Banca de QUALIFICAÇÃO: ROBSON RAFAEL DE OLIVEIRA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : ROBSON RAFAEL DE OLIVEIRA
DATA : 14/12/2018
HORA: 09:00
LOCAL: Sala 24 - Departamento de Geologia
TÍTULO:

TYPOLOGY OF THE CATOLÉ DO ROCHA BATHOLITH (RN-PB) REVISITED: A REDUCED A-TYPE GRANITIC MAGMATISM?

PALAVRAS-CHAVES:

Catolé do Rocha Batholith; A-type Granites; Borborema Province

PÁGINAS: 35
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

The granitoids forming the ediacaran-cambrian (700-450 Ma) plutonic magmatism in the Borborema Province (northeast Brazil) have been subject of different typological classifications over the last decades and are currently grouped into six distinct suites. The Catolé do Rocha Batholith (CRB), in the southwest of the Rio Piranhas-Seridó Domain of the Borborema Province is currently classified as an important I-type granite body of the porphyritic high K calc-alkaline suite. However, there are many characteristics of the CRB that are typical of reduced A-type granites, which are better located within the alkaline suite. This work presents a revaluation of the BCR granites typology based on geological, petrographical and chemical data. The BCR is composed of three main granitic facies, as well as associated basic rocks and leucomicrogranites. Two facies have coarse grained porphyritic textures, and the other one shows coarse grained inequigranular textures, and are more leucocratic. Biotite and amphibole are the main mafic minerals. Ilmenite (± magnetite), zircon, apatite, allanite, epidote, and fluorite are accessories. CaO contents are low, whereas K2O and Fe2O3t are high, giving the rocks a ferroan, alkali-calcic to alkalic signatures that are more akin to the alkaline suite. The rocks have moderate enrichment in the light rare-earth elements, and pronounced negative Eu anomalies, as well as high Ga/Al ratios. The application of the Ce-in-zircon oxybarometer confirms the reduced character of the BCR, which corroborates with the chemistry of amphibole and biotite. Based on the described attributes, it is proposed that the BCR rocks are classified as reduced A2-type granites.

MEMBROS DA BANCA:
Presidente - 2042352 - FREDERICO CASTRO JOBIM VILALVA
Interno - 080.368.454-15 - ANTONIO CARLOS GALINDO - UFRN
Interno - 1513243 - MARCOS ANTONIO LEITE DO NASCIMENTO