facies. The emplacement of the tonalitic diapirs of the Serra do Boqueirão Suite is related to this event; c) a foliation gently inclined to the SE resulting from a simple low-angle ductile-brittle shearing process which affected the west part of this domain, transforming the rocks of the Goiano Complex into mylonitic gneisses under amphibolite facies conditions. Domain 2 includes the counties of Porto Nacional, Brejinho de Nazaré, and Natividade in the east-central part of the area. It is characterized by granulitic gneisses (Porto Nacional Complex), by tonalitic gneisses with associated supracrustal rocks (Manoel Alves Complex), including metasediments and metavolcanics (Morro do Aquiles Formation), and by pegmatitic granites such as the Xobó Suite. The different lithologic units take the form of lenses or sub-horizontal concordant to sub-concordant bodies with strike N30°E. They show structural features produced by a low-angle ductile-brittle shearing process under amphibolite facies conditions. Superposed on the low-angle features are various zones of high-angle directional shear having different intensities of deformation, but all in greenschist facies conditions. Domain 3 is within the NW part of Paraiso do Norte county and is interpreted as a granite-greenstone terrane similar to that of Domain 1. This Domain includes the Colméia Complex, the Rio do Coco Group, and the alkaline gneisses of Monte Santo. Two principal deformational phases are responsible for the structures in this domain: a) folding (S) of the gneissic granitoids of the Colméia Complex into recumbent folds oriented E-W. The axial plane schistosity (S1) formed in medium to amphibolite facies conditions; b) deposition of the Rio do Coco Group, discordant with the Colméia Complex, followed by sub-vertical folding oriented E-W. The second generation of folds in the Colméia Complex is related to this deformational event. Domain 4, in the west-central part of the area, includes parts of Paraíso do Norte, Fatima, Gurupi, and Porto Nacional counties. This domain is composed of the Rio dos Mangues Complex, the Matança and Serrote Suites, and the alcaline gneisses of the Serra da Estrela, distributed in sub-concordant sheets oriented N30°E. Similarly to that observed in Domain 2, these rock assemblages show structural features related to low-and high-angle shearing events. The transition between Domains 1 and 2 and between Domains 3 and 4 is gradational, such that two ancient blocks of crust are defined (Domains 1+2 and 3+4] separated by a belt of granulitic rocks (Porto Nacional Complex). The zone of juxtaposition corresponda to a belt of low-angle ductile shearing developed by the overthrusting of the Brazilian block, on the east, onto the Araguacema block to the west. Similar geologic conditions have been well characterized in South Africa, in western Greenland, and in NW Scotland and are beginning to be described in various regions in Brazil, constituting a new way to understand the relations between Archean terranes. Granite bodies of the Lajeado Suite at the end of the Lower Proterozoic and ultrabasic bodies in the first half of the Middle Proterozoic were injected into this crustal segment stabilized at the end of the Archean. During this epoch the Transbrazilian Lineament became defined as a brittle shear zone. Basins were developed in the second half of the Middle Proterozoic, with deposition of the Baixo Araguaia Supergroup and the Natividade Group. These two are separated today by a block limited by the cities of Paraíso do Norte, Gurupi, and Porto Nacional. The Transbrazilian Lineament was reactivated in this period.At the end of the Middle Proterozoic an E-W regional compression produced the Araguaia and Uruaçu fold belts. The evolution of the Araguaia fold belt involved four stages of structural deformation. In the first stage, N-S recumbent folds were formed having axial plane schistosity (S1) developed in intermediate amphibolite facies to intermediate greenschist facies conditions. The intermediary stages involved folding and refolding of the S1. The last stage is related to the formation of domai structures resulting from the intrusion of the granite bodies of the Santa Luzia Suite. As a result of this evolution, the Araguaia belt has an importent asymmetry characterized by intensification of deformation and mineralogical transformations from west to east. The Uruaçu fold belt is In general characterized by folds with variably-oriented axial planes and mineralogical changes tipical of greenschist facies. In the studied region, regular variations In deformational intensity and metamorphic degree were not found. The immature sediments of the Monte do Carmo Formation are the products of the last lithogenetic processes of the Middle Proterozoic in the area. During the evolution of the Araguaia and Uruaçu fold belts, the north part of the Goiano massif had a limited participation in such a way that it functioned as a rigid block with respect to the folding on either side. The final products related to the polycyclic evolution of this crustal segment during the Priecambrian are represented by directional fault systems oriented principally N40º -60ºE and N40º -50º W. The NE system of faults reflects a reactivation of the Transbrazilian Lineament in the Upper Proterozoic. Thick sedimentary sequences were deposited in the Phanerozoic and new movements on the Transbrazilian Lineament caused the development of important block faulting which is reflected in part by the present-day geomorphology of the area.
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Avaliação geofísica e geológica de um porção de quebra de talude da Bacia do Jequitinhonha
(Universidade Federal do Pará, 2013) SANTOS, Renata Vieira dos; SARGES, Roseane Ribeiro; http://lattes.cnpq.br/9737447758598999; GOMES, Ellen de Nazaré Souza; http://lattes.cnpq.br/1134403454849660
The seismic reflection methods use at the exploration and development hydrocarbon reservoirs is due to its vast and dense sampling in both area and depth, combined with techniques refinement to processing seismic reflection data, from these data, are generated seismic sections, which after applying appropriate treatment, are used in the interpretation of the strata and/or the subsurface geologic structures. At this paper have made one Geophysics Geological analysis at two real marine seismic lines 2D of break portion embankment Jequitinhonha Basin. Therefore, we performed a set of seismic processing in order to mitigate the multiple reflections common marine data, moreover, were estimated velocity models in depth, used to determine the depth migrated seismic sections. At these were identified reflective surfaces. Through analysis at these surfaces markings of sismofacies. have made based on the initial concepts seismic stratigraphy in order to evaluate the product quality derived from the seismic processing used at this study for seismic stratigraphic interpretation, which is based on the analysis termination patterns of reflectors and internal standard of sismofacies.
