Stromatolite, Puerto Rico
Publications Related to this Project
This research seeks to constrain geochemical and microbiological controls on the mineralization and macro-morphology of microbial mats that form stromatolitic structures. We are studying recent (<500 years) stromatolitic structures found in hyper saline lacustrine environments in southwest Puerto Rico.
Microbialites can serve as proxies for ancient microbial communities and can also comprise productive petroleum reservoirs in many carbonate plays. In this study, we have identified unique stromatolites—layer carbonate rocks that preserve microbial mats—in an abandoned saltern in Puerto Rico. Curiously, unlike this saltern of interest, adjacent salterns of similar size and shape in the area only exhibit flat-lying, laminated mats with no documented mineral formation. This study site therefore presents an ideal opportunity for comparative analysis.
Samples were taken from the saltern containing stromatolitic textures in July 2018 and December 2018. Satellite images demonstrate that the stromatolitic morphology has been present in this saltern of interest since at least 2006, while adjacent ponds do not appear to have such morphologies in satellite images nor were they observed in the field. Photomicrographs of the mats demonstrate bound allochthonous grains as well as pore-filling precipitates that consist of Mg-calcite and aragonite. Preliminary characterization of the microbial mat communities reveals a consortium of photosynthetic algae and bacteria, abundant bacterial groups related to sulfur metabolism, and methanogens, suggesting persistent anoxic conditions locally and perhaps even more broadly.
This project will provide new understanding of the spatial distribution of stromatolitic bodies, linked with detailed textural, mineralogic, geochemical, and microbiological datasets, and analyzed in comparison to similar environments that do not develop stromatolitic textures. Taken together, these data will provide a comprehensive and, we expect, mechanistic approach to understanding a) the formation of stromatolitic mats and b) parameters that influence their mineralization.
Collaborators: Bryan Rodriguez-Colon, University of Kansas; Wilson Ramirez-Martinez, University of Puerto Rico, Mayguez.
Funding: We are currently seeking funding for this project.