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The Puna-Altiplano region, located in the Southern Central Andes between 13° and 27° south latitude constitute a non-collisional orogenic plateau (e.g., Isacks 1988, Allmendinger et al. 1997) characterized by high topography, low internal relief, and pronounced relief contrasts compared to adjacent areas. This particular architecture makes the Andean plateau a good example for studying the influence of tectonism on the long-term behavior of climate (Alonso et al. 2006, Strecker et al. 2007). In addition, due to the arid climate, relief conditions and excellent outcrops, particularly the southern rim of the plateau is well suited to evaluate the structural and topographic evolution of this region. We have selected Las Papas area (27°00S 67° 45W), located in the border between the Southern Puna and Sierras Pampeanas, in order to study the spatiotemporal frame of the topographic construction. We have carried out geological mapping and structural analysis as well as sampling of volcanic and basement rocks for geochronological and thermochronologic analysis in the study area. Along the Las Papas valley schist, amphibolites and gneisses of the Neoproterozoic-Lower Paleozoic basement are outcropping, with some Ordovician plutonic intrusions. This basement is overly by ignimbrite deposits of Upper Miocene (Las Papas Ignimbrite, Montero López 2009) and Quaternary age (Cerro Blanco Volcanic Complex, Seggiaro et al. 2000, Arnosio et al. 2005, Montero López 2009), and sedimentary deposits of Pliocene and Quaternary ages (Punaschotter Formation, Penck 1920). Las Papas Ignimbrite comprises pinkish-white to pale purple in color, welded deposits with characteristic columnar jointing and fiamme texture. A white, slightly-welded ignimbrite deposit that belongs to the youngest volcanic event of Cerro Blanco Volcanic Complex crop out at the intersection of Las Papas and quebrada Blanca valleys. The Punaschotter deposits in this area consist of proximal alluvial fan conglomerates (Schoenbohm and Strecker 2009), including clasts derived from the igneous-metamorphic basement, Ordovician and Neogene volcanic rocks. To the west of the Las Papas valley a N-S oriented fault carried the metamorphic basement over this ignimbrite and the Neogene-Quaternary sedimentary deposits, accommodating an E-W shortening (Montero López 2009, Schoenbohm and Strecker 2009). An E-W oriented fault to the north of the Las Papas valley is affecting the Las Papas Ignimbrite and the metamorphic basement, accommodating a nearly N-S extension (Fiambalá Fault, Schoenbohm and Strecker 2009, Montero López 2009). Previous studies in the northern section of the Bolsón de Fiambalá (Carrapa et al. 2006), immediately to the south of the study area, have proposed that the uplift of the ranges flanking the southern margin of the Puna has occurred by about 6 Ma. However, we suppose an older age for the construction of the paleotopography inferred by the presence of the thick welded Las Papas Ignimbrite filling a portion of the gorge, which has been dated to ca. 9 Ma. This is a crucial observation, because these pyroclastic deposits fill a paleorelief and provide an important minimum constrain on the timing of the existence of paleorelief along the southern Puna rim. In order to further refine this hypothesis and place more constraints on the development of paleorelief, we collected 7 samples along an altitude transect in the Las Papas valley, located between 2100 and 3200 ma.s.l., from the Neoproterozoic-Lower Paleozoic basement. Apatite grains were separated to analyses them by (U-Th)/He methodology which is used to constrain the history of exhumation and relief development at the southern margin of the Puna plateau. To date, 40Ar/39Ar geochronologic and (U-Th)/He thermochronological analyses are being processed and the results help us to provide a minimum constraint on the timing of surface uplift (which must have preceded valley incision) at the plateau margin. In summary, thermochronologic studies have been performed in the surrounding regions of the Las Papas area, but these were done using the apatite fission-track (AFT) methodology, which is useful for determining exhumation history, but is not sufficiently sensitive to record the near-surface thermal perturbations induced by valley incision. However, the low closure temperatures of the (U-Th)/He system in apatite makes it particularly sensitive to near-surface cooling and thermal perturbations (Braun et al. 2006). Because isothermal surfaces close to the surface tend to follow the form of the topography (Braun 2002), apatite (U-Th)/He cooling ages should reflect the rapid cooling induced by downward movement of the closure isotherm in response to deep valley incision (Schildgen et al. 2007). We apply the (U-Th)/He methodology in apatites to resolve the differences in ages that have been suggested for the development paleorelief based on AFT exhumation data (e.g., 6 Ma, Carrapa et al. 2006) and our data based on infilling volcanic units of Upper Miocene age