Abstract
The clay mineral assemblages of the Sambesan loam and of the Daisen loam have been investigated on the basis of stratigraphic successions by mean of X-ray diffraction and of differential thermal analyses. The both loam beds are generally composed of four or more pumice layers and intercalated clayey layers. The clay minerals of the Sambesan loam and of the Daisen loam comprise mainly of 14Å minerals (chlorite, Al-vermiculite), 10Å minerals (illite, hydrated halloysite), 7Å minerals (kaoline minerals, chlorite), allophane and imogolite. The pumice layers are divided into three types, such as, I. allophane type, II. type which contains 14Å, 10Å and 7Å minerals and III. hydrated halloysite type. In general, the upper pumice layers are allophanic, however the hydrated halloysite are dominant in the lower pumice layers. The same tendency are also observable in the intercalated clayey layers which are characterized by the occurrences of various type clay minerals mentioned above. The results of differential thermal analyses for the samples from columnar sections support the same conclusion.
