TRANSVERSAL SEGMENTATION OF THE SOUTHERNMOST ANDES: INTERACTION BETWEEN MIDD-LATE JURASSIC RIFTING AND WRENCH TECTONICS

GHIGLIONE, M.C.; SUE, C.; GONZÁLEZ GUILLOT, M.; BUJALESKY, G.; BURLANDO FARÍAS, J.F.

Congreso; XVIII Congreso Geológico Argentino, Mayo 2011, Neuquén; 2011

New data from the Fuegian fold-thrust belt north of Fagnano Lake – río Irigoyen allowed a detailed reconstruction of the interaction between mid-late Jurassic faulting and Neogene strike-slip deformation. The presented detailed mapping and serial structural cross-sections define lateral variations in the structural style and a transversal segmentation of the fold-thrust felt. The folds in some segments are symmetric, display synclinal sinking, changes in bed thickness, intermediate detachment levels and have a high slip to propagation ratio denoting a detachment mechanism for their formation. In others, the anticlines are asymmetrical, northward verging, their bed thickness is maintained, and conform a fault-propagation fold geometry. This passage from detachment folds in some segments to fault-propagation folds, although they shear a similar shortening rate, maybe denoting lateral changes in the rheological properties of the detachment level (Ghiglione et al., 2010). There are also changes in the basement depth of each segment, reflecting differential extensional faulting during the Mesozoic rifting.