Banca de DEFESA: PEDRO HENRIQUE MOURA DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : PEDRO HENRIQUE MOURA DA SILVA
DATA : 30/08/2019
HORA: 09:30
LOCAL: Auditório do LGGP I
TÍTULO:

Structural controls and stratigraphic relations of the Early Jurassic magmatism in central-western portion of the Parnaíba Basin

PALAVRAS-CHAVES:

CAMP; Contact metamorphism; Contact relations; Flows; Fluidization; Sills; Structural signature; Syneclises

PÁGINAS: 101
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

Early Jurassic basic magmatism of the Parnaíba Syneclise (Northeast Brazil) is represented by the Mosquito Suite, which is part of the important Central Atlantic Magmatic Province (CAMP). The unit is relatively well studied from the petrological and geochemical points of view and has a number of geochronological ages. This magmatism is mapped in a regional scale and described at the surface as dominated by flows. In subsurface, it is characterized by an important sill complex, evidenced by magnetometric, seismic reflection, and well data. Besides subordinate exposures in southern portion of the basin, the main occurrence of (sub)volcanic rocks of this suite is located in central-western portion of the basin, focus of this study. Magmatic bodies of the unit are associated with an E-W to ENE-trending expressive lineament pattern, also observed in plateaus supported by these basic rocks and eolian sandstones of the Sambaíba Formation, for which a Middle Triassic age is assumed. In this work, the structural controls and stratigraphic relations of the Mosquito Magmatic Suite were approached. The methodology involved interpretation of orbital remote sensing images (optical and radar) and field data, including the characterization of faults and contact relations of magmatic bodies with the sedimentary units. Petrographic studies were performed and subsurface information was obtained from well profiles. As a result, the area previously mapped as Mosquito Suite was restricted, mostly corresponding to the Sambaíba Formation sandstones intruded by sills (besides feeder intrusions). A younger unit of sandstones was named as intervolcanic, displaying clasts of the basic rocks. It occurs intercalated with likely flows and shallow sills, at the top of the plateaus or at lower elevations, when affected by faults. Macro and mesoscale structural analysis characterized an Early Jurassic deformational event, with NNW-trending extension direction, which controlled the emplacement of magmatic bodies of the Mosquito Suite. Previous fractures were also used for the intrusion emplacement. Different types of interactions between sills, feeder bodies, and their sedimentary country rocks are described, ranging from non-brittle style (viscous regime structures) to brittle style. The tabular sub-horizontal geometry of the bodies (including cross-sections with shapes of steps and fingers), xenoliths, contact-metamorphic aureoles, besides the country rock fluidization, as shown by the thermal carapaces, peperites, and injection clastic dikes attest the dominance of sills at the present surface. The Early Jurassic deformation, responsible for the structural control of these magmatic bodies, represents distal effects related to the opening of the Central Atlantic. The important magmatic component in this syneclise certainly contributed to its history of subsidence and uplifts. This magmatic event has important implications for the formation of atypical petroleum systems in this basin, which is still considered as an exploratory frontier.

MEMBROS DA BANCA:
Presidente - 346469 - EMANUEL FERRAZ JARDIM DE SA
Interno - 080.368.454-15 - ANTONIO CARLOS GALINDO - UFRN
Externo à Instituição - VLADIMIR CRUZ DE MEDEIROS - SGB