Evidences of seismic events during the sedimentation of Sete Lagoas Formation (Bambui Group - Ediacaran, Brazil)
Autor(a) principal: | |
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Data de Publicação: | 2020 |
Outros Autores: | , , , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional da UNESP |
Texto Completo: | http://dx.doi.org/10.1016/j.jsames.2019.102461 http://hdl.handle.net/11449/196634 |
Resumo: | The Sete Lagoas Formation (Ediacaran), located in the central part of the Sao Francisco Craton (Brazil), consists of limestones and dolostones deposited in very shallow waters in the inner part of the carbonate platform. Four breccia types occur throughout the stratigraphic succession: evaporitic breccia with tepees, flat-pebble breccia, hydrothermal breccia and brecciated stromatolites. Here we combine a detailed sedimentological and stratigraphic analyses of the flat-pebble breccia in order to determine its origin and the processes and environmental conditions that originated these brecciated facies. The studied interval consists of a 20 m thick succession of tabular beds composed of flat-pebble breccia interbedded with laminated microbialites. In these breccia beds, the clasts are usually platy or oblate with angular edges and are mainly disposed horizontally within the sedimentary bed, suggesting that they were not transported or reworked. The presence of microbialite clasts with sharp edges and vertices in the Sete Lagoas flat-pebble breccia suggests that the lithification process started very early in diagenesis and, even the sediments exposed at the bottom were, at least, partially lithified. Some breccia levels show bidirectional imbrication and clast size analyses reveal a NE-SW long-axis clast orientation whereas square clasts tend to fill the space among oriented clasts. Breccia clasts are vertically oriented and show deformation features increasing upwards, typically of deforming beds formed by ascendant expulsion of liquefied sediment. Disrupted layers or presenting folds and synsedimentary faults commonly occur confined between undeformed beds. Other evidences of liquefaction and soft-sediment deformation are the injection structures, as flame and load cast-like features, in the base of the brecciated beds. These structures commonly penetrate the upper bed and disrupt the sedimentary layer immediately above promoting local brecciation. These features are found both in modern and ancient deposits of seismic influence, which suggests a similar origin for the Sete Lagoas flat-pebble breccia. Thus, the processes that led to the formation of the studied flat-pebble breccia are interpreted as seismically triggered, since: a) the breccia beds are laterally continuous and extend for several kilometers; b) the breccia beds are restricted to a 20 m thick stratigraphic interval; c) the clasts of the breccia are the same lithology of non- deformed beds below and above the interval of breccia; d) the interbedding of breccia beds and laminated microbialite beds is recurrent; e) the breccia beds are subhorizontal and present irregular upper and lower contacts; f) the presence of liquefaction structures and dyke injection. Thus, this seismic-triggered breccia deposits represent the product of the synsedimentary tectonism occurred within the Sao Francisco Craton during the terminal Ediacaran and correspond to a very well-defined local stratigraphic marker in the Bambui Basin. The seismic activities could be related to the NW regional faults in the regional Paleoproterozoic basement of the study area, which were reactivated during the deposition of the Sete Lagoas Formation in the Ediacaran Period. |
