Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil
Autor(a) principal: | |
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Data de Publicação: | 2007 |
Outros Autores: | , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Institucional de Geociências - RIGEO |
Texto Completo: | https://rigeo.cprm.gov.br/handle/doc/533 |
Resumo: | Fluid inclusion microthermometry and structural data are presented for quartz vein systems of a major dextral transcurrent shear zone of Neoproterozoic–Cambrian age in the Ribeira River Valley area, southeastern Brazil. Geometric and microstructural constraints indicate that foliation–parallel and extensional veins were formed during dextral strike–slip faulting. Both vein systems are formed essentially by quartz and lesser contents of sulfides and carbonates, and were crystallized in the presence of CO2–CH4 and H2O–CO2–CH4–NaCl immiscible fluids following unmixing from a homogeneous parental fluid. Contrasting fluid entrapment conditions indicate that the two vein systems were formed in different structural levels. Foliation–parallel veins were precipitated beneath the seismogenic zone under pressure fluctuating from moderately sublithostatic to moderately subhydrostatic values (319–397 °C and 47–215 MPa), which is compatible with predicted fluid pressure cycle curves derived from fault–valve action. Growth of extensional veins occurred in shallower structural levels, under pressure fluctuating from near hydrostatic to moderately subhydrostatic values (207–218 °C and 18–74 MPa), which indicate that precipitation occurred within the near surface hydrostatically pressured seismogenic zone. Fluid immiscibility and precipitation of quartz in foliation–parallel veins resulted from fluid pressure drop immediately after earthquake rupture. Fluid immiscibility following a local pressure drop during extensional veining occurred in pre-seismic stages in response to the development of fracture porosity in the dilatant zone. Late stages of fluid circulation within the fault zone are represented dominantly by low to high salinity (0.2 to 44 wt.% equivalent NaCl) H2O–NaCl–CaCl2 fluid inclusions trapped in healed fractures mainly in foliation–parallel veins, which also exhibit subordinate H2O–NaCl–CaCl2, CO2–(CH4) and H2O–CO2–(CH4)–NaCl fluid inclusions trapped under subsolvus conditions in single healed microcracks. Recurrent circulation of aqueous-carbonic fluids and aqueous fluids of highly contrasting salinities during veining and post- veining stages suggests that fluids of different reservoirs were pumped to the ruptured fault zone during faulting episodes. A fluid evolution trending toward CH4 depletion for CO2–CH4–bearing fluids and salinity depletion a nd dilution (approximation of the system H2O–NaCl) for aqueous–saline fluids occurred concomitantly with decrease in temperature and pressure related to fluid entrapment in progressively shallower structural levels reflecting the shear zone exhumation history |
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FALEIROS, Frederico MeiraCAMPANHA, Ginaldo Ademar da CruzBELLO, Rosa Maria da SilveiraFUZIKAWA, Kazuo2013-12-19T16:32:36Z2013-12-19T16:32:36Z2007FALEIROS, Frederico Meira; CAMPANHA, Ginaldo Ademar da Cruz; BELLO, Rosa Maria da Silveira; FUZIKAWA, Kazuo. Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil. Tectonophysics, Amsterdam, v.438, n.1-4, p.1-32.https://rigeo.cprm.gov.br/handle/doc/533Fluid inclusion microthermometry and structural data are presented for quartz vein systems of a major dextral transcurrent shear zone of Neoproterozoic–Cambrian age in the Ribeira River Valley area, southeastern Brazil. Geometric and microstructural constraints indicate that foliation–parallel and extensional veins were formed during dextral strike–slip faulting. Both vein systems are formed essentially by quartz and lesser contents of sulfides and carbonates, and were crystallized in the presence of CO2–CH4 and H2O–CO2–CH4–NaCl immiscible fluids following unmixing from a homogeneous parental