InSAR Observations of Crustal Deformation Mechanics in the Interior of the Puna Plateau of the Southern Central Andes.
Eckelmann, Felix1; Motagh, Mahdi1; Bookhagen, Bodo2; Strecker, Manfred3
1Deutsches GeoForschungsZentrum Potsdam, GERMANY; 2Geography Department, UC Santa Barbara, CA, United States., UNITED STATES; 3Erd- und Umweltwissenschaften, Universitšt Potsdam, Germany., GERMANY
The Altiplano-Puna Plateau of the Southern Central Andes with an average elevation of about 3.5 km is the world's second highest plateau after the Tibetan plateau. The southern sector of the plateau, the Argentine Puna, is characterized by a basin and range morphology exhibiting internal drainage and thick continental evaporate and clastic deposits. Active extension, which superseded contractile deformation in the late Miocene is thought to predominate at the plateau interior whereas the plateau flanks in contrast are characterized by sustained contraction and a migration of deformation toward the foreland. This paper presents presents new Interferometric Synthetic Aperture Radar (InSAR) observations based on ENVISAT and TerraSar-X radar data to investigate assumed contraction in the southern central part of the Puna, despite widespread evidence for extensional tectonism. We present an InSAR time series from the Salar de Pocitos basin spanning about four and a half years for ENVISAT (2005-2009) and about three months for TerraSar-X (2012-2013). The Pocitos basin forms a N-S orientated, salt-bearing, hydrologically isolated basin with a surface area of 435 Km2 at an elevation of 3650 m asl being located in the interior of the Puna plateau. For the ENVISAT time series analysis a total of 14 images were used, whereas for the TerraSAR-X analysis a total of 10 images were available. Both data sets were calculated with a Small Baseline (SBAS) approach. Our analysis of InSAR measurements suggests that two deformation signals exist: (1) the salt-basin center seems to change elevation seasonally most likely due to volume changes related to the crystallization of evaporate minerals and (2) an anticline to the west of the Salar de Pocitos grows which implies continued shortening. The present study emphasizes the diachronous evolution of crustal deformation on the Puna Plateau and the need to reconsider models that suggest coeval plateau-wide extension.