Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos
Autor(a) principal: | |
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Data de Publicação: | 2022 |
Tipo de documento: | Tese |
Idioma: | por |
Título da fonte: | Biblioteca Digital de Teses e Dissertações da UERJ |
Texto Completo: | http://www.bdtd.uerj.br/handle/1/20566 |
Resumo: | The new data presented here, stable isotopes (δ13Ccarb and δ18Ocarb), elemental composition by x-ray fluorescence, and organic geochemistry (TOC, pyrolysis, biomarkers, and δ13CTOC) from core samples, provide clues that may help to understand climate variations, assumed to have been contemporary in the lake evolution for the whole basin during the rift and post-rift. This study proposes a high-resolution stratigraphy based on chemostratigraphic units. The Piçarras Formation (Fm.) (unit A) was deposited under fresh-brackish water conditions. Biomarkers showed a high abundance of 4-methyl sterane and dinosterane can be explained by algal input, diatoms, and dinoflagellates in a reducing environment. Followed by a lake-level fall, Unit B, positive value δ13Ocarb (+9‰) and the occurrence of magnesian clays suggest high evaporation rates predominantly oxidizing lake period with warmer, hypersaline, and alkaline waters. The passage from the Piçarras Fm. to the Itapema Fm. is characterized by the depletion of isotopic values of δ13Ccarb and δ18Ocarb, which represented freshening of the lacustrine environment intensified terrigenous inputs and organic productivity (TOC>3.3% and HI>500 mg HC/g TOC). In addition, high hopane/sterane, and TPP/Dia support freshwater input with increasing bacterial and green algae assemblage under anoxic conditions. The alternating cycles of high and low salinity are related to a semi-arid climate with periods of higher humidity, represented by the rhythmicity pattern in the logs of SiO2, CaO, Al2O3, MgO, δ13Ccarb and δ18Ocarb in subunits C2 and C3, respectively. The lake progressively was drowned by episodes of freshwater influx promoted by subsidence; favorable conditions in water chemistry allowed the deposition of the bioclastic carbonates (coquinas) along interval D. After a regional regression, Pre-Alagoas unconformity marked by an excursion with positive shifted and towards positive δ13Ccarb and δ18Ocarb suggest a more stressful environment in the geological record of the Barra Velha Fm. The isotopic distribution, mineralogical and chemical markers (Sr/Ca; Mg/Ca; Mn/Sr) allowed defining four chemostratigraphic intervals. In BV-1 and BV-2 intervals, the δ13Ccarb and δ18Ocarb values vary according to shallowing-upward cycles, in general becoming lighter in their bases, appear to be related to periods of relative humidity, which resulted in less saline water input with higher extrabasinal contribution. In contrast, heavier isotope values are related to conditions of progressive evaporation of the lake. The unit BV-3 remarks the sag phase; throughout this interval, there are cycles of maximum aridity, and reduction of the water table, favoring the nucleation of these carbonates, which have higher δ13Ccarb and δ18Ocarb values and predominance of shrub facies. The BV-04 interval is characterized by relatively negative δ13Ccarb and δ18Ocarb values, which suggests lake-level fluctuations in a semi-arid climate with a lower evaporation rate in shallow lake conditions. In addition, chemozones with the most negative δ18Ocarb values (-9‰) and high Mg supported post-depositional hydrothermal alterations in units BV3 and BV4. This study shows that climatic condition is the primary driver of the lake level variations and, consequently, the water chemistry. |
