Banca de DEFESA: TULIO MARQUES SOARES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : TULIO MARQUES SOARES
DATE: 20/12/2023
TIME: 14:00
LOCAL: Sala de videoconferência e Teams
TITLE:

Provenance and tectonic setting of the metasedimentary sequences of the Serra de Santa Rita Greenstone Belt: Implications for the tectonic evolution of the Goiás Massif, Central Brazil.

KEY WORDS:

Greenstone Belt Serra de Santa Rita; Goiás Massif; Sedimentary Provenance; U-Pb and Lu-Hf Isotope Systems applied to detrital zircon; Whole rock Sm-Nd isotopes.

PAGES: 76
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

The Crixás-Goiás Domain is situated in the Goiás Massif, central-western portion of the Brasília Fold Belt, and consists of an assemblage of TTGs (Tonalites, Trondhjemites, and Granodiorites) and greenstone belts. The Serra de Santa Rita Greenstone Belt is in the southern part of the Crixás-Goiás Domain and is composed, from base to top of sequences of ultramafic and mafic metavolcanic rocks underlying younger metasedimentary units. This study presents U-Pb, Sm-Nd, and Lu-Hf isotopic geochemistry data of the metasedimentary rocks from the Serra de Santa Rita Greenstone belt with the aim of characterizing potential sedimentary sources, basin styles, deposition environments, and maximum depositional ages, as well as proposing the evolutional history of these basins within the regional context. The results obtained in this research have allowed the identification of sedimentary sequences belonging to two distinct basins: the Serra de Santa Rita Basin and the Serra de Cantagalo Basin. The Serra de Santa Rita Basin is composed of meta-arkose, meta-graywacke, metapelites, carbonaceous phyllites, marble, and fine-grained sandstones. It presents detrital zircon data with Archean and Rhyacian ages. Archean sources exhibit Lu-Hf and Sm-Nd isotopic signatures consistent with older crustal sources, while Rhyacian sources display a juvenile crustal signature. The maximum deposition age, obtained based on the weighted mean of the youngest zircon grains, points to a 2.14Ga age. The Serra de Cantagalo Basin is a metasedimentary sequence composed of meta conglomerates, meta-arenites, and quartzites, with detrital zircon data indicating Archean, Rhyacian, Orosirian, and Statherian ages. The maximum deposition age for the sedimentary sequence in this basin is 1.98 Ga. The Lu-Hf and Sm-Nd isotopic signatures obtained for the sedimentary sequence of the Serra de Cantagalo Basin are consistent with the influence of older crustal sources. The possible Archean sources are the TTGs present in the Crixás-Goiás Domain. Rhyacian sources likely originated from igneous and metamorphic rocks of the Campinorte, Cavalcante-Arraias, and Almas-Conceição do Tocantins Domains. In turn, it is suggested that Statherian and Orosirian sources are related to volcanic rocks in a rift-related geological context, comparable to the Araí and Serra da Mesa Groups. The tectono-sedimentary evolution of the Serra de Santa Rita Basin presents two cycles: the first is related to its opening, adopting a pull-apart basin style, with the deposition of arkoses and graywackes of the Fazenda Cruzeiro Formation. The second cycle is associated with a sea-level rise and the deposition of a marine sequence characterized by pelites, organic-rich phyllites, carbonates, and finegrained sandstones of the Fazenda Limeira Formation. This latter cycle is followed by basin uplift after diagenesis and the onset of erosion. The Serra do Cantagalo Basin may be related to post-collisional rifting, resulting from the subsidence of the Rhyacian orogen, or to the same tectonic event that formed the Araí and Serra da Mesa basins. Finally, the Serra do Cantagalo Formation was tectonically positioned over the Serra de Santa Rita Greenstone Belt during the Brasiliano-Pan African orogenic event.

COMMITTEE MEMBERS:
Presidente - 1555904 - CATARINA LABOURE BEMFICA TOLEDO
Interna - 1897668 - NATALIA HAUSER
Externa ao Programa - 3000894 - ELIZA INEZ NUNES PEIXOTO - UnBExterno à Instituição - FARID CHEMALE JUNIOR - UNISINOS