The Frobisher-Alida interval is a well log-marker-defined interval, not lithologically based, which extends across middle and upper Mission Canyon carbonates into lower Charles evaporite from the basin center toward the eastern basin margin. The interval represents a regressive sequence with superimposed minor transgressive pulses. A wide spectra of depositional and diagenetic environments with associated fabrics and porosities are represented in these carbonates.

Basin-margin carbonates are dominated by supratidal sediments with lesser amounts of intertidal and subtidal sediments. Major fabric types of important producing zones consist of major developments of hypersaline, and minor development of caliche and vadose, ooid and pisolite wackestones to grainstones. Intercalated with these are fenestral mudstones to laminated dolomudstones, gastropod mudstones, and evaporite "mush" dolomudstones. In addition, desiccation cracks and minor occurrences of karst breccias and laminated crusts indicate periods of subaerial exposure. Porosities associated with the supratidal-subaerial realm include well-developed interparticle, fenestral, vuggy, and intercrystal types, and in places are filled with clear spar and/or void-filling clear anhydrite cement. >

Basinward, subtidal sediments dominate the interval. These consist of cyclic, shallow open-marine bioclastic mudstones to packstones-grainstones and, partly restricted marine burrowed peloidal mudstones to bioclastic wackestones. Upsection, non-cyclic burrowed bioclastic peloidal mudstones to wackestones indicate increasingly restrictive conditions. Interparticle porosity is exhibited in the bioclastic grainstones. Intercrystal porosities are developed from selective dolomitization of burrows and mudstones.

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