Banca de DEFESA: LUCAS FERREIRA BITTENCOURT

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LUCAS FERREIRA BITTENCOURT
DATE: 27/06/2023
TIME: 14:00
LOCAL: Sala de videoconferência e Teams
TITLE:

Isotopic chemostratigraphy of the Sete Lagoas Formation in the central and southern region of the São Francisco Basin.

KEY WORDS:

Sete Lagoas Formation, Neoproterozoic, carbon isotopes, chemostratigraphy.

PAGES: 92
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

The Neoproterozoic is marked by intense changes in the carbon cycle. These changes are unique in the Earth's history and can be used in chemostratigraphic correlations through the parameter δ13C, obtained in carbonate rocks. The Sete Lagoas Formation is a predominantly carbonate unit in the Bambuí Group. Therefore, due to the scarcity of paleontological and geochronological data, isotopes start to have great importance in regional and global correlations. In this context, different sections of the Sete Lagoas Formation were studied in detail in the central and southern portion of the São Francisco Basin. These sections were evaluated from a sedimentological and chemostratigraphic features (δ18Ocarb, δ13Ccar, δ13Corg) to understand how isotopic and depositional environment changes interfere with each other and whether they reflect primary, secondary, local or regional characteristics. The PSB-14 Section is located in the central region of the São Francisco Basin, in south of Januária (MG), and represents the middle and upper portion of the Sete Lagoas Formation. The δ13Ccarb and δ13Corg values vary respectively from 0.01‰ to +12.27‰ and -27.54‰ to -19.31‰. Most of its sedimentation occurs in a shallow depositional environment and presents a great variation of carbonate lithofacies and pelitic contribution. However, the Gruta Rei do Mato Section is located in the southern region of the basin, in the Sete Lagoas (MG). It represents the top of the unit and contains δ 13Ccarb values above 9‰ and δ13Corg scattered and high, with an average of -16‰. This section presents characteristics of a deeper environment of mid ramp with no pelitic or dolomitic contribution. In addition to these sections, other previously studied sections were used for regional chemostratigraphic correlation of the Sete Lagoas Formation in the Bambuí Basin. Thus, six chemostratigraphic intervals are identified using δ13Ccarb and indicate good precision for unit correlations: SL-1, SL-2, SL3, SL-4, SL-5 and SL-6. These chemostratigraphic intervals of the Sete Lagoas Formation can be used in a composite curve to correlate with other Ediacaran units. Therefore, with the unification of chemostratigraphy, geochronology and paleontology data, the Sete Lagoas Formation correlates better with the lower Ediacaran.

BANKING MEMBERS:
Externo à Instituição - GABRIEL JUBÉ UHLEIN - UFMG
Interno - 113.138.381-87 - CARLOS JOSE SOUZA DE ALVARENGA - AMU
Interna - 1658822 - LUCIETH CRUZ VIEIRA
Presidente - 2339865 - MARTINO GIORGIONI