Caracterização estrutural do Lineamento Tietê, porção central do estado de São Paulo
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2019-11-18
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Universidade Estadual Paulista (Unesp)
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Na porção central do Estado de São Paulo são observados traços principais do substrato rochoso que marcam estruturas com orientação preferencial NW-SE. Entre estas estruturas, destaque para o Lineamento Tietê, com forte orientação NW-SE e estruturas marcadas desde o Planalto Ocidental até os terrenos pré-cambrianos do território paulista. O objetivo desta pesquisa foi investigar as estruturas em uma área compreendida entre as cidades de Piracicaba e Itu, buscando reconhecer a orientação principal dos planos de falhas e tipos de movimentos associados. Pela caracterização da geometria, atitudes dos planos de falhas e estrias, sentido de movimento e compartimentação em blocos, além das juntas, foi realizada a análise do fraturamento associado ao Lineamento Tietê. As estruturas relacionadas ao Lineamento Tietê têm os traços de orientação predominante NW-SE bem marcadas por feições geomorfológicas de relevo e de drenagem. Como resultado foram reconhecidas falhas e juntas com predomínio de orientação também NW-SE, que na região de Itu se ajustam a um sistema transcorrente dextral com segmentos transtensivos e transpressivos associados. Na região de Saltinho, os traços se ajustam a um sistema de falhas normais relacionadas a estruturas regionais, como grabens e horstes. A projeção dos traços de falhas do embasamento para o interior da Bacia do Paraná é um forte indicativo do papel dessa estruturas na evolução tectônica regional, indicando possíveis reativações. O quadro estrutural geral obtido com o trabalho aponta para a existência de importante zona de fraturas associada ao Lineamento Tietê.
In the central portion of the São Paulo State there are major features of the rocky substrate that mark structures with preferential orientation NW-SE. Among these structures, the highlight is the Tietê Lineament, with strong NW-SE orientation and marking the landscape from the Western Plateau to the precambrian basement rocks of São Paulo territory. The objective of this research was to investigate the structures into an area comprised between the cities of Piracicaba and Itu, seeking to recognize the main orientation of faults and associated movement types. Using the characterization of the geometry, attitudes of the faults planes and striations, sense of movement and block compartmentation, besides the joints, the fracturing analysis associated with the Tietê Lineament was performed. Structures related to the Tietê Lineament have the NW-SE predominant orientation well marked by relief and drainage geomorphological features. As a result, faults and joints with a NW-SE predominance of orientation were also recognized and in the Itu region fit into a dextral transcurrent system with associated transtensive and transpressive segments. In the Saltinho region, recognised structures fit to a normal faults system related to regional structures such as grabens and horsts. The projection of basement fault traces into the Paraná Basin is a strong indication of the role of these structures in regional tectonic evolution, indicating possible reactivations. The general structural framework obtained with this work points to the existence of an important fracture zone associated with the Tietê Lineament.
In the central portion of the São Paulo State there are major features of the rocky substrate that mark structures with preferential orientation NW-SE. Among these structures, the highlight is the Tietê Lineament, with strong NW-SE orientation and marking the landscape from the Western Plateau to the precambrian basement rocks of São Paulo territory. The objective of this research was to investigate the structures into an area comprised between the cities of Piracicaba and Itu, seeking to recognize the main orientation of faults and associated movement types. Using the characterization of the geometry, attitudes of the faults planes and striations, sense of movement and block compartmentation, besides the joints, the fracturing analysis associated with the Tietê Lineament was performed. Structures related to the Tietê Lineament have the NW-SE predominant orientation well marked by relief and drainage geomorphological features. As a result, faults and joints with a NW-SE predominance of orientation were also recognized and in the Itu region fit into a dextral transcurrent system with associated transtensive and transpressive segments. In the Saltinho region, recognised structures fit to a normal faults system related to regional structures such as grabens and horsts. The projection of basement fault traces into the Paraná Basin is a strong indication of the role of these structures in regional tectonic evolution, indicating possible reactivations. The general structural framework obtained with this work points to the existence of an important fracture zone associated with the Tietê Lineament.
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Tectônica, Reativação de falhas, Ambiente intraplaca, Tectônica transcorrente, Lineamentos continentais, Tectonics, Fault reactivation, Intraplate environment, Trancurrent tectonics, Continental lineaments