Banca de DEFESA: DALTON DA SILVA PINHEIRO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : DALTON DA SILVA PINHEIRO
DATE: 24/05/2022
TIME: 15:00
LOCAL: videoconferência https://www.youtube.com/c/PPGGUFRNTransmiss%C3%A3odeBancas
TITLE:

Rare-Earth distribution patterns and Sm-Nd analysis of Ediacaran to Cambrian plutonic suites from northeastern Borborema Province, Brazil

KEY WORDS:

Rare-Earth Elements; plutonic suites; shape coefficients; Sm-Nd isotopes.

PAGES: 72
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

The Ediacaran to Cambrian magmatism in the Rio Grande do Norte Domain, in the extreme NE of the Borborema Province, is represented by six suites defined by chemical, mineralogical and petrographic criteria: Shoshonitic, Porphyritic high-K Calc-alkaline, Equigranular high K Calc-alkaline, Calc-alkaline, Alkaline and Charnockitic Alkaline. However, as some divergences were observed between the results of a specific body classified in the
alkaline suite, the Stock Flores, it was analyzed separately. This work presents as main object the study of Rare Earth Element patterns using a new methodology for applying the patterns in petrogenetic problems having the Ediacaran/Cambrian magmatism of the Rio Grande do Norte Domain as a sample universe. Thus, the use of the lambda method to obtain the shape coefficients (i.e. λ0, λ1, λ2, λ3). The mean values for the shape coefficients (λ0/λ1/λ2/λ3 notation) observed are for Shoshonitic (5.36/8.68/108.65/-1438.32), Porphyritic high-K Calc- alkaline (5 .34/11.83/141.35/-1464.81), Equigranular high K Calc-alkaline (5.43/9.29/152.15/-1486.88), Calc-alkaline (4.77 /5.44/149.65/-1383.71), Alkaline (3.85/3.49/174.37/-1282.47), Alkaline-Flores (5.63/4.12/152.31 /-1166.31) and Charnockitic Alkaline (5.60/9.98/128.10/-1638.25). The results show a strong influence on the fractionation of feldspars on the observed ETR patterns, mainly regarding to the Eu anomalies observed using λ0 as a plagioclase fractionation marker. Other minerals such as garnets, clino and orthopyroxenes may have an influence on low values of λ1 and high values of λ3 while minerals that partition alkali influence high values of λ2. The Sm-Nd results point to negative εNd values, indicating an enriched source. The TDM model ages indicate age variations between the Paleoproterozoic (Staterian) and the Mesoarchean, which shows a possible age for the sources of these rocks. Furthermore, the T2DM model ages present a variation between Paleoproterozoic and Paleoarchean. Furthermore, the interpretation is that the shoshonitic suite has as its source the enriched mantle associated with a subduction zone related to the Transamazonian/Eburnian event (ca. 2.15 Ga), while the rocks of the other suites are sourced from the relative continental crust to the Paleoproterozoic to Archean gneiss-migmatitic basement.

BANKING MEMBERS:
Externa à Instituição - ANELISE LOSANGELA BERTOTTI - UFPE
Externo à Instituição - ANTOMAT AVELINO DE MACÊDO FILHO - PETROBRAS
Presidente - 1513243 - MARCOS ANTONIO LEITE DO NASCIMENTO