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Rodrigues, Renéhttp://lattes.cnpq.br/7539756220629540Santos Neto, Eugenio Vaz dosTrindade, Luiz AntônioPereira, EgbertoBergamaschi, Sergiohttp://lattes.cnpq.br/9838030974581098Sanabria, Lina Liliana Osório2023-11-06T17:57:12Z2022-09-30SANABRIA, Lina Liliana Osório. Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos. 2022. 224 f. Tese (Doutorado em Geociências) - Faculdade de Geologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, 2022.http://www.bdtd.uerj.br/handle/1/20566The new data presented here, stable isotopes (δ13Ccarb and δ18Ocarb), elemental composition by x-ray fluorescence, and organic geochemistry (TOC, pyrolysis, biomarkers, and δ13CTOC) from core samples, provide clues that may help to understand climate variations, assumed to have been contemporary in the lake evolution for the whole basin during the rift and post-rift. This study proposes a high-resolution stratigraphy based on chemostratigraphic units. The Piçarras Formation (Fm.) (unit A) was deposited under fresh-brackish water conditions. Biomarkers showed a high abundance of 4-methyl sterane and dinosterane can be explained by algal input, diatoms, and dinoflagellates in a reducing environment. Followed by a lake-level fall, Unit B, positive value δ13Ocarb (+9‰) and the occurrence of magnesian clays suggest high evaporation rates predominantly oxidizing lake period with warmer, hypersaline, and alkaline waters. The passage from the Piçarras Fm. to the Itapema Fm. is characterized by the depletion of isotopic values of δ13Ccarb and δ18Ocarb, which represented freshening of the lacustrine environment intensified terrigenous inputs and organic productivity (TOC>3.3% and HI>500 mg HC/g TOC). In addition, high hopane/sterane, and TPP/Dia support freshwater input with increasing bacterial and green algae assemblage under anoxic conditions. The alternating cycles of high and low salinity are related to a semi-arid climate with periods of higher humidity, represented by the rhythmicity pattern in the logs of SiO2, CaO, Al2O3, MgO, δ13Ccarb and δ18Ocarb in subunits C2 and C3, respectively. The lake progressively was drowned by episodes of freshwater influx promoted by subsidence; favorable conditions in water chemistry allowed the deposition of the bioclastic carbonates (coquinas) along interval D. After a regional regression, Pre-Alagoas unconformity marked by an excursion with positive shifted and towards positive δ13Ccarb and δ18Ocarb suggest a more stressful environment in the geological record of the Barra Velha Fm. The isotopic distribution, mineralogical and chemical markers (Sr/Ca; Mg/Ca; Mn/Sr) allowed defining four chemostratigraphic intervals. In BV-1 and BV-2 intervals, the δ13Ccarb and δ18Ocarb values vary according to shallowing-upward cycles, in general becoming lighter in their bases, appear to be related to periods of relative humidity, which resulted in less saline water input with higher extrabasinal contribution. In contrast, heavier isotope values are related to conditions of progressive evaporation of the lake. The unit BV-3 remarks the sag phase; throughout this interval, there are cycles of maximum aridity, and reduction of the water table, favoring the nucleation of these carbonates, which have higher δ13Ccarb and δ18Ocarb values and predominance of shrub facies. The BV-04 interval is characterized by relatively negative δ13Ccarb and δ18Ocarb values, which suggests lake-level fluctuations in a semi-arid climate with a lower evaporation rate in shallow lake conditions. In addition, chemozones with the most negative δ18Ocarb values (-9‰) and high Mg supported post-depositional hydrothermal alterations in units BV3 and BV4. This study shows that climatic condition is the primary driver of the lake level variations and, consequently, the water chemistry.No presente trabalho apresentamos e discutimos novos dados geoquímicos de isótopos estáveis (δ13Ccarb e δ18Ocarb), elementos maiores por FRX e geoquímica orgânica (COT, pirólise, biomarcadores e δ13CCOT) em amostras de testemunhos de um poço no campo de Lula. A integração destes proxies foi possível estabelecer unidades quimioestratigráficas que refletem a evolução paleoambiental do sistema lacustre durante a fase rifte e pós-rifte. Os folhelhos da Formação (Fm.) Piçarras (unidade A) foram depositados em condições de água salobra, a presença de 4-metilesteranos e dinosteranos indicam uma contribuição de diatomáceas e dinoflagelados na matéria orgânica num ambiente redutor. Os valores isotópicos