Mineralogical Investigation of Soils Formed in Calcareous Gravelly Alluvium, Eastern Crete, Greece
Timpson, M. E. | Lee, S. Y. | Ammons, J. T. | Foss, J. E.
The mineralogical composition of soils along a toposequence formed on Quaternary-aged alluvium from the northeastern portion of the island of Crete, Greece, and the examination of their mineral weathering characteristics 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 combination of x-ray diffraction and electron microprobe techniques. Coarse and fine silt fractions from each soil contained dolomite, calcite, quartz, feldspars, mica, and chlorite. Feldspar content generally decreased with depth, whereas calcite increased with depth. Minerals identified in the silt fractions resulted from a combination of physical and chemical weathering and possible eolian additions. Clay fractions were dominated by trioctahedral ferrous chlorite and dioctahedral mica (muscovite), with minor amounts of kaolinite, quartz, dolomite, and calcite. Goethite was also identified in the clay fraction of some soil horizons. The source of the phyllosilicates was inheritance from phyllite gravels in the alluvium and chemical dissolution of the dolostone releasing entrained clay minerals. Some portion of the kaolinite in surface horizons was probably the result of eolian additions. Goethite formation resulted from release of Fe from the chlorite. The extent of clay mineral inheritance, limited expansion of the chlorites, and lack of a chlorite or mica weathering product (vermiculite), as well as the presence of carbonates in the clay fractions, all suggest that these soils are still in the initial stages of weathering.
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