An Overview of the Main Quaternary Deformation of South America

Abstract

Deformation affecting continental South America during Quaternary is related to the Neogene geodynamic processes. These structures are mainly controlled by anisotropies inherited after a long and complex history as well as by the kinematic and geometric features of the ongoing plate interaction. Main Quaternary structures at both ends of South America are directly linked to plate interaction and some of them are considered to be plate boundaries. The main structures with Quaternary activity along the Caribbean coast have an E-W trend and a strike-slip regime. Between the Venezuelan Andes and the Gulf of Guayaquil, NE trending structures are dominant, with a kinematic regime ranging from strike-slip to transpressive and compressive. At the Central Andes (4ºS-46º30'S) most Quaternary deformation results from a complex stress distribution and stress-partitioning at the interior of the South American plate, reactivating preexisting discontinuities. The present geometry of the subducted Nazca plate is here the main control with respect to the distribution and characteristics of Quaternary deformation, being them better exposed at the Andean eastern slope and foreland regions. The main structure with Quaternary activity at the southernmost Andes is represented at Tierra del Fuego by a left-lateral transform boundary, resulting from the South American and Scotia plate interaction.