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A capa carbonática do sudoeste do cráton amazônico, estado de Rondônia: nova ocorrência e extensão dos eventos pós-glaciação marinoana (635 Ma)
(Universidade Federal do Pará, 2014-11-27) GAIA, Valber do Carmo de Souza; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998
In the Western Amazon Craton, specifically in Western Parecis Basin, Rondônia State, carbonate rocks exposed on border of Pimenta Bueno and Colorado Grábens are considered to be part of the eopaleozoic basin fill. The facies and microfacies analysis together with chemostratigraphy of theses rocks in Chupinguaia and Pimenta Bueno Region, confirmed the occurrence of pinkish dolostone that overlie glaciogenic diamictite, previously interpreted as alluvial fan. Previous works reported δ13C negative excursions, confirmed in this work as well, ranging from -4.6 e -3,8‰VPDB in Chupinguaia, and average of -3,15‰VPDB in Pimenta Bueno. This sedimentation and chemostratigraphic pattern, uncommon in paleozoic rocks, is widely found in the anomalous neoproterozoic carbonates. In the Southern Amazon Craton, Mato Grosso State, rocks with the same features were described as cap carbonates related to the Marinoan Glaciation (635 Ma). Therefore this work considers this dolostones at the same context of the cap carbonate in Mato Grosso. Additionally we stand out the sharp and loaded contact between dolostone and diamictite, which happens in both occurrences, and is seemingly a typical feature of cap carbonates in the Amazon Craton. This paradoxal relationship has been interpreted as rapid change from icehouse to greenhouse conditions, and the loaded contact is attributed to isostatic rebound. The Rondônia cap carbonate presents two facies associations (FA2 and FA3) that overlie glaciomarine deposits (FA1) subdivided in two facies: Polymitic paraconglomerates (Pp) and laminated pebbly sandstone (Asl). The FA2 consists into: peloidal dolomudstone/dolopackstone with planar to quasi-planar laminations and low-angle truncations (Dp), megarriple bedding (Dm) and wave truncated laminations. This association is interpreted as shallow platform deposits wave influenced. This coastal succession is overlaid by FA3, which comprises the facies: dolomudstone/dolopackstone and dolomudstone/ dolograinstone with shale partition (Df) and laminated shaly siltstone (Sl). Df comprises 6m-thick of dolomite with parting shale, showing laterally continuous laminations of fibrous calcite (pseudomorph of gypsum) and dolomite with current wavy lamination. The Sl comprises 5m-thick of planar-laminated shaly siltstone. This association is interpreted as shallow platform deposits tide influenced. Finally, this inner platform succession is overlaid unconformably, in angular contact, by eopaleozoic glaciogenic diamictite. The isotopic values of C and O are negative and reflect the primary signal of C, however it can be considered a slight influence of meteoric diagenesis in the signal. The main shifts in negative signals are associated with meteoric influences, expressed by replacement and pores filling by calcite, and also by its proximity of stratigraphic surfaces, which reflect some patterns of diagenetic alteration, represented by the most negative signals. Differently from Mato Grosso cap carbonate, the Rondônia occurrence presents levels of pseudomorph of evaporites and dolomite with parting shale (rhythmites), order in succession of shallow marine facies, where the dolomites of wavy influenced shallow platform pass up-section to rhythmites and shaly siltstone of tide influenced shallow platform, setting up a retrogradational succession. This new occurrence of cap carbonate has strong implications to the stratigraphy of the base of Parecis Basin, since it excludes these carbonate rocks from the eopaleozoic sequence. Moreover, it provides information that allows reconstruct the coastal paleogeography of neoproterozoic basin that accumulated deposits of Araras Platform, as well extends the postmarinoan events of the Snowball/Slushball Earth hypothesis to the southwesternmost Amazon Craton, exposed in the Rondônia State.
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Caracterização paleoambiental dos sedimentos Códo-Grajaú, Bacia de São Luis (MA)
(Universidade Federal do Pará, 1992-06-25) BATISTA, Ana Maria Nunes; TRUCKENBRODT, Werner Hermann Walter; http://lattes.cnpq.br/5463384509941553
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O cenozoico superior do centro-oeste da Bacia do Amazonas: paleobotânica do embasamento cretáceo e evolução do Rio Amazonas
(Universidade Federal do Pará, 2018-11-08) BEZERRA, Isaac Salém Alves Azevedo; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998
At the end of the Neogene and during the Quaternary, the development of the Amazon River caused significant paleoenvironmental and geomorphological changes that generated current ladscape at Amazonia. Previous models elaborated on a continental scale were based on data obtained from a drill core carried out on the Atlantic continental shelf, distant 200 km of the Amazon River mouth, suggesting the establishment of this drainage with Andean provenance from the Middle to Upper Miocene. In contrast, studies based on outcrops in the western and central portions of the Amazon have indicated younger ages for this ecosystem, from Pliocene to Quaternary. The sedimentological-stratigraphic study of the fluvial terraces of the Amazon River, exposed in the center-west portion of the Amazon Basin, assisted by luminescence geochronology, allowed to sequence the sedimentation events and discuss the paleoenvironmental and paleogeographic since Late Neogene. The studied Neogene- Quaternary deposits overlies Cretaceous rocks whose sedimentological and paleobotanical study revealed the preservation of impressions and counter-impressions of leaves and other macro-plant remains in pelites interpreted as flood plain and abandoned channel deposits of meandering rivers. The first record of angiosperms in this unit with possible affinities to the families Moraceae, Fagaceae, Malvaceae, Sapindaceae and Anarcadiaceae with appearance from Late Cretaceous, and the family Euphorbiaceae with record starting in the Mid- Cretaceous confirm the Cretaceous age for these rocks. The terraces of the Amazon River informally subdivided into lower and upper units are composed of sand, gravel and clay, organized in finning upward cycles representative of channel filling and overbank deposits. The lower unit was interpreted as a record of the proto-Amazonas, with migration to the east and deposition around 2 Ma. During this stage, the alluvial plain was restricted, preferentially following weakness zones coincident with fractures in the Paleozoic and Cretaceous basement. The climatic oscillations during the Quaternary and the increase of the volume of orographic rains in the headwaters region of the fluvial systems, in the eastern flank of the Andean ridge modified the hydrological regime, amplifying the escarpment erosion. The gradual expansion of the alluvial plain formed a large area of 120 km around 1 Ma to 140 ka, recorded by the upper unit deposits. At this stage, the eastern portion of the Amazon Basin topographically higher restricted the Pleistocene sedimentation in minimum accommodation space. The lower unit deposits are correlate in part to the Miocene-Pliocene deposits of the Amazon Basin, while the upper units are correlate with the Pleistocene deposits of the Solimões and Amazon basins. The dynamics of the construction of the Amazon River valley during the end of the Neogene and Quaternary was influenced by neotectonics (106 yr) and climatic oscillations (104-105 yr). The landscape of the central-eastern portion of the Amazon dominated no Pleistoceno by terra firme in elevated areas was governed by the dynamics of expansion and contraction of the alluvial plain. At the end of the Quaternary, the várzea formed by floodplains within the alluvial plain, which used to occupy a wide area, became increasingly restricted by the continuous processes of fluvial incision during the glacial maximum (18 to 22 ka). The continuous lateral migration of the meandering channel to the north led to the confinement of the channel by the fluvial scarps developed in the Cretaceous basement, which culminated in the current landscape in the Center-East of the Amazon. Testing the reliability and accuracy of some Pleistocene and older OSL ages for Amazon River deposits revealed that are much more minimum ages than buried ages for pre- Quaternary deposits.
