| Grant number: | 18/23650-4 |
| Support Opportunities: | Scholarships abroad - Research Internship - Doctorate |
| Effective date (Start): | May 30, 2019 |
| Effective date (End): | May 29, 2020 |
| Field of knowledge: | Physical Sciences and Mathematics - Geosciences - Geophysics |
| Principal Investigator: | Leila Soares Marques |
| Grantee: | Karine Zuccolan Carvas |
| Supervisor: | Paulo Marcos de Paula Vasconcelos |
| Host Institution: | Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil |
| Research place: | University of Queensland, Brisbane (UQ), Australia |
| Associated to the scholarship: | 17/18232-6 - Late Cretaceous and Paleogene tholeiitic intrusions from Região dos Lagos (RJ): 40Ar/39Ar thermochronological data inversion and nature of mantle sources, BP.DR |
Abstract In contrast to the Paraná Magmatic Province, which is characterized by fast eruption rates, the associated subalkaline rocks of Serra do Mar Dyke Swarm (Southeast Brazil) show a much larger time span, suggesting the involvement of distinct lithospheric processes. However, the compositional features of the dykes, the presence of inclusions and secondary minerals, and the possible thermal disturbance related to the posterior alkaline pulses have influenced previous geochronological data, making difficult the investigation of the emplacement events. The Região dos Lagos in Rio de Janeiro, particularly, is of great interest because of the presence of dykes and alteration processes that occurred in the Albian and Paleogene, as indicated by paleomagnetic and 40Ar/39Ar studies, therefore, consisting in an outstanding example of all the challenges listed above.A better understanding of the thermotectonic events related to these dykes and their involvement in the Southeast margin evolution during the Cretaceous needs not only better geochronological constraints but also thermochronology data in order to estimate the magnitude and duration of thermal disturbances. The acquisition and interpretation of new data is the main objective of the research period in the Argon Geochronology Laboratory of the University of Queensland described in this proposal, in which a new analytical approach will be performed, based on the Ar thermochronology and geochronology analysis of K-rich minerals from wall-rock xenoliths samples found in the mafic dykes. The reset and partial reset of these minerals will provide ways to overcome all the difficulties faced by previous studies, and, in the second case, allow the application of Ar multi-domain diffusion modeling, a powerful thermochronology tool that has never been applied in this context before. SEM analyses will integrate further interpretations. The refinement of the thermal and alteration histories of subalkaline mafic dykes in southeastern Brazil can supply unique and complementary information on the thermotectonic processes that shaped the region. (AU) | |
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