Abstract

Scanning electron microscopic examination of surface textures of quartz grains digested from dolomite-cemented sandstones and sandy dolostones revealed that dolomite precipitation can affect quartz surfaces by 1) impeding syntaxial quartz overgrowth precipitation and 2) causing detrital quartz dissolution. Both of these processes resulted in the formation of dolomite rhombohedron-shaped molds on quartz grain surfaces, which are diagnostic for the recognition of secondary porosity formed by cement dissolution. Precipitation-controlled dolomite replacement of quartz along euhedral dolomite crystal faces is consistent with the force of crystallization-controlled replacement model. Some dolomite cement precipitation occurs without noticeable alteration of quartz grain surfaces. Dolomite cementation is also associated with surface reaction-controlled dissolution textures that may have formed by either 1) host grain-controlled replacement of quartz by dolomite or 2) void-filling dolomite precipitation into etch-pits formed by earlier quartz dissolution in undersaturated bulk pore waters.

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