A B S T R A C TIntrasalt carbonates of the Ediacaran-Cambrian Ara Group constitute a significant reservoir element of the intrasalt "stringer" play in Oman, in which dolomitic carbonates are encased in salt at depths of 3 to 7 km (1.9 to 4.3 mi). These reservoir carbonates have significant microbial influences. Although Ara Group reservoirs are mostly latest Precambrian, the models developed here may be applicable to younger microbially dominated carbonate reservoirs in basins of higher salinity when higher organisms are excluded, in lacustrine settings where calcified invertebrates are not a significant source of carbonate, or after periods of mass extinction before faunal recovery. A broad range of carbonate facies provides the context in which to understand the origin of the microbialite-dominated reservoirs developed across both ramp and rimmed shelf profiles. Major facies associations include carbonate-evaporite transition zone, deep ramp and slope, subtidal microbialites, clastic-textured carbonates, and restricted peritidal carbonates. Microbialites are subdivisible into a number of facies that all have significance in terms of understanding environmental history as well as reservoir properties, and that help in predicting the location of reservoir fairways. Microbially influenced facies include shallow subtidal thrombolites with massive clotted textures and very high initial porosities (>50 ), shallow subtidal pustular laminites with cm-scale variability of lamina morphology, deeper subtidal crinkly laminites that show mm-scale variability of lamina morphology, and intertidal tufted laminates that