Controls on gravel composition in a proglacial environment Kaunertal, Austria
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Date
2014-05
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The Ohio State University
Abstract
Proglacial environments, the settings in front of glaciers, are increasingly targeted for study as global climate change affects many of the world’s glaciers. This study focuses on a proglacial environment in Kaunertal, Austria, located in the drainage basin of the Gepatschferner Glacier, one of the biggest glaciers in Austria (Baewert and Morche, 2013). Effects of transport in proglacial drainage systems like this one are hypothesized to influence the distribution patterns of different rock types supplied by glacial erosion. The main goals of this project are to: 1) describe the composition of gravel-sized clasts along an ~4 km length of the Fagge River, the proglacial stream that drains the Gepatschferner Glacier in order to test the results presented in similar research; and 2) interpret the spatial changes in gravel composition in terms of the distribution of bedrock types in the area and the effects of transport, such as the greater persistence of stronger rock types during transport. Sixteen sites were sampled along the Fagge River, with ~50 grains collected at each site. Fifty grains were also taken from each major tributary or moraine. In addition, a sample was collected from each of 20 outcrops, distributed among the 3 lithologies in the study area. The composition of each grain was determined by visual examination with a hand lens and standard rock identification charts. The abundance of each rock type has been examined as a function of sampling location. The most abundant gravel compositions are “Orthogneiss,” “Paragneiss” and “Ortho- or Paragneiss.” There was a wide variation of abundances in all rock types throughout the length of the drainage basin. Although no significant trends were found, “Orthogneiss,” “Amphibolite,” and “Other” became somewhat more abundant downstream, while “Paragneiss,” “Ortho- or Paragneiss” and “Jointed Gneiss” are still present.
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Keywords
gravel composition, proglacial environment, gravel distribution