Banca de QUALIFICAÇÃO: MIRO FELICIANO DORING DOS SANTOS

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : MIRO FELICIANO DORING DOS SANTOS
DATE: 20/08/2020
TIME: 14:30
LOCAL: Videoconferencia
TITLE:

Crustal structure under the Recôncavo-Tucano basin from receiver functions

KEY WORDS:

Recôncavo-Tucano Basin; crustal structure, receiver functions

PAGES: 40
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

The stresses that led to the opening of the South Atlantic were also responsible for intracontinental extension and, consequently, for the formation of a number of aborted rifts in Northeast Brazil. The extension started in the Neojurassic, with the formation of an Afro-Brazilian depression south of the Patos Lineament, and continued in the Eoberriasian along two NS-trending axes of deformation: Recôncavo-Tucano-Jatobá (RTJ) and Gabon-Sergipe-Alagoas (GSA). Rifting took place north of the Pernambuco Lineament in the Neoberriasiano-Eobarremiano, migrating later to the West along the NE-SW trending Cariri-Potiguar (CP) trend. In the Neobarremian, approximately coinciding with the opening of the Equatorial Atlantic, the rift was aborted along the RTJ and CP axes, and continued along the GSA axis, eventually resulting in continental breakup. Magmatic activity on the Brazilian continental margin seems to have been restricted to the north of the Patos Lineament, as represented by the dykes of the Ceará-Mirim dyke-swarm. The geological history of the continental rifting process in NE Brazil suggests a the control Precambrian structures in the different rifting styles. In order to better understand the influence of Precambrian structures on possible rift models, 11 seismological stations were deployed in and around the RTJ trend in october 2018. The installation was supported by the national oil company Petrobrás, and included both short-period and broadband stations. In addition, 10 stations from the Rede Sismográfica do Nordeste (RSISNE), close to the study area, were utilized. In this work I will report on crustal thickness measurements and bulk Vp/Vs ratios obtained from the analysis of P-to-S conversions in telesseismic P waveforms (receiver functions). Preliminary results reveal crustal thickness values of 32.2±1.6 km and a bulk Vp/Vs ratio of 1.85±0.05 under the Tucano basin, and 34.8±0.8 km and a bulk Vp/Vs ratio of 1.72±0.13 below the Recôncavo basin. Comparing these results with values around the basin, which vary from 36 to 44 km, there is an apparent crustal thinning, perhaps suggesting more consistency with pure shear models than previously thought.

BANKING MEMBERS:
Interno - 1451214 - ADERSON FARIAS DO NASCIMENTO
Interno - 350640 - FRANCISCO HILARIO REGO BEZERRA
Presidente - 1863578 - JORDI JULIA CASAS