fluid. Contrasting fluid entrapment conditions indicate that the two vein systems were formed in different structural levels. Foliation–parallel veins were precipitated beneath the seismogenic zone under pressure fluctuating from moderately sublithostatic to moderately subhydrostatic values (319–397 °C and 47–215 MPa), which is compatible with predicted fluid pressure cycle curves derived from fault–valve action. Growth of extensional veins occurred in shallower structural levels, under pressure fluctuating from near hydrostatic to moderately subhydrostatic values (207–218 °C and 18–74 MPa), which indicate that precipitation occurred within the near surface hydrostatically pressured seismogenic zone. Fluid immiscibility and precipitation of quartz in foliation–parallel veins resulted from fluid pressure drop immediately after earthquake rupture. Fluid immiscibility following a local pressure drop during extensional veining occurred in pre-seismic stages in response to the development of fracture porosity in the dilatant zone. Late stages of fluid circulation within the fault zone are represented dominantly by low to high salinity (0.2 to 44 wt.% equivalent NaCl) H2O–NaCl–CaCl2 fluid inclusions trapped in healed fractures mainly in foliation–parallel veins, which also exhibit subordinate H2O–NaCl–CaCl2, CO2–(CH4) and H2O–CO2–(CH4)–NaCl fluid inclusions trapped under subsolvus conditions in single healed microcracks. Recurrent circulation of aqueous-carbonic fluids and aqueous fluids of highly contrasting salinities during veining and post- veining stages suggests that fluids of different reservoirs were pumped to the ruptured fault zone during faulting episodes. A fluid evolution trending toward CH4 depletion for CO2–CH4–bearing fluids and salinity depletion a nd dilution (approximation of the system H2O–NaCl) for aqueous–saline fluids occurred concomitantly with decrease in temperature and pressure related to fluid entrapment in progressively shallower structural levels reflecting the shear zone exhumation historyMINERALOGIABRASILFault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazilinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleAmsterdamengreponame:Repositório Institucional de Geociências - RIGEOinstname:Companhia de Pesquisa de Recursos Minerais (CPRM)instacron:CPRMinfo:eu-repo/semantics/openAccessTEXTfaleiros_etal_2007.pdf.txtfaleiros_etal_2007.pdf.txtExtracted texttext/plain96804http://rigeo.cprm.gov.br/jspui/bitstream/doc/533/2/faleiros_etal_2007.pdf.txt1b9f733bcf07af036e509aa52a9a2d8eMD52THUMBNAILfaleiros_etal_2007.pdf.jpgfaleiros_etal_2007.pdf.jpgGenerated Thumbnailimage/jpeg1716http://rigeo.cprm.gov.br/jspui/bitstream/doc/533/3/faleiros_etal_2007.pdf.jpgb06a779aad8662f71f6099c351a8decdMD53ORIGINALfaleiros_etal_2007.pdffaleiros_etal_2007.pdfproducao cientificaapplication/pdf5544985http://rigeo.cprm.gov.br/jspui/bitstream/doc/533/1/faleiros_etal_2007.pdfd122006d5d9f2c242ac5442f15dae567MD51doc/5332023-02-13 11:10:47.03oai:rigeo.sgb.gov.br:doc/533Repositório InstitucionalONGhttps://rigeo.sgb.gov.br/oai/request https://rigeo.cprm.gov.br/oai/requestrigeo@sgb.gov.bropendoar:2023-02-13T14:10:47Repositório Institucional de Geociências - RIGEO - Companhia de Pesquisa de Recursos Minerais (CPRM)false |
dc.title.none.fl_str_mv |
Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil |
title |
Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil |
spellingShingle |
Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil FALEIROS, Frederico Meira MINERALOGIA BRASIL |
title_short |
Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil |
title_full |
Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil |
title_fullStr |
Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil |
title_full_unstemmed |
Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil |
title_sort |
Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil |
author |
FALEIROS, Frederico Meira |
author_facet |
FALEIROS, Frederico Meira CAMPANHA, Ginaldo Ademar da Cruz BELLO, Rosa Maria da Silveira FUZIKAWA, Kazuo |