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Correlação de poços com múltiplos perfis através da rede neural multicamadas
(Universidade Federal do Pará, 2001-11-23) AMARAL, Mádio da Silva; ANDRADE, André José Neves; http://lattes.cnpq.br/8388930487104926
Stratigraphic correlation using well logs is a non-trivial geological activity and subject to endless possibilities of misunderstanding about the geometry or continuity of rock layers, for many reasons, like the geological variability and the ambiguous answers of the log tools. Thus, it is common to utilize a great log suite from the same well, for better comprehension. The stratigraphic correlation is a fundamental tool for a geologist or petroleum geophysist, because from its knowledge it is possible to interpret the hydraulic continuities of the reservoirs and to reconstruct the geological setting environment, which may corroborate for the construction of the reservoir geological model. This work produces an automation of manual activities involved in the stratigraphic correlation, with the use of the various well logs, and a convenient architecture of artificial neural network, trained with the backpropagation algorithm. The stratigraphic correlation, obtained from this method, makes the transport of the geological information possible along the basin and gives the interpreter, a general view of the structural behavior of the oil reservoir. With This methodology was possible the automatic construction of a geological block diagram showing the spatial disposition of a particular shale layer, from the well logs: Gamma Ray (GR), Clay Volume (Vsh), Density (ρb) and the Neutron Porosity (φn), selected in the five wells on the Maracaibo Lake basin, in Venezuela.
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Estratigrafia da sucessão sedimentar Pós-Barreiras (Zona Bragantina, Pará) com base em radar de penetração no solo
(2001-08) ROSSETTI, Dilce de Fátima; GÓES, Ana Maria; SOUZA, Lena Simone Barata
Ground penetrating radar (GPR) is a geophysical method that consists in the emission of electromagnetic waves of high frequency (between 10-2500 Mhz). This equipment has been increasingly applied for mapping of physical properties and chemical compositions of rocks at shallow depth, as well as for stratigraphic and facies analysis. The application of this methodology in Brazil is still reduced to a few studies, mostly emphasizing soil stratigraphy and eolian paleoenvironments. However, previous studies undertaken in northern Brazil have demonstrated that, in combination with traditional studies using outcrop data, the GPR might be a powerful additional tool to help correlating sedimentary successions and reconstruct depositional environments throughout the Neogene in the Bragantina Zone. In this paper, we will document a pioneer investigation applying a SYR-2 GPR system (Geophysical Survey Systems Inc.) in the Praia do Atalaia area, Salinópolis, northern Brazil, which allowed us to characterize, for the first time, facies and stratigraphy of the deposits known informally as Pós-Barreiras Sediments (Pliocene and younger). The equipment was operated using a 200 Mhz monostatic antenna in continuous mode. The acquired sections were processed using the RADANWIN software in order to increase the reflection resolution and thus allow a refined interpretation of the sections. Based on this procedure, it was noticed that the studied sedimentary succession overlies unconformably the Miocene basement, represented by the Pirabas/Barreiras formations. Three stratigraphic units were also distinguished. The lowermost Unit 1 consists of an interval up to 6 m thick dominated by poorly-defined, low amplitude reflections, which intergrade with medium-scale, tangential oblique and hummocky reflections. This unit revealed to be discontinuous throughout the studied radar sections, occurring mainly where the Miocene basement is depressed. The middle Unit 2 is circa 9 m thick and mostly includes large-scale oblique reflections varying in style from parallel, tangential, sigmoidal to sigmoidal complex. The two latter ones might reach up to 7 m thick. A strong, high amplitude and laterally continuous reflection marks the top of Unit 2, forming a bounding surface having local depressions of up to 40 m in relief. The uppermost Unit 3 corresponds to an interval ranging from 3.5 to 9 m thick, which is dominated by hummocky reflections, followed by medium-scale oblique, parallel to sub-parallel and cut and fill reflections. The GPR data allows the interpretation that the Pós-Barreiras Sediments were unconformably deposited over the Miocene deposits, as revealed by the mapping of an erosional bounding surface at the base of Unit 1. In addition, the analysis of internal reflection configurations and reflection geometries led us to propose that the Pós-Barreiras Sediments is more variable in terms of facies than previously thought, including eolian deposits (coastal dunes), as well as beach ridge, tidal flat, channel and mangrove deposits. Furthermore, the mapping of the three stratigraphic units described above is important to unravel the complexity of sedimentation versus erosion during the latest Neogene in northern Brazil. The conclusions obtained from the GPR data lead to suggest a drop in relative sea level after the end of the Miocenelower Pliocene in the Bragantina Zone, which was followed by a transgression and deposition of Unit 1 along embayments and adjacent eolian dunes and/or beach ridges. Renewed phase of relative sea level drop took place, which led to erosion of the uppermost portions of Unit 1, forming a bounding surface that is locally cut by fluvial channel scouring. Large-scale eolian dunes laterally intergraded with tidal flat, filling the depressions formed by channel erosion during a subsequent transgressive phase. At least one more drop in relative sea level appears to have taken place in the study area, as revealed by the discontinuity surface between units 2 and 3, which is in turn mantled by modern sedimentation along mangroves, tidal channels and coastal dune environments.
