Banca de QUALIFICAÇÃO: HEMERSON LUCAS DA COSTA SILVA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : HEMERSON LUCAS DA COSTA SILVA
DATE: 15/08/2022
TIME: 14:30
LOCAL: videoconferência - https://www.youtube.com/c/PPGGUFRNTransmiss%C3%A3odeBancas
TITLE:

CHARACTERIZATION OF THE BASIC EDIACARAN MAGMATISM OF SHOSHONITIC AFFINITY IN THE RIO PIRANHAS-SERIDÓ AND SÃO JOSÉ DO CAMPESTRE DOMAINS, NE OF THE BORBOREMA PROVINCE

KEY WORDS:

Shoshonites; Mineral Chemistry; Lithochemistry; RND; Geobarometry, Geothermometry.

PAGES: 57
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

In the extreme NE of the Borborema Province, in the tectonostructural context of the Rio Grande do Norte Domain (DRN), the Ediacaran-Cambrian magmatism consists in one of the main geological and geomorphological features, being represented by different magmatic suites formed by several batholiths, plutons, stocks and dykes of granitic rocks. In this context, there is a range of studies from the petrographic/textural, chemical (lithogeochemical and mineral chemistry) points of view for the six identified granitic suites. However, regarding the  shoshonitic suite, even with important contributions (Jardim de Sá, 1994; Hollanda et al., 2003; Dias, 2006; Paiva, 2020; Paiva et al., 2021; Guimarães, 2021) in terms of cartography, petrography, lithochemistry, geochronology, and intensive crystallization parameters, it lacked an integration work about the different bodies. Thus, the possibility of integrating existing data in the literature with some unpublished data was seen, aiming the petrogenetic characterization of shoshonitic magmatism in the DRN based on petrographic, lithochemical, and mineral chemistry data, including intensive crystallization parameters such as (P, T and fO2). For the development of the research, twelve plutons were selected: Casserengue, Japi, Monte das Gameleiras, Poço Verde, Riachão, Serrinha, Acari, Quixaba, São João do Sabugi, Serra do Caramuru, Tapuio and Totoró, of which lithochemical analyzes were available in the literature. From the compiled database and integration of these, it was noticed that the rocks belonging to the shoshonitic suite in the DRN are typically transitional rocks between calc-alkaline to alkaline or sub-alkaline, but chemically they exhibit particularities. The belonging rocks are typically basic to intermediate, enriched in Fe2O3, MgO, CaO, TiO2, MnO and K2O, all with negative correlations in Harker-type variation diagrams, except for K2O, which is positively correlated. Geochronologically, the rocks of this series are the oldest representatives of Ediacaran magmatism in the DRN. Regarding the intensive crystallization parameters, the pressures were calculated based on empirical and experimental Al geobarometers in hornblende, and it was initially noted that these rocks are relatively similar for both São José do Campestre (DJC) and Rio Piranhas-Seridó (DPS) domains, with average pressures of 5.6 kbar and 5.2 kbar respectively. Average temperatures also showed a small difference between the two domains, where DJC plutons exhibit approximate averages of 782 ± 22 °C; while the DPS 746 ± 22 °C. Such features are suggestive of a single generating magma for these plutons in both domains. The estimation of oxygen fugacity conditions based on amphibole composition indicates that they are predominantly high and subordinately intermediate, typical characteristics for this type of rock.

COMMITTEE MEMBERS:
Presidente - 1513243 - MARCOS ANTONIO LEITE DO NASCIMENTO
Interno - 2042352 - FREDERICO CASTRO JOBIM VILALVA
Externa à Instituição - MARIA DE FÁTIMA APARECIDA SARAIVA BITENCOURT - UFRGS