A structural model of the Fábrica Nova region, Santa Rita syncline, Quadrilátero Ferrífero: flanking folds as a folding mechanism

Abstract

This study focuses on the eastern flank of the Santa Rita syncline (Dorr 1969), with specific emphasis on the region known as Fabrica Nova. Important iron ore deposits are located on the flanks of this structure, such as Timbopeba, Alegria, Sao Luiz, Tamandua, Almas and Fabrica Nova. The Santa Rita syncline is a fold with N-S axial direction and of subregional scale, with roots in the adjacent basement of the Santa Barbara Complex and sectioned by the Agua Quente thrust fault. The hypothesis of this study is that the structural framework of the region resulted from the superposition of at least three deformation phases on the Ouro Preto nappe. The Fabrica Nova mine, located in the central portion of the study area, is embedded in a synformal structure with a 100/20 trending axis named Fabrica Nova synform. The proposed model to explain the particular structural geometry of this region is based on the flanking folding mechanism (Passchier 2001). This mechanism may have been developed by E-W crustal shortening during the F4 tectonic deformation phase.