Acesso aberto (Open Access)
Estratigrafia de dunas costeiras de Salinópolis/PA em associação com variações pluviométricas
(Universidade Federal do Pará, 2010-09-24) LEITE, Wladson da Silva; SOUZA FILHO, Pedro Walfir Martins e; http://lattes.cnpq.br/3282736820907252; ASP NETO, Nils Edvin; http://lattes.cnpq.br/7113886150130994
The present study was carried out at Salinópolis covering the Atalaia and Maçarico beaches (PA/North Brazil) to obtain a morpho-stratigraphic overview of the local coastal dunes and their evolution in Late Holocene, considering also climatic oscillations. Ground Penetrating Radar (GPR), auger coring, granulometric analysis and dating were used. The GPR-system SIR-2000 with a 400MHz antenna was used to reveal dune stratigraphy, including sedimentary facies and reactivation surfaces. At key-points of profiles sediment cores were obtained to proper interpretation of radargrams and sediment samples collection for grain size analysis and optical dating. At the Maçarico beach two main foredune crests were identified and dated at 69 and 80 years B.P. revealing a progradation rate of around 6 meters/year. The Atalaia beach presented a transgressive scenario, including retrogradation of the Holocene beach over older sediment layers, which include a feature interpreted as of Pleistocene age, although optical dating indicates an age of only 58 years B.P. due to actual sun light exposition. There, a parabolic dune was investigated and had revealed a migration rate of around 4 meters/year, where the reflectors indicate annual episodes of migration, possibly corresponding to the seasonal cycles of dryer periods and stronger winds. The general stratigraphy of the area seems to be a good tool for further studies on climate for the region, due to its good correlation with seasonal climatic patterns and long term register.
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Estratigrafia e evolução estrutural do segmento setentrional da faixa de desdobramentos Paraguai - Araguaia
(Universidade Federal do Pará, 1979-06-13) ABREU, Francisco de Assis Matos de; HASUI, Yociteru; http://lattes.cnpq.br/3392176511494801
The northern part of the Paraguai-Araguaia orogenic belt comprises a significant portion of the South American Platform. Here, the Brazilian geotectonic cycle (550-900 m.y), produced a mountain chain through a complex sequence of sedimentary metamorphic, magmatic, and structural events along the eastern margin of the Amazon craton. The lithologic sequence is designated stratigraphically as the Baixo Araguaia Supergroup which comprises the Estrondo Group and the overlying Tocantins Group. The basal formation in the Estrondo Group is the Morro do Campo Formation which consists of quartzites and subordinate schists and gneisses. The Xambioá overlies the Morro do Campo and includes several kinds of schists. The Tocantins Group is formed by Couto Magalhães Formation, represented by phyllites and intercalated quartzites and the overlying Pequizeiro Formation consiwts of pelitic sediments and Mg-rich igneous derivatives. The Estrondo and the Tocantins groups are intruded by ultramafic, mafic, and granitic rocks that are associated with late and post-tectonic igneous events. The Rio das Barreiras Formation, a sedimentary sequence represented by a polymictic conglomerate with carbonate matrix and sandy and silty interlayers, unconformably overlies the Pequizeiro Formation and may represent erosional remnants of a final phase of the Brazilian cycle. Primary lithologic structures in Baixo Araguaia Su pergroup are preserved as relict compositional stratification, inclined, parallel, and graded bedding in metasediments, and flow structures in the igneous rocks. Superposed penetrative planar and linear deformation structures are present in several generations. The regional N-S striking schistosity is of axial-plane type and is related to the intrafolial folds, with an easterly dip getting vergence to Amazon craton. The regional dip is 309 and decreases to abaut 159 adjacent to the Amazon craton. Gneissic banding parallels schistosity of overlying schists in the larger folds and they share a common mineral lineation. Polyphase deformation is recorded by a fold sequence which varies in scale from 1 cm to 30 km and is related to the differents structural levels within the crust. The lower structural level includes: a) similar-type intrafolial isoclinal folds which are contemporaneous with regional metamorphism; b) similar tight folds which involve the s.chistosity and transposed bedding; c) shear folds of crenulation developed near to the top of the level in the more plastic horizons. The intermediate level comprises; d) isolated regional flexures near the localities of Colméia, Xambioà-, Lontra, Muricizal; e) two generations of open and cross folds associated with the Iriri-Martírios lineament zone. N-S and NW-SE fracture and fault systems cut ali stratigraphi.c units of the Baixo Araguaia Supergroup. The faults consist of: 1) NW treding transcurrent fault with strike iengths of severa]. Kilometers; 2) thrust faults with N-S- strike such as those near Andorinhas and Muricizal mountains; 3) N-S striking normal faults developed at the edge of the Parnaíba basin and elsewhere. The mapped facies sequence ranges from incipient greenschist facies in the west to amphibolite facies in the east implying an Bastward increase in metamorphic grade. Sericite to garnet isograds are discernibles. Three magmatic events are distinguished. They comprises: a) pre-tectonic basic and ultrabasic plutonic-volcanic magmatism; b) late-tectonic granitic intrusion; c) post- tectonic unfoliated granitic intrusions. Eleven K-Ar mica dates from gneisses and schists of the orogenic belt yield values in the range of 516 ± 10 m.y to 358 ± 19 m.y. (Brazilian Cycle). Five Rb/Sr determinations from the gneissic core of the Colméia fold gives values around 2,000 m.y (Amazonic cycle). The geologic evolution of the northern Paraguai-Araguaia orogenic belt consists of three sequential stages: I) deposition of psammitic and pelitic sediments comprising the Estrondo and lower Tocantins Groups. Basic and ultrabasic igneous activity in late Tocantins time result in the deposition of mixture of pelitic sediments and Mg-rich igneous material which comprise the Pequizeiro Formation. II) polyphase deformation, metamorphism, magmatism, and orogenic uplift followed. These events are subdivided as follows: 1) F1 - deformation and regional metamorphism (Ma) in which So (original bedding) was transposed by isoclinal folding to S1 (regional schistosity) and progressive metamorphism produced sericite and garnet map zunes; 2) F2 - deformation produced tight folds in the schistosity (S1) resulting an axial plane surface (S2); well-marked mineral lineation (L2); 3) F3 deformation developed crenulation folds and a second phase of transposition (S3); e) F4 - deformation produced large folds accopanied by migmatization and late-tectonic granitic intrusions; 5) F5 - deformation formed small-scale plastic folds in cataclastic zones along the Iriri-Martírios lineament. III) The post-metamorphic Rio das Barreiras Formation was then deposited unconformably over this structural sequente and the final deformation event produced fault movements (transcurrent, thrust and normal), established joints, and permitted the rise of post-tectonic granitic plutons. This stage marks a transition from an environment of compressional stress to one of tensional stress on the regional scale. Subsequent to stageIII, consolidation of the South American platform occurred. Related erosional, sedimentary, magmatic, and'tectonic processes affedted this ares at numerous times throughout post-Brazilian cycle time.
