Banca de DEFESA: INGRID BARRETO MACIEL

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : INGRID BARRETO MACIEL
DATE: 30/09/2020
TIME: 08:30
LOCAL: Videoconferencia
TITLE:

Hydrothermal silicification and deformation bands: Influence on internal fault architecture in the Rio do Peixe Basin, Brazil

KEY WORDS:

Deformation bands; Hydrotermal silicification; Rio do Peixe Basin

PAGES: 107
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

The present work investigates the formation and compartmentalization processes of the fault zones and hydrothermal silicification in the Rio do Peixe Basin, Brazil, observing these processes' impact on the host siliciclastic rocks. For this, we mapped six outcrops with the aid of unmanned aerial vehicle (UAV), structural mapping, petrography, scanning electron microscopy (SEM), spectroscopy dispersive energy (SDE), X-ray diffractometry (XRD), and fluid inclusion analyses. We observed that the fault zones have a core with a high degree of cataclase, reducing the size of the grains, primary and secondary porosity. Next to the core, a damage zone is characterized by single deformation bands or clusters, where the content of clay minerals vary significantly. The borders fault zones have silicification bands up to 250 m thick. Throughout these bands, silicification varies in intensity and can show a static or dynamic pattern. Deformation bands, hydraulic gaps close to the main fault plane, and silicified basement rocks with quartz veins are found in these places. Within the primary or secondary pores, there are occurrences of newly formed minerals such as kaolinite, chalcedony, apatite, and barite, representing the interaction between the heated hydrothermal fluid and the host rock. Silicification is associated with ascents of hydrothermal fluids along the deepest faults, varying in temperature conditions between 89 ° C and 240 ° C and 30-80 Mpa pressure. From the results obtained, we conclude that the composition of the framework and the clays' mineralogy do not vary along the fault zone, despite the content of clay minerals being systematically lower in the most deformed rocks. They have a weathering origin, unrelated to the fault activity. On the other hand, the silicification of the border faults is linked to the fault dynamics, because they suffer reactivation from the rise of hydrothermal fluids formed at high pressures and prices. Therefore, the cataclase and the hydrothermal silicification processes have important implications for aquifers and hydrocarbon reservoirs

BANKING MEMBERS:
Interno - 1217847 - FERNANDO CESAR ALVES DA SILVA
Presidente - 350640 - FRANCISCO HILARIO REGO BEZERRA
Externo ao Programa - 349812 - LAECIO CUNHA DE SOUZA
Externa à Instituição - Paola Ferreira Barbosa - UnB
Externo à Instituição - Tiago Siqueira de Miranda - UFPE