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Evidences of seismic events during the sedimentation of Sete Lagoas Formation (Bambui Group - Ediacaran, Brazil)Intraformational brecciaCarbonate platformSynsedimentary deformation structuresIntraplate seismicityEdiacaranThe Sete Lagoas Formation (Ediacaran), located in the central part of the Sao Francisco Craton (Brazil), consists of limestones and dolostones deposited in very shallow waters in the inner part of the carbonate platform. Four breccia types occur throughout the stratigraphic succession: evaporitic breccia with tepees, flat-pebble breccia, hydrothermal breccia and brecciated stromatolites. Here we combine a detailed sedimentological and stratigraphic analyses of the flat-pebble breccia in order to determine its origin and the processes and environmental conditions that originated these brecciated facies. The studied interval consists of a 20 m thick succession of tabular beds composed of flat-pebble breccia interbedded with laminated microbialites. In these breccia beds, the clasts are usually platy or oblate with angular edges and are mainly disposed horizontally within the sedimentary bed, suggesting that they were not transported or reworked. The presence of microbialite clasts with sharp edges and vertices in the Sete Lagoas flat-pebble breccia suggests that the lithification process started very early in diagenesis and, even the sediments exposed at the bottom were, at least, partially lithified. Some breccia levels show bidirectional imbrication and clast size analyses reveal a NE-SW long-axis clast orientation whereas square clasts tend to fill the space among oriented clasts. Breccia clasts are vertically oriented and show deformation features increasing upwards, typically of deforming beds formed by ascendant expulsion of liquefied sediment. Disrupted layers or presenting folds and synsedimentary faults commonly occur confined between undeformed beds. Other evidences of liquefaction and soft-sediment deformation are the injection structures, as flame and load cast-like features, in the base of the brecciated beds. These structures commonly penetrate the upper bed and disrupt the sedimentary layer immediately above promoting local brecciation. These features are found both in modern and ancient deposits of seismic influence, which suggests a similar origin for the Sete Lagoas flat-pebble breccia. Thus, the processes that led to the formation of the studied flat-pebble breccia are interpreted as seismically triggered, since: a) the breccia beds are laterally continuous and extend for several kilometers; b) the breccia beds are restricted to a 20 m thick stratigraphic interval; c) the clasts of the breccia are the same lithology of non- deformed beds below and above the interval of breccia; d) the interbedding of breccia beds and laminated microbialite beds is recurrent; e) the breccia beds are subhorizontal and present irregular upper and lower contacts; f) the presence of liquefaction structures and dyke injection. Thus, this seismic-triggered breccia deposits represent the product of the synsedimentary tectonism occurred within the Sao Francisco Craton during the terminal Ediacaran and correspond to a very well-defined local stratigraphic marker in the Bambui Basin. The seismic activities could be related to the NW regional faults in the regional Paleoproterozoic basement of the study area, which were reactivated during the deposition of the Sete Lagoas Formation in the Ediacaran Period.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)PetrobrasFundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)Univ Estadual Paulista, Inst Geociencias & Ciencias Exatas, Dept Geol Aplicada, Ave 24A,1515, BR-13506900 Rio Claro, BrazilUniv Estadual Paulista, Inst Geociencias & Ciencias Exatas, Dept Petrol & Metalogenia, Ave 24A,1515, BR-13506900 Rio Claro, BrazilUniv Fed Sao Paulo, Dept Ecol & Biol Evolut, Rua Prof Artur Riedel 275, BR-09972270 Diadema, BrazilUniv Fed Minas Gerais, Inst Geociencias, Ave Antonio Carlos 6627, BR-31270901 Belo Horizonte, MG, BrazilUniv Estadual Paulista, Inst Geociencias & Ciencias Exatas, Dept Geol Aplicada, Ave 24A,1515, BR-13506900 Rio Claro, BrazilUniv Estadual Paulista, Inst Geociencias & Ciencias Exatas, Dept Petrol & Metalogenia, Ave 24A,1515, BR-13506900 Rio Claro, BrazilFAPESP: 2015/07391-0FAPESP: 