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Estratigrafia e tectônica da Faixa Paraguai Norte: implicações evolutivas neoproterozóicas no Sudeste do Cráton Amazônico
(Universidade Federal do Pará, 2016-11-11) SANTOS, Iara Maria dos; PINHEIRO, Roberto Vizeu Lima; http://lattes.cnpq.br/3251836412904734; NOGUEIRA, Afonso César Rodrigues; http://lattes.cnpq.br/8867836268820998
The Northern Paraguay Belt, located at Southeast of Amazonian Craton, was established during the final stages of Brasiliano Cycle (940-620 My.) marked by the collisions among Amazonian, San Francisco and Rio de La Plata cratons to assembly the Gondwana West Supercontinent. The Northern Paraguay Belt consists mainly of metasedimentary rocks of the Cuiabá Group (720 My.), assigned to passive margins basins in an extensional context during the break-up of Supercontinent Rodinia (1.0 Gy.). These basins were affected by tectonic inversion by Brasiliano Orogeny, causing regional metamorphism and ductile crustal level deformation. Subsequently, the orogen had been uplifted, exposed to erosion and subjected to extensional episodes, developing intracratonic basin where sedimentary rocks of the Puga Formation (635 My.), Araras Group (627 ± 32 My.), Raizama Formation (645 ± 15 My.) and Diamantino Formation (541 ± 7 Ma.) were unconformably deposited in moderately deep to shallow storm influenced plataformal environment, tidal affected transitional environment and, lacustrine deltaic environment, respectively. These rocks are classically assigned to a Foreland Basin, however, ancient suture zones usually exposes the orogen roots, and these basins are currently not well preserved. These intracratonic or plataformal basin sedimentary rocks show considerable thicknesses and outcrop in Northeast-Southwest aligned trending mountain ranges. The São Vicente Granite (518 My.) and the Tapirapuã Formation basalts (197 My.) occur as intrusive rocks in the studied area along the Northern Paraguay Belt. The geological contacts between the metasedimentary rocks of the Cuiabá Group with sedimentary rocks of Puga Formation, Araras Group and Alto Paraguay Group, is interpreted as non-conformity. The Cuiabá Group rocks (720 My.) are mainly composed by quartz, plagioclase, muscovite, biotite and phengite and correspondent to greenschist facies affecting a low grade pelitic protolith. These rocks were deformed by ductile shear zone trending Northeast-Southwest, with strain partitioning, described as Transpressional Structural Domain D1, which was divided into two deformation facies: (1) D1-A and (2) D1-B. (1) The D1-A features a fine continuous foliation and stretching mineral lineation, with a rake of 40º, moderately inclined to recumbent, “S” type asymmetrical flexural folds; ductile-brittle thrustfaults and late strike-slip dextral ductile-brittle shear bands; (2) The D1-B is marked by a mylonitic foliation, with its stretching mineral lineation, with a 15º rake. These deformational facies comprises a mainly transpressional sinistral flow mostly dominated by simple shear and influenced by the strain partitioning. All structures indicate tectonic vergence from Northwest toward Southeast, as a result of the collisional setting of the Brasiliano Orogeny (620 Ma.). The sedimentary rocks were deformed under brittle crustal level conditions. Consequently they show inclined to subvertical, asymmetric "Z" type drag folds indicating dextral movement, besides normal faults and cataclastic foliation. The drag folds in the sedimentary rocks indicate tectonic vergence toward both Southeast and Southwest, therefore they were not generated under directed tectonic effort. Normal faults which deform sedimentary rocks are related to later transtensional reactivation episodes of ancient structures forming drag folds and Post-Paleozoic grabens affecting both the Parecis and Parana sedimentary basins. Late quartz veins occur emplaced only in the Cuiabá Group rocks. In conclusion, the Northern Paraguay Belt rocks were affected for at least two main tectonic episodes: (1) The Brasiliano Orogeny, only represented by Cuiabá Group rocks which show metamorphism and ductile deformation; (2) and transtensional reactivation that had been responsible for the establishment of the sedimentary basins followed by brittle deformation of Puga Formation, Araras Group, Raizama and Diamantino Formation.
