Plume-lithosphere interaction at Santiago Island (Cape Verde) : implications for ocean island magma genesis models

Bibliographic Details
Main Author: Martins, Sofia Maria Marques
Publication Date: 2014
Language: eng
Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
Download full: http://hdl.handle.net/10451/16025
Summary: Tese de doutoramento, Geologia (Geoquímica), Universidade de Lisboa, Faculdade de Ciências, 2014
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spelling Plume-lithosphere interaction at Santiago Island (Cape Verde) : implications for ocean island magma genesis modelsTeses de doutoramento - 2014Tese de doutoramento, Geologia (Geoquímica), Universidade de Lisboa, Faculdade de Ciências, 2014Santiago Island is the largest one in the Cape Verde archipelago with a total area of 991 km2. It belongs to the southern group with Maio, Fogo and Brava Islands. Apart from the substrate (Complexo Antigo) Santiago's volcanostratigraphy is largely composed of subareal and submarine alkaline lavas outcrops, which cover a time span of circa 5 Ma. Santiago alkaline lavas are testimony of a complex magmatic history, where chemical and lithological heterogeneous mantle sources and the interaction of advecting magmas with thick metasomatized oceanic lithosphere is preponderant in the observed isotopic and trace element signatures. The distinctive major and trace element characteristics of Santiago lavas stand as a strong indicator of a carbonated mantle source with contributions from peridotitic and silica deficient garnet pyroxenite domains. The correlation of these elemental evidences with radiogenic isotopic data attests the presence of these domains within the plume, as well as their ancient signature. Young (< 3.3 Ma) primitive Santiago lavas show evidence for the equilibration with modal and cryptically metasomatized oceanic lithospheric mantle. The metasomatism is responsible for the inferred hydrous mineral assemblage (amphibole and phlogopite) as well as specific geochemical tracers. Interestingly this signature is not ubiquitous in Santiago lavas mantle source, since the older formations do not show strong evidences for interaction with metasomatized domains of the lithosphere. The carbonatitic nature of the metasomatic agent is attested from indirect geochemical signatures in alkaline lavas and direct evidence portrayed by lherzolitic xenoliths. It is important to acknowledge that the metasomatic agent composition is elemental and isotopically distinct from outcropping carbonatites. In accordance with the overall isotopic characteristics of the Southern Cape Verde Islands, elemental and isotopic signatures of Santiago alkaline lavas suggest the involvement of HIMU and EM1-type mantle end-members, with the contribution a relatively undegassed and unradiogenic reservoir (Lower Mantle). The geochemical characteristics of Santiago allow us to consider the EM-1 like end-member as resulting from the involvement of subcontinental lithospheric mantle in Santiago’s magma genesis. Tholeiitic outcropping lavas in the Santiago’s northern area are considered as formed in a mid oceanic ridge environment. The lavas are highly depleted in LREE and incompatible elements, even when compared with D-MORB values. This depletion seems to be ubiquitous in Central Atlantic MORB erupted between 160 to 118 Ma. The eruption of highly depleted lavas at the initial stages of the Atlantic opening is here interpreted as the result of high degrees of partial melting induced by sub-lithospheric elevated temperatures brought on by continental thermal insulation. Santiago gabbroic xenoliths show geochemical similarities with Santiago MORB affinity lavas attesting their cumulate formation from abyssal-type magmas. The enrichment observed in some is most certainly derived from the interaction of ascending alkaline magmas with the pre-existing N-MORB crust.Fundação para a Ciência e a Tecnologia (FCT)Mata, João Manuel Lima da Silva, 1957-Munhá, José Manuel Urbano, 1951-Repositório da Universidade de LisboaMartins, Sofia Maria Marques2015-02-13T18:10:57Z201420142014-01-01T00:00:00Zdoctoral thesisinfo:eu-repo/semantics/publishedVersionapplication/pdfhttp://hdl.handle.net/10451/16025TID:101229372enginfo:eu-repo/semantics/openAccessreponame:Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)instname:FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologiainstacron:RCAAP2025-03-17T13:16:44Zoai:repositorio.ulisboa.pt:10451/16025Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireinfo@rcaap.ptopendoar:https://opendoar.ac.uk/repository/71602025-05-29T02:39:40.211433Repositórios Científicos de Acesso Aberto de Portugal (RCAAP) - FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologiafalse
dc.title.none.fl_str_mv Plume-lithosphere interaction at Santiago Island (Cape Verde) : implications for ocean island magma genesis models
title Plume-lithosphere interaction at Santiago Island (Cape Verde) : implications for ocean island magma genesis models
spellingShingle Plume-lithosphere interaction at Santiago Island (Cape Verde) : implications for ocean island magma genesis models
Martins, Sofia Maria Marques
Teses de doutoramento - 2014
title_short Plume-lithosphere interaction at Santiago Island (Cape Verde) : implications for ocean island magma genesis models
title_full Plume-lithosphere interaction at Santiago Island (Cape Verde) : implications for ocean island magma genesis models
title_fullStr Plume-lithosphere interaction at Santiago Island (Cape Verde) : implications for ocean island magma genesis models
title_full_unstemmed Plume-lithosphere interaction at Santiago Island (Cape Verde) : implications for ocean island magma genesis models
title_sort Plume-lithosphere interaction at Santiago Island (Cape Verde) : implications for ocean island magma genesis models
author Martins, Sofia Maria Marques
author_facet Martins, Sofia Maria Marques
author_role author
dc.contributor.none.fl_str_mv Mata, João Manuel Lima da Silva, 1957-
Munhá, José Manuel Urbano, 1951-
Repositório da Universidade de Lisboa
dc.contributor.author.fl_str_mv Martins, Sofia Maria Marques
dc.subject.por.fl_str_mv Teses de doutoramento - 2014
topic Teses de doutoramento - 2014
description Tese de doutoramento, Geologia (Geoquímica), Universidade de Lisboa, Faculdade de Ciências, 2014
publishDate 2014
dc.date.none.fl_str_mv 2014
2014
2014-01-01T00:00:00Z
2015-02-13T18:10:57Z
dc.type.driver.fl_str_mv doctoral thesis
dc.type.status.fl_str_mv info:eu-repo/semantics/publishedVersion
status_str publishedVersion
dc.identifier.uri.fl_str_mv http://hdl.handle.net/10451/16025
TID:101229372
url http://hdl.handle.net/10451/16025
identifier_str_mv TID:101229372
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:Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
instname:FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologia
instacron:RCAAP
instname_str FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologia
instacron_str RCAAP
institution RCAAP
reponame_str Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
collection Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
repository.name.fl_str_mv Repositórios Científicos de Acesso Aberto de Portugal (RCAAP) - FCCN, serviços digitais da FCT – Fundação para a Ciência e a Tecnologia
repository.mail.fl_str_mv info@rcaap.pt
_version_ 1833601444751605760

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