Premium
Bed sediment sources and mixing in the glacierized upper Fraser River watershed, east‐central British Columbia
Author(s) -
Dirszowsky Randy W.
Publication year - 2004
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.1044
Subject(s) - geology , tributary , bedrock , drainage basin , sediment , dolostone , dolomite , lithology , hydrology (agriculture) , carbonate , geochemistry , geomorphology , glacier , carbonate rock , sedimentary rock , materials science , cartography , geotechnical engineering , geography , metallurgy
Abstract The geochemical, mineralogical and lithological composition of modern stream bed material is examined in order to characterize sources and evaluate downstream mixing of sediments in the upper Fraser River drainage basin, British Columbia. The <63 µm fraction is emphasized for its relative mobility and ease of analysis using instrumental neutron activation. Overall, the composition of the stream sediments closely reects bedrock distribution. Samples dominated by limestone and dolostone, calcite and dolomite, and related elements (Ca, Mg, Sr etc.) correspond to Lower and Middle Cambrian carbonate bedrock largely conned to the Moose River sub‐basin. Clastic and non‐quartzite metamorphic lithologies, primary and secondary aluminosilicate minerals and related elements (Al, Cs, Rb etc.) are largely derived from Miette Group bedrock and associated with the uppermost Fraser River sub‐basin. Except in the case of the Moose River/Fraser River junction, the determination of proportional tributary contributions is complicated by variable or delayed mixing, localized oodplain or valley side sources, and limited contrast between source areas. At present the Moose River sub‐basin contributes a greater proportion of the total and ne‐grained sediment loads of the combined Fraser River than would be expected from drainage basin area alone. The imbalance is related to greater relief, precipitation and runoff in the Moose River sub‐basin; however, the spatial association of carbonate‐rich stream sediments, ice cover and carbonate bedrock exposure indicates that glaciers play a particularly important roll in generating ne‐grained uvial sediment. Since differences in glacier cover and glacier potential in the two major sub‐basins are likely to be persistent, and since relative sediment yields from the sub‐basins can be determined from sediment composition, a potential indicator of glacier variation and climate change during the Holocene is therein available. Copyright © 2004 John Wiley & Sons, Ltd.