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An?lise estratigr?fica da sequ?ncia mesodevoniana-eocarbon?fera da Bacia do Parna?ba, nordeste do Brasil

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Previous issue date: 2015-08-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / A Sequ?ncia Mesodevoniana-Eocarbon?fera da Bacia do Parna?ba, litoestratigraficamente definida como Grupo Canind?, foi reinterpretada empregando-se o modelo b?sico da estratigrafia de sequ?ncias. Para tanto, foram analisados perfis litol?gicos e de raios gama de po?os e linhas s?smicas da regi?o central da bacia, elaborando-se a partir da? diagramas 1D, mapas de is?coras e uma se??o estratigr?fica.
Como resultados deste trabalho, foram definidos dois ciclos deposicionais de segunda ordem, referidos como Sequ?ncia Deposicional 1 (SEQ1) e Sequ?ncia Deposicional 2 (SEQ2). A SEQ1, com cerca de 37 Ma, ? limitada abaixo pela Discord?ncia Eodevoniana e equivale ?s forma??es Itaim, Pimenteiras e Cabe?as.
A SEQ1 se inicia com o Trato de Sistemas de N?vel Baixo, constitu?do por conjuntos de parassequ?ncias progradacionais em que a parte basal, predominantemente pel?tica, depositou-se em um contexto de prodelta sob influ?ncia de tempestades e a superior ? composta por arenitos de frente deltaica, tendo como limite superior a superf?cie regressiva m?xima. O Trato de Sistemas Transgressivo, depositado acima, ? caracterizado por conjuntos de parassequ?ncias retrogradacionais, compostos predominantemente por pelitos de plataforma rasa, depositados sob a??o de tempestades. A superf?cie transgressiva m?xima, limite superior deste trato, ? posicionada em um n?vel de folhelho cuja radiatividade no perfil de raios gama ? pr?xima a 150 API. O Trato de Sistemas de N?vel Alto apresenta conjuntos de parassequ?ncias progradacionais, compostos por pelitos e arenitos depositados em ambientes plataformal, fl?vio-estuarino e periglacial, tendo como limite superior a Discord?ncia Neodevoniana.
A SEQ2, que se segue, compreende um intervalo de cerca de 15 Ma e equivale ? Forma??o Long?. A mesma foi depositada em ambiente plataformal, iniciando com o Trato de Sistemas de N?vel Baixo, caracterizado por um conjunto de parassequ?ncias progradacional, seguido do Trato de Sistemas Transgressivo, de car?ter retrogradacional. O limite superior deste trato corresponde ? superf?cie transgressiva m?xima ou ainda, a fus?o desta superf?cie com o limite de sequ?ncia, que constitui a Discord?ncia Eocarbon?fera, onde a se??o sobreposta foi erodida. Tal se??o, que corresponde ao Trato de Sistemas de N?vel Alto, ? restrita ?s por??es em que a eros?o que originou a Discord?ncia Eocarbon?fera foi menos efetiva, preservando os registros desta unidade. / The Middle Devonian-Early Carboniferous sequence of the Parna?ba Basin, lithostratigraphically
defined as Canind? Group, has been reinterpreted using the basic model of sequence stratigraphy.
Therefore, lithology and gamma ray well-logs and seismic lines of central portion of the basin
were analyzed, producing up from there diagrams 1D, isochore maps and stratigraphic sections.
As results of this study, were defined two depositional cycles of second order, referred as
Depositional Sequence 1 (SEQ1) and the Depositional Sequence 2 (SEQ2). The SEQ1, with interval
about 37 Ma, is limited below by Early Devonian Unconformity and is equivalent to the formations
Itaim, Pimenteiras and Cabe?as. The SEQ2, which follows, comprises a range of about 15 Ma and is
equivalent to the Long? Formation
The SEQ1 starts with the lowstand systems tract, consisting of progradational parasequence
set in the basal part, predominantly pelitic, deposited on a prodelta under influence of storms and the
upper part consists in sandstones of deltaic front, with the maximum regressive surface on the upper
limit. The transgressive systems tract, deposited above, is characterized by retrogradacional parasequence
set composed of shallow shelf mudstones, deposited under storm conditions. The maximum
flooding surface, upper limit of this tract, is positioned in a shale level whose radioactivity in gammaray
well-log is close to 150 API. The highstand systems tract presents progradational parasequence
set, comprising mudstones and sandstones deposited in shelf, fluvial-estuarine or deltaic and periglacial
environments, with the upper limit the Late Devonian Unconformity. The SEQ2 was deposited in shelf environment, starting with the lowstand systems tract, that is characterized by a progradational parasequence set, followed by the transgressive systems tract, with retrogradational character. The upper limit of the tract corresponding to the fusion between maximum flooding surface with the upper limit of this sequence, which is the Early Carboniferous Unconformity, where the overlapping section was eroded. This section, which corresponds the highstand systems tract is restricted to portions at which the erosion that generate the Early-Carboniferous Unconformity was less effective, preserving the records of this unit.

Identiferoai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/21060
Date20 August 2015
CreatorsFerraz, Nadja Cruz
Contributors59176911691, Antunes, Alex Francisco, 97038210491, Cruz, Liliane Rabelo, 03026147451, Cordoba, Valeria Centurion
PublisherUniversidade Federal do Rio Grande do Norte, PROGRAMA DE P?S-GRADUA??O EM GEODIN?MICA E GEOF?SICA, UFRN, Brasil
Source SetsIBICT Brazilian ETDs
LanguagePortuguese
Detected LanguageEnglish
Typeinfo:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis
Sourcereponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN
Rightsinfo:eu-repo/semantics/openAccess

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