Loess/soil sequences have been proven to be excellent
paleoclimate indicators. Large areas of northern Iran are covered by loess
deposits which provide a good condition to carry out research on
paleoclimate, paleosols and discontinuities. The objectives of this research
were to identify clay minerals of soil-loess sequences, to determine the role
of climate change in clay mineral transformation and to estimate the relative
ages of soil development based on archaeological information. Samples were
analyzed by X-ray Diffraction (XRD) and Scanning Electron Microscopy
(SEM). The results showed that kaolinite, illite, quarts and feldspar were
dominant in the fine clay, coarse clay and silt fractions. The type and the
quantity of clay minerals in soils are highly correlated with parent material.
Semiquantitative estimation indicated that different clay minerals are
quantitatively different in the profiles. This may be due to different
weathering rates caused by cool/dry and wet/warm periods. A high degree of
chlorite to smectite transformation was observed in deep soil horizon (130–
170 cm) where a developed horizon was buried. Differences between soil
layers development were confirmed by comparison of oxalate and dithionite
extractable Fe.