2018/26230-6CNPq: 301294/2018-6CNPq: 447449/2014-1CNPq: 444070/2014.1Petrobras: Sigitec 2014/-00519-9FAPEMIG: APQ-01711-14Elsevier B.V.Universidade Estadual Paulista (Unesp)Universidade Federal de São Paulo (UNIFESP)Universidade Federal de Minas Gerais (UFMG)Okubo, J. [UNESP]Warren, L. [UNESP]Luvizotto, G. L. [UNESP]Varejao, F. G. [UNESP]Quaglio, F.Uhlein, G. J.Assine, M. L. [UNESP]2020-12-10T19:51:17Z2020-12-10T19:51:17Z2020-03-01info:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/article12http://dx.doi.org/10.1016/j.jsames.2019.102461Journal Of South American Earth Sciences. Oxford: Pergamon-elsevier Science Ltd, v. 98, 12 p., 2020.0895-9811http://hdl.handle.net/11449/19663410.1016/j.jsames.2019.102461WOS:000517664800021Web of Sciencereponame:Repositório Institucional da UNESPinstname:Universidade Estadual Paulista (UNESP)instacron:UNESPengJournal Of South American Earth Sciencesinfo:eu-repo/semantics/openAccess2021-10-23T08:53:36Zoai:repositorio.unesp.br:11449/196634Repositório InstitucionalPUBhttp://repositorio.unesp.br/oai/requestopendoar:29462021-10-23T08:53:36Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP)false |
dc.title.none.fl_str_mv |
Evidences of seismic events during the sedimentation of Sete Lagoas Formation (Bambui Group - Ediacaran, Brazil) |
title |
Evidences of seismic events during the sedimentation of Sete Lagoas Formation (Bambui Group - Ediacaran, Brazil) |
spellingShingle |
Evidences of seismic events during the sedimentation of Sete Lagoas Formation (Bambui Group - Ediacaran, Brazil) Okubo, J. [UNESP] Intraformational breccia Carbonate platform Synsedimentary deformation structures Intraplate seismicity Ediacaran |
title_short |
Evidences of seismic events during the sedimentation of Sete Lagoas Formation (Bambui Group - Ediacaran, Brazil) |
title_full |
Evidences of seismic events during the sedimentation of Sete Lagoas Formation (Bambui Group - Ediacaran, Brazil) |
title_fullStr |
Evidences of seismic events during the sedimentation of Sete Lagoas Formation (Bambui Group - Ediacaran, Brazil) |
title_full_unstemmed |
Evidences of seismic events during the sedimentation of Sete Lagoas Formation (Bambui Group - Ediacaran, Brazil) |
title_sort |
Evidences of seismic events during the sedimentation of Sete Lagoas Formation (Bambui Group - Ediacaran, Brazil) |
author |
Okubo, J. [UNESP] |
author_facet |
Okubo, J. [UNESP] Warren, L. [UNESP] Luvizotto, G. L. [UNESP] Varejao, F. G. [UNESP] Quaglio, F. Uhlein, G. J. Assine, M. L. [UNESP] |
author_role |
author |
author2 |
Warren, L. [UNESP] Luvizotto, G. L. [UNESP] Varejao, F. G. [UNESP] Quaglio, F. Uhlein, G. J. Assine, M. L. [UNESP] |
author2_role |
author author author author author author |
dc.contributor.none.fl_str_mv |
Universidade Estadual Paulista (Unesp) Universidade Federal de São Paulo (UNIFESP) Universidade Federal de Minas Gerais (UFMG) |
dc.contributor.author.fl_str_mv |
Okubo, J. [UNESP] Warren, L. [UNESP] Luvizotto, G. L. [UNESP] Varejao, F. G. [UNESP] Quaglio, F. Uhlein, G. J. Assine, M. L. [UNESP] |
dc.subject.por.fl_str_mv |
Intraformational breccia Carbonate platform Synsedimentary deformation structures Intraplate seismicity Ediacaran |
topic |
Intraformational breccia Carbonate platform Synsedimentary deformation structures Intraplate seismicity Ediacaran |
description |
The Sete Lagoas Formation (Ediacaran), located in the central part of the Sao Francisco Craton (Brazil), consists of limestones and dolostones deposited in very shallow waters in the inner part of the carbonate platform. Four breccia types occur throughout the stratigraphic succession: evaporitic breccia with tepees, flat-pebble breccia, hydrothermal breccia and brecciated stromatolites. Here we combine a detailed sedimentological and stratigraphic analyses of the flat-pebble breccia in order to determine its origin and the processes and environmental conditions that originated these brecciated facies. The studied interval consists of a 20 m thick succession of tabular beds composed of