Correlations of suspended sediment size with bedrock lithology and glacier dynamics

Abstract

The hypothesized link between glacier surging and bedrock geology motivates this study of the suspended sediment size distributions (SSSD) from surge-type and non-surge-type glaciers. We analyze SSSDs from proglacial streams in 20 individual basins comprising various fractions of metasedimentary (MS) and felsic plutonic rocks. We compare the size distributions by performing tests of significance on the distribution statistics, and a principal component analysis on discrete grain sizes. We find that surge-type and non-surge-type glaciers underlain solely by MS rocks have significantly different SSSDs, while surge-type glaciers as a whole have remarkably similar SSSDs, regardless of the underlying bedrock geology. These observations hint at a relationship between sediment characteristics and glacier surging, though causation in either direction cannot be established without additional data.

Keywords

• glacier surges
• subglacial processes
• subglacial sediment
• grain size distribution
• St. Elias Mountains