Experimental models of 'Basement'-controlled salients - application to the proterozoic fold-thrust belt of the quadrilátero ferrífero (Minas Gerais, Southeastern Brazil)

摘要

Scaled sandbox models are used to simulate the development of ′basement′-controlled, salients. We investigate the controlling factors on the development of closed curvatures in map-view, considering constant both the sand pack thickness and the space between obstacles. These models are compared with the Fund?o-Cambotas Fault System in the Proterozoic fold-thrust belt in the Quadrilátero Ferrífero region, along the southeastern margin of the S?o Francisco craton. In the experiments, a pronounced curvature resulted from the margin-controlled salient process in the presence (i) of a basal ductile detachment, or (ii) of pre-existing structures. The results suggest that the convex-to-the-foreland, west-vergent Fund?o-Cambotas Fault System that borders the Archean basement highs and displaced older Transamazonian structures westward, is partly a consequence of interaction of propagating thrusts with obstacles in the foreland.