Diagenesis of Knox Group (Cambrian-Ordovician) Carbonates Exposed Along Alligator Creek, Bibb County, Alabama: ABSTRACT

Abstract

Diagenetic products observed in Knox Group carbonates from the Alligator Creek section have been described from thin section and placed into a paragenetic sequence on the basis of cross-cutting relationships. Eogenetic processes include freshwater granular calcite cementation and vug formation in exposed carbonate highlands that developed during relative sea level falls. Later transgressions produced a mixing zone between advancing marine water and interstitial meteoric water. Extensive replacement dolomitization and silicification occurred in the mixing zone, including the formation of silica cements in pore space. Mesogenetic processes produced fractures, stylolites, and pressure seam dolomite. Burial fluids migrated along fractures and through previously formed intercrystalline porosity to produce vugs. Dolomite-bearing fluids later reduced intercrystalline, fracture, and vuggy porosity by precipitating dolomite cement. Folding and thrusting associated with the Allegheny orogeny produced fracturing, brecciation, and calcite mineralization. Blocky calcite cement occluded much of the remaining fracture and vuggy porosity in the section. End_of_Article - Last_Page 1417------------