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Estudo sedimentológico da formação Pedra de Fogo-Permiano: Bacia do Maranhão
(Universidade Federal do Pará, 1979-10-17) FARIA JUNIOR, Luis Ercílio do Carmo; TRUCKENBRODT, Werner Hermann Walter; http://lattes.cnpq.br/5463384509941553
The Pedra de Fogo Formation of the Early-Middle-Permian in the Maranhão Basin is characterized by a ciclic sedimentation with fine sandstone intercalated with siltstones, shales and carbonatic banks which have abundant sílex beds and concretions. On surface this unit is divided into three members named Basal' Silex, Middle and Upper, Trisidela. Silicified oolites, pellets, coquinas with ' fish remains, stromatolitic beds and wood remains are found in the Pedra de Fogo. Formation sediments. The lithologies indicate a shallow, restricted, marine environment ' with two transgressions phases separated by a regression phase. The lateral facies changes reflect the sedimentary dynamism and suggest that the marine environment progressed from a transitional, deltaic to shallow neritic one. The main source areas of the clastic sediments and some of the sílica are, located in the northestern to the southern parts of the Basin and derived ' from the Borborema and São Francisco Provinces rockes. The Tocantins and. Tapajós Provinces to the west and southest have supplied material also. The climate during the Pedra de Fogo sedimentation has varied from moderate to arid as a consequence of the northward South American continent slow migration. The Maranhão had tectonic stability during the Permian. The marine in cursions took place from west, through the Amazonas Basin. Besed on the cyclothemes thickness, it seems that the Pedra de Fogo sedimentation occured from the water level oscilations in the Basin, which had also motivated the transgressions and regressions phases and whose origin should be related to the climatic changes during the Permian time.
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Estudo sedimentológico dos sedimentos Barreiras, Ipixuna e Itapecuru no nordeste do Pará e noroeste do Maranhão
(Universidade Federal do Pará, 1981-06-24) GÓES, Ana Maria; TRUCKENBRODT, Werner Hermann Walter; http://lattes.cnpq.br/5463384509941553
Barreiras, Itapecuru and Ipixuna are exposed in large regions of Pará and Maranhão State. The Barreiras sedimente are divided in conglomeratic, sandy clay and sandy lithofacies. Textural imaturity and abundant mud-s.upported clastics in particular, suggest depositions mainly by debris flows under semiarid conditions. The three lithofacies were probably derived from Precambrian schists of Santa Luzia Formation and preexisting sedimente. The Itapecuru sedimenta consist of crossbedded sandstones, locally with minor conglomerates and mudstones, deposited in fluvial environment, probably tending to a semiarid conditions. The Ipixuna facies consiste of crossbedded kaolinitic sandstones, minor mudstones (lithology A) and laminated mudstonefine sandstone units including thick kaoline layers (lithology B). The fine sandstones are texturally and mineralogically mature. Lacustrine-fluvial origin is proposed for Ipixuna facies. The impoverished heavy-mineral assemblage and thick kaoline-layers suggest humid hot climate that probably prevailed before (during?) the Ipixuna sedimentation. Textural and structural characteristics of the sedimente studied show that there is a olear difference between Barreiras Group and Ipixuna facies and that the latter is correlated with the Itapecuru Formation. Bauxitization of lower Tertiary age affected only the Ipixuna and Itapecuru sedimentary rocks.
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Estudo sedimentológico e estratigráfico dos sedimentos holocênicos da costa do Amapá - setor entre a ilha de Maracá e o cabo Orange
(Universidade Federal do Pará, 1994-02-21) MENDES, Amilcar Carvalho; FARIA JUNIOR, Luis Ercílio do Carmo; http://lattes.cnpq.br/2860327600518536
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Evolução geológica da porção centro-sul do Escudo Guianas com base no estudo geoquímico, geocronológico (evaporação de Pb e U-Pb ID-TIMS em zircão) e isótopo (Nd-Pb) dos granitóides paleoproterozóicos do sudeste de Roraima, Brasil
(Universidade Federal do Pará, 2006-11-17) ALMEIDA, Marcelo Esteves; MACAMBIRA, Moacir José Buenano; http://lattes.cnpq.br/8489178778254136
This study focuses the granitoids of center-southern portion of Guyana Shield, southeastern Roraima, Brazil. The region is characterized by two tectono-stratigraphic domains, named as Central Guyana (GCD) and Uatumã-Anauá (UAD) and located probably in the limits of geochronological provinces (e.g. Ventuari-Tapajós or Tapajós-Parima, Central Amazonian and Maroni-Itacaiúnas or Transamazon). The aim this doctoral thesis is to provide new petrological and lithostratigraphical constraints on the granitoids and contribute to a better understanding of the origin and geodynamic evolution of Guyana Shield. The GCD is only locally studied near to the UAD boundary, and new geological data and two single zircon Pb-evaporation ages in mylonitic biotite granodiorite (1.89 Ga) and foliated hastingsite-biotite granite (1.72 Ga) are presented. These ages of the protholiths contrast with the lithostratigraphic picture in the other areas of CGD (1.96-1.93 Ga). Regional mapping, petrography, geochemistry and zircon geochronology carried out in the UAD have showed widespread paleoproterozoic calc-alkaline granitic magmatism. These granitoids are distributed into several magmatic associations with different paleoproterozoic (1.97-1.89 Ga) ages, structural and geochemical affinities. Detailed