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| Author(s): |
Daniel Henrique de Souza
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Rio Claro. 2018-06-20. |
| Institution: | Universidade Estadual Paulista (Unesp). Instituto de Geociências e Ciências Exatas. Rio Claro |
| Defense date: | 2018-04-27 |
| Advisor: | Peter Christian Hackspacher |
| Abstract | |
This work investigates how the landscape of the continental margin of southeast Brazil evolves from an approach that integrates several temporal scales. The main goals of this thesis are to identify the main tectonic pulses that defined the regional landscape shape and how this landscape is changing in the current times. The main tools used was the apatite U-Th-Sm/He thermochronology (million years time scale) and the cosmogenic 10Be analysis (thousand years time scale). Apatite U-Th/He data yields average ages between 58 ± 17 e 124 ± 12 Ma. The thermal histories highlight fast cooling periods in the Late Cretaceous, Upper Cretaceous and Paleogene, in agreement with the tectonic reactivation phases registered by the regional geological data. The 10Be-derived modern erosion rates range between 5 ± 0.5 to 53 ± 4 m/Ma, which is similar to observed in others passive margin. This indicates relative tectonic stability in the Quaternary, which is strengthened by the comparison with the high rates observed in the U-Th-Sm/He-derived thermal histories for the reactivations phases. The precipitation and temperature define the regional variation in erosion rates, although under topographic regulation. Thus, the ocean-side Serra do Mar escarpments erode faster than the other regions. The river incision and the hillslopes processes are balanced, so that the high relief of the escarpments remains constant. River capture episodes results in the low-relief highlands dissection and in the discontinuous migration of the escarpments to the regional divide. The modern erosion rates extrapolation shown that in maintaining the current conditions it would be needed between 20 to 40 Ma to reach the total amount of incision observed in the escarpments. The integration between long and short-term erosion rates indicates that in periods of moderate tectonics, the rates are similar at key points of evolution, such as incised valleys. Thus, around mean oscillations, there is a balance between surface uplift and erosion. (AU) | |
| FAPESP's process: | 14/14702-0 - Landscape evolution of Sapucaí River Basin - MG: relationships between long-and short-term dynamics of geological time |
| Grantee: | Daniel Henrique de Souza |
| Support Opportunities: | Scholarships in Brazil - Doctorate |