The age and origin of the barite-fluorite (Pb-Zn) veins of the Sierra del Guadarrama (Spanish Central System, Spain): a radiogenic (Nd, Sr) and stable isotope study

Fluorite and barite-rich veins ( + sulphides) of the Sierra del Guadarrama (Spanish Central System) are usually hosted by Hercynian granitoids. Zoned fluorites from one of these veins have a Sm-Nd age of 145 ± 18 Ma. This age is similar to the K-Ar ages obtained in other hydrothermal rocks of the Sp...

Descripción completa

Detalles Bibliográficos
Autores: Galindo Francisco, María Del Carmen, Tornos Arroyo, Fernando, Darbishyre, D.P.F., Casquet Martín, César
Tipo de recurso: artículo
Fecha de publicación:1994
País:España
Institución:Universidad Complutense de Madrid (UCM)
Repositorio:Docta Complutense
Idioma:inglés
OAI Identifier:oai:docta.ucm.es:20.500.14352/56986
Acceso en línea:https://hdl.handle.net/20.500.14352/56986
Access Level:acceso abierto
Palabra clave:550.4(234.1)
Hercynian granitoids
Isotope study
Spanish Central System
Geoquímica
2503 Geoquímica
id ES_22fb60d9ce2aa5b5a56ea9bf267fa609
oai_identifier_str oai:docta.ucm.es:20.500.14352/56986
network_acronym_str ES
network_name_str España
repository_id_str
spelling The age and origin of the barite-fluorite (Pb-Zn) veins of the Sierra del Guadarrama (Spanish Central System, Spain): a radiogenic (Nd, Sr) and stable isotope studyGalindo Francisco, María Del CarmenTornos Arroyo, FernandoDarbishyre, D.P.F.Casquet Martín, César550.4(234.1)Hercynian granitoidsIsotope studySpanish Central SystemGeoquímica2503 GeoquímicaFluorite and barite-rich veins ( + sulphides) of the Sierra del Guadarrama (Spanish Central System) are usually hosted by Hercynian granitoids. Zoned fluorites from one of these veins have a Sm-Nd age of 145 ± 18 Ma. This age is similar to the K-Ar ages obtained in other hydrothermal rocks of the Spanish Central System (156-152 Ma) and confirms the existence of an important hydrothermal event during the Late Jurassic, probably related to extensional fracturing accompanying the opening of the North Atlantic Ocean. The 87Sr/86Sr ratio found in fluorite and barite (0.7154-0.7207) is in most cases lower than that found in the host granitoids (0.7194 and 0.7209), suggesting more than one source of strontium. This, in turn, supports previous models that involve mixing of two fluids during mineralization, an ascending hot ( > 300 ° C) and low-salinity fluid and a shallow, cooler ( < 100 ° C) and more saline brine. The ascending fluid probably reacted to a variable extent with the host granitoids, and the most likely source for the shallow fluid derived from a marine/evaporitic environment, with a low 87Sr/86Sr ratio (0.7069 in the Late Jurassic) . The calculated ENd composition of the fluorites (-8.8 to -7.6) as well as the 147Sm/144Nd variation found in this mineral (0.153-0.405) do not conflict with the mixing model although they can be largely explained by interaction of the ascending fluid with the host granitoids. Sulphur isotopic compositions of sulphides range between - 3.4 and - 0.8 ‰ and those of barites from + 15.5 to + 15.8‰. The near δ34S-value of the sulphides suggests that their sulphur was derived from the hydrothermal leaching of the granitoids by the ascending fluid. The δ34S-value of barite is consistent with Upper Jurassic marine sulphate as the source of sulphate in the shallow fluid. The absence of equilibrium between reduced and oxidized sulphur species can be easily interpreted as a consequence of the short residence time of the mixed fluid in the open fractures at temperatures between 250° and lOO°C. Although no pre-Cretaceous sediments are found on this part of the Iberian Hercynian basement, the data presented here support the existence of a shallow platform joining central Spain with the Iberian or the Subbetic realm in Late Jurassic times.Elsevier Science B.V., Amsterdam.Universidad Complutense de Madrid19941994-01-0119941994-01-01journal articlehttp://purl.org/coar/resource_type/c_6501info:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/20.500.14352/56986reponame:Docta Complutenseinstname:Universidad Complutense de Madrid (UCM)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2info:eu-repo/semantics/openAccessoai:docta.ucm.es:20.500.14352/569862026-06-02T12:44:21Z
dc.title.none.fl_str_mv The age and origin of the barite-fluorite (Pb-Zn) veins of the Sierra del Guadarrama (Spanish Central System, Spain): a radiogenic (Nd, Sr) and stable isotope study
title The age and origin of the barite-fluorite (Pb-Zn) veins of the Sierra del Guadarrama (Spanish Central System, Spain): a radiogenic (Nd, Sr) and stable isotope study
spellingShingle The age and origin of the barite-fluorite (Pb-Zn) veins of the Sierra del Guadarrama (Spanish Central System, Spain): a radiogenic (Nd, Sr) and stable isotope study
