| Summary: | Trends in relative sea-level change, shown by curves drawn from drill core and outcrop sections in Llandoverian carbonates of the Hudson Bay Platform, were used to correlate individual parasequences among widely separated localities. Two sequences, bounded by regional disconformities, include: (1) the Severn River Formation, and (2) the Ekwan River, Attawapiskat, and Kenogami River Formations. Initial onlap of marine facies at the base of the Severn River Formation progressed from north to south, occurring first in the Hudson Bay Basin, then in the Moose River Basin; final retreat of the seas at the end of Attawapiskat time was in the opposite direction. The most extensive inundations occurred during Ekwan River and Attawapiskat depositional times. Large-scale trends in the curves delineate four major Early Silurian sea-level highstands also recognized in other basins. Reefs in outcrops along the Attawapiskat River represent one interval of reef growth, had a syndepositional relief of 8-10 meters, and were terminated by a relative sea-level fall. Their present distribution is controlled by variously uplifted fault blocks. The most important diagenetic processes were early marine cementation and shallow burial diagenesis, and in the southwestern Moose River Basin early secondary dolomitization.
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