Submitted by Boris Flegr (boris@uerj.br) on 2021-01-05T15:33:49Z No. of bitstreams: 8 Pre textuais Pt1 a Pt 3 A.pdf: 3339789 bytes, checksum: 0041ccd83ccb26f6bab09a770a5e3ba4 (MD5) Pt 3 B a Pt 4 A.pdf: 3263159 bytes, checksum: 5c819b729171a32e4bdd6d7b8438d79a (MD5) Pt 4 B.pdf: 1890462 bytes, checksum: 665a7bce713a5686fdfca5f0091d475d (MD5) Pt 5 a Pt 6.pdf: 1598202 bytes, checksum: 2f2fa776d9c4a25cadf2f6fe09a4345a (MD5) Anexo A p 134.pdf: 5787335 bytes, checksum: ce858c0fb8a20def0f80515f6c1c3317 (MD5) Anexo A p 135 a 137.pdf: 2291749 bytes, checksum: adf75206bcea37f9451828e769dd8359 (MD5) Anexo A p 138 a 140.pdf: 3597495 bytes, checksum: fe93b79dba188562f31d43416238c350 (MD5) ANEXO B a F.pdf: 643455 bytes, checksum: 8c397bd4a56c4f8d48af20efac2592f1 (MD5) Made available in DSpace on 2021-01-05T15:33:49Z (GMT). No. of bitstreams: 8 Pre textuais Pt1 a Pt 3 A.pdf: 3339789 bytes, checksum: 0041ccd83ccb26f6bab09a770a5e3ba4 (MD5) Pt 3 B a Pt 4 A.pdf: 3263159 bytes, checksum: 5c819b729171a32e4bdd6d7b8438d79a (MD5) Pt 4 B.pdf: 1890462 bytes, checksum: 665a7bce713a5686fdfca5f0091d475d (MD5) Pt 5 a Pt 6.pdf: 1598202 bytes, checksum: 2f2fa776d9c4a25cadf2f6fe09a4345a (MD5) Anexo A p 134.pdf: 5787335 bytes, checksum: ce858c0fb8a20def0f80515f6c1c3317 (MD5) Anexo A p 135 a 137.pdf: 2291749 bytes, checksum: adf75206bcea37f9451828e769dd8359 (MD5) Anexo A p 138 a 140.pdf: 3597495 bytes, checksum: fe93b79dba188562f31d43416238c350 (MD5) ANEXO B a F.pdf: 643455 bytes, checksum: 8c397bd4a56c4f8d48af20efac2592f1 (MD5) Previous issue date: 2010-08-25 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior The diabase dykes of the study area (Ubatuba region) consist, predominantely, of NE-SW (N40-50E) subvertical bodies which follow the main trend of fractures in the area. This pattern is concordant with that of the high-TiO2 suite of the Serra do Mar Dykes Swarm in southeast coast of Brazil. Subordinately, these dikes follow a NW-SE or a NE-WSW orientation. The thickness of those bodies varies from 0,3 to 55 meters, although most of them have thickness between 1,5 and 8 meters. Regarding the forms of the fracture-conduit, the great majority of the dikes are emplaced within straight fractures. However, features like steps, bridges, stubs, bifurcations, stagger and dykes in zigzag are also observed. The studied diabases have black color, per times varying in red tones, as a reflection of the alteration degree. Most often, diabases are aphanitic or fine grained and, commonly, display porphyritic texture with plagioclase phenocrysts. In some cases, white carbonate-filled milimetric amigdals can be observed. The mineralogical composition of those diabases is little variable, consisting, essentially, of plagioclase, Ca-rich clinopyroxene (augite) and/or Ca-poor clinopyroxene (pigeonite). Acessory minerals are, commonly, olivine, opaque mineral(s) and apatite. Considering the lithogeochemical study, results indicate that, of the 27 samples selected for analysis of major and trace elements, 22 are tholeiitic diabases. The tholeiitic affinity of the great majority of the samples (22 in a population of 27) is corroborated by the presence of quartz and hypersthene (and absence of nepheline) in the CIPW norm, which lead to the classification of these diabases as quartz- tholeiites. In three of the studied samples, the presence of normative olivine and hypersthene (and absence of normative quartz) includes them in an olivine- tholeiite group. Of all the 25 samples of tholeiitic diabases, 24 were accounted to a high-TiO2 suite (TiO2> 2%peso) and only 1 was accounted to a low TiO2 one (TiO2 2%peso) e apenas 1 foi inserida dentro de uma suíte de baixo TiO2 (TiO2 < 2%peso). O estudo petrológico revela a existência de quatro suítes de alto-TiO2, tendo sido as mesmas discriminadas com base nas razões La/Yb de amostras com o teor semelhante de MgO. Destas, apenas as suítes 2 e 3 tem quantidade mínima de amostras para avaliação de processo evolutivo e os resultados indicam a cristalização fracionada com mudança de assembléia fracionante como processo evolutivo mais provável. A discriminação de fontes mantélicas foi feita exclusivamente com base nas razões entre elementos traços de amostras representativas de líquidos parentais das quatro suítes discriminadas. Os resultados indicam que todas as suítes originaram-se pela fusão de fontes mantélicas enriquecidas, tendo, assim, pelo menos uma contribuição de componentes litosféricos.