Banca de QUALIFICAÇÃO: DAYVISON BRUNO CORDEIRO DE PAIVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : DAYVISON BRUNO CORDEIRO DE PAIVA
DATA : 13/12/2018
HORA: 09:00
LOCAL: Sala 1 - PPGG
TÍTULO:

PETROGRAPHY AND GEOCHEMICAL MODELING OF SHOSHONITIC ROCKS IN THE SÃO JOÃO DO SABUGI REGION, RN

PALAVRAS-CHAVES:

Shoshonitic suíte; Geochemical Modelling; Borborema Province

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

The São João do Sabugi pluton and associated satellite bodies, nearby the homonymous city in the Rio Grande do Norte state, are one of the most expressive individual occurrences of shoshonitic rocks within the Rio Piranhas-Seridó Domain of the Borborema Province. Thus, a detailed study of these rocks allows for the better understanding of the genetic and evolutive processes of the shoshonitic suite in the northern Borborema Province. The pluton and some of the satellite bodies were object of petrographic and litochemical studies, including geochemical modelling, in order to characterize their magmatic differentiation processes and the intensive crystallization parameters. The identified lithotypes were grouped into two petrographic facies: Facies I (more mafic rocks), made of gabbroic rocks with labradorite (An50-63%) and the mafic paragenesis clinopyroxene ± orthopyroxene + amphibole ± biotite; and Facies II, composed of mafic to intermediate rocks, from diorites and monzodiorites to quartz-monzonites and granodiorites, with the mafic paragenesis amphibole + biotite and oligoclase-andesine (An22-45%). Rocks from the facies I have calc-alkaline affinity, whereas those from facies II show high-K calc-alkaline to shoshonitic signatures (alkai-calcic). The solidus and liquidus temperatures were modeled with the MELTS software between 1300-1070 and 860-770 ^oC, respectively. Geochemical modelling suggest that the fractional crystallization of augite, labradorite, orthopyroxene, and minor magnetite and titanite from the facies I gabbros can give rise to the monzonitic rocks of facies II. These can evolve towards the granodioritic compositions through fractionation crystallization of andesine, hornblende, biotite, magnetite, titanite, and apatite.

MEMBROS DA BANCA:
Interno - 2042352 - FREDERICO CASTRO JOBIM VILALVA
Interno - 1513243 - MARCOS ANTONIO LEITE DO NASCIMENTO
Interno - 350630 - ZORANO SERGIO DE SOUZA