Abstract:

Using the scaning electronic microscope (JSM-6700F) and energy spectrum (INCA), the micromorphology and microcompositon of clay minerals were analyzed. The authigene illite and chlorite platy crystals are generally straight and 1-3 μm in diameter. Clastic (secondary or primary) illite and chlorite are generally＞3 μm in diameter and irregular platy cluster. In chemical composition, both the authigene and clastic illite or chlorite are almost the same. Research on the probability of occurrence of coexisting clay minerals and their relative contents (XRD) suggests that the clay minerals in the studied area are mainly illite (I), chlorite (C), kaolinte (K) and illite/smectite (I/S) mixtures. The chlorite/smectite (C/S) and smectite (S) are rare. The correlation analysis of the crystallinity of illite(IC) and the relative content of clay minerals suggests that correlation coefficients of IC with I/S, K, I, I/S, C, C/S, C/S and S are 0.611, 0.262, -0.447, -0.290, -0.265, -0.190, -0.160 and -0.117 respectively. Factor analysis is also used to study the spatial distribution of the clay minerals. F1 factors are mainly contributed by IC, relative contents of I/S+C/S and the relative content of I+C. F2 factors are attributed mainly to IC, polymorphism of illite (muscovite), b₀ dimension of illite (muscovite)；F3 factors are ratios of I/S and C/S；F4 factor contributes with S+K. Using the retrogressive analysis, the relationship between the IC and S, I/S,I, K,C and C/S has been set up.

Key words: argillaceous rock, clay minerals, statistics, very low metamorphism, the Upper Paleozoic, Northeast China