Grain surface characteristics of periglacial aeolian and fluvial sands

Abstract

Surface features of quartz grains from periglacial aeolian and fluvial deposits from two areas in The Netherlands and adjacent Germany have been studied with a Scanning Electron Microscope. The relative abundance of the 29 distinguished characteristics is statistically analysed in an attempt to correlate the surface features with the regionally and genetically determined sediment types. Frequencies of individual grain surface characteristics vary widely and are usually insufficient to separate the sediment types. This is partly due to the variable degree of surface pattern overprint caused by the polygenetic nature of the sediments concerned. However, linear combination of the sample variables (using principal component analysis) allows the discrimination of several distinct clusters, that show a fair correspondence with the macroscopically defined depositional groups. The regional and stratigraphical patterns observed, seem to be dominated by two factors: one which is related to the transport energy and the mode of deposition involved and perhaps connected with the prevailing wind regime; the other with chemical alterations, probably reflecting the source area of the sediment. New perspectives are opened for the genetical interpretation of sediments by grain morphoscopic analysis when combined with multivariate statistics.