Banca de DEFESA: ANDRE GAVA HEITOR

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ANDRE GAVA HEITOR
DATE: 26/11/2025
TIME: 09:00
LOCAL: PPGMEG
TITLE:

RADIOMETRIC CHARACTERIZATION OF THE ALKALINE MASSIF OF MORRO DE SÃO JOÃO - RJ

KEY WORDS:

Gamascan spectrometry, natural radionuclides, radiogenic heat, Morro de São João, alkaline soils.

PAGES: 59
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

The Morro de São João Alkaline Massif (MSJ), part of the Poços de Caldas–Cabo Frio Alkaline Alignment (PCCF), consists predominantly of syenites, exhibiting wide compositional variation represented by melanocratic, mesocratic, and leucocratic lithotypes. Unlike other alkaline massifs in the same alignment, the MSJ does not have significant outcrops, and its lithotypes are mainly recognized in blocks and boulders of different shapes and sizes, which, combined with the difficult access to the interior of the massif, limits the detail of the lithological mapping. In this study, the geophysical method of gamma spectrometry was used at different scales (aerial, field, and laboratory) to radiometrically characterize the massif and associate the distribution of K, Th, and U with the lithotypes present. The aerial and field data were processed using Oasis Montaj Student Version software, resulting in maps of the distribution of radioelements, as well as interpretive maps (ternary, F factor) and isotopic ratios. A good correlation was observed between the aerial and field surveys; however, the field data revealed localized variations not detected by the aerial surveys, attributed to the higher resolution and proximity to the source of the portable equipment. Laboratory analyses confirmed a pattern of enrichment in K, Th, and U directly related to the degree of magmatic evolution, in which melanocratic rocks have lower contents, while felsic rocks exhibit progressive enrichment, due to the incompatible behavior of these elements during magmatic differentiation. In addition, radiogenic heat production rates were estimated from data measured in samples and in the field, highlighting the contribution of radiogenic elements to the crustal thermal regime in the region.

COMMITTEE MEMBERS:
Presidente - 1648928 - ARTUR CORVAL VIEIRA
Interna - ***.540.817-** - LILIANE PAIVA PANETTO - ON/MCT
Externa ao Programa - 3360139 - SUZE NEI PEREIRA GUIMARAES - UFRRJExterno à Instituição - THOMAS FERREIRA DA COSTA CAMPOS - UFRN
Externo à Instituição - FRANCISCO JOSÉ FONSECA FERREIRA - UFPR