Banca de DEFESA: FERNANDO SÉRGIO GOIS SMITH

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : FERNANDO SÉRGIO GOIS SMITH
DATE: 19/03/2020
TIME: 14:30
LOCAL: Auditório do CCET
TITLE:

Sedimentary Provenance Analyses And Holocene Evolution Of Parnaíba River Delta Through vibrocores

KEY WORDS:

Delta; sedimentary provenance; mineralogy; core

PAGES: 49
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

The present work comprises the results of the description of vibra cores collected in recent sediments deposited in the Parnaíba river delta, located on the border between the states of Piauí and Maranhão, in the Barreirinhas basin. Because of the low number of inhabitants and the low socioeconomic development of the Brazilian Northeast region, the Parnaíba River delta is a rare example of this environment deposit system that still presents a large part of its natural features with few human interventions. On the delta, 9 cores were collected by the method of vibration which result in 14,86 meters. A granulometric, compositional, mofoscopic and mineralogical analysis was carried out in a total of 295 samples from these 9 cores aiming to carry out a study of sedimentary provenance in the delta and identify changes in the depositional environment that may be related to the lateral migration of the main channel of the Parnaíba river and to the isolation of the western portion of the delta during the Holocene. Ascending granodecresence was observed in the four cores. At the tops, we have very fine sands or mud with high contents of organic matter and calcium carbonate (CaCO3). At the intermediary section occurs a variation between very fine sand and medium sand with present a decrease in the contents of organic matter and CaCO₃. At the base occurs fine sand with low levels of organic matter and CaCO₃. The transition between mudy and sandy environments occurs abruptly, however concordantly, between depths of 42 and 72 cm. The mineralogy at the basis of the cores in the western portion of the delta, close to the city of Tutóia shows great similarities with the mineralogy of the cores located in the main channel of the Parnaíba river. However, tops have significant variations indicating that in the past, the Parnaíba river deposited sediments directly in the western portion of the delta but at some point this reality has changed Possibly, in this period the main channel ran through the western portion and the great tidal channels of the delta are in fact ancient main channels that were abandoned during the evolution of the lateral migration of the river

BANKING MEMBERS:
Presidente - 2218779 - HELENICE VITAL
Externo à Instituição - JOSÉ MARIA LANDIM DOMINGUEZ - UFBA
Externo à Instituição - WERNER FARKATT TABOSA - IDEMA