Microbioherms of the Waldron Shale (Silurian, Indiana); implications for organic framework in Silurian reefs of the Great Lakes area

Identification of an organic framework within Silurian bioherms of the Great Lakes area has not been widely accepted because of extensive dolomitization and diagenesis. Detailed analyses of small, organically constructed masses, or microbioherms, in the Waldron Shale of southern Indiana, however, yield evidence of encrusting organisms that are congeneric with biohermal organisms and were capable of producing rigid, organically bound reefal frameworks. Diagenesis of this framework-producing assemblage could have resulted in structures common within many large-scale Silurian buildups in the Great Lakes area.