Upper Cretaceous weakly to strongly silica-undersaturated alkaline dike series of the Mantiqueira Range, Serra do Mar alkaline province: Crustal assimilation processes and mantle source signatures

Upper Cretaceous weakly to strongly silica-undersaturated alkaline dike series of the Mantiqueira Range, Serra do Mar alkaline province: Crustal assimilation processes and mantle source signatures

dc.contributoren-US
dc.contributorpt-BR
dc.creatorAzzone, Rogério Guitarrari
dc.creatorRuberti, Excelso
dc.creatorSilva, Júlio César Lopes da
dc.creatorGomes, Celso de Barros
dc.creatorEnrich Rojas, Gaston Eduardo
dc.creatorHollanda, Maria Helena Bezerra Maia de
dc.creatorTassinari, Colombo Celso Gaeta
dc.date2018-06-01
dc.date.accessioned2022-12-15T20:12:36Z
dc.date.available2022-12-15T20:12:36Z
dc.identifierhttps://ppegeo.igc.usp.br/index.php/bjg/article/view/12301
dc.identifier10.1590/2317-4889201820170089
dc.identifier.urihttps://repositorioslatinoamericanos.uchile.cl/handle/2250/5360206
dc.descriptionThree series of alkaline dikes are characterized in a restricted area of the Mantiqueira Range: a weakly silica-undersaturated series (normative ne < 7), of potassic character, represented by basanite, tephrites, alkali basalts, basaltic trachyandesites, phonotephrites, tephriphonolites, and trachyandesites, an intermediate series (7 > normative ne > 13), of potassic character, consisting only of basanites and tephrites, and a strongly silica-undersaturated series (normative ne > 13), of sodic character, consisting of basanites, tephrites, phonotephrites, and phonolites. Ar-Ar data for biotite from a tephriphonolite dike yielded an average age of 85.4±0.4 Ma. All three series show similar evolution trends controlled mainly by early-fractionation of olivine, spinel and clinopyroxene and, secondly, fractionation of plagioclase and apatite. Different degrees of crustal assimilation are suggested for each series. Assimilation processes are responsible for the wide 87Sr/86Sri (0.70447-0.71172) and 143Nd/144Ndi (0.51237-0.51244) ranges, for the increased K2O/Na2O, Ba/Sr and Rb/Sr ratios, and for the reduced Ce/Pb ratios. In general, a significant contribution from partially melted host rocks is associated to the weakly silica-undersaturated potassic series. A phlogopite-bearing carbonate-metasomatized heterogeneous peridotite source accounts for the main chemical variations in the least contaminated samples of each series. Geochemical signatures of the strongly sodic alkaline series indicate a greater contribution from carbonated pyroxene-rich veins in the mantle source.en-US
dc.descriptionThree series of alkaline dikes are characterized in a restricted area of the Mantiqueira Range: a weakly silica-undersaturated series (normative ne < 7), of potassic character, represented by basanite, tephrites, alkali basalts, basaltic trachyandesites, phonotephrites, tephriphonolites, and trachyandesites, an intermediate series (7 > normative ne > 13), of potassic character, consisting only of basanites and tephrites, and a strongly silica-undersaturated series (normative ne > 13), of sodic character, consisting of basanites, tephrites, phonotephrites, and phonolites. Ar-Ar data for biotite from a tephriphonolite dike yielded an average age of 85.4±0.4 Ma. All three series show similar evolution trends controlled mainly by early-fractionation of olivine, spinel and clinopyroxene and, secondly, fractionation of plagioclase and apatite. Different degrees of crustal assimilation are suggested for each series. Assimilation processes are responsible for the wide 87Sr/86Sri (0.70447-0.71172) and 143Nd/144Ndi (0.51237-0.51244) ranges, for the increased K2O/Na2O, Ba/Sr and Rb/Sr ratios, and for the reduced Ce/Pb ratios. In general, a significant contribution from partially melted host rocks is associated to the weakly silica-undersaturated potassic series. A phlogopite-bearing carbonate-metasomatized heterogeneous peridotite source accounts for the main chemical variations in the least contaminated samples of each series. Geochemical signatures of the strongly sodic alkaline series indicate a greater contribution from carbonated pyroxene-rich veins in the mantle source.pt-BR
dc.formatapplication/pdf
dc.languageeng
dc.publisherSociedade Brasileira de Geologiapt-BR
dc.relationhttps://ppegeo.igc.usp.br/index.php/bjg/article/view/12301/11860
dc.rightsDireitos autorais 2018 Brazilian Journal of Geologypt-BR
dc.sourceBrazilian Journal og Geology; v. 48, n. 2 (2018); 373-390en-US
dc.sourceBrazilian Journal of Geology; v. 48, n. 2 (2018); 373-390pt-BR
dc.source2317-4692
dc.source2317-4889
dc.subjectAlkaline magmatism; Potassic and sodic series; Crustal assimilation; Metasomatized mantle source.en-US
dc.subjectAlkaline magmatism; Potassic and sodic series; Crustal assimilation; Metasomatized mantle source.pt-BR
dc.titleUpper Cretaceous weakly to strongly silica-undersaturated alkaline dike series of the Mantiqueira Range, Serra do Mar alkaline province: Crustal assimilation processes and mantle source signaturesen-US
dc.titleUpper Cretaceous weakly to strongly silica-undersaturated alkaline dike series of the Mantiqueira Range, Serra do Mar alkaline province: Crustal assimilation processes and mantle source signaturespt-BR
dc.typeinfo:eu-repo/semantics/article
dc.typeinfo:eu-repo/semantics/publishedVersion
dc.typeen-US
dc.typept-BR


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