Banca de QUALIFICAÇÃO: INGRID BARRETO MACIEL

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : INGRID BARRETO MACIEL
DATA : 03/12/2018
HORA: 09:00
LOCAL: Labsis
TÍTULO:

Structural Diagenesis of Fault Zones in Sandstones of Rio do Peixe Basin

PALAVRAS-CHAVES:

Clay Minerals; deformation bands; silicified rocks

PÁGINAS: 24
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

The Rio do Peixe Basin is insert in a complex structural network between NE-SW and E-W shear zones, which influence the strata fill of the the basin. It is mainly filled by poorly consolidated siliciclastic sedimentary rocks and have depositional and diagenetic characteristics modified by major faults, single deformation bands and clusters of deformation bands. In this context, we intend to understand the effect of the deformation on the diagenesis processes and silicification in the sedimentary rocks of this basin. Analytical methods, such as polarized light microscopy, scanning electron microscopy associated with X-ray spectroscopy and X-ray diffraction, were adopted in the first stages of this work in order to describe depositional, compositional and deformation of undeformed and deformed rocks. The undeformated parameter rock, or host rock, is a fluvial succession, ranging from fine sandstones to massive conglomerate sandstones or with cross-bedding stratifications. The finer facies have a fine to medium sandy shell with moderately selected and subangled grains, while the thicker facies have a poorly selected, well rounded, granular and coarse sand structure in a medium fine sand matrix. They are poorly consolidated rocks with predominantly primary porosity. In them, diagenetic modifications such as generation of pseudomatrix and autigenesis of clay minerals such as ilites and smectites interstratified or not, often filling necks or some pores completely. On the other hand, sandstones with bands of deformation and faults usually have fine-grained to very fine-grained sandstones, are moderately selected and very angular, where porosity is mainly secondary, generated by dissolution of feldspars or fractures, and of very small size. In the deformed rocks, no autigenic clay phases were identified. It is important to mention that single deformation bands, clusters and faults present in the sandstones are always with great positive relief in the outcrops, which indicates that the deformed rock better withstands the effects of erosion and weathering. Therefore, as part of the results of this research, it is possible to affirm that deformed rocks have permoporous conditions impaired by the cataclasis and the high degree of compaction of the grains, so the rutile deformation that affects the Rio do Peixe Basin does not preserve or contribute to the autigenesis of clay phases, contrary to many cases described in the literature. Studies related to silicification and breccias formation in major faults of the basin are being developed and should facilitate the understanding of the formation of seals in sedimentary basins. In this case, deformation bands, clusters and faults have acted as barriers to the flow of fluids such as water, hydrocarbons and in relation to the transport of contaminants.

MEMBROS DA BANCA:
Presidente - 350640 - FRANCISCO HILARIO REGO BEZERRA
Interno - 1161652 - FRANCISCO PINHEIRO LIMA FILHO
Externo ao Programa - 347536 - NARENDRA KUMAR SRIVASTAVA
Externo à Instituição - RENATO RODRIGUEZ CABRAL RAMOS - UFRJ