Danakil Ethiopia

Field Context :

Although gypsum-based microbialites have been reported in saline lakes around the world, e.g., Egypt, Chile, Venezuela, little is known about: I) the microbial communities building these microbialites, II) if and how the mic. communities may affect mineral precipitation/dissolution and III) which chemical and biologic biosignatures can be hosted in gypsum microbialites.

During an interdisciplinary expedition at the Danakil salt-lakes in NE Ethiopia in January 2019, López-García and DEEM team (ESE-IDEEV, UPSaclay-CNRS) in collaboration with Benzerara, K. (IMPMC, SU-CNRS) and López-García J.M., (IGME-CSIC) discovered the presence of extensive fossil and living gypsum(-based) microbialites in Bakili Lake and surroundings. In particular, Bakili hosts subaerial mineralized microbial mats and subaqueous living stromatolites, as well as fossil gypsum-based stromatolites. These atypical microbialites are not present in all of the NE Danakil lakes, the majority of which merely hosts gypsum deposits.

Field Goals:

1. Characterize the microbial content of the gypsum(-based) microbialites and determine the environmental parameters that affect microbial community structure and possibly stromatolite formation. 2. Characterize the bulk, microscale and nanoscale mineral composition of living and fossil microbialites and gypsum sediments. 3. Look for mineral-microbial associations and morphological/chemical biosignatures possibly preserved in the gypsum deposits.

Implemented actions:

Funding was obtained from the French national grants ANR ‘Microbialites’ (ESE- CNRS-UPSaclay, IMPMC-CNRS, UBourgogne) and EC2CO-2020 awarded to López-García (UPSaclay-CNRS). Currently, this research is performed in the framework of the MSCA grant “NanoBioS” awarded to Kotopoulou Electra (ESE-IDEEV, UPSaclay) supervised by López-García, P., and Benzerara, K.