Mapping sediment–landform assemblages to constrain lacustrine sedimentation in a glacier-fed lake catchment in northwest Spitsbergen

Willem G.M Van Der Bilt,Jostein Bakke,Nicholas L Balascio

doi:10.1080/17445647.2015.1113391

Willem G.M Van Der Bilt, Jostein Bakke + Show 1 more

Open Access

https://doi.org/10.1080/17445647.2015.1113391

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Abstract

ABSTRACTChanges in the deposition of fine-grained rock-flour in glacier-fed lakes reflect glacier variability. This meltwater-driven signal is, however, often overprinted by other processes. To constrain the signature of lacustrine sedimentation, we mapped the catchment of glacier-fed Lake Hajeren in northwest Spitsbergen, identifying sediment sources and linking them to surface processes. To this end, we employed a combined approach of aerial image interpretation and field mapping. Our map comprises sediment–landform assemblages commonly found in pro-, peri- and paraglacial landsystems on Spitsbergen, including weathered moraines outboard Little Ice Age limits. Based on the presented map, we argue that mass-wasting does not directly impact lake sedimentation. Also, due to the scarcity of fines in historical glacial deposits, we suggest that modified glacigenic sediments only briefly affect a recorded glacier signal, following retreat. These findings highlight the value of geomorphological maps as tools to constrain catchment processes, improving the interpretation of lake sediment records.

Highlights

Glaciers are highly sensitive to climate change as demonstrated by their rapid retreat in response to current warming (WGMS, 1988–2011)
Based on the discussed 1936 aerial photograph (NPI, 1936), as well as a similar relation to present ice extent as nearby glacier systems (Evans, Strzelecki, Milledge, & Orton, 2012; Hambrey et al, 2005; Hodson et al, 1998; Røthe et al, 2015), Stage 2 moraines are assumed to have been deposited during the LIA chronological control is lacking, a high degree of weathering and deposition outside of Stage 2 deposits indicates that Stage 1 moraines at the North Glacier represent a Holocene glacier maximum that predates the LIA
Most observed landform assemblages are solely found in these areas, as shown on our map (Main Map)

Summary

Introduction

Glaciers are highly sensitive to climate change as demonstrated by their rapid retreat in response to current warming (WGMS, 1988–2011). Sedimentation in glacier-fed lakes is frequently affected by other sediment sources that leave a similar imprint in the lacustrine sediment record (Rubensdotter & Rosqvist, 2009; Vasskog et al, 2011) These commonly include reworked glacigenic sediments that have been modified by non-glacial processes (Ballantyne, 2002; Dahl, Bakke, Lie, & Nesje, 2003). In addition to such paraglacial modification (Church & Ryder, 1972), mass-wasting can overprint the signature of a glacier signal (Vasskog et al, 2011). The impact of these processes should be understood to ensure an accurate reconstruction of a glacier variability (Jansson, Rosqvist, & Schneider, 2005; Rubensdotter & Rosqvist, 2009)

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