Banca de DEFESA: ANDRESSA LIMA FERREIRA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ANDRESSA LIMA FERREIRA
DATE: 23/11/2020
TIME: 08:30
LOCAL: Videoconferencia - https://cutt.ly/6fcqwHK
TITLE:

SEISMIC ARCHITECTURE OF THE GALINHOS-GUAMARÉ TIDE CHANNEL SYSTEM (NE OF BRAZIL) AS EVIDENCE TO THE HOLOCENIC SEA LEVEL VARIATIONS

KEY WORDS:

SEISMIC FACIES; EQUATORIAL MARGIN; HIGH RESOLUTION SEISMIC; SEA LEVEL; BARRIER ISLAND; SPIT; PALEOCHANNELS.

PAGES: 131
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

This study aims to reconstruct the seismic stratigraphy of a Holocene tropical tidal channel system through the interpretation of shallow seismic data associated with vibracores analyses. Therefore, it was necessary to recognize the chronostratigraphic limits, the termination patterns  of the seismic reflectors, the analysis of the facies seismic and the external geometry of the packages. This shallow system, with a maximum depths around 10 m, is located on the north coast of the state of Rio Grande do Norte - Brazil, having developed from a system of spit-barrier islands (~ 5900 BP) on a coast dominated by tide, with semidiurnal mesotidal regime. 42km of high resolution seismic data were collected, with an average spacing of 30m, using a Chirp seismic (0.5kHz-7kHz). The data were processed using the software ReflexWin and Petrel. A seismic analysis allowed to identify five c seismic facies (U01-U05). The basal unit (U01) was formed in a low energy environment with thickness ranging from 1.4 to 3.5m. A U02 unit indicates a high energy environment, averaging between 1.4m to 3.5m. The U03 unit represents a moderate energy environment with an average thickness between ~ 0.35m and 2.45m. The shallower surface (SF05) is ~ 14m deep from the current sea level. The younger units (U04 and U05) are similar, with the lowest thickness and aggradational characteristics, formed in a low energy environment. An analysis and interpretation indicate new discoveries, specifically (1) that the formation of paleochannels occurs in the current spit may have been done before the middle Holocene; (2) that the closure of the paleochannels and the formation of the spit occurred between the formation of the U03 and U04 unit; (3) that there was a network of pre-existing channels with a different configuration from the current formed by U02 and U03; (4) that the Pisa Sal tidal channel has been active since the formation of the U01 unit; (5) that the current configuration of the system has been active since the formation in the U03 unit, that is, since the closure of the paleochannels; (6) as units U04 and U05 are formed by deposits of the tidal plain.

BANKING MEMBERS:
Presidente - 2218779 - HELENICE VITAL
Externo à Instituição - LUIZ ANTONIO PEREIRA DE SOUZA - IPT-SP
Externa à Instituição - MARY LUCIA DA SILVA NOGUEIRA - UFES