MINERALOGICAL INVESTIGATION OF SOILS FORMED IN CALCAREOUS GRAVELLY ALLUVIUM, EASTERN CRETE, GREECE

The mineralogical composition of soils along a toposequence formed on Quaternary-aged alluvium from the northeastern portion of the island o f Crete, Greece, and the examination of their mineral weathering chara cteristics should help provide an insight into the stage of weathering and relative age of the soils, Four soils were described and sampled from three landscape positions along the toposequence and the clay and silt fractions from all horizons of each soil were examined using a c ombination of x-ray diffraction and electron micro-probe techniques, C oarse and fine silt fractions from each soil contained dolomite, calci te, quartz, feldspars, mica, and chlorite, Feldspar content generally decreased with depth, whereas calcite increased with depth, Minerals i dentified in the silt fractions resulted from a combination of physica l and chemical weathering and possible eolian additions. Clay fraction s were dominated by trioctahedral ferrous chlorite and dioctahedral mi ca (muscovite), with minor amounts of kaolinite, quartz, dolomite, and calcite. Goethite was also identified in the clay fraction of some so il horizons. The source of the phyllosilicates was inheritance from ph yllite gravels in the alluvium and chemical dissolution of the dolosto ne releasing entrained clay minerals. Some portion of the kaolinite in surface horizons was probably the result of eolian additions. Goethit e formation resulted from release of Fe from the chlorite. The extent of clay mineral inheritance, limited expansion of the chlorites, and l ack of a chlorite or mica weathering product (vermiculite), as well as the presence of carbonates in the clay fractions, all suggest that th ese soils are still in the initial stages of weathering.