Application of Automated Scanning Electron Microscope Analysis on Fluvial and Glaciofluvial Sands

Brandenburg’s surface geology predominantly consists of Quaternary sediments, with sequences averaging 50 to 80 meters (locally up to 500 meters) in thickness. Research up to 2008 on heavy mineral composition facilitated the lithostratigraphic classification of fluvial deposits, revealing frequency and compositional variations. Stratigraphic classification in Brandenburg relies primarily on pollen analysis of interglacial, predominantly limnic deposits, and small-scale gravel counts of (glacio-)fluvial and till sediments, leaving sandy components unrepresented methodologically.

To establish a comprehensive provenance analysis, the method development presented here includes both the heavy and light mineral fractions. The geochemical composition of the samples is determined semi-quantitatively using spectral analysis. In this project, 24 sand samples from the drill core Kb Borgisdorf 1/06 were examined to reconstruct the distribution patterns of Saale Late Glacial to Weichsel Early Glacial sediments in Brandenburg. The focus of method development is on sand deposits that cannot be classified by pollen and clast analysis. All samples were prepared for both polarization microscopy and Mineral Liberation Analysis (MLA), maintaining a grain size range of <200 μm. This saves time and provides a comprehensive dataset that is better comparable with conventional analyses. The data produced by the MLA are compiled into large databases and statistically analyzed, utilizing mineralogy and grain parameters such as size, length, width, and roundness. By comparing with comprehensive geochemical and mineralogical data, the method was validated. Initial results show that additional preparation yields comparable results and that samples without density separation are statistically reliable for heavy mineral analysis.