Banca de DEFESA: ELIENARA FAGUNDES FERREIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ELIENARA FAGUNDES FERREIRA
DATA : 25/06/2020
HORA: 14:00
LOCAL: Video Conferência
TÍTULO:

Magnetotelluric characterization of the Santa Marta impact structure – Piauí.

PALAVRAS-CHAVES:

Impact Structure, Magnetotelluric Method, 3D Inversion.

PÁGINAS: 96
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
SUBÁREA: Geofísica
RESUMO:

Brazil has 7 documented impact structures in its territory up to date. The Santa Marta impact structure is located in the southwestern state of Piauí, in Corrente County. It is a complex impact structure, about 10 km in diameter with a central uplift 3,5 km-wide. It has an estimated age between 93 and 100 Ma and was formed in a complex geological context, where the Mesozoic rocks of the Sanfranciscana Basin are overlying the sequences of the Paleozoic Basin of Parnaíba. In this sense, understanding its stratigraphy and its formation process is a big challenge. This thesis aims to characterize the units of the Santa Marta using magnetotelluric data. Broadband magnetotellurics data were collected along two profiles, which were analyzed using 1D and 3D inversions. The results show that the western anular basin is characterized by Sanfranciscan Basin rocks (_ > 50 :m) and breccias (_ > 800:m) resulting from the impact event. Under this layer, slightly smaller resistivity units are observed in the range of 100 - 800 :m probably related to the basement of the Parnaíba Basin. Its central region is characterized by the discontinuity of the basement and a peak of Bouguer anomaly. These characteristics are possibly related to faults resulting from the central uplift formation, and may indicate the location and diameter of the central elevation, estimated at about 4 km. Finally, the eastern annular basin is characterized by low resistivity values in the range of 5 to 100 :m, which are identified as rocks of the Parnaíba Basin and by the presence of a conductor body of unknown origin, but possibly not related to the impact event. The results demonstrate the great complexity of the Santa Marta structure due to the proposed mapping, and the distribution of anomalies shows that, the geological units are not distributed as expected, although it has a circular shape. On the contrary, the pattern of the anomalies shows that Santa Marta is an asymmetric structure, which is roughly related to the impact angle.

MEMBROS DA BANCA:
Interno - 1976196 - ALANNA COSTA DUTRA
Interno - 2127827 - MARCOS ALBERTO RODRIGUES VASCONCELOS
Externo ao Programa - 2583722 - JOELSON DA CONCEICAO BATISTA