Banca de DEFESA: Frankie James Serrano Fachetti

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : Frankie James Serrano Fachetti
DATE: 13/12/2023
TIME: 14:00
LOCAL: Sala de videoconferência e Teams
TITLE:

Geological Evolution of Migmatites from the Patos Shear Zone, Borborema Province, Northeast Brazil: An Integrated U-Pb, Lu-Hf, and Sm-Nd Approach.

KEY WORDS:

crustal reworking, crustal growth, continental collision, crustal evolution, migmatization, Hf-Nd isotopes and disequilibrium.

PAGES: 131
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geologia
SUMMARY:

The tectonic configuration of the Borborema Province exhibits a complex structural framework defined by polycyclic history from the Archean to the end of the Neoproterozoic. Different crustal blocks have been accreted, amalgamated, and reworked, forming a set of sub-provinces, each with a distinct evolutionary history separated by an interconnected system of shear zones. The Patos Shear Zone corresponds to an extensive structure over 400 km in length, oriented E-W, separating the Rio Grande do Norte Domain from the Transversal Zone to the south in the state of Paraíba. Within the shear corridor, whose kinematics are essentially dextral, migmatites, foliated granites, various gneisses, and mylonite zones are exposed, affected to varying degrees by deformation. In this study, we present results from different phases of migmatization in rocks within the belt defined by the Patos Lineament. The main objective was to determine the sequence of events that allowed the establishment of different phases of migmatite generation in rocks subjected to different episodes of partial melting and crustal reworking. U-Pb ages of 3.5 and 3.3 Ga are interpreted as the crystallization of these migmatites in the Paleoarchean. Meso-Neoarchean ages found in dated rocks show a continuous history of magmatism and deformation at 3.2, 3.0, and 2.65 Ga, with contemporaneous phases of migmatite generation. A new pulse of magmatic events with associated migmatization developed in the Paleoproterozoic, with ages of 2.2, 2.1, and 2.0 Ga. Finally, an event at 575 Ma is clearly evident in the generation of pinkish-red migmatites, with K-rich granitic magmatism cutting across and injecting the previously described rocks. Thus, although the Brasiliano Orogeny is responsible for the development of extensive strike-slip shear zones in the region and the development of the tectonic framework of the Patos Lineament, our results show that fragments of ancient crust have been preserved along it. The similarity between the ages and geological structure of these rocks allows us to conclude that these Paleoproterozoic crustal units of the São Francisco Craton and the adjacent basement inliers, which carry a similar tectonic history, should be considered as a coeval orogenic system, possibly continuous in its formation, and be known as the Greater São Francisco Orogen.

COMMITTEE MEMBERS:
Externo à Instituição - LAURO CÉZAR MONTEFALCO DE LIRA SANTOS - UFPE
Interno - 6404885 - NILSON FRANCISQUINI BOTELHO
Presidente - ***.539.401-** - REINHARDT ADOLFO FUCK - UnB
Externo à Instituição - TICIANO JOSE SARAIVA DOS SANTOS - UNICAMP