Diques mesozoicos básicos e intermediários como condicionantes do relevo na porção noroeste da Ilha de São Sebastião - SP

• Autor(a) principal: Valle, Victor Arroyo da Silva do [UNESP]
• Data de Publicação: 2016
• Tipo de documento: Trabalho de conclusão de curso
• Idioma: por
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/155493; http://www.athena.biblioteca.unesp.br/exlibris/bd/capelo/2017-06-06/000884887.pdf
• topic: Geomorfologia; Diques (Geologia); Relevo; São Sebastião (SP)

The study of aspects related to relief evolution is an important tool for achieving an optimal management of the environment in which we live and extract essential resources to the modern life. The analysis of factors responsible for the origin of determined landforms is an example of those studies. In the case of the study area, the northwest portion São Sebastião Island (SP), different landforms are related to distinct geological units. The main units described in the area are: a Precambrian granite-gneissic basement, Mesozoic basic and intermediate dykes, and Mesozoic alkaline stocks and dykes. The landforms associated with the basic and intermediate dykes show an interesting pattern. There are cases in which they are characterized by elongated ridges, which represent landforms that are more resistant to surface processes (weathering and erosion). In other cases, they define the course of streams, therefore, representing landforms that are less resistant to surface processes. In that context, the main objective of this study is to identify which factors determine the resistance of the dykes to surface processes, and, therefore, are responsible for the landforms associated with them. In order to achieve that objective, a characterization of the dykes was made focusing aspects such as mineralogical composition, structural pattern, rock age, and the characteristics of the relief units in which the dykes are present. A comparative chart containing aspects related to both dykes and basement was prepared in order to establish which of those aspects are in fact responsible for the different landforms associated with the dykes. The obtained results indicate that the mineralogical composition, the fracture pattern and the thickness of the dykes are the main factors that determine the resistance of those rocks to ... (Complete abstract electronic access below)