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Geração, Mobilização E Cristalização De Um Fundido Rico Em Álcalis Na Estrutura De Impacto De Araguainha

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Geração, Mobilização E Cristalização De Um Fundido Rico Em Álcalis Na Estrutura De Impacto De Araguainha Número 409/2009 UNIVERSIDADE ESTADUAL DE CAMPINAS INSTITUTO DE GEOCIÊNCIAS PÓS-GRADUAÇÃO EM GEOCIÊNCIAS UNICAMFI ÁREA DE GEOLOGIA E RECURSOS NATURAIS ROGÉRIO AMARO MACHADO GERAÇÃO, MOBILIZAÇÃO E CRISTALIZAÇÃO DE UM FUNDIDO RICO EM ÁLCALIS NA ESTRUTURA DE IMPACTO DE ARAGUAINHA Dissertação apresentada ao Instituto de Geociências como parte dos requisitos para a obtenção do título de Mestre em Geociências, Área de Geologia e Recursos Naturais Orientador: Pro f. Dr. Carlos Roberto de Souza Filho Co-orientador: Pro f Dr. Cristiano de Carvalho Lana CAMPINAS- SÃO PAULO Agosto - 2009 Catalogação na Publicação elaborada pela Biblioteca do Instituto de Geociências/UNICAMP ~· \~~ (\ Machado, Rogério Amaro ÁffiJ.0iü Geração, Mobilização e Cristalização de um Fundido Rico em Álcalis na Estrutura de Impacto de Araguainha I Rogério Amaro Machado.-- Campinas,SP.: [s.n.], 2009. Orientador: Carlos Roberto de Souza Filho. Co-Orientador: Cristiano de Carvalho Lana. Dissertação (mestrado) Universidade Estadual de Campinas, Instituto de Geociências. l. Estrutura de Impacto de Araguainha. 2. Fundidos de Impacto. 3. Geoquúnica. 4. Componente Meteorítica I. Souza Filho, Carlos Roberto de. Il. Lana, Cristiano de Carvalho. I. Universidade Estadual de Campinas, Instituto de Geociências. li. Universíty o f Stellenbosch, Centre for Clllstal Petrology, Department of(leo togy, Geography and Environmcnta! Stuclies. IIL Título. Título em inglês: Generation, Mobilization and Crystallization of an Alkali-Rich Melt on Araguainha Impact Structure. Palavras-chave em inglês (Keywords): Araguainha Impact Structure, Impact Melts, Geochemistry, Meteoritic Component. Área de concentração: Geologia e Recursos Naturais. Titulação: Mestre em Geociências. Banca examinadora: Carlos Roberto de Souza Filho; Lena Virgínia Soares Monteiro; Ruy Paulo Philipp. Data da defesa: 31108/2009. Programa de Pós-Graduação em Geociências. i i t:NIVERSIDADE f:STADUAL DF: CAMPINAS INSTITUTO I)E GEOCIÊNCIAS PÓS-GRADUAÇÃO EM GEOCIÊNCIAS ÁREA DE GEOLOGIA E RECURSOS NATURAIS UNICAMP AliTOR: Rogério' Amaro Machado "Geração, Mobilização e Cristalização de Melts Ricos em Álcalis na Estrutura de Impacto de Araguainha (GO/MT)." ORIENTADOR: Prol. Dr. Carlos Roberto Souza Filho Co-orientador; Prol. Dr. Cristiano de Carvalho Lana Aprovada em: :a I I O~ IZOQ:J EXAMINADORES: C1.J2 (' i Prol. Dr. Carlos Roberto Souza Filho ~--~-----""----"(;_-~_. ... L:.!_- Presidente Profa. Dra. Lena Virgínia Soares Monr';:.o i\ ~-- ' \ ) /,' 1 11 \ . 'i-/-A/ i ; . J, ' _). i I \ • I . tY ' • .i17iJ1 Prof. Dr. Ruy Paulo Philipp ---H:'LvU j -v~ ~c 1 v " ,Jít i 11! Campinas. 31 de agosto de 2009 jjj A minha família, Jorge, Terezinha, Thiago e Michelly v AGRADECIMENTOS Gostaria de agradecer a todos que fizeram parte desta etapa da minha vida. Aos meus orientadores Prof. Dr. Carlos Roberto de Souza Filho e Prof. Dr. Cristiano Lana, pela oportunidade e apoio incondicional. Aos professores do Instituto de Geociências por compartilhar o conhecimento. Aos funcionários do Instituto de Geociências, em especial a Valdirene e Edinalva. Aos meus ,amigos de graduação e do LAPIG, pela convivência e amizade demonstrada. Ao CNPq, ao Instituto de Geociências e a Universidade de Stellenbosch por fornecerem toda a infraestrutura para a realização deste trabalho. Ao Instituto de Geofísica da USP, pelo apoio na atividade campo, em especial ao Prof. Dr. Ricardo Trindade e Pro f' Dra. Y ára Marangoni. Ao Geólogo e amigo Elder Yokoyama, por me apresentar a estrutura de Araguainha. Aos amigos que fiz na África do Sul, por me acolherem de braços abertos nesta aventura, em especial ao Cristiano, Gwenaelle e Leila. Ao Prof. Dr. Gary Stevens e Pro f. Dr. Alex Kisters pelos conselhos. Ao Iain McDonald, da Cardiff University, pelas análises geoquímicas. A Barringer Crater Company pelo auxílio viagem disponibilizado para o Large Meteorite !mpacts and Planetary Evolution IV. A minha família e namorada pelo apoio e amor incondicional. vn SUMÁRIO I. INTRODUÇÃO ................................................................................................................................. I. 1.1. OBJETIVOS ............................................................................................................................... 2. 1.2. ESTRUTURA DA DISSERTAÇÃ0 .......................................................................................... 3. 1.3. LOCALIZAÇ;\0 E VIAS DE ACESS0.................................................................................... 3. 1.4. MATERIAIS E MÉTODOS ..........••..•.......................••.••....................••••••..........................•••... .4. 