Banca de DEFESA: NEILA CALDAS ABREU

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : NEILA CALDAS ABREU
DATA : 30/08/2019
HORA: 14:00
LOCAL: INSTITUTO DE GEOCIENCIAS
TÍTULO:

DEPOSITIONAL PALEO ENVIRONMENT OF NEO-DEVONIAN SECTION PIMENTEIRAS FORMATION, WEST EDGE OF PARNAÍBA BASIN.

PALAVRAS-CHAVES:

Organic geochemistry, Organic facies, Palinofacies, Depositional paleoenvironment, Devonian.

PÁGINAS: 115
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

The Parnaíba Sedimentary Basin is located in northeastern Brazil in greater proportion and occupies approximately 600,000 km², has a thickness of sedimentary column reaching about 3,500 m and is distributed across the states of Piauí, Maranhão, Pará, Tocantins, Bahia and Ceará. Of its Formations, the main highlight is the Pimenteiras Formation, which was deposited during successive transgressions and marine regressions during the Devonian. During the deposition of this formation in the Frasnian age, there was the event of global anoxia through a large marine flood and a period of mass extinction on Earth. The objective of the present work is to describe the depositional paleoenvironment of Neo Devonian shales of the Pimenteiras Formation on the western edge of the Parnaíba Basin.
The samples were collected in Aparecida do Rio Negro (TO), in outcrops along the highway, where there were black shales and a possible contact between the Pepper and Head Formations. The characterization of the depositional environment by geochemistry and palinofacies, allowed to evaluate the depositional conditions with proximal tendencies along the studied section.
The total organic carbon index (TOC: 0.21 - 2.43%) results show low to high hydrocarbon generation potential. Data from rock-eval pyrolysis suggest little or no natural generation and also thermal immaturity, presenting a low free hydrocarbon content (S1) and low Tmax values. S2 values indicated low hydrocarbon potential.
The results of the readings of the 300 organic components in palynological slides of shale samples, present the main groups of organic matter: Palinomorphs, Phytoclasts and Amorphous Organic Matter (MOA). Some samples resulted from deposition in an environment with high preservation potential and low energy with large amount of MOA, but with toxic environment. Other samples presented environments close to terrestrial sources, with greater presence of spores and phytoclasts. A large number of prasinophytes belonging to the genera Pterospermella, Cymatiosphaera, Durvenaysphaera, Leiosperidia, Tasmanites, Hemiruptia and Maranhites were identified, indicating that there was marine ingress, stating a period of great flooding.
The analysis of the organic carbon isotopes (δ13C) presented values that ranged from -25.9 to -29.5 characteristic values of marine environment and terrestrial environment. Saturated biomarkers with distribution of the regular C27-C28-C29 steranes also suggest an alternation in the input of the predominantly terrestrial organic matter.

MEMBROS DA BANCA:
Presidente - 950.990.506-20 - KARINA SANTOS GARCIA - UFF
Interno - 1701531 - LUIZ CARLOS LOBATO DOS SANTOS
Externo à Instituição - LUZIA ANTONIOLI - UERJ