flat-pebble breccia interbedded with laminated microbialites. In these breccia beds, the clasts are usually platy or oblate with angular edges and are mainly disposed horizontally within the sedimentary bed, suggesting that they were not transported or reworked. The presence of microbialite clasts with sharp edges and vertices in the Sete Lagoas flat-pebble breccia suggests that the lithification process started very early in diagenesis and, even the sediments exposed at the bottom were, at least, partially lithified. Some breccia levels show bidirectional imbrication and clast size analyses reveal a NE-SW long-axis clast orientation whereas square clasts tend to fill the space among oriented clasts. Breccia clasts are vertically oriented and show deformation features increasing upwards, typically of deforming beds formed by ascendant expulsion of liquefied sediment. Disrupted layers or presenting folds and synsedimentary faults commonly occur confined between undeformed beds. Other evidences of liquefaction and soft-sediment deformation are the injection structures, as flame and load cast-like features, in the base of the brecciated beds. These structures commonly penetrate the upper bed and disrupt the sedimentary layer immediately above promoting local brecciation. These features are found both in modern and ancient deposits of seismic influence, which suggests a similar origin for the Sete Lagoas flat-pebble breccia. Thus, the processes that led to the formation of the studied flat-pebble breccia are interpreted as seismically triggered, since: a) the breccia beds are laterally continuous and extend for several kilometers; b) the breccia beds are restricted to a 20 m thick stratigraphic interval; c) the clasts of the breccia are the same lithology of non- deformed beds below and above the interval of breccia; d) the interbedding of breccia beds and laminated microbialite beds is recurrent; e) the breccia beds are subhorizontal and present irregular upper and lower contacts; f) the presence of liquefaction structures and dyke injection. Thus, this seismic-triggered breccia deposits represent the product of the synsedimentary tectonism occurred within the Sao Francisco Craton during the terminal Ediacaran and correspond to a very well-defined local stratigraphic marker in the Bambui Basin. The seismic activities could be related to the NW regional faults in the regional Paleoproterozoic basement of the study area, which were reactivated during the deposition of the Sete Lagoas Formation in the Ediacaran Period. |
publishDate |
2020 |
dc.date.none.fl_str_mv |
2020-12-10T19:51:17Z 2020-12-10T19:51:17Z 2020-03-01 |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://dx.doi.org/10.1016/j.jsames.2019.102461 Journal Of South American Earth Sciences. Oxford: Pergamon-elsevier Science Ltd, v. 98, 12 p., 2020. 0895-9811 http://hdl.handle.net/11449/196634 10.1016/j.jsames.2019.102461 WOS:000517664800021 |
url |
http://dx.doi.org/10.1016/j.jsames.2019.102461 http://hdl.handle.net/11449/196634 |
identifier_str_mv |
Journal Of South American Earth Sciences. Oxford: Pergamon-elsevier Science Ltd, v. 98, 12 p., 2020. 0895-9811 10.1016/j.jsames.2019.102461 WOS:000517664800021 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
Journal Of South American Earth Sciences |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
12 |
dc.publisher.none.fl_str_mv |
Elsevier B.V. |
publisher.none.fl_str_mv |
Elsevier B.V. |
dc.source.none.fl_str_mv |
Web of Science reponame:Repositório Institucional da UNESP instname:Universidade Estadual Paulista (UNESP) instacron:UNESP |
instname_str |
Universidade Estadual Paulista (UNESP) |
instacron_str |
UNESP |
institution |
UNESP |
reponame_str |
Repositório Institucional da UNESP |
collection |
Repositório Institucional da UNESP |
repository.name.fl_str_mv |
Repositório Institucional da UNESP - Universidade Estadual Paulista (UNESP) |
repository.mail.fl_str_mv |
|
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1799965562261995520 |