Mineralogy of recent pelitic sediments from the Fiskenæsset region, southern West Greenland

Abstract

Recent muds were sampled during the summer of 1973 from different fjords and lakes in the Fiskenæsset region of southern west Greenland. The samples were analysed for their mineralogical composition in order to study sorting effects and possibie mineral alteration by transport action under subarctic climatic conditions. In an investigation of the composition of sands from the Fiskenæsset region Kalsbeek et al. (1974) revealed a close correspondence between the mineralogical composition of the coarser clastic components and that of the bedrock. Such relationships occur when chemical weathering of the sediment material is negligibie due to low temperatures and in connection with fast transport (high relief) and corresponding high sedimentation rates. All these influencing factors are active in southern west Greenland. Sampling was undertaken in Buksefjorden, Sermilik, Grædefjord, Fiskenæsfjorden, Bjørnesund and at the margin of Frederikshåbs Isblink. Further bottom samples were taken from the lakes marked in fig. 45. A total of 121 samples were recovered from depths ranging from Oto 275 m using grab sampling devices. Almost the entire sediment material under consideration has been produced by glacial abrasion and only a negligibie proportion by soil formation processes. Both bed load and suspension load are brought by melt water streams from beneath the glaciers. The melt waters run into glaciaIly eroded lakes, where most of the coarse sediment material and some of the clay fraction is trapped. Most of the clay fraction remains in suspension, however, and is transported downstream to sea level. Considerable amounts of clay in suspension are carried far into the fjords.