Jökull - 01.01.2012, Blaðsíða 113

Reviewed research article
Late Holocene and modern glacier changes in the marginal
zone of Sólheimajökull, South Iceland
Anders Schomacker1, Ívar Örn Benediktsson2,3, Ólafur Ingólfsson2, Bjarki Friis4,
Niels Jákup Korsgaard 5, Kurt H. Kjær 5 and Jakob Kløve Keiding 6
1Department of Geology, Norwegian University of Science and Technology (NTNU),
Sem Sælands Veg 1, N-7491 Trondheim, Norway
2Institute of Earth Sciences, University of Iceland, Askja, Sturlugata 7, IS-101 Reykjavík, Iceland
3Department of Geology, Lund University, Sölvegatan 12, S-223 62 Lund, Sweden
4Store Norske Spitsbergen Grubekompani AS, Postboks 613, N-9171 Longyearbyen, Norway
5Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen,
Øster Voldgade 5-7, DK-1350 Copenhagen K., Denmark
6GFZ German Research Centre for Geosciences, Telegrafenberg, D-14473 Potsdam, Germany
Corresponding author. anders.schomacker@ntnu.no
Abstract – The forefield of the Sólheimajökull outlet glacier, South Iceland, has a variety of glacial landforms
and sediments that are products of late Holocene and modern glacier oscillations. Several sets of moraine
ridges reflect past ice front positions and river-cut sedimentary sections provide information about past en-
vironments. Here, we describe sediments and landforms deposited during the late Holocene. Chronology is
obtained by 14C dating and cosmogenic exposure dating. The age determinations suggest that Sólheimajökull
had major advances in the late Holocene prior to the Little Ice Age, and more restricted advances during the
Little Ice Age, after AD 1539. Oscillations of the Sólheimajökull ice margin between 1938 and 2010 are docu-
mented by aerial photographs. Digital elevation models were produced from selected years in order to quantify
ice thickness changes at the glacier margin over the last 50 years. The glacier margin thickened 70–100 m from
1960 to 1996 and then thinned 120–150 m between 1996 and 2010. In 2010, the glacier snout was 20–40 m
thinner than in 1960. Additionally, the DEM time-series detect areas of erosion and deposition in the forefield.
INTRODUCTION
Research at Sólheimajökull (Figure 1) has mainly
focused on the glacial and climate history of the
Holocene (e.g. Dugmore, 1989; Dugmore and Sug-
den, 1991; Dugmore et al., 2000; Mackintosh et al.,
2002; Casely and Dugmore, 2004; Grove, 2004),
and glacial and sedimentary processes and landforms
(e.g. Maizels, 1991; Lawler et al., 1996; Roberts
et al., 2003; Le Heron and Etienne, 2005; Russell
et al., 2010; Schomacker et al., 2010). Dugmore
(1989), Dugmore and Sugden (1991), and Dugmore
et al. (2000) applied tephrochronology and 14C dat-
ing and concluded that Sólheimajökull experienced
its Neoglacial maximum 7–4.5 kyr BP, reaching the
mouth of the valley. They also identified subsequent
and more restricted pre-Little Ice Age (LIA) advances
at >3.1 kyr BP, 1.2–1.4 kyr BP and 1 kyr BP. However,
all were larger than the LIA advances. These advances
are asynchronous with other recognized advances of
outlet glaciers in southern Iceland (Björnsson and
JÖKULL No. 62, 2012 111