Banca de DEFESA: LILIAN MERCES PEREIRA VARJAO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : LILIAN MERCES PEREIRA VARJAO
DATE: 30/05/2022
TIME: 14:00
LOCAL: https://conferenciaweb.rnp.br/webconf/angela-beatriz-de-menezes-leal
TITLE:

PETROLOGY OF MAFIC DYKES IN CHAPADA DIAMANTINA-PARAMIRIM PROVINCE, BAHIA, BRAZIL.

KEY WORDS:

lithogeochemistry; petrography; mafic dikes; Gavião Block; isotopic geochemistry

PAGES: 89
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SPECIALTY: Petrologia
SUMMARY:

Dyke swarms and mafic sills occur intrusive in metasediments of the Paraguaçu Group, in the southern portion of Chapada Diamantina (CHD) and in the Archean basement in the Brumado region (BG). This work presents the lithogeochemical and isotopic results in order to analyze the behavior of the elements during the differentiation process and define the characteristics of the mantle source. The behavior of the major, trace and rare earth elements (REE) show similar magmatic evolution for the two swarms. The REE pattern for both sets demonstrates a similar spatial distribution, typical of tholeiitic magmas, which may suggest a single source, although the BG dykes present a more enriched pattern than those of the CHD, characterizing a more differentiated mantle source. Most samples showed high ɛNd values in relation to CHUR. Analyzing the fractionation factor, the mantle character of these rocks became clear. ɛNd values (t=1.5 Ga) show that the CHD dykes are more primitive than those of the BG, also confirmed by the values of Mg# (CHD = 0.56 to 0.66 and BG = 0.25 to 0 .45) and were more intensely affected by the process of crustal contamination. Integrated analysis of the data shows an increase in Mg# values towards the North of the Study Area (CHD), possibly approaching the origin of the thermal source (plume) that gave rise to magmatism in this sector with high rates of mantle melt . The two sets are typical continental tholeiites differentiated from a “primitive” magma, presenting an iron-rich differentiation trend.

BANKING MEMBERS:
Presidente - 1295799 - ANGELA BEATRIZ DE MENEZES LEAL
Interno - 273.251.727-53 - ELSON PAIVA DE OLIVEIRA - UNICAMP
Externo à Instituição - PAULO CÉSAR CORREA DA COSTA - UFMT
Externa à Instituição - ANA CAROLINA PINHEIRO AMORIM - IFBA
Externa à Instituição - MICHELE CÁSSIA PINTO SANTOS