Dept. of Earth, Atmospheric & Planetary Sciences
Massachusetts Institute of Technology
Mineral precipitation, sedimentation and microbial activity have shaped landscapes in coastal environments for nearly 3.5 billion years, forming stromatolites and other sedimentary structures. The shapes and textures of these structures may record evolutionary and chemical changes during the first 80% of Earth's sedimentary history. However, as complex products of physical processes, microbial ecology, metabolic processes and mineral precipitation, these textures and shapes are often difficult to interpret. This talk will describe recent experiments that link spatial patterns in microbial ecology, sedimentary biogeochemistry and lithification to the flow and sedimentation conditions in sandy sediments. These experiments enable the recognition of photosynthetic processes in the textures and shapes of Archean and Proterozoic conical stromatolites, reveal the origin of the previously mysterious wrinkle structures, explain the shapes of modern, large elongated stromatolite mounds and provide general models for the formation and growth of carbonate hard grounds in the presence of waves and currents.