Diagenetic alteration of Early Jurassic carbonate rocks and their impact on the rock texture, Bay of Fundy, Canada

الملخص

The rocks of Scots Bay Formation occur only along the south shore of the Bay of Fundy where they are exposed in small coves from east of Baxters Harbour to west of Scots Bay, Nova Scotia.  Lithologically, the Scots Bay Formation is dominated by clastic sediments, including sandstone, silty sandstone, conglomertic sandstorm, and shale. Carbonate and silicified carbonate rocks include calcareous sandstone, packstone,mudstone, wackcstone, and stromrtolitic limestone. Jasperoid chert nodules and bedded chertsare common throughout much of the formation .The intense shallow burial diagenesis resulted in extensive cementation, recrystallization and authigenic silica mineralization which cause low values of porosity/permeability throughout the carbonate section of Scots Bay Formation. Phreatic and vadose meteoric cements make up most of the cements of Scots Bay lirnestones. Three types of calcite cement occur in the Scots Bay Formation : drusy mosaic, blocky, and minscus cement. The chert is principally  diagenetic in origin and consists of chalcedony and mirocrystalline quartz that  formed as pore filling cement and replacements of carbonate sediments and calcareous fossils. The source of the silica was hot-spring fluids associated with the underlying basaltic volcanic flows.