Inherited basement structures and their influence in foreland evolution: A case study in Central Patagonia, Argentina

Abstract

Continental crust exhibits areas of recurrent deformation and reactivation of faults that can be persistent for hundreds of millions of years. Associated with weak lithospheric zones, the characterization of long-lived deformational zones and inherited structures are critical aspects in the construction of orogens and rift systems, playing a major role in magmatism and basin evolution. Central Patagonia, which is situated in the Andean foreland of southern South America, presents a complex and multi-episodic tectonic history related to intraplate deformation at a significant distance from the Andean trench. Its ∼NW-SE structural trend, which is anomalously oblique to the Andean orogen, has been proposed as an inherited crustal anisotropy that controlled Mesozoic basins and Cenozoic volcano-sedimentary foreland basins development. However, a systematic regional study focused on the basement structural anisotropy has not been undertaken so far. In this contribution, we use aeromagnetic and gravimetric datasets that are integrated with field geological and structural data to address this issue. We define a series of ∼NW-SE regional structures which governed the present-day basement-block architecture of the foreland and exerted an important control in the deposition of Mesozoic-Cenozoic sedimentary and volcanic sequences. The tectonic significance of these structures and their paleogeographic implications in the context of the Late Paleozoic Gondwanide magmatic arc are also discussed.