Sulphur geochemistry and mineralogy of the dyke-gabbro transition, Semail Ophiolite, Oman: implications for the genesis of Volcanogenic Massive Sulphide (VMS) Deposits

Detalhes bibliográficos
Autor(a) principal: Silva, Diogo Manuel Cristóvão Farinha Rasteiro da
Data de Publicação: 2021
Tipo de documento: Dissertação
Idioma: eng
Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
Texto Completo: http://hdl.handle.net/10451/51330
Resumo: Relatório de estágio de mestrado, Geologia Económica, Universidade de Lisboa, Faculdade de Ciências, 2021
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spelling Sulphur geochemistry and mineralogy of the dyke-gabbro transition, Semail Ophiolite, Oman: implications for the genesis of Volcanogenic Massive Sulphide (VMS) DepositsOfiolito de Semailalteração hidrotermalgeoquímica do enxofreisótopos de enxofreVMSRelatórios de estágio de mestrado - 2021Departamento de GeologiaRelatório de estágio de mestrado, Geologia Económica, Universidade de Lisboa, Faculdade de Ciências, 2021The Semail ophiolite represents an obducted crustal section of Cretaceous oceanic crust and mantle. The Oman Drilling Project carried out extensive scientific drilling, among which, hole GT3 (400 m) aimed at characterizing magmatic and hydrothermal processes at the sheeted dike-gabbro transition zone (DGT). This work presents a study of sulphur geochemistry and stable isotopes with the purpose of understanding the role of the DGT as the source of metals and sulphur in the origin of volcanogenic massive sulphide deposits such as those found in the volcanic section of the Semail ophiolite. Samples were also characterized mineralogically and petrographically to determine hydrothermal alteration features. This study revealed a near complete overprint of most magmatic minerals, during three alteration stages which follow a retrograde metamorphic path from high temperature, amphibolitic facies, to widespread greenschist facies and low temperature prehnite to zeolite facies. Sulphur mobility was predominantly enabled during the medium temperature alteration stage. Sulphur stable isotopes revealed δ34S values mostly falling between 5.1‰ and 13.6‰, with two anomalous values of -0.5‰ and -12.8‰. The obtained values suggest that the sulphur in the hydrothermal fluid is the result of simple two component mixing between magmatic sources and sulphur derived from the thermochemical reduction of seawater sulphate, with seawater contributions between 23.7–73.7% and an weighted average of 41%. Sulphur leaching estimates, obtained from the comparison of estimated magmatic sulphur concentrations and measured sulphur concentrations, revealed an overall loss of sulphur with measured concentrations averaging at 27.4% of the estimated magmatic sulphur concentration (excluding two locally constrained very high concentrations). The extent of the leaching registered in the studied samples, along with the evidence of significant interaction with seawater derived fluids, indicates that the sheeted dyke – gabbro transition of the Semail ophiolite, despite locally constrained exceptions, constituted the reaction zone of the hydrothermal cycle.Gonçalves, Mário Abel Carreira, 1965-Jesus, Ana Patrícia Marques de, 1975-Repositório da Universidade de LisboaSilva, Diogo Manuel Cristóvão Farinha Rasteiro da2022-02-16T09:22:45Z202120212021-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/masterThesisapplication/pdfhttp://hdl.handle.net/10451/51330TID:202931420enginfo:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2023-11-08T16:55:57Zoai:repositorio.ul.pt:10451/51330Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-19T22:02:38.076503Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse
dc.title.none.fl_str_mv Sulphur geochemistry and mineralogy of the dyke-gabbro transition, Semail Ophiolite, Oman: implications for the genesis of Volcanogenic Massive Sulphide (VMS) Deposits
title Sulphur geochemistry and mineralogy of the dyke-gabbro transition, Semail Ophiolite, Oman: implications for the genesis of Volcanogenic Massive Sulphide (VMS) Deposits
spellingShingle Sulphur geochemistry and mineralogy of the dyke-gabbro transition, Semail Ophiolite, Oman: implications for the genesis of Volcanogenic Massive Sulphide (VMS) Deposits
Silva, Diogo Manuel Cristóvão Farinha Rasteiro da
Ofiolito de Semail
alteração hidrotermal
geoquímica do enxofre
isótopos de enxofre
VMS
Relatórios de estágio de mestrado - 2021
Departamento de Geologia
title_short Sulphur geochemistry and mineralogy of the dyke-gabbro transition, Semail Ophiolite, Oman: implications for the genesis of Volcanogenic Massive Sulphide (VMS) Deposits
title_full Sulphur geochemistry and mineralogy of the dyke-gabbro transition, Semail Ophiolite, Oman: implications for the genesis of Volcanogenic Massive Sulphide (VMS) Deposits
title_fullStr Sulphur geochemistry and mineralogy of the dyke-gabbro transition, Semail Ophiolite, Oman: implications for the genesis of Volcanogenic Massive Sulphide (VMS) Deposits
title_full_unstemmed Sulphur geochemistry and mineralogy of the dyke-gabbro transition, Semail Ophiolite, Oman: implications for the genesis of Volcanogenic Massive Sulphide (VMS) Deposits
title_sort Sulphur geochemistry and mineralogy of the dyke-gabbro transition, Semail Ophiolite, Oman: implications for the genesis of Volcanogenic Massive Sulphide (VMS) Deposits
author Silva, Diogo Manuel Cristóvão Farinha Rasteiro da
author_facet Silva, Diogo Manuel Cristóvão Farinha Rasteiro da
author_role author
dc.contributor.none.fl_str_mv Gonçalves, Mário Abel Carreira, 1965-
Jesus, Ana Patrícia Marques de, 1975-
Repositório da Universidade de Lisboa
dc.contributor.author.fl_str_mv Silva, Diogo Manuel Cristóvão Farinha Rasteiro da
dc.subject.por.fl_str_mv Ofiolito de Semail
alteração hidrotermal
geoquímica do enxofre
isótopos de enxofre
VMS
Relatórios de estágio de mestrado - 2021
Departamento de Geologia
topic Ofiolito de Semail
alteração hidrotermal
geoquímica do enxofre
isótopos de enxofre
VMS
Relatórios de estágio de mestrado - 2021
Departamento de Geologia
description Relatório de estágio de mestrado, Geologia Económica, Universidade de Lisboa, Faculdade de Ciências, 2021
publishDate 2021
dc.date.none.fl_str_mv 2021
2021
2021-01-01T00:00:00Z
2022-02-16T09:22:45Z
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
dc.type.driver.fl_str_mv info:eu-repo/semantics/masterThesis
format masterThesis
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10451/51330
TID:202931420
url http://hdl.handle.net/10451/51330
identifier_str_mv TID:202931420
dc.language.iso.fl_str_mv eng
language eng
dc.rights.driver.fl_str_mv info:eu-repo/semantics/openAccess
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron:RCAAP
instname_str Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
instacron_str RCAAP
institution RCAAP
reponame_str Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
collection Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
repository.name.fl_str_mv Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação
repository.mail.fl_str_mv
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