Banca de DEFESA: TARSILA BARBOSA DANTAS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : TARSILA BARBOSA DANTAS
DATE: 22/05/2024
TIME: 09:00
LOCAL: Videoconferência / Canal Youtube PPGG
TITLE:

EXPLORING STRUCTURAL AND STRATIGRAPHIC CONTROLS IN THE FURNA FEIA KARST SYSTEM

KEY WORDS:

Karst, analogue reservoir, nonmatrix porosity.

PAGES: 81
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SPECIALTY: Sedimentologia
SUMMARY:

The Furna Feia cave is the second largest cave in the state of Rio Grande do Norte, and it
was developed within the Cretaceous carbonates of the Jandaíra Formation. The aim of this
study was to analyze the geological indicators that affected the development of this karst
system, combining geological and geophysical data from surface and subsurface. Therefore,
a multidisciplinary approach was adopted, utilizing field visits, GPR, drone, LiDAR, gamma
rays, porosity, permeability, uniaxial compression strength, and petrography. The cave is
shallow, with 766m of linear development, linear meandering geometry, and its walls and
ceiling exhibit domes and pockets. The facies associations identified were tidal bars at the
base and top of the cave, intercalated with the lagoon facies association. Within this lagoon
interval, the rocks are intensely dolomitized. The tidal bars at the base indicate paleocurrent
to the northwest, and the tidal bars at the top of the section indicate northeast. LiDAR data
showed that the dolomitized interval is also the most dissolved, along which the cave exhibits
the greatest widening. This interval also showed a greater amount of fracturing in GPR data
and field analyses. Controversially, this interval presents the lowest values of porosity and
permeability in its matrix. Additionally, structural analyses also showed a tectonic influence on
the development of this karst system. The Poço Verde Fault, with a northwest direction,
affected the orientation of both the galleries and the pockets and domes found in the cave.
Therefore, we conclude that dolomitization exerted the greatest control on the formation of
the cave, as it provided the highest concentrations of fracturing and consequent horizontal
fluid percolation for the subsequent dissolution of carbonates. Tectonics, on the other hand,
guided this dissolution in preferential directions (northwest and northeast). These findings can
be extrapolated and used as guidelines in carbonate reservoirs affected by the same
process, indicating a dual porosity behavior for these rocks.

COMMITTEE MEMBERS:
Externa à Instituição - ALINE CRISTINE TAVARES - UFRN
Externo à Instituição - DAVID LINO VASCONCELOS - UFCG
Externo à Instituição - Felipe Guadagnin - Unipampa
Externo à Instituição - JOSÉ ANTONIO BARBOSA - UFPE
Interno - ***.785.944-** - VINCENZO LA BRUNA - NÃO INFORMADO