Banca de DEFESA: Giulia Guimaraes Barbosa Trivelli

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Giulia Guimaraes Barbosa Trivelli
DATE: 07/10/2022
TIME: 14:30
LOCAL: Sala de videconferência do IGD
TITLE:

MAGMATIC EVOLUTION OF CHARNOQUITE-ALTO CANDEIAS ASSOCIATION, SW MESOPROTEROZOIC OF THE AMAZON CRATON.

KEY WORDS:

Magmatism; Provincia Estanífera de Rondônia; Geochemistry; Geochronology.

PAGES: 154
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

The State of Rondônia hosts, in its central-north region, a voluminous rapakivi granitic, of Meso-Neoproterozoic, the chematism to the event, formed during successive incidents that occurred between 1610 and 950 Ma, the focus of the Rondônia Staniferous Province (RSP). This magma has been subdivided into intrusive environments, plutonic by associations of actions, which generally present a geochemical signature, meta- to peraluminous, type A and from intra-plate to post-collisional tectonics. The Alto Candeias charnockite-granite association is part of the reginional homonymous intrusive suite unit, is an important representative of this polyphasic rapakivi granitic magmatism in the PER, and its exposure area (about 15,000 Km²) is marked by faciological and geochemical variations that have been the focus of heated petrogenetic discussions regarding its origin, evolution and tectonic environment. These rocks are surrounded by charnockite lithologies with metaluminous and calc-alkaline characteristics (I and A) showing syn- to post-collisional signature with subordinate lithologies related to subvolcanic rocks and alkaline granites of the type (A1 and A2) with intraplate signature. This voluminous polyphase magmatism had its evolution marked by the differentiation process mainly controlled by fractional crystallization of feldspars and ferromagnesian minerals, as well as some accessory minerals, which favored the progressive increase of the HFSE and REE content. On the other hand, the Campo Novo alkaline lithologies represent the most fractional or evolved members identified in the Alto Candeias magmatism, which do not follow the geochemical trend of the other lithologies, suggesting a plutono-volcanic association with distinct magmatic evolution. Furthermore, the rapakivi charnockite, syenogranite and monzogranite lithologies have post-collisional geochemical signature, while the Campo Novo alkaline lithologies have typical intraplate geochemistry. The available isotopic data of Pb-Pb, U-Pb, Sm-Nd and Lu-Hf indicate that the CG-type Alto Candeias magmatism, which occurred between 1357 – 1329 Ma, involved the interaction of fusion of mantle and crustal sources in the Rondonian- San Ignacio (1356 – 1330 Ma). Although it does not represent a specialized tin magmatic phase, the Alto Candeias polyphase batholith hosts some small polymetallic deposits (Sn ± Cu, Pb, As), which are associated with the intrusions of younger magmatic phases.

BANKING MEMBERS:
Externo à Instituição - DAVIS CARVALHO DE OLIVEIRA - UFPA
Interno - 1303786 - ELTON LUIZ DANTAS
Externo à Instituição - MOACIR JOSE BUENANO MACAMBIRA - UFPA
Interno - 6404885 - NILSON FRANCISQUINI BOTELHO
Presidente - 1057547 - VALMIR DA SILVA SOUZA