Pb isotope geochemistry and reappraisal of Sr-Nd isotopes of the Cerro Morado basic magmatism (Ischigualasto-Villa Union Triassic basin, NW Argentina): Implications for the mantle sources

Pb isotope geochemistry and reappraisal of Sr-Nd isotopes of the Cerro Morado basic magmatism (Ischigualasto-Villa Union Triassic basin, NW Argentina): Implications for the mantle sources

dc.contributoren-US
dc.contributorpt-BR
dc.creatorSommer, Carlos Augusto
dc.creatorBarreto, Carla Joana S.
dc.creatorLafon, Jean Michel
dc.creatorLima, Evandro Fernandes de
dc.creatorAlexandre, Felipe Marcelo
dc.creatorChemale Jr., Farid
dc.creatorKoester, Edinei
dc.date2018-04-13
dc.date.accessioned2022-12-15T20:11:10Z
dc.date.available2022-12-15T20:11:10Z
dc.identifierhttps://ppegeo.igc.usp.br/index.php/bjg/article/view/12066
dc.identifier10.1590/2317-4889201820170106
dc.identifier.urihttps://repositorioslatinoamericanos.uchile.cl/handle/2250/5360111
dc.descriptionSr-Nd-Pb isotopic signatures were determined for silica-undersaturated hypabyssal alkaline basic rocks of the Los Baldecitos Formation in the Cerro Morado area, situated in the Ischigualasto — Vale de la Luna Provincial Park (northernmost San Juan Province, Argentina). The basic rocks show slight variations of the Sr-Nd-Pb isotopes and similar behavior of whole-rock geochemistry, which suggest a single source for the Cerro Morado volcanic rocks. The present-day Pb isotopic data show moderately radiogenic Pb compositions (206Pb/204Pb = 18.31 – 18.35), in addition to low values of 87Sr/86Sr initial ratios of 0.70314 – 0.70386 and highly radiogenic Nd initial isotopic compositions (+7.1 < εNd (228 Ma) < +9.3), which point to a PREMA mantle reservoir signature for the alkaline basalts with little evidence of crustal contamination. The involvement of a HIMU component in the source, previously suggested for the Cerro Morado volcanics, should be disregarded in the light of the Pb isotopic signature. The Sr-Nd signature together with Nd-TDM model ages not older than 295 Ma does not support the involvement of an ancient crust.en-US
dc.descriptionSr-Nd-Pb isotopic signatures were determined for silica-undersaturated hypabyssal alkaline basic rocks of the Los Baldecitos Formation in the Cerro Morado area, situated in the Ischigualasto — Vale de la Luna Provincial Park (northernmost San Juan Province, Argentina). The basic rocks show slight variations of the Sr-Nd-Pb isotopes and similar behavior of whole-rock geochemistry, which suggest a single source for the Cerro Morado volcanic rocks. The present-day Pb isotopic data show moderately radiogenic Pb compositions (206Pb/204Pb = 18.31 – 18.35), in addition to low values of 87Sr/86Sr initial ratios of 0.70314 – 0.70386 and highly radiogenic Nd initial isotopic compositions (+7.1 < εNd (228 Ma) < +9.3), which point to a PREMA mantle reservoir signature for the alkaline basalts with little evidence of crustal contamination. The involvement of a HIMU component in the source, previously suggested for the Cerro Morado volcanics, should be disregarded in the light of the Pb isotopic signature. The Sr-Nd signature together with Nd-TDM model ages not older than 295 Ma does not support the involvement of an ancient crust.pt-BR
dc.formatapplication/pdf
dc.languageeng
dc.publisherSociedade Brasileira de Geologiapt-BR
dc.relationhttps://ppegeo.igc.usp.br/index.php/bjg/article/view/12066/11611
dc.rightsDireitos autorais 2018 Brazilian Journal of Geologypt-BR
dc.sourceBrazilian Journal og Geology; v. 48, n. 1 (2018); 115-126en-US
dc.sourceBrazilian Journal of Geology; v. 48, n. 1 (2018); 115-126pt-BR
dc.source2317-4692
dc.source2317-4889
dc.subjectIschigualasto-Villa Unión Triassic Basin; Silica Undersaturated Rocks; Northwestern Argentina; Sr-Nd-Pb Isotopes.en-US
dc.subjectIschigualasto-Villa Unión Triassic Basin; Silica Undersaturated Rocks; Northwestern Argentina; Sr-Nd-Pb Isotopes.pt-BR
dc.titlePb isotope geochemistry and reappraisal of Sr-Nd isotopes of the Cerro Morado basic magmatism (Ischigualasto-Villa Union Triassic basin, NW Argentina): Implications for the mantle sourcesen-US
dc.titlePb isotope geochemistry and reappraisal of Sr-Nd isotopes of the Cerro Morado basic magmatism (Ischigualasto-Villa Union Triassic basin, NW Argentina): Implications for the mantle sourcespt-BR
dc.typeinfo:eu-repo/semantics/article
dc.typeinfo:eu-repo/semantics/publishedVersion
dc.typeen-US
dc.typept-BR


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