How topographic and biological systems co-evolve through time is determined to a large extent by their spatial connectivity. This is particularly true for the ‘dry-limit’, where episodic climate change and tectonic forcing causes rearrangement of the fluvial network, dictating the focal points for landscape development and isolating, or connecting, biological communities. In both the Atacama and Namib deserts, east to west flowing river systems that drain from highland regions across low relief plains are interrupted and sometimes redirected by north‑south trending barriers in the form of fault-created topography. In such desert settings, the reorganization of the fluvial systems and riverine dependent life to tectonic uplift and fault displacement is poorly understood. Developing specific knowledge of the interactions between fluvial systems and tectonics under desert climates was the overarching topic for C05 in the first two CRC phases. In the third phase we will:

1. bring together information on the timing of landscape change with the timing of biological speciation in arid landscapes and explicitly consider how tectonic and climate mechanisms are linked to their evolution;
2. test previous findings in the Atacama Desert by comparisons with the Namib and iii) build on and integrate the results from this and the earlier phases in a modeling framework to investigate the most compatible tectonic and climatic histories.

Our multi-methodological approach spans geological and biological disciplines and aims to provide us with generalized findings, applicable to other hyper/arid regions outside of our focus areas.

Tectonic geomorphology: Adaptation of drainage to tectonic forcing

Research areas: Tectonic Geomorphology, Fluvial Geomorphology, Landscape evolution, Geochronology

Principal investigators: Dr. Steven Binnie, Prof. Dr. Klaus Reicherter, Dr. Pia Victor, PD Dr. Kathrin Lampert

This project aims to investigate how faulting and tectonic uplift have influenced the evolution of drainage in northern Chile. Surface uplift due to fault displacement can cause channel avulsion and force reorganization of stream networks. This process has been shown to be prevalent in northern Chile, where relatively minor amounts of fault displacement have forced streams to abandon their courses. We propose to utilize both established and novel geochronological techniques to date stream channel avulsions at multiple fault locations throughout the Atacama Desert. This will be combined with surface and subsurface imaging of the responsible fault structures, improving our understanding of how faulting influences drainage and providing temporally constrained models of landscape evolution by estimating rates of deformation.

The central question is if drainage reorganization in the Atacama Desert is related primarily to local tectonic events, or rather to broad-scale shifts in climate, given that both are episodic and possibly related.

This project aims to investigate how tectonic uplift has influenced drainage evolution in northern Chile. Surface displacement due to faulting can reroute and force reorganization of stream networks. This process has been shown to be prevalent throughout northern Chile, where relatively minor amounts of fault slip can result in channel avulsion. We propose to utilize both established and novel geochronological techniques to date stream channel diversions at multiple fault sites throughout the Atacama Desert.

This will be combined with surface and subsurface imaging of the fault structures allowing us to develop chronologies that help better understand the interactions between fault displacement and drainage reorganization and how fast the landscape is reacting to these changes. The central question is whether the apparent pulses of tectonic drainage reorganization are related to tectonic uplift alone, or whether climatic shifts are also responsible.

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