This suite of projects funded through an Emmy Noether grant, the Alexander von Humboldt Foundation, and the Research Focus Area Earth Sciences at the University of Potsdam explores how millennial-scale climate forcing influences landscape erosion rates, erosion processes, and sedimentation patterns in NW Argentina and the SW United States.
A better understanding of how landscapes react to climate change is essential not only for interpreting the sedimentary record, but also predicting the impacts of future climate changes on surface processes and landscape hazards. Catchment-fan systems are small sediment-transport systems with rapid source-to-sink transfer of material and rich sedimentary archives of information about surface processes. We are studying coupled mountain catchment-alluvial fan systems in NW Argentina and the SW United States, and examining how alluvial fan morphology, stratigraphy, and sedimentology records transient signals of past climate variability. By using catchment-fan systems as analogues for broader landscapes, we are investigating
Our research into sediment routing systems combines field geomorphology and sedimentology, stratigraphy, geochemistry, geochronology, and remote sensing.
The presently dry and unglaciated southern Central Andes of northwest Argentina feature a wealth of geomorphic and sedimentological evidence that indicate cooler and/or wetter conditions in the past. Among these are glacial moraines on the highest ranges and lacustrine deposits in the intermontane basins. We use cosmogenic nuclides to date moraines and determine the timings of glaciations associated with
Constraining the spatial and temporal patterns of past glaciation in the Andes is essential for advancing our knowledge of South American climate dynamics. In addition, we use physically-based computer models of ice-flow and hydrology to infer former temperature and precipitation values during particular past climate events (e.g., the Younger Dryas). The boundary conditions for the baseline models are derived from global circulation models, satellite data and ground observations. As well as combining field work, geochemistry, glacier- and lake-level modeling, we also work closely with climate modelers and use general climate simulations.
To better predict how landscapes evolve in the future, it is essential to understand how landscapes have responded to past changes in external forcing. Sedimentary archives like fluvial fill terraces and lake sediments provide clear evidence that tectonic and/or climatic boundary conditions have changed over time. With a range of methods, it is possible to reconstruct erosion rates, erosion processes, and also hydrological conditions from those archives. We study fluvial fill terraces and lake sediments in the Quebrada del Toro, an intermontane basin within the Eastern Cordillera of the southern Central Andes. We are dating the sedimentary deposits with 14C, zircon U/Pb, and cosmogenic radionuclides, measuring modern and paleo erosion rates with cosmogenic radionuclides, and reconstructing hydrological conditions with lipid biomarkers. In addition, we perform physical experiments to investigate how rivers respond to changes in sediment supply and discharge. Our aim is to understand how sediment flux and erosion processes have changed over time, and how those changes might be linked to climatic or tectonic forcing.