Banca de DEFESA: ROBSON MAURO DOS ANJOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ROBSON MAURO DOS ANJOS
DATA : 08/08/2019
HORA: 14:00
LOCAL: IGEO/UFBA
TÍTULO:

The alkaline rocks of the Jaguaquara region – petrography and  litogeochemistry, Jequié block - Bahia, Brazil

PALAVRAS-CHAVES:

São Francisco Craton, Jequié Block, Alkaline rocks, Petrography and Litogeochemistry.

PÁGINAS: 68
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
SUBÁREA: Geologia
ESPECIALIDADE: Petrologia
RESUMO:

The geological evolution of the São Francisco Craton (CSF), in the State of Bahia, is evidenced by Archean and Paleoproterozoic lands, by metasedimentary and sedimentary coverings, besides the mafic magmatism whose origin corresponds to the Meso-Neoproterozoic. In Bahia, the CSF was structured by the amalgamation of four Archean crustal segments: the Gavião Block (BG), the Serrinha Block (BS), the Jequié Block (BJ) and the Itabuna-Salvador-Curaçá Block (BISC). In this context, the rare records of occurrences of alkaline magmatism in the State of Bahia date from the Archean to the Neoproterozoic. In the Jaguaquara region, the focus of this study, these rocks comprise one of the alkaline igneous occurrences in the Center-South portion of the State of Bahia, inserted in rocks of the Jequié Complex located in the homonymous block, close to the transition with the Itabuna-Salvador-Curaçá Belt.. The objective of this study is to proceed to the geological mapping of the anomalous magnetic zone, which at first is related to the existence of the alkaline rocks of the Jaguaquara region and their granulitic nesting. Thus, the fieldwork aided by petrography allowed the individualization of two sets of lithophages, the first alkaline composed by: Metasienite, Albitated Metasienite, Quartz-Syenite, Albitrated Quartz-Syenite and Albitite, and the second comprising the enclosing rocks, in its granulitic essence divided into: Kinzigitos, Grunerita-Gondito, Bandada Ferrous Formation, Tremolithito, all of origin of dererivatives and the Enderbites, Charnoenderitus and Charnockitos of orthoderivative origin. Based on lithogeochemistry, alkaline lithofacies are classified as quartz monozonite syenites, predominantly peralcaline. The parallelism observed between the ETR and multi-element lithofacies spectra indicates that the alkaline rocks are cogenetic and possibly reflect the geochemical signature of the magma generating source. Tectonic classification diagrams for the alkaline rocks of Jaguaquara suggest that the lithotypes are late post-orogenic. Finally, the lithogeochemistry allowed a better understanding of the geological processes acting in both the alkaline lithotypes and the embedded rock protoliths, being important for the understanding of the role of tectonics and metamorphism of the study area.

MEMBROS DA BANCA:
Presidente - 2982944 - JAILMA SANTOS DE SOUZA DE OLIVEIRA
Interno - 005.454.575-72 - JOHILDO SALOMAO FIGUEIREDO BARBOSA - UFBA
Externo à Instituição - ERON PIRES MACEDO - SGB