mapping, petrographic and geochronological studies have distinguished two main subdomains in UAD. In the northern UAD, the high-K calc-alkaline Martins Pereira (1.97 Ga) and Serra Dourada S-type granites (1.96 Ga) are affected by NE-SW and E-W ductile dextral shear-zones, showing coexistence of magmatic and deformational fabrics related to heterogeneous deformation. Inliers of basement (2.03 Ga) crop out to northeastern part of this area, and are formed by metavolcano-sedimentary sequence (Cauarane Group) and TTG-like calc-alkaline association (Anauá Complex). Xenoliths of meta-diorites (Anauá Complex) and paragneisses (Cauarane Group) reinforce the intrusive character of Martins Pereira Granite. On the other hand, xenoliths of Martins Pereira and biotitebearing enclaves are founded in the younger, undeformed, and SiO2-rich Igarapé Azul Granite (1.89 Ga). This last and the high-K calc-alkaline Caroebe Granite (1.90-1.89 Ga, Água Branca Suite), including coeval volcanic rocks (1.89 Ga, Jatapu volcanics) and charnockitoids (1.89 Ga, e.g. Santa Maria Enderbite), crop out in the southern UAD. This subdomain is characterized only by local and slight NE-SW ductile-brittle dextral shear zones. A-type granites such as Moderna (ca. 1.81 Ga) and Mapuera (ca. 1.87 Ga) granites, cross cut both areas of UAD. Furthermore, the geological mapping also identified three main types of metalotects in this region. Gold mineralization is observed in Martins Pereira-Serra Dourada granitoids (northern UAD), alluvial columbite-tantalite is related to Igarapé Azul granitoids (southern UAD), and amethyst is associated to pegmatites from Moderna A-type granites. The Nd-Pb isotope data suggest that all granitoids of UAD are generated by reworking of older and pre-existence crustal sources (sialic Rhyacian-Archean and/or juvenile Transamazonian origin) and mantle input is not problably a viable model. Although the dominant process may be one subduction in the early stage of NUAD evolution, post-colisional magmatism may be a significant process in the production of new continental crust in the southern UAD. It is possible that, following oceanic closure in the Anauá arc system (2.03 Ga) and subsequent collisional orogeny (1.97-1.94 Ga?), underplated mantle melts (basalt liquids) were trapped below preexisting lower crustal rocks of various compositions (e.g. granulites, metatonalites, amphibolites). The basalt liquids and subsequently melted lower crust could produced the immense volumes of granite (and volcanics) observed at 1.90-1.87 Ga. This geological picture is similar to the Tapajós Domain (TD) in the southern Amazonian Craton and suggest that both belongs to the same province (Ventuari-Tapajós or Tapajós-Parima). Nevertheless, the scarcity of S-type granites and high-grade metamorphic rocks show that the collisional stage is not so evident in TD.
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Evolução geológica da região de Araguacema-Pequizeiro-Goiás-Brasil
(Universidade Federal do Pará, 1981-12-21) GORAYEB, Paulo Sérgio de Sousa; ALBUQUERQUE, Carlos Alberto Ribeiro de
The region around Araguacema, Pequizeiro and Conceição do Araguaia, belongs to the Araguaia Fold Belt and exhibits a metasedimantary litological sequence which was subjected to deformation and metamorphism at least in the Upper Proterozoic. Geological mapping, structural-stratigraphic, petrographic and chemical analises permit the elucidation of the geological evolution of the ares. The sequences have been included in the Tocantins. Group constituted of Pequizeiro and Couto Magalhães Formations. Ultramafic and mafic-ultramafic bodies represent both pre and post-tectonic magmatic events. The Rio das Barreiras Formation overlays with an angular unconformity the Tocantins sequences. Pequizeiro Formation is the lower unit of the Tocantins Group and is litogically composed of micaschists, with some quartzites, calcschits, and magnetite-muscovite-phyllites. These rocks represente a metasedimentary sequence derived mostly of pelite and graywacks. The unit Couto Magalhães comprises essentially phyllites and slates with minor metapsammites, metapelites, cherts, lenses of limestones and metagraywackes. Most of these rocks represent an original pelitic sequence. Lenticular serpentinitic bodies of dunitic nature have been introduced in the Couto Magalhães Formation by tectonic processes. All of these bodies are associeted to fault zones and have N-S trends.. They are of alpine type but, they may represent ophiolitic bodies. These sequences underwent poliphasic deformational and metamorphic processes during the Middle Proterozoic and up to the Brasiliano Cycle. The structural evolution comprised three plastic deformation phases called F1, F2 and F3. The metamorphic history included two different events called M1 and M2 with synchronical relation between Ml-F1 and M2-F3, and has a large variation.from ankimetamorphism (west) to greenschist facies (east). Three isograds (sericite, chlorite and biotite) have been defined from W to E, as the temperature grows. In the Upper Proterozóic (Brasiliano Event) ruptural tectonic processes reactiveld ancient basement faults and formed new normal faults and fractures. Hornblends Peridotite plutons; diabase dikes and gabbro stocks were emplaced in the Couto Magalhães Formation, representing post-tectonic magMatfc events. Polymitic conglomerates and siltstonea of Rio das Barreiras Formatian acumuiated in grabens, reflecting the Brasiliano tectonic rellef. In the Phanerozoic, intensiva laterization and weathering have developed in an extensive area in the Araguaia valley with sandy and argillaceous sedimentation along the rivers.