1.4.1. Levantamento Bibliográfico ..........••.••.••.••••••••...............••••••••.••••...............•.••••••.•••.•••......... 4. 1.4.2. Trabalho de Campo ••.••.••.••.••.•••••.••.••••.••.••.••.•••••••••••.•••.••••.••.••.•••••.••••••.•...••.•••.••••••••••.•••••••. 4. 1.4.3. Petrograjia ......................................................................................................................... 4. 1.4.4. Microscopia Eletrônica de Varredura (MEV) e Espectroscopia por Energia Dispersiva ... 4. 1.4.5. Litogeoquímica ................................................................................................................. 5. 1.4.6. Geoquimica dos Elementos do Grupo da Platina (EGPs) ................................................. 6. 2. CRATERAS DE IMPACTO ............................................................................................................ 7. 21. Background ................................................................................................................................ 1. 22. Mecanismos de Impacto ............................................................................................................. 9. 2.3. Tipos Morfológicos de Crateras de Impacto ............................................................................... 11. 2.4. Rochas Fundidks no Impacto ..................................................................................................... l3. 3. CONTEXTO GEOLÓGICO DO SOERGUIMENTO CENTRAL DO DOMO DE ARAGUAINHA •••••..............•••............................................................................................................ IS. 4. LITOTIPO ESTUDADOS .............................................................................................................. 20. 4. ]. Granito Cristalino Alcalino ....................................................................................................... 20. 4.2. Melt Veins ................................................................................................................................. 21. 4.3. Melt Sheet.................................................................................................................................. 31. JX 5. GEOQUÍMICA ............................................................................................................................... 36. 5.1. Litogeoquímica' .......................................................................................................................... 36. 5.2. Análises da matriz por EDS....................................................................................................... 41. 5.3 Geoquímica dos Elementos do Grupo da Platina (EGPs) ........................................................... 43. 5.3.1. Background ...................................................................................................................... 43. 5.3.1. Análises dos EGPs ............................................................................................................ 45. 6. DISCUSSÃO ................................................................................................................................... 46. 6.1 A Origem das Rochas Fundidas ................................................................................................. 41. 6.2. Implicações para Brechas Pseudotaquiliticas ............................................................................ 50. REFERÊNCIAS BIBLIOGRÁFICAS .................................................................. .,........................... 53. APÊNDICE 1 ...................................................................................................................................... 58. Localização dos Pontos Estudados ................................................................................................... 58. ANEXO ......... , ..........~ .......................................................................................................................... 59. X LISTA de FIGURAS Figura 1.1. Localização da cratera de impacto de Araguainha (Modificado de Crósta, 2002) .................. 3. Figura 2.1. Cratera do Meteoro, Arizona, E.U.A. (Osinki, 2008) . ........................................................... 8. Figuras 2.2. Representações esquemáticas dos estágios característicos de um evento de impacto. a) Estágio de contato e compressão. b) Estágio de escavação. c). Estágio de modificação (Fonte: Osinski, 2008) .................................................................................................................................................... 10. Figuras 2.3. a) Representação esquemática de uma cratera simples. b) Representação esquemática de uma cratera complexa com o centro soerguido. c} Representação esquemática de uma cratera complexa com o centro soerguido em forma de aneL d) Representação esquemática de uma
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