Banca de QUALIFICAÇÃO: ANA MILENA NEMOCON ROMERO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ANA MILENA NEMOCON ROMERO
DATE: 17/09/2020
TIME: 10:00
LOCAL: Videoconferencia
TITLE:

Lithospheric structure of the western Borborema Province from receiver functions and surface-wave dispersion: Implications for Araripe Basin inversion

KEY WORDS:

Lithospheric structure; Borborema Province; São Francisco craton; basin inversion; Araripe Basin

PAGES: 60
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

New constraints on crustal thickness, Poisson's ratio and lithospheric S-velocity structure have been obtained along a NS-trending profile crossing the western Borborema Province and the northern São Francisco craton from the joint inversion of receiver functions and surface-wave dispersion velocities. The main N-S profile consists of 11 broadband stations interspaced at ~60 km and 2 short-period stations, while a shorter E-W profile consists of 2 broadband and 2 short-period stations. All short-period stations were located on top of the Chapada do Araripe, an aborted rift basin presently standing at ~1000 m a.m.s.l. Our results show that the crust is typically 34-38 km thick under the western Province, with a bulk Vp/Vs ratio of 1.73 and S-velocities between 3.3 km/s and 4.0 km/s; in contrast, the crust is 43-46 km thick under the northern craton, with a bulk Vp/Vs ratio of 1.70 and S-velocities between 3.5 km/s and 3.9 km/s. No apparent crustal thinning is observed under the Araripe Basin, due to the presence of a relatively thick (10-14 km) high-velocity (4.1-4.3 km/s) layer at the bottom of the crust. Our velocity models also image a drop in S-velocity (from 4.6 km/s to 4.3 km/s) at about 150 km depth under the profile, shallowing to about 120 km depth under the Araripe Basin. Our findings confirm the presence of thin lithosphere under the Araripe Basin - originally postulated by a colocated MT survey - that might have facilitated tectonic inversion of this basin through regional stress concentration and thermal buoyancy. These findings also suggest additional buoyancy contributed by a layer of mafic cumulates right under the basin.

BANKING MEMBERS:
Interno - 1451214 - ADERSON FARIAS DO NASCIMENTO
Interno - 350640 - FRANCISCO HILARIO REGO BEZERRA
Presidente - 1863578 - JORDI JULIA CASAS
Externo à Instituição - XAVIER GARCIA MARTINEZ