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Evolução geológica da região de Colméia
(Universidade Federal do Pará, 1980-09-03) COSTA, João Batista Sena; HASUI, Yociteru; http://lattes.cnpq.br/3392176511494801
A geological mapping of the Colmeia region, in northern Goiás, has been carried out on a 1:100.000 scale. Semi-detailed geological observations coupled with stratigraphic, structural and petrological data are integrated aiming at the geological evolution of that region. The oldest recognized unit, the Archean Colmeia Complex, is represented by gneisses, granites and migmatites with associated schists, quartzites and amphibolites, and forms the central core of the Colmeia brachyanticline. Two main deformation periods have affected these rocks at the end of the Archean: the earliest period, F1deformed the rock banding surfaces into folds with E-W orlented axes and originated a well-defined axial-plane schistosity; the other one, F2, caused the refolding of the banding surfaces and folded the schistosity planes as to produce folds also with E-W oriented axes. Furthermbre, two migmatization phases were recognized: the first phase was contemporaneous with F1 and formed quartz-feldspar-rich neossomes in which minerais show a preferred orientation; the second phase predates F2 but post-dates F1, and is characterized by neossomes consisting essentially of non-oriented quartz and feldspar minerals. In the Middle Proterozoic, the Amazon Craton was regenerated leading to the accumulation of a thick volcano-sedimentary pile known as the Baixo Araguaia Super Group (Abreu, 1978). The lower unit of this pile is represented by the Estrondo Group which consists, from bottom to top of the Morro do Campo Formation (quartzites with schist intercalations), the Xambioá Formation (schists of various lithologies) and the Canto da Vazante Formation (feldspathic schists with biotite schist intercalations). The upper unit constitutes the Tocantins Group which is represented in the Colmeia region by the chlorite-quartz schists of the Pequizeiro Formation. Metamorphosed mafic and ultramafic rocks are associated with both the Estrondo and the Tocantins Group. In the Colmeia region, the Baixo Araguaia Super Group had a poliphasic evolution throughout the Middle Proterozoic. Its rocles recorded three major deformation periods: the first one is represented by intrafolial folding of the So surfaces and by the formation of an axial-plane schistosity; the second deformation event disturbed the schistosity surfaces generatinÉ folds with inclined axial planes and N-S oriented axes; the third deformation period is characterized by crenulation of the schistosity. The resulting folds have milimetric to kilometric dimensione and their axes parallel. NW-SE directions. Where the schistosity was completely transposed, crenulation cleavage was developed and biotite and chlorite recrystallizations took place on the transposition planes. The planar structures of the Baixo Araguaia basement were bent in response to shearing. Regional metamorphism of greenschist and amphibolite facies is concomitant with the first deformation episode while the second event affected the underlying Colmeia Complex superirnposing a similar folding style; at the same time contemporaneous migmatization originated N-S oriented quartz-feldspathic neossomes. Subsequent remobilization of the Colmeia Complex and the emplacement of intrusive granitic bodies gave rise to the Colmeia brachyanticline with which minor N-S oriented folds are associated. Radial faults were developed cutting both the basement and the metasedimentary cover. Other major discontinuities are also related to this event. The sedimentation of the Rio das Barreiras Formation marks the final act of the evolutionary history of the Colmeia region. Such an evolution included lithogenetic processes of the Archean and Middle Proterozoic as well as thermo-tectonic phenomena related to the Jequié and Uruaçuano cycles. K-Ar and Rb-Sr radiometric dating indicates reheating associated with the Transamazonic and Brazilian cycles.
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Evolução tectono-estrutural da região de Dianópolis-Almas, SE do estado de Tocantins
(Universidade Federal do Pará, 1993-12-17) BORGES, Maurício da Silva; COSTA, João Batista Sena; http://lattes.cnpq.br/0141806217745286
Several geological sequences of rocks with distinct ages of evolution were mapped in the Dianopólis-Almas region (southwestern part of the State of Tocantins) in the Brasília block: an extensive segment of an Archean-Lower Proterozoic granite-greenstone terrain, Proterozoic metasediments of the Bambuí Group, Cretaceous continental deposits of the Urucuia Formation, colluvial and alluvial (partially lateritized) and Holocenic fluvial-lacustrine deposits. The granite-greenstone terrains include several strands of supracrustal rocks (Riachão do Ouro Group) and granitoid bodies (Serra do Boqueirão Suite), both developed over migmatized tonalitic gneisses, granulites and amphibolites of the Alto Paranã Complex. The Riachão do Ouro Group is composed of phyllite, schist, meta-rhyolite, meta-dacite, iron formation, quartzite, metaconglomerate and breccia; phyllite, schist and metavolcanic rocks are the dominant lithologies. The Serra do Boqueirão Suite includes granitoids of tonalitic, trondhjemitic, granodioritic and granitic compositions, which were strongly deformed in the border zones and cut by pegmatite and aplite veins. All there lithological units underwent ductile deformation which formed an anastomosed pattern of N10-20E, N45E, and N55W transcurrent shear zones. Along the shear zones there are asymmetric or symmetric transpressive duplexes alternating with straigth segments. These structures can be seen extensively developed at supracrustal rock-granitoid boundaries and are characterized by mylonitic foliation parallel to the tectonic layering; other structures are represented by internal duplexes, shear bands, pods of less deformed rocks, extensional cleavage of C' type (crenulation cleavage) and brittle-ductile shear zones expressed by dilatation structures (tension gashes). The stretching lineation is defined by rods of quartz, axes of agregates of elliptical minerais and elongated micas. Dextral sense of shearing is determined from kinematic criteria. Microfabric investigation suggest that the deformation was accommodated mainly by crystal plasticity and the crystallographic shape fabrics confirm the dextral sense of shearing. Only the N55W shear zones underwent sinistral movement. The observed sets of structures is interpreted as linked to a N20E dextral strike-slip system and, in this case, the N10-20E, N45E, N25W and N55W zones correspond respectively to Y, R, P and R' zones. The Archean-Lower Proterozoic evolution is understood in terms of an oblique collision of continental segments which uplifted the granulitic rocks and was followed by transtension regime which originated several basins in where the supracrustal rocks of the Riachão do Ouro Group were deposited, and the granitoids of the Serra do Boqueirão Suite were emplaced. The progressive deformation involved transpression characterized by ductile shear zones. The Middle to Upper Proterozoic is represented by the Bambuí Group which includes slates, metasiltites, phyllites and carbonate rocks. The tectonic structures linked to the São Francisco Basin inversion in the Upper Proterozoic, are represented by N-S oblique thrusts and NE-SW lateral ramps. During the Mesozoic (Upper Cretaceous) the Alto Sanfranciscana Basin was filled by continental sediments of the Urucuia Formation. The lithostratigraphic sequence is composed of the following lithofacies: 1) conglomeratic facies which represents residual paviments of.deflation and in part interdune deposits and wadifans related to an intermittent drainage system; 2) sandstone facies formed by ortoquartzite, arkose and subarkose which constitute wind deposits; 3) and stratified chert facies which represent chemical lacustrine deposits. The basin architecture includes also NNW-SSE listric normal faults and NE-SW transfer faults related to a N5OE extensional axis. During the Tertiary coluvial and aluvial deposits, which underwent lateritization as an immature profile, were formed. The Quaternary is represented by a lacustrine-fluvial sedimentary system. The drainage system is related to the basin of the Manoel Alves and Araguaia rivers, strongly controlled by NE-SW lineaments and associated to pull-apart structures linked to a dextral system.