Verkiezelingsverschijnselen bij belemnieten uit het Zuidlimburgse krijt

Silicification phenomena on belemnite rostra from the Dutch Upper Senonian limestones are discussed. Accretionary quartz rings are supposed to have formed when silicification is slow. Rough silicifications form when the original calcareous subject is porous or when dissolution of calcite is faster than silicification. Radiating quartz growth inside the belemnite occurs when the belemnite surface is completely silicified and diffusion towards the belemnite axis is very slow. Silicification is post depositional.