Structural setting of the Chanic orogen (Upper Devonian) at central-western Argentina from remote sensing and aeromagnetic data. Implications in the evolution of the proto-Pacific margin of Gondwana

摘要: Abstract The basement of the Central Andes located in central-western Argentina (31o20′S - 69o22′W) is composed by Cuyania and Chilenia terranes which were amalgamated to Gondwana Early-Mid Paleozoic. Between Precordillera (Cuyania) Frontal Cordillera (Chilenia) there are exposures marine metasedimentary rocks associated with mafic an E-MORB chemical signature that represent remnants extensional basin developed between both terranes. stratigraphic features distribution Paleozoic units along Western constrained remote sensing techniques. This allowed us identify two stages evolution sedimentary in-fill basin: initial stage (Mid-Late Ordovician) marked widespread tectonics a finning-upwards sequence interbedded volcanic-plutonic rocks; Late Ordovician?-Devonian where sedimentation was characterized development coarsening-upwards sequences low participation rocks. Flattened parallel folds pre-Andean thrusts have locally top-to-the SW vergence. These (Late Devonian) structures relics Chanic orogen whose double vergence result control exerted previous related ordovician rifting. residual regional magnetic anomalies reflect important correlation deep surface structures. We propose inception subduction zone eastward polarity on proto-Pacific margin as responsible for compressive geotectonic framework led closure during Devonian thick-skinned-dominated orogen.