Banca de QUALIFICAÇÃO: JOSÉ ALEXANDRE PAIXÃO DA CUNHA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOSÉ ALEXANDRE PAIXÃO DA CUNHA
DATE: 04/12/2020
TIME: 09:00
LOCAL: https://youtu.be/SgfQfHbb4vU
TITLE:

Lithogeochemical, petrophysics and 2D geophysical modeling of primary carbonatites from the Archean São José do Campestre Massif, Boborema Province

KEY WORDS:

Carbonatites; Ultramafic; Gravimetry; Petrophysics; São José do Campestre

PAGES: 27
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

Carbonatites are exotic rocks with more than 50% carbonate of igneous origin and SiO2 <20% in their geochemical composition. Ultramafic rocks with associated carbonatites are found in the São José do Campestre Archean Nucleus (NASJC), NE of Brazil, State of Rio Grande do Norte. The NASJC is formed by different generations of dioritic and granitic and meta-suppurative metagranitoids. In this context, ultramafic rocks with associated carbonatites are characterized by having circular / elliptical bodies, truncating low-angle basement structures and a dark massapé soil. The ultramafic rock contains essential minerals and accessories: diopside, ± escapolite, ± garnet, ± titanite, ± plagioclase and ± opaque minerals. Carbonatite consists of calcite, olivine, ± phlogopite, ± garnet and ± Mg-ferrite / magnetite. The lithochemistry of carbonatites reveals that SiO2 values are less than 20% and CaO values are around 40%. The trace and ETR elements are low when compared to the average of carbonatites in the world. The density contrast of ultramafic, carbonatite and country rock results in a strong positive gravimetric anomaly. 2D modeling suggests a potato-shaped geometry, similar to other carbonatitic bodies in the world. The data presented here in this work allow to classify these carbonate rocks as carbonatites and strongly suggests that they are primary, that is, from a mantle source

BANKING MEMBERS:
Presidente - 350630 - ZORANO SERGIO DE SOUZA
Interno - 1513243 - MARCOS ANTONIO LEITE DO NASCIMENTO
Interno - 349684 - WALTER EUGENIO DE MEDEIROS
Externo à Instituição - ELTON LUIZ DANTAS