positivos de δ13Ocarb (+9‰) e a ocorrência de argilas magnesianas marcam um período de lago em retração (unidade B) predominantemente oxidante com águas mais quentes, alcalinas com tendências hipersalinas. A passagem da Fm. Piçarras para Fm. Itapema é marcada pela forte excursão negativa de δ13Ccarb e δ18Ocarb e seria o reflexo do aumento da umidificação climática que intensificou o aporte siliciclásticos e a produtividade orgânica (COT>3,3%, IH>500 mgHC/gCOT). Os folhelhos foram depositados num ambiente anoxico de baixa salinidade, as razões C29/C27 esterano, hopano/esterano e TPP/Dia indicam uma matéria orgânica composta de bactérias e algas verdes na subunidade C1. A alternância de ciclos de alta e baixa salinidade relacionados a um clima semiárido com períodos úmidos, está representado pelo padrão de ritmicidade nas curvas de SiO2, CaO, Al2O3 e MgO, δ13Ccarb e δ 18Ocarb nas subunidades C2 e C3. O lago progressivamente ficou menos salino por episódios de influxo de água doce, condições favoráveis na química d’água permitiram a deposição dos carbonatos bioclásticos (coquinas) ao longo da unidade D, limitada no topo pela discordância Pré-Alagoas. Uma excursão positiva nos valores de δ13Ccarb e δ18Ocarb refletem condições ambientais de um lago com maior evaporação, alcalinidade e salinidade no registro geológico da Fm. Barra Velha. A distribuição isotópica, mineralógica e marcadores qumioestratigraficos (Sr/Ca; Mg/Ca; Mn/Sr) permitiu definir quatro intervalos quimioestratigráficos. Nos intervalos BV-1 e BV-2 os valores de δ13Ccarb e δ18Ocarb variam de acordo com ciclos de arrasamento interpretados como produto de variações climáticas. Assim, valores isotópicos com valores mais leves parecem estar relacionados com períodos de relativa umidade, que resultou em entrada de água menos salina responsável da contribuição extrabacial. Razões isotópicas positivas estariam relacionados a condições de evaporação progressiva do corpo de água. A unidade BV-3, marca a fase sag, os valores muito elevados de δ13Ccarb e δ18Ocarb e o predomínio de fácies shurbs estão relacionados a períodos de máxima aridez e redução da lâmina d’água, favorecendo a nucleação desses carbonatos. O intervalo BV-04 é caracterizado por valores isotópicos mais negativos δ13Ccarb e δ18Ocarb e flutuações em alta frequência sugerem clima semiárido com menor taxa de evaporação em condições de lago muito rasas. A presença de quimiozonas com valores muito negativos δ18Ocarb (<-6‰) e alto Mg indicam alterações hidrotermais pós-deposicionais nas unidades BV3 e BV4. Portanto, os dados aqui apresentados fornecem evidencias claras que as condições climáticas controlaram as variações do nível do lago e consequentemente a química d’água.Submitted by Priscila CTC/C (prisfreitas8@gmail.com) on 2023-11-06T17:57:12Z No. of bitstreams: 1 Tese - Lina Liliana Osorio Sanabria - 2022 - Completa.pdf: 10138690 bytes, checksum: 3fee2f05352da80cfd993cef148f93b6 (MD5)Made available in DSpace on 2023-11-06T17:57:12Z (GMT). No. of bitstreams: 1 Tese - Lina Liliana Osorio Sanabria - 2022 - Completa.pdf: 10138690 bytes, checksum: 3fee2f05352da80cfd993cef148f93b6 (MD5) Previous issue date: 2022-09-30application/pdfporUniversidade do Estado do Rio de JaneiroPrograma de Pós-Graduação em GeociênciasUERJBrasilCentro de Tecnologia e Ciências::Faculdade de GeologiaPré-salIsótopos estáveisGeoquímica de carbonatosEstratigrafia químicaCarbonatos lacustresPre-saltIsotope geochemistryCarbonate geochemistryChemostratigraphyLacustrine carbonateCIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIAGeoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de SantosOrganic and Isotopic geochemistry of the formation: Piçarras, Itapema, and Barra Velha in the Lula field, Santos Basininfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/openAccessreponame:Biblioteca Digital de Teses e Dissertações da UERJinstname:Universidade do Estado do Rio de Janeiro (UERJ)instacron:UERJLICENSElicense.txtlicense.txttext/plain; charset=utf-82123http://www.bdtd.uerj.br/bitstream/1/20566/3/license.txte5502652da718045d7fcd832b79fca29MD53ORIGINALTese - Lina Liliana Osorio Sanabria - 2022 - Completa.pdfTese - Lina Liliana Osorio Sanabria - 2022 - Completa.pdfapplication/pdf10138690http://www.bdtd.uerj.br/bitstream/1/20566/2/Tese+-+Lina+Liliana+Osorio+Sanabria+-+2022+-+Completa.pdf3fee2f05352da80cfd993cef148f93b6MD521/205662023-11-06 15:57:12.729oai:www.bdtd.uerj.br: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Biblioteca Digital de Teses e Dissertaçõeshttp://www.bdtd.uerj.br/PUBhttps://www.bdtd.uerj.br:8443/oai/requestbdtd.suporte@uerj.bropendoar:29032023-11-06T17:57:12Biblioteca Digital de Teses e Dissertações da UERJ - Universidade do Estado do Rio de Janeiro (UERJ)false |
dc.title.por.fl_str_mv |
Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos |
dc.title.alternative.eng.fl_str_mv |
Organic and Isotopic geochemistry of the formation: Piçarras, Itapema, and Barra Velha in the Lula field, Santos Basin |
title |
Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos |
spellingShingle |
Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos Sanabria, Lina Liliana Osório Pré-sal Isótopos estáveis Geoquímica de carbonatos Estratigrafia química Carbonatos lacustres Pre-salt Isotope geochemistry Carbonate geochemistry Chemostratigraphy Lacustrine carbonate CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA |
title_short |
Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos |
title_full |
Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos |
title_fullStr |
Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos |
title_full_unstemmed |
Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos |
title_sort |
Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos |
author |
Sanabria, Lina Liliana Osório |
author_facet |
Sanabria, Lina Liliana Osório |
author_role |
author |
dc.contributor.advisor1.fl_str_mv |
Rodrigues, René |
dc.contributor.advisor1Lattes.fl_str_mv |
http://lattes.cnpq.br/7539756220629540 |
dc.contributor.referee1.fl_str_mv |
Santos Neto, Eugenio Vaz dos |
dc.contributor.referee2.fl_str_mv |
Trindade, Luiz Antônio |
dc.contributor.referee3.fl_str_mv |
Pereira, Egberto |
dc.contributor.referee4.fl_str_mv |
Bergamaschi, Sergio |
dc.contributor.authorLattes.fl_str_mv |
http://lattes.cnpq.br/9838030974581098 |
dc.contributor.author.fl_str_mv |
Sanabria, Lina Liliana Osório |
contributor_str_mv |
Rodrigues, René Santos Neto, Eugenio Vaz dos Trindade, Luiz Antônio Pereira, Egberto Bergamaschi, Sergio |
dc.subject.por.fl_str_mv |
Pré-sal Isótopos estáveis Geoquímica de carbonatos Estratigrafia química Carbonatos lacustres Pre-salt Isotope geochemistry Carbonate geochemistry Chemostratigraphy Lacustrine carbonate |
topic |
Pré-sal Isótopos estáveis Geoquímica de carbonatos Estratigrafia química Carbonatos lacustres Pre-salt Isotope geochemistry Carbonate geochemistry Chemostratigraphy Lacustrine carbonate CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA |
dc.subject.cnpq.fl_str_mv |
CIENCIAS EXATAS E DA TERRA::GEOCIENCIAS::GEOLOGIA |
description |
The new data presented here, stable isotopes (δ13Ccarb and δ18Ocarb), elemental composition by x-ray fluorescence, and organic geochemistry (TOC, pyrolysis, biomarkers, and δ13CTOC) from core samples, provide clues that may help to understand climate variations, assumed to have been contemporary in the lake evolution for the whole basin during the rift and post-rift. This study proposes a high-resolution stratigraphy based on chemostratigraphic units. The Piçarras Formation (Fm.) (unit A) was deposited under fresh-brackish water conditions. Biomarkers showed a high abundance of 4-methyl sterane and dinosterane can be explained by algal input, diatoms, and dinoflagellates in a reducing environment. Followed by a lake-level fall, Unit B, positive value δ13Ocarb (+9‰) and the occurrence of magnesian clays suggest high evaporation rates predominantly oxidizing lake period with warmer, hypersaline, and alkaline waters. The passage from the Piçarras Fm. to the Itapema Fm. is characterized by the depletion of isotopic values of δ13Ccarb and δ18Ocarb, which represented freshening of the lacustrine environment intensified