Over the last years major efforts have been made to better constrain the evolution of the Earth surface, also referred to as the Earth Critical Zone (ECZ), including its life sustaining ecosystem services which play a key role in making the Earth a habitable place. Yet, Earth surface process interactions in arid to hyper-arid soil-landscape systems are poorly understood compared to their semi-arid and temperate counter-parts. Although hyper-arid soil-landscape systems can be regarded as end-members of ECZ evolution, they provide the unique opportunity to catch a glimpse at basic process interrelationships that are otherwise overshadowed by ECZ processes associated to water and/or biota. This project ("Hyper-arid landscapes in transition - understanding soil-landscape evolution at the transition from biotic to abiotic driven Earth surface dynamics through novel luminescence-based methods") aims at addressing two main questions: (i) What Earth surface processes drive the evolution of the upper ECZ at the dry limit? And (ii) how does the transition work from the biotically/water to the abiotically driven eco-geomorphic process regime and what are the associated thresholds? The Atacama Desert in northern Chile (S America) is the perfect natural laboratory to address these questions and the currently running CRC-1211 provides excellent breeding conditions to successfully develop this project as part of the C cluster on Earth surface evolution.

We aim at utilizing new luminescence-based dating and Earth surface process tracing methods to bridge between on-site instrumental observations providing insights into short-term Earth surface processes and large-scale reconstructions of the general Earth surface dynamic by terrestrial cosmogenic nuclides (TCN) or other geochronological techniques. Cutting-edge feldspar single-grain luminescence methods in combination with recently developed numerical models will be tailored and adjusted to eventually quantify the production and fluxes of siliciclastic particles in the upper ECZ at the critical spatial-temporal resolution. To gain Earth surface process understanding associated to varying arid to hyper-arid eco-geomorphological regimes we will apply these new techniques to different sites along two transects which cross the Atacama Desert from the fog-dominated Costal Cordillera (West) to the Andean Precordillera (East). Our hypothesis is that the transition from a biotically to an abiotically driven upper ECZ system passes through an eco-geomorphic tipping point. We will use the WP2 data in combination with environmental information and numerical models to shed a new light on this critical eco-geomorphic transition. Furthermore, we will use our data to get a better grip on the evolution of the Atacama-specific “deep soils”, which are possibly associated to enigmatic deep biosphere food-webs. This project on Earth surface processes and eco-geomorphic transitions at the dry limit will lay the foundation for improved quantitative understanding of terrestrial and also extra-terrestrial hyper-arid soil and landscape systems.