Landscape evolution reconstructed from lake sediment archives in the Northern Ecuadorian Andes

Lake sediments are valuable natural archives of environmental change, providing insights into sediment transport, deposition, and landscape evolution. To better understand the landscape evolution and past environmental change in the northern Andes, a region known for its high biodiversity and vulnerability to climate change, we analyzed lake sediment archives from three areas near Ecuador's capital, Quito. Our pilot study combined sub-bottom profiling (SBP) with a multi-proxy analysis of short sediment cores from lakes Muertepungo, San Pablo, as well as Caricocha and Chiriyacu in the Mojanda Lake Region. These lakes are situated at high elevations (2500-4000 m a.s.l.) and are of different volcanic origin.

In this contribution, we focus on SBP data to understand the bathymetry, morphology, and sediment infill characteristics of the studied lakes, providing a first interpretation of the sedimentary evolution. We used an Innomar "compact" parametric sediment profiler to record sub-bottom profiles in lakes with water depths ranging from a few meters to over 100 m. Stratigraphic correlation was supported by five short sediment cores collected from different water depths. Radiocarbon and tephra analysis were used to establish a chronological framework.

Preliminary results indicate differences in sediment properties and thicknesses, as well as distinct layering patterns, which may be linked to past environmental conditions such as shifts in water levels, temperature, trophic state, and other factors. These findings have important implications for understanding the complex interactions between climate, geology, ecosystems, and natural hazards, such as volcanic eruptions and landslides, in this region.