Banca de DEFESA: Lucas Cesar Vaz dos Santos

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Lucas Cesar Vaz dos Santos
DATE: 12/06/2024
TIME: 09:00
LOCAL: Sala de Videoconferência do IGD
TITLE:

TECTONIC RECONFIGURATION IN THE AMAZON CENTRAL FROM U-PB AND SMND DATA IN ROCKS OF THE NEW FORMATIONS REMANSO AND ALTER OF THE GROUND

KEY WORDS:

Provenance; Amazon Basin; Alter do Chão Formation; Novo Remanso Formation.

PAGES: 104
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

The period spanning from the Upper Cretaceous to the Middle Miocene in the Amazon Basin represents a crucial time interval for comprehending the paleogeography of sedimentary deposits in eastern Amazonia. Although there is a consensus regarding the paleoenvironment of these continental deposits, there is still no consistent depositional model that integrates tectonic and depositional events during the Upper Cretaceous and its transition to the Middle Miocene. Furthermore, the limited dating of detrital zircons and the absence of Sm-Nd data in total rock present challenges in understanding the interval. The existing studies are isolated and do not provide a robust regional-scale integration. To gain a better understanding of this interval and develop an integrated paleogeographic depositional model, we present updated lithofacies data, U-Pb data on detrital zircons, and the first Sm/Nd analyses of fine sediments from the Amazon Basin. The data obtained for the Upper Cretaceous of the Amazon Basin indicate the presence of a vast transcontinental fluvial system, flowing westward from anastomosing to meandering as it moved away from the Gurupá Arch. The system was still being supplied by sources from the Amazon Craton, mainly from the eastern provinces (Central Amazonia, Maroni-Itacaiunas, Ventuari-Tapajós, and Rio Negro Juruena) according to negative εNd values and U-Pb data pointing to Paleo and Mesoproterozoic sources. Regarding the Middle Miocene, the fluvial system would start to flow eastward. However, the εNd (-13) and U-Pb data on Paleozoic detrital zircons in this unit allow for the formulation of two hypotheses for the paleogeography of this interval. The first hypothesis attributes the correlation of Paleozoic zircons of Andean origin in the sediment supply of the Amazon Basin to suggest that the Purus Arch did not completely block the sediments, nor did they travel the entire extent of the Amazon Basin and reach the mouth of the Amazon. The second hypothesis explains that these same Paleozoic detrital zircons found with ages are attributed to phases of recycling of Paleozoic units in the Amazon Basin in the Purus Arch region through fluvial incision that acts on the remobilization and redistribution of these sediments.

COMMITTEE MEMBERS:
Externo à Instituição - JEAN MICHEL LAFON - UFPA
Interna - 1658822 - LUCIETH CRUZ VIEIRA
Interna - 1897668 - NATALIA HAUSER
Presidente - 418662 - ROBERTO VENTURA SANTOS