Banca de DEFESA: MATHEUS DENEZINE

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : MATHEUS DENEZINE
DATE: 01/11/2022
TIME: 09:00
LOCAL: Sala de videoconferência do IGD
TITLE:

TAXONOMY OF ORGANIC-WALLED MICROFOSSILS FROM THE SETE LAGOAS FORMATION, BRAZIL: BIOSTRATIGRAPHY AND PALEOBIOGEOGRAPHY OF GONDWANA DURING EDIACARAN

KEY WORDS:

Sete Lagoas Formation, Ediacaran, lectostratotype section, hypostratotype section, biostratigraphy, paleobiogeography.

PAGES: 140
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

This thesis presents a detailed taxonomic study on organic-walled microfossils from the Sete Lagoas Formation, Ediacaran, Bambuí Group, São Francisco basin, Brazil. This formation was described from carbonate expositions in its type locality, Sete Lagoas County, Minas Gerais State. However, the stratotype section was never described. The present work presents the first description of the lectostratotype section of the Sete Lagoas Formation and the proposal of two hypostratotype sections based on the lithological description and fossil record. The studied sections are located in the Minas Gerais State and the Federal District, southeast Brazil: 1. Lectostratotype section, Sete Lagoas County; 2. Hypostratotype section from the PRF, Sete Lagoas County; 3. Hypostratotype section from the Barreiro community, Januária County; 4. Fercal section, Brasília. Nine species of organic-walled microfossils were recovered in the four studied sections from Sete Lagoas Formation: Germinosphaera bispinosa Mikhailova, 1986, Leiosphaeridia crassa (Naumova, 1949), Leiosphaeridia jacutica (Timofeev, 1966), Leiosphaeridia minutissima (Naumova, 1949), Leiosphaeridia tenuissima Eisenack, 1958, Leiosphaeridia ternata (Timofeev, 1966), Bambuites erichsenii Sommer, 1971, Siphonophycus robustum (Schopf, 1968), and Ghoshia januarensis new species. Additionally, an undetermined stromatolite species is also reported: Gymnosolen sp. Two biostratigraphic units are currently recognized in the Sete Lagoas Formation, approaching all four studied sections. Two zones are described: Leiosphaeridia minutissima Zone, a lowest-occurrence interval zone, lower/mid Ediacaran, and Bambuites erichsenii Zone, a range zone, upper Ediacaran. Stratigraphic data and organic-walled microfossil taxonomy indicate that the Sete Lagoas Formation was deposited in a neritic marine environment. The connection by a neritic zone of Amazonia with other cratons that form the western Gondwana, including the São Francisco craton, in 550 Ma is corroborated based on Bambuites erichsenii and Ghoshia januarensis occurrences. At the same time, Laurentia, Baltica, and Siberia were paleocontinents apart.

BANKING MEMBERS:
Externo à Instituição - CLAUDIO GAUCHER - UdelaR
Externa à Instituição - JULIANA DE MORAES LEME - USP
Presidente - 1279072 - DERMEVAL APARECIDO DO CARMO
Interna - 1658822 - LUCIETH CRUZ VIEIRA
Interno - 2520585 - RODRIGO MILONI SANTUCCI