Neotectônica no Planalto de Campos do Jordão, SP

Abstract

The Campos do Jordão Plateau, on the southwestern border of the main block of the Serra da Mantiqueira presents evidence of recent tectonic reactivations, as expressed by the organization of the drainage network and the presence of morphotecton ic features. Morphometric analyses usually used in morphotectonic studies revealed neotectonic control of the morphology of the plateau. lsovalue maps of drainage density, relief roughness, hydraulic gradients, isobase surface and slope confirm the compartimentalization of the plateau in blocks delimited by the main trend of lineaments. This compartimentalization coincides with the limits of geosystemic units established for the plateau. Morphotectonic featuresriver captures, assymetric valleys with straight scarps, triangular and trapezoidal facets, suspended amphitheaters, shutter ridges, indistinct drainage divides, truncated hill crestsare directly associated with recent faults caused mainly by tectonic reactivation of zones of weakness represented by metamorphic foliation in Precambrian rocks. Morphostructural analysis of the Campos do Jordão Plateau, including characterization of Quaternary deposits and brittle tectonic structures, has led to the identification of three superposed neotectonic regimes. an initial E-W right-lateral transcurrent binary with left-lateral movement of NNW-SSE and right-lateral movement of ENE-WSW ¡/NW-ESE transcurrent faults (Late Pleistocene/Holocene), followed by E-W extension characterized by normal faults and a final E-WNW-SE compression that generated neotectonic joints in colluvium, organic-rich soils and peat deposits, compatible with the present-day horizontal maximum stress obtained from geophysical data. ïhus, the same pattern and ages of the tectonic regimes identified in neighboring areas, such as in the Paraíba do Sul Valley and in the area of the Queluz Structural High, are confirmed for the Campos do Jordão Plateau.

Quaternary tectonics in Brazil

“…These structures have resulted from the most recent manifestations of the successive reactivations of old ENE-orientated structural lines that have occurred intermittently ever since the Neoproterozoic Brasiliano or Pan-African Cycle, including the generation of new faults (Riccomini, 1989;1992). Inversion of striae from Holocene faults shows different stress regimes which varies with time (Riccomini, 1989;Salvador and Riccomini, 1995;Mancini, 1995;Hiruma et al, 1997, Hiruma, 1999. The oldest movements were related to a NW-SE compressive stress field, during the Late Pleistocene-Holocene.…”

Análise morfométrica em neotectônica: o exemplo do Planalto de Campos do Jordão, SP

“…As direções N-S e NW -SE têm sua origem relacionada a uma estruturação mais recente e correspondem, na maior parte dos casos, a falhas com compon,ente transcorrente que deslocam cristas e escarpas de direção NE-SW/ENE-WSW e, por vezes, condicionam a drenagem conseqüente do planalto. Essas falhas estão associadas a diferentes regimes de esforços neotectônicos (HIRUMA 1999) A visão realística do modelo digital de ter-…”

Padrões de Fotolineamentos Aplicados à Análise Morfoestrutural da Bacia do Rio Mamanguape, Paraíba

“…A compreensão dos elementos condicionantes dos lineamentos, assume, portanto, extrema importância na análise morfoestrutural e geomorfológica, pois pode expressar em diferentes graus, a influência da estrutura geológica na evolução da paisagem, bem como apontar indícios e até corroborar a vigência de reativações tectônicas durante o Quaternário (GONTIJO, 1999;HIRUMA et al, 2001;MODENESI-GAUTTIERI et al, 2002;HIRUMA, 2007).…”