It’s a trap!: Modern and ancient halite as Lagerstätten

Abstract

Chemical sediments, such as bedded halite (NaCl), are strongly influenced by environmental conditions during deposition and, if unaltered, may preserve microorganisms, microfossils, and organic compounds for hundreds of millions of years. Recent studies show that halite is an excellent repository for organic materials, as well as a variety of environmental data. Halite is a perfect trap. Due to its rapid growth, parent brine, gas, crystals of other minerals, and any organic material are encased within primary fluid inclusions or as solid inclusions along growth bands. These inclusions function as “snapshot” repositories of the hydrosphere, atmosphere, lithosphere, and biosphere. However, organic material in halite is still relatively unknown in the sedimentological and paleontological communities. Here, we present highlights of preservation in halite to showcase the diversity of life that has been documented within it. We also discuss: 1) the properties of halite that give it such excellent preservation potential, 2) the challenges to and strategies for studying organic material in halite, 3) preservation in other salt minerals such as gypsum, and 4) implications for astrobiological research. Recommendations for the future study of organic material in halite include collaboration amongst chemical sedimentologists, paleontologists, and microbiologists.