Banca de QUALIFICAÇÃO: SAMIR DO NASCIMENTO VALCÁCIO

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : SAMIR DO NASCIMENTO VALCÁCIO
DATA : 13/12/2017
HORA: 09:00
LOCAL: Sala 1 - PPGG
TÍTULO:

Thermal effects provoked by the Ediacaran Umarizal pluton (RN) over rocks of the Seridó Group, NE Brazil: structural, mineralogical and petrophysical characterization

PALAVRAS-CHAVES:

Plutonism; Thermal Aureole; Ediacaran; Borborema Province; NE of Brazil

PÁGINAS: 27
GRANDE ÁREA: Ciências Exatas e da Terra
ÁREA: Geociências
RESUMO:

The Umarizal charnockitic alkaline suite, located on the center-southern portion of the Rio Grande do Norte State, corresponds to a batholithic body with approximately 300 km2 intrusive into Paleoproterozoic basement and Neoproterozoic supracrustal rocks. No deformational evidence or magmatic fabric is displayed by these plutons. The main igneous body shows magmatic zoning, which permits recognize three distinct petrographic facies. The central one includes a chanockitic core with fayalite and hyperstene, that is followed by monzonites and syenogranites with or without fayalite, that, in turn, is followed by granites associated with gabbros, norites and anorthosites. The contact of the Umarizal pluton is marked by widespread migmatization with generation of granitic to tonalitic neosomes. The metamorphism is reflected in the formation of different amounts of sillimanite, andalusite, garnet, diopside and scapolite in calcsilicate gneisses and biotite gneisses, as well as phlogopite and calcite megacrysts in marbles. This mineral association suggests temperatures of at least 800-700oC and pressures less than 4-3 kbar. The liquidus temperature of the magma, estimated by using the zirconium saturation, indicated an average of 943±3oC. Structural evidences permit interpreting a magmatic emplacement system under transtrative regime by propagation of sills and lopoliths through shear zones adjacent to the pluton. Simulations for heat configuration involved in the magma emplacement were done by numerical modeling. In this way, it was possible to identify temperature isotherms of the metamorphic aureole, calculate internal temperatures zones and estimate the time elapsed for the magma heating. The thermal aureole extended to approximately 500 to 300 m from the contact of the magma. The time elapsed to acquire the thermal equilibrium in the region was estimated at around 106 years, calculated for a geothermal gradient of 60oC/km, considered the more representative according to the available data

MEMBROS DA BANCA:
Presidente - 350630 - ZORANO SERGIO DE SOUZA
Interno - 080.368.454-15 - ANTONIO CARLOS GALINDO - UFRN
Interno - 2042352 - FREDERICO CASTRO JOBIM VILALVA
Externo ao Programa - 346302 - JAZIEL MARTINS SA
Externo ao Programa - 346468 - JOSE ANTONIO DE MORAIS MOREIRA