CONTINENTAL MICROBIALITES THROUGH TIME: THE PROBLEM OF LIMITED ANALOGUES AND A POSSIBLE SOLUTION

Although stromatolites are ubiquitous in Proterozoic shallow marine and lacustrine carbonates, their patchy distribution in space and time during the Phanerozoic has resulted in a long and discouraging quest for modern analogues. Further, disparity among modern microbialite-bearing environments challenges development of a coherent general model of microbialite formation. One approach to unraveling the physical, chemical, and biological factors that contribute to microbialite formation is to examine components of microbialites that are similar across environments and seek their common textural and chemical traits. Much as is done with physical sedimentary structures, interpretations of these features at this scale would allow us to discern the local-scale processes that build the macroform and might apply across spatial scales. Despite the perils of taking a reductionist approach to a complex system, this limited-analogue approach has the potential to unravel scale-dependent relationships that produce identifiable features, at specific scales, of stromatolites across environments. Viewed this way, the stromatolites produced in a particular environment represent the concatenation of unique combinations of common features, rather than biosedimentary structures that must be interpreted de novo in each instance. We present examples of the application of this method from a range of continental settings that allows us to make qualified generalizations about the processes that lead to the formation of microbial textures and the larger-scale structures they produce.