Application and Comparison of the Results of Optical and Scanning Electron Microscopic Methods for Grain-Shape Examination on Quaternary Formations

Grain-shape studies were made with traditional and scanning electron microscopic methods on sand samples from Quaternary geological profiles in the Nyírség area in North Hungary. It was found that the sand layers had originally undergone fluvial transport, then suffered aeolian reworking. However, the latter impact did not completely eliminate the features brought about by fluvial transportation. The scanning electron microscopic examinations enabled us to distinguish between grain types originating in the host rock, those displaying diagenetic impacts, grains transported in the fluvial or aeolian way, and those showing chemical effects or polygonal cracks due to insolation. The impacts began with the diagenetic effect, and continued with fluvial and/or aeolian transportation. The chemical effect presumably took place partly during transportation, but mainly following it. The most reliable results for the determination of the sedimentary environment can be obtained through the joint application of the traditional and the scanning electron microscopic methods.