Clément G. L. Pollier

Ph.D. candidate in Geochemistry (University of Miami, USA) 

Research Overview

My Ph.D. research investigates how biosignatures—both morphological and chemical (trace elements and stable isotopes)—are incorporated into microbial sediments during formation and how they are later modified through taphonomic processes. Microbialites, mats, endoevaporites, and muds provide some of the oldest evidence of life on Earth, yet distinguishing true biological signals from abiotic or altered ones remains a fundamental challenge.

I address this problem through three exceptional natural laboratories:

• Hamelin Pool (Western Australia): the largest modern marine microbial carbonate system, where diverse microbialite morphologies reveal how architecture controls trace-element partitioning.
  
  

• Laguna de Los Cisnes (Tierra del Fuego, Chile): a subpolar lake where green algae and microbes co-build microbialites, offering insights into how biotic and environmental forces jointly shape microbialite morphogenesis.
  
  

• Salar de Atacama (Chile): one of Earth’s most extreme lacustrine environments, where microbial sediments capture distinctive biosignature pathways under polyextreme conditions.
  
  

My expertise includes sequential leaching protocols, major and trace element analysis (ICP-QQQ-MS), and stable isotope analysis (IRMS), complemented by experience in XRD, Raman spectroscopy, petrography, SEM, and FIB-SEM nanotomography. By combining these approaches, I track how biosignatures evolve from initial accretion through early alteration. Ultimately, this work aims to refine the criteria for recognizing ancient life in the rock record and to strengthen our ability to interpret biosignatures on Earth and in extraterrestrial settings.