The Eastern Sierras Pampeanas of central Argentina are composed of a series of basement-cored ranges, located in
the Andean foreland c. 600 km east of the Andean Cordillera. Although uplift of the ranges is partly attributed to
the regional Neogene evolution (Ramos et al. 2002), many questions remain as to the timing and style of deformation.
In fact, the Eastern Sierras Pampeanas show compelling evidence of a long lasting brittle history (spanning
the Early Carboniferous to Present time), characterised by several deformation events reflecting different tectonic
regimes. Each deformation phase resulted in further strain increments accommodated by reactivation of inherited
structures and rheological anisotropies (Martino 2003). In the framework of such a polyphase brittle tectonic
evolution affecting highly anisotropic basement rocks, the application of paleostress inversion methods, though
powerful, suffers from some shortcomings, such as the likely heterogeneous character of fault slip datasets and
the possible reactivation of even highly misoriented structures, and thus requires careful analysis. The challenge
is to gather sufficient fault-slip data, to develop a proper understanding of the regional evolution. This is done by
the identification of internally consistent fault and fracture subsets (associated to distinct stress states on the basis
of their geometric and kinematic compatibility) in order to generate a chronologically-constrained evolutionary
conceptual model.
Based on large fault-slip datasets collected in the Sierras de Cordoba (Eastern Sierras Pampeanas), reduced stress
tensors have been generated and interpreted as part of an evolutionary model by considering the obtained results
against: (i) existing K\u2013Ar illite ages of fault gouges in the study area (Bense et al. 2013), (ii) the nature and
orientation of pre-existing anisotropies and (iii) the present-day stress field due to the convergence of the Nazca
and South America plates (main shortening oriented WSW-ENE). Although remarkable differences in reactivation
mechanisms have been observed for the various studied lithological domains (schist, gneiss and granitic rocks),
the brittle regional polyphase deformation of the Eastern Sierras Pampeanas appears to be dominated by two
extensional episodes (sigma3 oriented NE/ENE and WNW, respectively), which can be associated with Middle-Late
Permian to Early Cretaceous tectonism, followed by a compressional paleostress (sigma1 oriented ENE), which is
compatible with the present day Andean convergence. Paleostress inversion techniques, despite all uncertainties
involved, represent a robust approach to disentangle complex polyphase deformation histories both in term of
reactivation mechanisms and strain partitioning