MICROBIALITES OF MODERN SILICICLASTIC ROCK COASTS

Contemporary microbialite formation has been documented on rock coasts in a variety of geomorphic, oceanographic, and climatic settings. Based on a synthesis of these diverse occurrences plus new observations, a generalized model is presented. At each locality microbialite development is associated with discharge of mineralized freshwater in the coastal zone. Microbialite formation in the high intertidal and supratidal zones of rock coasts occurs in a variety of sub-environments (cliff face, shore platform surface, platform surface pools, boulder beach, and sand beach) and forms a variety of laminated rock encrustations and oncoids. Allochthonous microbialites occur on the backshore as breccias of reworked microbialite clasts, oncoids transported from rock pools, and partly encrusted boulders. The microbialite-influenced rock coast is a distinct type of siliciclastic environment that offers potential comparison for ancient microbialite occurrences. It has preservation potential in both transgressive and regressive settings. Potential ancient examples are suggested.

Automated summary

This article documents the formation of contemporary microbialites on rock coasts in various environments and presents a generalized model based on synthesis of diverse occurrences. It discusses the different sub-environments where microbialite formation occurs and the potential for using modern microbialites as analogs for ancient occurrences. The article also suggests potential ancient examples.