Banca de DEFESA: Kawinã Cardoso de Araújo

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : Kawinã Cardoso de Araújo
DATE: 17/11/2022
TIME: 14:00
LOCAL: Sala de videoconferência do IGD
TITLE:

STRUCTURAL CONTROLS ON GOLD MINERALIZATION IN THE FAINA GREENSTONE BELT, CENTRAL BRAZIL.

KEY WORDS:

Orogenic gold deposits, structural controls, Faina greenstone belt.

PAGES: 94
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

The Faina greenstone belt is part of Crixás-Goiás Domain, one of the main components of the Goiás Massif. It is located in the central portion of the Brasília Belt, Central Brazil. The gold mineralization is orogenic in nature, strongly controlled by tectonic structures. Investigation of regional structures distributed in different domains of Faina greenstone belt and the meso-structures present in the main targets and mining at the region allowed the identification of a complex cluster of structural elements genetically related to thrusts system and regional folding. Through descriptive and kinematic analysis it was possible to identify six successive deformational phases, generated in at least three different deformational events. The first E1 event, probably Paleoproterozoic, is characterized by three progressive deformational phases, D1, D2 and D3, developed in a ductile to ductile-ruptile regime. The D1 phase is marked by schistosity parallel to sedimentary bedding. The structures attributed to D2 deformation phase are the most prominent structural features of the Faina greenstone belt. They were generated in a ductile regime and include folding at diverses scales (F2), axial plane foliation (S2), mylonitic foliation (Sm2), stretch lineation (Le2) and intersection lineation (Li2). Allied to these features, a complex system of NW-SE regional thrusts was observed, associated with reverse shear zones with kinematic indicators indicating tectonic transport from south to north. Phase D2 evolves into NW-SE strike-slip shear zones, interpreted as tectonic escape during phase D3. The E2 event, which is ductile-ruptile in nature, has a neoproterozoic age and is characterized by two deformational phases D4 and D5. The main D4 phase structure is the Faina Fault, a NE dextral directional regional fault that separates the Faina and Serra de Santa Rita greenstone belts. The D5 phase is marked by open folds developed at shallower crustal levels and present throughout the Brasília Belt. The last E3 event, represented by the brittle D6 phase, is characterized by E-W to NE-SW trending breccias and faults. The main gold mineralization control in the Faina greenstone belt is associated with D2 deformation phase. The D2 regional thrusts are the main conduits for mineralizing fluids migration that are hosted by secondary structures, where mineralization is associated with monoclinic shear zones. Mineralization occurs as free gold in quartz veins, concordant with D2 shear zones, pluging parallel to Le2 stretch lineation. The veins are structured in ramps and plateaus and the mineralization is concentrated in pressure shadows of regional sigmoidal structures, ranging from large to microscopic scale.

BANKING MEMBERS:
Presidente - 1555904 - CATARINA LABOURE BEMFICA TOLEDO
Externa ao Programa - 3000894 - ELIZA INEZ NUNES PEIXOTO
Interno - 2370895 - LUIS GUSTAVO FERREIRA VIEGAS
Externo à Instituição - ROBERTO VIZEU LIMA PINHEIRO - UFPA