Neotectônica no Lineamento Guapiara, médio e baixo vale do Rio Ribeira de Iguape
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Data
2017-03-22
Autores
Vedovello, Paulo [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
A região do médio e baixo vale do Rio Ribeira de Iguape, no sul do estado de São Paulo e nordeste do estado do Paraná, apresenta fortes feições morfotectônicas regionais expressas na paisagem através de cristas alinhadas e segmentos retilíneos de drenagem em torno da direção NW-SE, apesar do forte controle estrutural imposto pelas estruturas relacionadas às rochas pré-cambrianas, direcionadas NE-SW. Essas feições direcionadas NW-SE são relacionadas ao Lineamento Guapiara, constituído por um expressivo enxame de diques básicos mesozoicos e combinado a um intenso fraturamento que afeta todo o substrato rochoso. A região foi palco também da tectônica rúptil formadora dos riftes cenozoicos. O principal objetivo deste trabalho é o reconhecimento de feições estruturais associadas aos traços do Lineamento Guapiara e sua caracterização com ênfase nas falhas que possam estar associadas ao controle da evolução da paisagem local e, com isso, contribuir com o entendimento da evolução neotectônica da região. As análises e integração de dados dos mapas de lineamentos de drenagens e de relevo, de compartimentação geomorfológica e mapa geológico conduziram a seleção de áreas de interesse para os trabalhos de campo e coleta de dados estruturais. Estes foram organizados de acordo com o tipo de estrutura, classificação do sentido de movimento e unidades em que cada estrutura afeta, com o intuito de se obter uma cronologia relativa dos eventos tectônicos, bem como deduzir os eixos de paleotensões associados aos sucessivos eventos. Entre as feições estruturais reconhecidas, destaca-se a principal família de juntas NW-SE, associada ao evento responsável pelo fraturamento e preenchimento de magmas básicos no Mesozoico e formação dos enxames de diques. Falhas normais de direção NE-SW, associadas aos sedimentos cenozoicos estariam relacionadas ao evento paleógeno de origem das bacias cenozoicas na região, com o quadro de paleotensões indicando o eixo de maior esforço segundo a direção NE-SW e distensão NW-SE. Falhas sin-deposicionais da Formação Pariquera-Açu indicam a persistência deste regime de esforços na região até o Mioceno Médio. Falhas transcorrentes sinistrais deformam os sedimentos cenozoicos e apontam para pulso compressivo NNW-SSE a N-S, atuante a partir do Plioceno. O Conjunto de falhas normais NW-SE, que deforma a Formação Pariquera-Açu, associado a falhas transcorrentes destrais WNW-ESE a E-W, que deformam sedimentos do terraço aluvionar do Rio Ribeira de Iguape e são interpretados como decorrentes do quadro neotectônico regional. A reconstrução dos eixos de paleotensões para este evento indica o posicionamento do eixo de maior esforço segundo a direção NW-SE.
The region of the middle and lower Ribeira de Iguape River valley, in the south of São Paulo state and the northeast of the Paraná state, is characterized by strong regional morphothectonic features expressed in the landscape through aligned ridges and rectilinear drainage segments around the NW-SE direction, despite the strong structural control imposed by NE-SW structures related to Precambrian rocks. These NW-SE directed features are related to the Guapiara Lineament, constituted by an expressive swarm of Mesozoic basic dikes and combined with an intense fracturing that affects all the rocky substrate. The region was also submitted to the brittle tectonic event that originated the Cenozoic riftes. The main objective of this work is the recognition of structural features associated to the Guapiara Lineament traces and its characterization, with emphasis in the faults that may be associated to the control of the local landscape evolution and to contribute to the understanding of the neotectonic evolution of the region. Data analysis and integration of drainage and relief lineaments maps, geomorphological compartments and geological map conducted to the selection of areas of interest for fieldwork and structural data collection. Data were organized according to the type of structure, classification of the sense of movement and units in which each structure affects, in order to obtain a relative chronology of tectonic events and to deduce the paleostress axes associated to successive events. Among the recognized structural features, standouts the NW-SE joints set, associated to the event responsible for fracturing and filling of basic magmas in the Mesozoic and the formation of the dyke swarms. NE-SW normal faults, associated to the Cenozoic sediments are related to the Paleogene event of Cenozoic basins in the region, with a paleostress frame indicating the axe of maximum compressive stress striking NE-SW and a NW-SE extension. Sin-depositional faults to the Pariquera-Açu Formation point to the persistence of this tectonic regime in the region until the Midlle Miocene. Sinistral transcurrent faults deforming Cenozoic sediments indicate a NNW-SSE to N-S compressive pulse aging during the Pliocene. The set of NW-SE normal faults, which deforms the Cenozoic Pariquera-Açu Formation, as well as the set of WNW-ESE to E-W directed dextral transcurrent faults that deform sediments from the alluvial terrace of Ribeira de Iguape River are interpreted as resulting from the regional neotectonic regime. The reconstruction of paleostress axes for this event indicates a NW-SE axis of maximum compressive stress.
The region of the middle and lower Ribeira de Iguape River valley, in the south of São Paulo state and the northeast of the Paraná state, is characterized by strong regional morphothectonic features expressed in the landscape through aligned ridges and rectilinear drainage segments around the NW-SE direction, despite the strong structural control imposed by NE-SW structures related to Precambrian rocks. These NW-SE directed features are related to the Guapiara Lineament, constituted by an expressive swarm of Mesozoic basic dikes and combined with an intense fracturing that affects all the rocky substrate. The region was also submitted to the brittle tectonic event that originated the Cenozoic riftes. The main objective of this work is the recognition of structural features associated to the Guapiara Lineament traces and its characterization, with emphasis in the faults that may be associated to the control of the local landscape evolution and to contribute to the understanding of the neotectonic evolution of the region. Data analysis and integration of drainage and relief lineaments maps, geomorphological compartments and geological map conducted to the selection of areas of interest for fieldwork and structural data collection. Data were organized according to the type of structure, classification of the sense of movement and units in which each structure affects, in order to obtain a relative chronology of tectonic events and to deduce the paleostress axes associated to successive events. Among the recognized structural features, standouts the NW-SE joints set, associated to the event responsible for fracturing and filling of basic magmas in the Mesozoic and the formation of the dyke swarms. NE-SW normal faults, associated to the Cenozoic sediments are related to the Paleogene event of Cenozoic basins in the region, with a paleostress frame indicating the axe of maximum compressive stress striking NE-SW and a NW-SE extension. Sin-depositional faults to the Pariquera-Açu Formation point to the persistence of this tectonic regime in the region until the Midlle Miocene. Sinistral transcurrent faults deforming Cenozoic sediments indicate a NNW-SSE to N-S compressive pulse aging during the Pliocene. The set of NW-SE normal faults, which deforms the Cenozoic Pariquera-Açu Formation, as well as the set of WNW-ESE to E-W directed dextral transcurrent faults that deform sediments from the alluvial terrace of Ribeira de Iguape River are interpreted as resulting from the regional neotectonic regime. The reconstruction of paleostress axes for this event indicates a NW-SE axis of maximum compressive stress.
Descrição
Palavras-chave
Lineamento Guapiara, Evolução tectônica, Neotectônica