Diagenetic zone and anchizone were recognized as a region rich in phyllosilicates in one-dimensional nanometer size by means of the X-ray diffraction technique. The Scherrer equation was used to calculate the domain sizes of illite, illite/smectite, smectite, chlorite, kaolinite, glauconite and pyrophylite. Anchizone boundaries were used as the calculation limits. The illite domain size was directly calculated according to the boundaries of anchizones. Based on selected data of clay minerals in the foreland of the Alpine orogene, the correlation between the Kiibler index of illite crystallinity and chlorite crystallinity and that between IC and I/S were expanded into the domain-size tendencies of chlorite and I/S with respect to IC. It was also deduced the domain-size tendencies of pyrophylite, kaolinite and smectite in the same way. Clay mineral assemblages in the diagenetic zone, anchizone and epizone were summarized. It is derived from the calculation that most of the clay minerals in the diagenetic zone and anchizone are from a few to tens of nanometers in size along c* and hence it is concluded that the diagenetic zone and anchizone are the resource of phyllosilicates in one-dimensional nanometer size.