The evolution of Neoproterozoic magmatism in Southernmost Brazil: shoshonitic, high-K tholeiitic and silica-saturated, sodic alkaline volcanism in post-collisional basins
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| Natura: | Artículo científico |
| Lingua: | en |
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Academia Brasileira de Ciências
2006
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| author | Carlos A. Sommer |
| author_facet | Carlos A. Sommer |
| contents | The evolution of Neoproterozoic magmatism in Southernmost Brazil: shoshonitic, high-K tholeiitic and silica-saturated, sodic alkaline volcanism in post-collisional basins Carlos A. Sommer Evandro F. Lima Lauro V. S. Nardi Joaquim D. Liz Breno L. Waichel Multidisciplinaria (Ciencias Naturales y Exactas) Na Post alkaline volcanism shoshonite The Neoproterozoic shoshonitic and mildly alkaline bimodal volcanism of Southernmost Brazil is repre- sented by rock assemblages associated to sedimentary successions, deposited in strike-slip basins formed at the post-collisional stages of the Brasilian/Pan-African orogenic cycle. The best-preserved volcano-sedimentary associations occur in the Camaquã and Campo Alegre Basins, respectively in theSul-rio- grandense and Catarinense Shields and are outside the main shear belts or overlying the unaffected base- ment areas. These basins are characterized by alternation of volcanic cycles and siliciclastic sedimentation developed dominantly on a continental setting under subaerial conditions. This volcanism and the coeval plu- tonism evolved from high-K tholeiitic and calc-alkaline to shoshonitic and ended with a silica saturated sodic alkaline magmatism, and its evolution were developed during at least 60 Ma. The compositional variation and evolution of post-collisional magmatism in southern Brazil are interpreted as the result mainly of melting of a heterogeneous mantle source, which includes garnet-phlogopite-bearing peridotites, veined-peridotites with abundant hydrated phases, such as amphibole, apatite and phlogopite, and eventually with the addition of an asthenospheric component. The subduction-related metasomatic character of post-collisional magmatism mantle sources in southern Brazil is put in evidence by Nb-negative anomalies and isotope features typical of EM1 sources. 2006 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32778315 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.3 Vol.78 |
| format | Artículo científico |
| id | redalyc_32778315 |
| institution | Redalyc |
| language | en |
| publishDate | 2006 |
| publisher | Academia Brasileira de Ciências |
| spellingShingle | The evolution of Neoproterozoic magmatism in Southernmost Brazil: shoshonitic, high-K tholeiitic and silica-saturated, sodic alkaline volcanism in post-collisional basins Carlos A. Sommer Multidisciplinaria (Ciencias Naturales y Exactas) Na Post alkaline volcanism shoshonite The evolution of Neoproterozoic magmatism in Southernmost Brazil: shoshonitic, high-K tholeiitic and silica-saturated, sodic alkaline volcanism in post-collisional basins Carlos A. Sommer Evandro F. Lima Lauro V. S. Nardi Joaquim D. Liz Breno L. Waichel Multidisciplinaria (Ciencias Naturales y Exactas) Na Post alkaline volcanism shoshonite The Neoproterozoic shoshonitic and mildly alkaline bimodal volcanism of Southernmost Brazil is repre- sented by rock assemblages associated to sedimentary successions, deposited in strike-slip basins formed at the post-collisional stages of the Brasilian/Pan-African orogenic cycle. The best-preserved volcano-sedimentary associations occur in the Camaquã and Campo Alegre Basins, respectively in theSul-rio- grandense and Catarinense Shields and are outside the main shear belts or overlying the unaffected base- ment areas. These basins are characterized by alternation of volcanic cycles and siliciclastic sedimentation developed dominantly on a continental setting under subaerial conditions. This volcanism and the coeval plu- tonism evolved from high-K tholeiitic and calc-alkaline to shoshonitic and ended with a silica saturated sodic alkaline magmatism, and its evolution were developed during at least 60 Ma. The compositional variation and evolution of post-collisional magmatism in southern Brazil are interpreted as the result mainly of melting of a heterogeneous mantle source, which includes garnet-phlogopite-bearing peridotites, veined-peridotites with abundant hydrated phases, such as amphibole, apatite and phlogopite, and eventually with the addition of an asthenospheric component. The subduction-related metasomatic character of post-collisional magmatism mantle sources in southern Brazil is put in evidence by Nb-negative anomalies and isotope features typical of EM1 sources. 2006 artículo científico 0001-3765 https://www.redalyc.org/articulo.oa?id=32778315 en http://www.redalyc.org/revista.oa?id=327 Anais da Academia Brasileira de Ciências application/pdf Academia Brasileira de Ciências Anais da Academia Brasileira de Ciências (Brasil) Num.3 Vol.78 |
| title | The evolution of Neoproterozoic magmatism in Southernmost Brazil: shoshonitic, high-K tholeiitic and silica-saturated, sodic alkaline volcanism in post-collisional basins |
| topic | Multidisciplinaria (Ciencias Naturales y Exactas) Na Post alkaline volcanism shoshonite |
| url | https://www.redalyc.org/articulo.oa?id=32778315 |