Banca de DEFESA: Raphael Teixeira Corrêa

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Raphael Teixeira Corrêa
DATE: 17/03/2023
TIME: 14:00
LOCAL: Sala de videoconferência e Teams
TITLE:

The Thermal and Electrical Structure of the Amazon Craton

KEY WORDS:

Curie surface, Magnetotelluric Method, Amazon Craton, Cryptic Suture

PAGES: 129
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

The Amazon Craton evolved in the Paleo-Mesoproterozoic through sucessive continental magmatic arcs, which ages decrease westwards. However, when, where and if these magmatic arcs collided to another continent closing an ocean-basin is a subject of ongoing debate. Geochronological Provinces have been proposed to explain the geological evolution of the Craton. However, the irregular geographic distribution of geochronological data associated to a certain degree of decorrelation with magnetic and gravity strucutres rised a series of questions about the continuation of these provinces and the meaning of their boundaries. Assuming that the reology of solids is primarly a function of temperature, we mapped the depth to the bottom of the magnetic’s lithosphere, which is a proxy of the depth to the Curie temperature thereby addressing the thermal structure. Furthermore, electrical resistivity models have been effective to map crustal scale discontinuities. Therefore, we acquired magnetotelluric data in key regions in order to compare the crusts formed during the evolutions of the magmatic arcs. The thermal model suggests that the limits between Carajás and Bacajas domains should be revisited, as well the limits between Tapajós and Iriri Xingu domains. It also suggests that the mantle of the eastern portion of the Carajás domain and Tapajós have preserved serpentinized minerals. The electrical resistivity model confirmed that the mantle of the Tapajós domain was hydrated and refertilized due to long lived subduction processes. This mantelic fertility has high correlation with the position of magmatic-hydrothermal mineral deposits. A major crustal-scale strucuture (more than 1000 km in extension) separates two tectonic fragments with remarkable differences in the magnetic gradient and the structures trend. Additionally, we also find along this major boundary: i) high and low bouguer anomalies of long-wavelenght paired; ii) step in Mohorovic discontinuity; and iii) a lower crust conductor. These evidence support the hypothesis of a collision in Paleoproterozoic times.

BANKING MEMBERS:
Externo à Instituição - ANTÔNIO LOPES PADILHA - INPE
Externo à Instituição - MAURICIO DE SOUZA BOLOGNA - USP
Interno - 1542246 - GEORGE SAND LEAO ARAUJO DE FRANCA
Presidente - 2341034 - ROBERTA MARY VIDOTTI
Interno - 1057547 - VALMIR DA SILVA SOUZA