Neogene ongoing tectonics in the Southern Ecuadorian Andes: analysis of the evolution of the stress field

Abstract Microtectonic analysis of infilling deposits in South Ecuadorian Neogene basins brings to light a compressive stress field with σ1 along a NNE-SSW to NE-SW direction in the early Miocene, changing to an E-W direction in the Middle and Late Miocene. The syn-sedimentary deformations which affect the deposits of the basins suggest similar stress regimes due to a compressive ongoing tectonic system in the Miocene, for at least 15 Ma. There is a good correlation between rapid convergence in the Neogene and the time period during which the continental South Ecuadorian basins were deformed by compression (Quechua period).