An increase in accumulation rates and a coarsening of clastic material has been observed all around the world in Late Pliocene and Quaternary time, and has been used to infer an increase in erosion rates. This global signal has been attributed to climate change, particularly to lowered sea-level, glacial expansion and increased climatic oscillation. However, in many cases this increase in erosion rate may be overstated due to re-deposition and compaction of older material, and a lack of well-studied, well-dated sites. Local structural deformation and tectonic uplift may adequately explain cases in which in increase in sedimentation rates in Plio-Quaternary time is truly observed. The marginal basins of the Puna Plateau in northwestern Argentina are an ideal natural laboratory in which to translate the information contained in the detrital, structural and geomorphic records into an understanding of the relative roles of tectonics and climate. This project aims to test the climate versus tectonics hypothesis by dating the timing of deposition of the Pliocene conglomerates, determining the provenance of the conglomerates, constraining the source region(s) exhumation and erosion history, and investigating the recent tectonic and geomorphological history of the basins. Correlations between source erosion, sedimentation and subsequent basin incision will be made with existing climatic and tectonic data to assess whether or not a genetic link exists between climate and/or tectonics and sedimentation and incision along the Puna Plateau.
The effect of climate versus tectonics on erosion and sedimentation is an ongoing debate. It has been proposed that global climate change triggered an apparent worldwide increase in erosion and sedimentation rates in the last 3.6 million years ago (Pliocene time). The goal of this study is to contribute to this debate by discriminating and constraining different processes responsible for the deposition of Pliocene conglomerates along the margin of the Puna Plateau, northwestern in Argentina. The plateau is part of the Puna-Altiplano plateau in South America, the second largest plateau on Earth. This project will lead to new results that will be able not only to inform the climate versus tectonics debate but will also elucidate the effects of tectonic and surface processes in the creation and preservation of the sedimentary rock record along continental plateaus in general.