author_role |
author |
author2 |
CAMPANHA, Ginaldo Ademar da Cruz BELLO, Rosa Maria da Silveira FUZIKAWA, Kazuo |
author2_role |
author author author |
dc.contributor.author.fl_str_mv |
FALEIROS, Frederico Meira CAMPANHA, Ginaldo Ademar da Cruz BELLO, Rosa Maria da Silveira FUZIKAWA, Kazuo |
dc.subject.por.fl_str_mv |
MINERALOGIA BRASIL |
topic |
MINERALOGIA BRASIL |
description |
Fluid inclusion microthermometry and structural data are presented for quartz vein systems of a major dextral transcurrent shear zone of Neoproterozoic–Cambrian age in the Ribeira River Valley area, southeastern Brazil. Geometric and microstructural constraints indicate that foliation–parallel and extensional veins were formed during dextral strike–slip faulting. Both vein systems are formed essentially by quartz and lesser contents of sulfides and carbonates, and were crystallized in the presence of CO2–CH4 and H2O–CO2–CH4–NaCl immiscible fluids following unmixing from a homogeneous parental fluid. Contrasting fluid entrapment conditions indicate that the two vein systems were formed in different structural levels. Foliation–parallel veins were precipitated beneath the seismogenic zone under pressure fluctuating from moderately sublithostatic to moderately subhydrostatic values (319–397 °C and 47–215 MPa), which is compatible with predicted fluid pressure cycle curves derived from fault–valve action. Growth of extensional veins occurred in shallower structural levels, under pressure fluctuating from near hydrostatic to moderately subhydrostatic values (207–218 °C and 18–74 MPa), which indicate that precipitation occurred within the near surface hydrostatically pressured seismogenic zone. Fluid immiscibility and precipitation of quartz in foliation–parallel veins resulted from fluid pressure drop immediately after earthquake rupture. Fluid immiscibility following a local pressure drop during extensional veining occurred in pre-seismic stages in response to the development of fracture porosity in the dilatant zone. Late stages of fluid circulation within the fault zone are represented dominantly by low to high salinity (0.2 to 44 wt.% equivalent NaCl) H2O–NaCl–CaCl2 fluid inclusions trapped in healed fractures mainly in foliation–parallel veins, which also exhibit subordinate H2O–NaCl–CaCl2, CO2–(CH4) and H2O–CO2–(CH4)–NaCl fluid inclusions trapped under subsolvus conditions in single healed microcracks. Recurrent circulation of aqueous-carbonic fluids and aqueous fluids of highly contrasting salinities during veining and post- veining stages suggests that fluids of different reservoirs were pumped to the ruptured fault zone during faulting episodes. A fluid evolution trending toward CH4 depletion for CO2–CH4–bearing fluids and salinity depletion a nd dilution (approximation of the system H2O–NaCl) for aqueous–saline fluids occurred concomitantly with decrease in temperature and pressure related to fluid entrapment in progressively shallower structural levels reflecting the shear zone exhumation history |
publishDate |
2007 |
dc.date.issued.fl_str_mv |
2007 |
dc.date.accessioned.fl_str_mv |
2013-12-19T16:32:36Z |
dc.date.available.fl_str_mv |
2013-12-19T16:32:36Z |
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.citation.fl_str_mv |
FALEIROS, Frederico Meira; CAMPANHA, Ginaldo Ademar da Cruz; BELLO, Rosa Maria da Silveira; FUZIKAWA, Kazuo. Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil. Tectonophysics, Amsterdam, v.438, n.1-4, p.1-32. |
dc.identifier.uri.fl_str_mv |
https://rigeo.cprm.gov.br/handle/doc/533 |
identifier_str_mv |
FALEIROS, Frederico Meira; CAMPANHA, Ginaldo Ademar da Cruz; BELLO, Rosa Maria da Silveira; FUZIKAWA, Kazuo. Fault valve action and vein development during strike slip faulting: an example from the Ribeira Shear Zone, Southeastern Brazil. Tectonophysics, Amsterdam, v.438, n.1-4, p.1-32. |
url |
https://rigeo.cprm.gov.br/handle/doc/533 |
dc.language.iso.fl_str_mv |
eng |
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