Evolução dos processos morfogenéticos em relevo cuestiforme: a bacia do Córrego do Cavalheiro – Analândia (SP)
Carregando...
Arquivos
Data
2016-06-10
Autores
Pinton, Leandro de Godoi [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
A presente pesquisa teve como objetivo geral avaliar a dinâmica dos processos morfogenéticos do relevo cuestiforme no Quaternário Tardio (Pleistoceno Superior-Holoceno Superior) e no período antrópico recente. Com base nessa avaliação, propôs-se reconstituir a sequência denudativa numa escala de tempo geológico, assim como verificar as implicações da constituição de morfologias antropogênicas na evolução desse compartimento numa escala histórica de tempo. A fim de atender tal objetivo, foram realizadas datações de episódios deposicionais por Luminescência Opticamente Estimulada (LOE) e pelo método do chumbo-210 (210Pb). Ademais, foram elaborados mapeamentos específicos para a obtenção de dados morfoestruturais, geomorfológicos e de uso e cobertura da terra. A bacia hidrográfica do Córrego do Cavalheiro – Analândia (SP) – foi selecionada como área de estudo em virtude de sua disposição natural, na transição entre as Cuestas Areníticas-Basálticas e a Depressão Periférica Paulista, associada, ainda, à evolução do uso da terra essencialmente rural. A análise sistêmica entre as idades LOE do material coluvionar com as flutuações paleoclimáticas regionais e o arranjo de feições morfoestruturais e antropogênicas possibilitou a proposição de um modelo evolutivo do relevo cuestiforme, caracterizado pela seguinte sequência denudativa: 1) Primeira fase seca de 30.770 ± 4.930 a 8.000 ± 1.000 anos A.P. (transição do Pleistoceno Superior com o Holoceno Inferior, estendendo-se até o início do Holoceno Médio); 2) Primeira fase úmida de 7.420 ± 980 a 4.500 ± 750 anos A.P. (Holoceno Médio-Superior); 3) Segunda fase seca de 3.940 ± 665 a 2.215 ± 250 anos A.P. (Holoceno Superior) e; 4) Fase antropogênica de 1962 a 2013 (série histórica de 51 anos). A datação dos sedimentos fluviais pelo método do 210Pb foi ineficaz como recurso complementar para o detalhamento da fase antropogênica nas cuestas em razão do predomínio de coberturas sedimentares na composição litopedológica desse compartimento. Todavia, a quantificação das mudanças morfológicas mediante a sistematização de geoindicadores corrobora a ação antropogênica condicionando a esculturação do relevo cuestiforme. A reconstituição paleomorfogenética das cuestas demonstrou que os processos denudativos no Quaternário Tardio (Pleistoceno Superior-Holoceno Superior) e no período antrópico recente se configuram de forma complexa, sendo a sua dinâmica cíclica e poligênica.
The present research aimed to evaluate the dynamics of the morphogenetic processes of the cuesta relief in the Late Quaternary (Upper Pleistocene-Upper Holocene) and in the current anthropic periods. Based on this evaluation, the denudative sequence was reconstituted in a geological time scale, and the implications of the anthropogenic morphology constitution in the evolution of this compartment in a historical time scale were verified as well. In order to achieve this objective, depositional dating were performed through Optically Stimulated Luminescence (OSL) and the Pb-210 method (210Pb). In addition, specific morphostructural, geomorphological and land-use/land-cover mapping were performed. The Cavalheiro Stream basin – Analândia (SP) – was chosen as the study area due to its natural distribution, in the transition of the sandstone-basaltic Cuestas and the Paulista Peripheral Depression and the essentially rural land-use evolution as well. The systemic analysis comparing the colluvium material ages (OSL) with the regional paleoclimatic fluctuations and the morphostructural/anthropogenic features arrangement provided an evolutionary model of the cuestas relief, characterized by the following denudative sequence: 1) First dry phase from 30,770 ± 4,930 to 8,000 ± 1,000 years BP (transition between the Upper Pleistocene and the Lower Holocene, extended until the beginning of the Middle Holocene); 2) First wet phase from 7,420 ± 980 to 4,500 ± 750 years BP (Middle-Upper Holocene); 3) Second dry phase from 3,940 ± 665 to 2,215 ± 250 years BP (Upper Holocene); and 4) Anthropogenic phase, from 1962 to 2013 (historical series of 51 years). Fluvial sediments dating through the 210Pb method was inefficient as a complementary resource to detail the anthropogenic phase in the cuestas due to the predominance of sedimentary covers in the lithopedologic composition of this compartment. However, the quantification of the morphological changes in relation with the systematization of the geoindicators corroborates the anthropogenic action on the cuestas relief formation. The cuestas paleomorphogenetic reconstitution demonstrated that the denudative processes in the Late Quaternary (Upper Pleistocene-Upper Holocene) and in the recent anthropic period display a complex configuration, with a cyclic and polygenic dynamics.
The present research aimed to evaluate the dynamics of the morphogenetic processes of the cuesta relief in the Late Quaternary (Upper Pleistocene-Upper Holocene) and in the current anthropic periods. Based on this evaluation, the denudative sequence was reconstituted in a geological time scale, and the implications of the anthropogenic morphology constitution in the evolution of this compartment in a historical time scale were verified as well. In order to achieve this objective, depositional dating were performed through Optically Stimulated Luminescence (OSL) and the Pb-210 method (210Pb). In addition, specific morphostructural, geomorphological and land-use/land-cover mapping were performed. The Cavalheiro Stream basin – Analândia (SP) – was chosen as the study area due to its natural distribution, in the transition of the sandstone-basaltic Cuestas and the Paulista Peripheral Depression and the essentially rural land-use evolution as well. The systemic analysis comparing the colluvium material ages (OSL) with the regional paleoclimatic fluctuations and the morphostructural/anthropogenic features arrangement provided an evolutionary model of the cuestas relief, characterized by the following denudative sequence: 1) First dry phase from 30,770 ± 4,930 to 8,000 ± 1,000 years BP (transition between the Upper Pleistocene and the Lower Holocene, extended until the beginning of the Middle Holocene); 2) First wet phase from 7,420 ± 980 to 4,500 ± 750 years BP (Middle-Upper Holocene); 3) Second dry phase from 3,940 ± 665 to 2,215 ± 250 years BP (Upper Holocene); and 4) Anthropogenic phase, from 1962 to 2013 (historical series of 51 years). Fluvial sediments dating through the 210Pb method was inefficient as a complementary resource to detail the anthropogenic phase in the cuestas due to the predominance of sedimentary covers in the lithopedologic composition of this compartment. However, the quantification of the morphological changes in relation with the systematization of the geoindicators corroborates the anthropogenic action on the cuestas relief formation. The cuestas paleomorphogenetic reconstitution demonstrated that the denudative processes in the Late Quaternary (Upper Pleistocene-Upper Holocene) and in the recent anthropic period display a complex configuration, with a cyclic and polygenic dynamics.
Descrição
Palavras-chave
Geomorfologia do quaternário, Luminescência Opticamente Estimulada (LOE), Bacia sedimentar do Paraná, Colúvios, Antropogeomorfologia, Quaternary geomorphology, Optically Stimulated Luminescence (OSL), Paraná sedimentary basin, Colluvium, Anthropogeomorphology