SCANNING ELECTRON-MICROSCOPY OF QUARTZ GRAINS FROM 2 GRANITE CAVES AND A GORGE SYSTEM IN BOHUSLAN, SOUTHWESTERN SWEDEN

Sand samples of quartz composition from two caves and a gorge in Bohus lan, Sweden, were studied by scanning electron microscopy to determine microtextural differences between subsamples of exfoliation flakes, n eotectonically-released grains (high velocity impact), weathered grani tic and glacially transported particles. While there are similarities amongst the different samples with respect to fracture patterns, only the glacial grains show multifaceted particles with sharp edges that a re typical of grains transported by continental ice. Glacial grains ex hibit fracture features on more than 50% of the particle surfaces and more than 70% of the grains studied were abraded. All microtextures on the cave samples consisted of irregular subparallel linear fractures that cover less than 10% of the particle surfaces. The presence of num erous upturned plates on quartz grains in Ulorna Cave may be neotecton ically produced.