Galindo Francisco, María Del Carmen
550.4(234.1)
Hercynian granitoids
Isotope study
Spanish Central System
Geoquímica
2503 Geoquímica
title_short The age and origin of the barite-fluorite (Pb-Zn) veins of the Sierra del Guadarrama (Spanish Central System, Spain): a radiogenic (Nd, Sr) and stable isotope study
title_full The age and origin of the barite-fluorite (Pb-Zn) veins of the Sierra del Guadarrama (Spanish Central System, Spain): a radiogenic (Nd, Sr) and stable isotope study
title_fullStr The age and origin of the barite-fluorite (Pb-Zn) veins of the Sierra del Guadarrama (Spanish Central System, Spain): a radiogenic (Nd, Sr) and stable isotope study
title_full_unstemmed The age and origin of the barite-fluorite (Pb-Zn) veins of the Sierra del Guadarrama (Spanish Central System, Spain): a radiogenic (Nd, Sr) and stable isotope study
title_sort The age and origin of the barite-fluorite (Pb-Zn) veins of the Sierra del Guadarrama (Spanish Central System, Spain): a radiogenic (Nd, Sr) and stable isotope study
dc.creator.none.fl_str_mv Galindo Francisco, María Del Carmen
Tornos Arroyo, Fernando
Darbishyre, D.P.F.
Casquet Martín, César
author Galindo Francisco, María Del Carmen
author_facet Galindo Francisco, María Del Carmen
Tornos Arroyo, Fernando
Darbishyre, D.P.F.
Casquet Martín, César
author_role author
author2 Tornos Arroyo, Fernando
Darbishyre, D.P.F.
Casquet Martín, César
author2_role author
author
author
dc.contributor.none.fl_str_mv Universidad Complutense de Madrid
dc.subject.none.fl_str_mv 550.4(234.1)
Hercynian granitoids
Isotope study
Spanish Central System
Geoquímica
2503 Geoquímica
topic 550.4(234.1)
Hercynian granitoids
Isotope study
Spanish Central System
Geoquímica
2503 Geoquímica
description Fluorite and barite-rich veins ( + sulphides) of the Sierra del Guadarrama (Spanish Central System) are usually hosted by Hercynian granitoids. Zoned fluorites from one of these veins have a Sm-Nd age of 145 ± 18 Ma. This age is similar to the K-Ar ages obtained in other hydrothermal rocks of the Spanish Central System (156-152 Ma) and confirms the existence of an important hydrothermal event during the Late Jurassic, probably related to extensional fracturing accompanying the opening of the North Atlantic Ocean. The 87Sr/86Sr ratio found in fluorite and barite (0.7154-0.7207) is in most cases lower than that found in the host granitoids (0.7194 and 0.7209), suggesting more than one source of strontium. This, in turn, supports previous models that involve mixing of two fluids during mineralization, an ascending hot ( > 300 ° C) and low-salinity fluid and a shallow, cooler ( < 100 ° C) and more saline brine. The ascending fluid probably reacted to a variable extent with the host granitoids, and the most likely source for the shallow fluid derived from a marine/evaporitic environment, with a low 87Sr/86Sr ratio (0.7069 in the Late Jurassic) . The calculated ENd composition of the fluorites (-8.8 to -7.6) as well as the 147Sm/144Nd variation found in this mineral (0.153-0.405) do not conflict with the mixing model although they can be largely explained by interaction of the ascending fluid with the host granitoids. Sulphur isotopic compositions of sulphides range between - 3.4 and - 0.8 ‰ and those of barites from + 15.5 to + 15.8‰. The near δ34S-value of the sulphides suggests that their sulphur was derived from the hydrothermal leaching of the granitoids by the ascending fluid. The δ34S-value of barite is consistent with Upper Jurassic marine sulphate as the source of sulphate in the shallow fluid. The absence of equilibrium between reduced and oxidized sulphur species can be easily interpreted as a consequence of the short residence time of the mixed fluid in the open fractures at temperatures between 250° and lOO°C. Although no pre-Cretaceous sediments are found on this part of the Iberian Hercynian basement, the data presented here support the existence of a shallow platform joining central Spain with the Iberian or the Subbetic realm in Late Jurassic times.
publishDate 1994
dc.date.none.fl_str_mv 1994
1994-01-01
1994
1994-01-01
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/20.500.14352/56986
url https://hdl.handle.net/20.500.14352/56986
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.publisher.none.fl_str_mv Elsevier Science B.V., Amsterdam.
publisher.none.fl_str_mv Elsevier Science B.V., Amsterdam.
dc.source.none.fl_str_mv reponame:Docta Complutense
instname:Universidad Complutense de Madrid (UCM)
instname_str Universidad Complutense de Madrid (UCM)
reponame_str Docta Complutense
collection Docta Complutense
repository.name.fl_str_mv
repository.mail.fl_str_mv
_version_ 1869404614145605632
score 15,300719

Similares en LA Referencia