STROMATOLITIC KNOBS IN STORRS LAKE, SAN SALVADOR, BAHAMAS: INSIGHTS INTO ORGANOMINERALIZATION

Storrs Lake, a hypersaline lake on the east coast of San Salvador Island, Bahamas, contains well-developed microbial mats, some of which have developed calcified structures called microbialites. Many of these microbialites are laminated, and therefore classified as stromatolites. This study focuses on small stromatolitic knobs located in the southern portion of Storrs lake, which are still actively forming, to gain insights into the early stages of stromatolite formation. These knobs appear to be forming as the result of in situ micritic precipitation mediated by both photosynthetic and heterotrophic microbial metabolisms. By comparing these small stromatolitic knobs to larger stromatolitic heads in deeper portions of the same lake, as well as other modern closed-system and open-marine stromatolites, a mechanism for organomineralization and laminae formation can begin to be determined. The mechanism for in situ precipitation is relatively comparible in each of these systems, though the mechanism of laminae formation varies from microbial to more extrinsic controls. This project can be used to inform future studies of fine-grained stromatolites in the fossil record, providing crucial knowledge about the history of Earth’s carbon cycle.