terrigenous inputs and organic productivity (TOC>3.3% and HI>500 mg HC/g TOC). In addition, high hopane/sterane, and TPP/Dia support freshwater input with increasing bacterial and green algae assemblage under anoxic conditions. The alternating cycles of high and low salinity are related to a semi-arid climate with periods of higher humidity, represented by the rhythmicity pattern in the logs of SiO2, CaO, Al2O3, MgO, δ13Ccarb and δ18Ocarb in subunits C2 and C3, respectively. The lake progressively was drowned by episodes of freshwater influx promoted by subsidence; favorable conditions in water chemistry allowed the deposition of the bioclastic carbonates (coquinas) along interval D. After a regional regression, Pre-Alagoas unconformity marked by an excursion with positive shifted and towards positive δ13Ccarb and δ18Ocarb suggest a more stressful environment in the geological record of the Barra Velha Fm. The isotopic distribution, mineralogical and chemical markers (Sr/Ca; Mg/Ca; Mn/Sr) allowed defining four chemostratigraphic intervals. In BV-1 and BV-2 intervals, the δ13Ccarb and δ18Ocarb values vary according to shallowing-upward cycles, in general becoming lighter in their bases, appear to be related to periods of relative humidity, which resulted in less saline water input with higher extrabasinal contribution. In contrast, heavier isotope values are related to conditions of progressive evaporation of the lake. The unit BV-3 remarks the sag phase; throughout this interval, there are cycles of maximum aridity, and reduction of the water table, favoring the nucleation of these carbonates, which have higher δ13Ccarb and δ18Ocarb values and predominance of shrub facies. The BV-04 interval is characterized by relatively negative δ13Ccarb and δ18Ocarb values, which suggests lake-level fluctuations in a semi-arid climate with a lower evaporation rate in shallow lake conditions. In addition, chemozones with the most negative δ18Ocarb values (-9‰) and high Mg supported post-depositional hydrothermal alterations in units BV3 and BV4. This study shows that climatic condition is the primary driver of the lake level variations and, consequently, the water chemistry. |
publishDate |
2022 |
dc.date.issued.fl_str_mv |
2022-09-30 |
dc.date.accessioned.fl_str_mv |
2023-11-06T17:57:12Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/doctoralThesis |
format |
doctoralThesis |
status_str |
publishedVersion |
dc.identifier.citation.fl_str_mv |
SANABRIA, Lina Liliana Osório. Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos. 2022. 224 f. Tese (Doutorado em Geociências) - Faculdade de Geologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, 2022. |
dc.identifier.uri.fl_str_mv |
http://www.bdtd.uerj.br/handle/1/20566 |
identifier_str_mv |
SANABRIA, Lina Liliana Osório. Geoquímica orgânica e isotópica das formações: Piçarras, Itapema e Barra Velha no campo de Lula, Bacia de Santos. 2022. 224 f. Tese (Doutorado em Geociências) - Faculdade de Geologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, 2022. |
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http://www.bdtd.uerj.br/handle/1/20566 |
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por |
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Universidade do Estado do Rio de Janeiro |
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Programa de Pós-Graduação em Geociências |
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UERJ |
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Brasil |
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Centro de Tecnologia e Ciências::Faculdade de Geologia |
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Universidade do Estado do Rio de Janeiro |
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Biblioteca Digital de Teses e Dissertações da UERJ |
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Biblioteca Digital de Teses e Dissertações da UERJ - Universidade do Estado do Rio de Janeiro (UERJ) |
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bdtd.suporte@uerj.br |
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