Abstract ref. 1994:
Laurentian shelf margin deposits typically are dolomitized or metamorphosed, but the Ledger Fm. contains an exceptionally well preserved microbialite reef complex, riddled with large submarine cavities. The microbialite consists of Renalcis-like shrubs, centimeter-scale domal stromatolites, dense fronds and laminated
fabrics. Petrographically, the microbialite is expressed as clots of spherulites, stringers, arborescent garlands, and dendritic shrubs. Microbial processes dominated all
ecological niches; forming the substrate, colonizing cryptic spaces, coating and encrusting other algae. Cavities within the microbialite formed through a number of previously undescribed processes, at least on the large scale reported here. Organic decay led to the development of stromatactis-like voids on a meter-scale, while syn-depositional slumping and channel formation led to microbial props and folds which resulted in further void generation.  
These large cavities were stabilized with multiple generations of radiaxial fibrous and herringbone calcite cements, intercalated with internal sediment. The herringbone calcite cement has depleted carbon isotopic values relative to the radiaxial fibrous cement, even those within the same cavity. This suggests that the herringbone morphology is related to unusual porewater conditions. In this instance I interpret that the herringbone calcite reflects near anoxic porewaters due to large quantities of decaying microbial material nearby. 

Marine cement stratigraphy, based on petrography, CL, stable isotopes, and trace element geochemistry, demonstrate that the cavities did not fill simultaneously.
Rather, even adjacent cavities exhibit complex patterns of cementation, encrustation, and cement breakage, indicating that the reef's location was in a high energy,
shelf margin setting where storms and local events impacted each cavity differently. 