Banca de DEFESA: RICARDO DE SOUZA RODRIGUES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : RICARDO DE SOUZA RODRIGUES
DATA : 26/02/2018
HORA: 14:30
LOCAL: Auditório do LGGP
TÍTULO:

Meso and microscopic analysis of deformation bands in porous sandstones: application in the Tucano basin (BA), NE Brazil basin

PALAVRAS-CHAVES:

Deformation bands, faults, Tucano basin.

PÁGINAS: 112
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

During the deformation of porous rocks present in sedimentary basins, structures like deformation bands (Dbs) can be nucleated. These structures are common in the Ilhas sandstones (Tucano Basin). A multiscale characterization of Dbs in this basin was undertaken between Bananeiras and Agua Branca districts (Jeremoabo city-Bahia State). Remote sensing products (ETM + Landsat, X-band radar, and aerial photographs) revealed important NE-SW trending photo lineaments highlighted in topography and, subordinately, two other sets trending NNE-SSW and E-W were recognized. At mesoscopic scale, these photo lineaments are represented by Dbs and related faults. The Dbs occur as individual and clusters structures that sometimes, due to the increase of the deformation, had evolved to faults. Geometrically, Dbs occur in various forms, eye, ramp, and those arranged according to the Riedel system or with an arrangement analogous to the S-C pair, present in low-temperature mylonites. This last geometry is exclusive of the Dbs originated in hydro ductile conditions, that is, pre-lithification stage of the host rock being the product of the granular flow. The other geometries developed in the syn- or post-lithification stage when cataclastic flow mechanism predominated. The faults related to the Dbs are associated with three different deformational events and exhibit variable kinematics (normal, normal obliques, transcurrent, reverse and reverse oblique). The NE-SW normal (sense strict) faults are the earliest structures associated with the deformation event D1p. These structures are partially affected by dextral (NNW-SSE) and sinistral (NE-SW) transcurrent faults, late to D₁ and referred to as D_1t. Event D₂ produced a set of NNE-SSW normal oblique faults. The early manifestation (D_3p) of the youngest event (D₃) is represented by NE-SW and NNW-SSE oblique faults. In a late pulse of this event (D_3t) were generated NE-SW dextral transcurrent, NNW-SSW reverse and N-S and NE-SW oblique reverse faults. These structures, however, are not widespread in the study area. The integrated data analysis allowed inserting this region in the geotectonic context in NE of Brazil. The active stress field during D₁ is compatible with the opening of the East Margin, which suggests a Neocomian age for this event. The D₂ event developed under an NNW-SSE extensional stress field, similarly to that responsible for the generation of Jatoba Basin master fault northward the study area. The NE-SW extensional stress field active during D₃ event suggests an association with the opening event of the Brazilian Equatorial Margin during the Aptian.

MEMBROS DA BANCA:
Externo à Instituição - CARLSON DE MATOS MAIA LEITE - UFBA
Interno - 346469 - EMANUEL FERRAZ JARDIM DE SA
Presidente - 1217847 - FERNANDO CESAR ALVES DA SILVA