First PROTOS Field Trip: El Tatio, Chile

The specific goal is to study the processes of silica nucleation and sinter precipitation under these extreme conditions

A team of Naturalis and the University of Hannover within the PROTOS consortium will conduct field work at the El Tatio geyser field in the Atacama Desert, Chile, from the 17^th till 28^th of July, 2025.

The El Tatio geyser field is situated at high-altitude in the Chilean Altiplano, and is characterized by extremely dry conditions, high UV-flux, strong wind, and large day-night temperature fluctuations. Geysers erupt silica-rich fluids that saturate upon cooling, leading to the precipitation of extensive terraces of amorphous silica sinter (opal-A). A rich variety of microbial communities thrive around the geysers and outflow streams, representing hyperthermophile bacteria and archaea, and photosynthesizing organisms such as chloroflexus and cyanobacteria. Given its extreme conditions, the El Tatio geyser field has been recognized by many scientists as an important analog site for studying the conditions of early life on Earth and possibly Mars.

Objectives

The specific goal of PROTOS in this El Tatio geyser field is to study the processes of silica nucleation and sinter precipitation under these extreme conditions. For this purpose samples of fluids and associated silica sinters will be taken at different temperature intervals along the outflow channels of two geyser sites. Furthermore, some samples will be taken of silica that is directly precipitating on cyanobacterial mats. All samples will then be analyzed for silicon isotope ratio (d30Si) and rare-earth element (REE) composition. This dataset will enable us to investigate silicon isotope fractionation in abiologic and biologically-influenced silica precipitation processes. 

Field work participants:

Prof. Mark van Zuilen (Naturalis Biodiversity Center)

Dr. Laurane Fogret (Naturalis Biodiversity Center)

Dr. Romane Le Dizes (University of Hannover)

Field work logistics:

We will join several other research groups from Cornell University and the University of Ghent, who are conducting their own field research in this area at the same time. All logistics, safety protocols, field permits and sample export permits are carried out and obtained in coordination with Prof. Carolina Munoz (Cornell University).