CINEMÁTICA DEL FLANCO NOROCCIDENTAL DE LOS ANDES DE MÉRIDA,

REQUENA JOAQUÍN; TURIENZO MARTÍN

Mendoza

Congreso; IX Congreso de Exploración y Desarrollo de Hidrocarburos; 2014

Instituto Argentino del Petróleo y Gas

The Mérida Andes (MA) constitutes a SW-NE trending asymmetric, doubly vergent orogen, located in the northern part of South America. The main deformation of this belt took place since the Late Miocene as a result of the interaction between the South America, Nazca and Caribbean plates. Study of structures in the northwestern flank of MA, based on subsurface and field data, allow us to recognize kilometric scale structures interpreted as stacked basement wedges. These wedges were inserted in the sedimentary cover following a detachment level located at the base of the early Cretaceous sequences, developing thin skinned thrusts that form duplex structures linked to a passive-roof detachment which generate a triangle zone. In addition, it was observed an important thin and thick-skinned backthrusting in the hangingwall and out of sequence faults that placed basement rocks against Neogene deposits. The balancing of three cross-sections allowed calculate shortenings of ~26 km and ~22 km in the south and central zones respectively, while in the north zone the shortening is about 8 km. This important variation in the tectonic contraction can be assigned to the presence of the Valera fault. Kinematic models were made for each balanced cross-section in order to illustrate the interaction between thick and thin skinned structures, responsible of the MA northwestern flank development from late Miocene to the present.