Geologia estrutural Rio das Velhas

Revista Brasileira de Geociências

30(4):631-638, dezembro de 2000

MODELOS FÍSICOS DO SISTEMA DE CAVALGAMENTO FUNDÃO-CAMBOTAS, NO
DOMÍNIO DA ZONA DE CISALHAMENTO DAS CAMBOTAS, QUADRILÁTERO
FERRÍFERO, MINAS GERAIS
CAROLINE JANETTE SOUZA GOMES1, CARLOS ALBERTO ROSIÈRE2 & MILTON PEREIRA FILHO3
ABSTRACT PHYSICAL MODELS O F THE FUNDÃO-CAMBOTAS FA ULT SYSTEM IN THE CAMBOTAS SHERA ZONE DOMAIN,
QUADRILÁTERO FERRÍFERO, MINAS GERAIS Experiments were undertaken to investigate the structural evolution of the transpressional
Cambotas Shear Zone, also known as the Cambotas Fault, which integrates the strongly curved Fundão-Cambotas Thrust System at the eastern portion of the Quadrilátero Ferrífero. The formation of the Cambotas Shear Zone was simulated in three physical models by the translation of a block which was supposed to reproduce the reactivation of preexisting structures, and by the formation of curvatures in fold-thrust belts. An orocline, associated to a thrust fault in the foreland, offered the most satisfying simulation of the study área. The first domain represents the Falha de Água Quente System, in the eastern extremity of the Quadrilátero Ferrífero, and the second one, the Fundão-Cambotas Thrust System. This system hás been formed under the boundary conditions of a thrust fault with staircase geometry, and the Cambotas Shear Zone as one of its lateral ramps. The Cambotas Shear Zone is charaçterized by a heterogeneous deformation, with transpression dominated by puré shear in the hinterland as a consequence of the oblique collision between the deformation front and the rigid block of the Caetés Metamorphic Complex in the northern part of the study área. In the foreland, the propagation of the deformation front along the rigid block hás produced a transpression dominated by simple shear.
Keywords: physical models; Quadrilátero Ferrífero, Fundão-Cambotas Thrust System; Cambotas Shear Zone; transpression; thrust fault with staircase geometry.