Coberturas sedimentares cenozóicas da Bacia do Rio Jundiaí – SP
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Data
2005
Autores
Neves, Mirna Aparecida [UNESP]
Morales, Norberto [UNESP]
Saad, Antônio Roberto [UNESP]
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Resumo
Este trabalho apresenta a caracterização geológica das coberturas sedimentares cenozóicas da bacia do Rio Jundiaí e suas relações com a evolução geológica regional. Sobre o Embasamento Cristalino, ocorrem depósitos paleozóicos pertencentes ao Grupo Itararé, depósitos terciários e quaternários. Os depósitos terciários constituem ocorrências locais, pois grande parte das seqüências foi removida pela erosão e os restos estão quase sempre encobertos pelas coberturas mais jovens. Correspondem a um antigo sistema de leques aluviais com área-fonte na Serra do Japi e sua origem se associa à formação das escarpas de falhas que controlam as áreas serranas. Os depósitos colúvio-eluviais são constituídos por material areno-argiloso maciço com linhas de pedra basais, que compõe corpos descontínuos controlados por estruturas geológicas. Os depósitos aluviais também acompanham importantes direções estruturais. A distribuição destas coberturas é condicionada pelo relevo, onde conjuntos de falhas de direção predominantemente NW-SE promoveram o abatimento da porção central da área, controlando a implantação da bacia hidrográfica do Rio Jundiaí. A ocorrência de depósitos aluviais em locais onde atuam esforços transtensivos é de grande importância para a exploração dos recursos hídricos subterrâneos. O afeiçoamento da paisagem condicionado por fatores endógenos atesta a importância dos processos neotectônicos em ambiente intraplaca.
This paper presents the geological characterization of sedimentary covers in the Jundiaí River Catchment, São Paulo State, Southeastern Brazil, as well as its relationships with the regional geologic evolution. Paleozoic deposits included in Itararé Group, besides Tertiary and Quaternary deposits, cover the Crystalline Basement. The Tertiary deposits constitute local occurrences, because they mostly were removed by erosion, and the remainders are under younger sedimentary covers. They correspond to an ancient alluvial fan system, which source area was the Japi Mountain Range, and their genesis is related to fault scarps that control the higher areas. Discontinuous bodies of colluvial-elluvial deposits are controlled by geologic structures and show, in their composition, massive sand-clayed material with stone lines at the bottom. The alluvial deposits also accompany the main geologic structures. The distribution of these sediments are controlled by local relief, where NW-SE faults caused subsidence of the central portion of the area, giving raise to the configuration of Jundiaí River catchment. The occurrence of alluvial deposits in sites where transtension efforts act is of great importance to the groundwater exploration. The landscape conditioned by endogenic factors shows the importance of neotectonic process in the intraplate environment.
This paper presents the geological characterization of sedimentary covers in the Jundiaí River Catchment, São Paulo State, Southeastern Brazil, as well as its relationships with the regional geologic evolution. Paleozoic deposits included in Itararé Group, besides Tertiary and Quaternary deposits, cover the Crystalline Basement. The Tertiary deposits constitute local occurrences, because they mostly were removed by erosion, and the remainders are under younger sedimentary covers. They correspond to an ancient alluvial fan system, which source area was the Japi Mountain Range, and their genesis is related to fault scarps that control the higher areas. Discontinuous bodies of colluvial-elluvial deposits are controlled by geologic structures and show, in their composition, massive sand-clayed material with stone lines at the bottom. The alluvial deposits also accompany the main geologic structures. The distribution of these sediments are controlled by local relief, where NW-SE faults caused subsidence of the central portion of the area, giving raise to the configuration of Jundiaí River catchment. The occurrence of alluvial deposits in sites where transtension efforts act is of great importance to the groundwater exploration. The landscape conditioned by endogenic factors shows the importance of neotectonic process in the intraplate environment.
Descrição
Palavras-chave
Coberturas sedimentares, Neotectônica, Água subterrânea, Jundiaí
Como citar
Geociências, v. 24, n. 3, 2005, p. 289-303.