Banca de DEFESA: ISABELLE TEIXEIRA DA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : ISABELLE TEIXEIRA DA SILVA
DATE: 16/06/2026
TIME: 14:30
LOCAL: Auditório do CCET (Híbrido)
TITLE:

Sedimentary Provenance of the Cretaceous Interval in the Barreirinhas and Pará– Maranhão Basins, Brazilian Equatorial Margin

KEY WORDS:

Brazilian Equatorial Margin; Barreirinhas Basin; Pará-Maranhão Basin; Sedimentary Provenance; Heavy Minerals; Detrital Zircon; U–Pb Geochronology 

PAGES: 112
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

 This study was conducted in the Barreirinhas and Pará-Maranhão basins, both located within the Brazilian Equatorial Margin. Currently, this region represents a new hydrocarbon exploration frontier due to recent petroleum discoveries in deep-water turbidite deposits adjacent to this area. Sedimentary provenance analysis based on heavy mineral assemblages constitutes an important tool for interpreting source-to-sink relationships, contributing to the understanding of the main source rock types and source terranes that supplied sediments to the studied basins. The methodology involved heavy mineral petrographic identification, coupled with morphological characterization and U–Pb geochronological dating of detrital zircons from sandstone intervals of Cretaceous age recovered from key reference wells in these basins. Petrographic analysis enabled the identification and characterization of the principal heavy mineral assemblage, dominated by zircon, tourmaline, rutile, and staurolite, whereas amphibole, garnet, monazite, epidote, kyanite, pyroxene, apatite, and olivine occur only in minor amounts.Based on the mineralogical composition, the provenance indices ZTR, RZi, and EST/(ZTR+EST) were calculated. These indices indicate that wells located closer to the coastline exhibit higher proportions of ultrastable heavy minerals (zircon, tourmaline, and rutile) and, consequently, greater mineralogical maturity. In contrast, more distal wells, located farther offshore, show better preservation of provenance signatures due to the more significant occurrence of staurolite, resulting in lower mineralogical maturity. These results suggest limited intrastratal dissolution and a reduced influence of additional sediment sources.Internal and external morphological analyses of detrital zircon grains revealed a predominance of metamorphic zircons throughout most stratigraphic intervals, whereas igneous zircons occur in subordinate proportions. U–Pb geochronological data indicate that the detrital zircon population is predominantly Neoproterozoic (Ediacaran) in age, with a significant contribution of Paleoproterozoic (Orosirian) grains.The mineralogical assemblages, combined with zircon typology, indicate a dominant metamorphic influence during the first sedimentary cycle, suggesting the Ediacaran supracrustal rocks of the Borborema Province as the principal primary source terranes. Morphological analysis of the zircon grains further indicates that most grains exhibit evidence of sedimentary recycling, having been removed from their original source rocks and subsequently reworked through an additional sedimentary cycle. This interpretation points to the Parnaíba and São Luís–Grajaú basins as the main intermediate source terranes for the intervals sampled in wells located near the coastline.However, the more significant occurrence of staurolite and rutile in the distal wells suggests that the Araguaia Belt, Gurupi Belt, and São Luís Craton may also have acted as potential source terranes for the wells located farther offshore.

 

COMMITTEE MEMBERS:
Externa ao Programa - 1884342 - DEBORA DO CARMO SOUSA - nullExterno à Instituição - MARCUS VINICIUS DORNELES REMUS - UFRGS
Externa à Instituição - NARELLE MAIA DE ALMEIDA - UFC
Externa ao Programa - 1298966 - RAQUEL FRANCO DE SOUZA - nullPresidente - 1149363 - VALERIA CENTURION CORDOBA