Granulometrie und Sandkornmorphoskopie alpiner Glazialsedimente
1990
Diekmann, Bernhard
Sediments from various subenvironments of alpine valley glaciers can be distinguished by their grain-size distributions. Glacio-aquatic deposits exhibit narrower grain-size spectra and better grain-size sorting than sediments of pure glacial origin. The various types of moraine sediments can be recognized by varying contents of fine-grained matrix (less than 0.063 mm in diameter). Glacially affected quartz grains show conchoidal, step- and block-fracture patterns of varying shapes and sizes, but it is difficult to discern whether these microtextures are of genomorphic or phenomorphic origin. Frequently a single grain exhibits sharply acute as well as notched and rounded edges, reflecting the uneven distribution of forces during subglacial transport. Likewise, feldspar grains show both abraded and rough (shatter-cleaved) surfaces.
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