CONICET | Buscador de Institutos y Recursos Humanos

The Main Andes at the northern Chilean-Pampean flat slab segment were formed by the inversion of late Oligocene to early Miocene extensional depocenters in Neogene times. Their structure, size and depth are loosely constrained by field data since these sequences have amalgamated forming an almost continuous blanket with scarce basement outcrops. Satellite and aerial gravity and magnetic data are used in this work to define a 3D model that shows the basement structure at depth and adjust 2D structural sections previously based on field data. The results indicate complex basin geometry with depocenters of variable size and depth buried beneath Paleogene and Neogene sections. Additionally, previously proposed crustal heterogeneities across this orogenic segment are geophysically constrained and a new crustal heterogeneity is identified on the basis of a modeled 2D crustal section. Hypothetically, this last crustal discontinuity could have controlled Paleogene extension at the hanging wall of an asymmetric rift basin, explaining the development of the Doña Ana Basin. Finally, this work provides new information about Cenozoic structure and Paleozoic amalgamation geometry for one of the highest and more inaccessible regions of the Andes.