日本ゼオライト学会　刊行物 Publication of Japan Zeolite Association

On the physical point of view, the zeolitization in the marine sediments during burial diagenesis is a kind of compaction phenomenon, such as the explusion of water and the increase in specific gravity. The zeolite zones in the Neogene marine sediments of the Japanese oil producing regions occur at various depth, and are oblique to the stratigraphic datums. But, the porosity of argillaceous rocks at the top of each zeolite zone is relatively constant: approximately 33% at the Zone II(clinoptilolite), 17% at the Zone III(analcime), and 12% at the Zone IV(albite). The specific gravity of zeolite is nearly equal to the bulk density of argillaceous rocks at the top of each zeolite zone.

The compaction of sediments is one of the important factors for the transformation of silicic glasses to clinoptilolite-analcime-albite reaction series, as same as maximum formation temperature and effective heating time. Silicic glasses or the existing zeolite are physically unstable mineral under the increasing overburden, and begin the transformation into high grade zeolite to keep with physical equilibrium in the surrounding sediments, as accompanied by the chemical exchanges of ions, the explusion of water and the increase of specific gravity.