Geochemical modelling of the tonalitic and trondhjemitic granulites from the Itabuna-Salvador-Curaçá Block, Bahia, Brazil

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• 作者：Ivana Conceiç ; ã ; o de Araú ; jo Pinho^a ; ^{ivanapinho@yahoo.com.br} ; Johildo Salomã ; o Figueiredo Barbosa^a ; ^{johildo@cpgg.ufba.br} ; Angela Beatriz de Menezes Leal^a ; ^{angelab@ufba.br} ; Hervé ; Martin^b ; ^{martin@opgc.univ-bpclermont.fr} ; Jean-Jacques Peucat^c ; ^{peucat@univ-rennes1.fr}
• 关键词：High temperature metamorphism ; Geochemical modelling ; Paleoproterozoic granulites ; Sã ; o Francisco craton ; Bahia ; Brazil
• 刊名：Journal of South American Earth Sciences
• 出版年：2011
• 出版时间：March 2011
• 年：2011
• 卷：31
• 期：2-3
• 页码：312-323
• 全文大小：1183 K

文摘

The studied tonalitic and trondhjemitic granulites are located in the SSE granulitic domain of the São Francisco craton, Bahia, Brazil, where they represent most of the southern part of the Archean and Paleoproterozoic Itabuna-Salvador-Curaçá Block (ISCB). Chemically, the tonalitic and trondhjemitic granulites belong to a low-K calc-alkaline suite; their REE patterns are steep with strong LREE/HREE fractionation and no significant Eu anomaly. Garnet-bearing mafic granulites that occur as enclaves in the tonalitic and trondhjemitic granulites were derived from basalts and/or gabbros of tholeiitic affinity. Geochemical modelling showed that the tonalitic and trondhjemitic granulites were produced by moderate fractional crystallization of an assemblage of hornblende and plagioclase, with subordinate amounts of magnetite, apatite, allanite and zircon. The garnet-bearing mafic granulites would be the source of the magmas that generated these rocks. Partial melting left a residue made up of plagioclase, garnet, orthopyroxene and hornblende.