Banca de QUALIFICAÇÃO: VINÍCIUS NÓBREGA DE MIRANDA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
DISCENTE : VINÍCIUS NÓBREGA DE MIRANDA
DATA : 07/12/2016
HORA: 14:30
LOCAL: Auditório do LGGP/UFRN
TÍTULO:

PRE-SILURIAN BASINS AT THE MID-WESTERN PORTION OF PARNAÍBA BASIN

PALAVRAS-CHAVES:

Parnaíba Basin, Pre-Silurian Basins, Tectonic Framework

PÁGINAS: 21
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

Pre-silurian grabens have been interpreted in the substrate of BPar, with implications for the control of subsidence and consequent genesis of the basin, from the Silurian. The interpretation of 1401 km of 2D seismic data, coupled with well data and gravimetric data, allows an improvement in the characterization of the stratigraphic and structural framework of the central-western region of the Parnaíba Basin (BPar). The seismostratigraphic/seismostructural analysis of the section underlying the Pre-Silurian Unconformity (base of the Serra Grande Group) allowed us to characterize two seismosequences, here denominated SEQ 1 and SEQ 2. SEQ 1 is characterized by parallel reflectors, with high amplitude and good lateral continuity, directly lying over the basement. At the extreme west of the area, this sequence is affected by thrusts, being locally folded. SEQ 2 has an external wedge-like geometry, consisting of low-amplitude reflectors that overlap SEQ 1 and are truncated by the Pre-Silurian Unconfomity. Chaotic, parallel and divergent seismofacies dip and thicken towards a fault of expressive normal displacement, which delimits an important half-graben to the east. Diabase sills intrude both the phanerozoic strata of the Parnaíba Basin and the pre-silurian sequences. The truncation of reflectors associated with the intrusions at the base of the Serra Grande Group suggests that they represent distinct igneous events. The integrated seismic interpretation of the studied sections identified the existence of an important depocenter elongated in the N-S direction in the region of Balsas (Maranhão State), having a minimum width of 50 km (reaching more than 100 km in the northern portion of this area) and sedimentary thickness around 6,000 m, taking into account the phanerozoic sequences of BPar and the pre-silurian section. This feature is bounded to the east by a normal fault with a minimum length of 100 km, which is aligned in the N-S direction, curving to NW-SE at its northern termination, possibly defining an oblique ramp. The western portion of the half-graben is marked by a partially collapsed structural high with axis oriented in the N-S direction. The data presented here suggest that the structure and deposition of the pre-silurian sequences in the Balsas region are closely linked to the development of the Araguaia Belt, probably corresponding to deposits of a foreland and/or rift type basin, the latter located in the most distal zones from the western edge of BPar.

MEMBROS DA BANCA:
Externo ao Programa - 2490483 - ALEX FRANCISCO ANTUNES
Presidente - 346469 - EMANUEL FERRAZ JARDIM DE SA
Interno - 1217847 - FERNANDO CESAR ALVES DA SILVA