Holocene glacial evolution of Mohnbukta in eastern Spitsbergen

Abstract

Submarine geomorphology is one of the main tools for understanding past fluctuations of tidewater glaciers. In this study we investigate the glacial history of Mohnbukta, on the east coast of Spitsbergen, Svalbard, by combining multibeam‐bathymetric data, marine sediment cores and remote sensing data. Presently, three tidewater glaciers, Heuglinbreen, Königsbergbreen and Hayesbreen calve into Mohnbukta. Hayesbreen surged at the end of the Little Ice Age, between 1901 and 1910. The submarine landform assemblage in Mohnbukta contains two large transverse ridges, interpreted as terminal moraines, with debrisflow lobes on their distal slopes and sets of well‐preserved geometric networks of ridges, interpreted as crevasse‐squeeze ridges inshore of the moraines. The arrangement of crevasse‐squeeze ridges suggests that both landform sets were produced during surge‐type advances. The terminus position of the 1901–1910 Hayesbreen surge correlates with the inner (R.2) terminal moraine ridge suggesting that the R.1 ridge formed prior to 1901. Marine sediment cores display 14C ages between 5700–7700 cal. a BP derived from benthic foraminifera, from a clast‐rich mud unit. This unit represents pre‐surge unconsolidated Holocene sediments pushed in front of the glacier terminus and mixed up during the 1901 surge. An absence of retreat moraines in the deeper part of the inner basin and the observation of tabular icebergs calving off the glacier front during retreat suggest that the front of Hayesbreen was close to flotation, at least in the deeper parts of the basin. As the MOH15‐01 core does not penetrate into a subglacial till and the foraminifera in the samples were well preserved, the R.1 ridge is suggested to have formed prior to the deposition of the foraminifera. Based on these data we propose that a surge‐type advance occurred in Mohnbukta in the early Holocene, prior to 7700 cal. a BP, which in turn indicates that glaciers can switch to and from surge mode.

Irish Ice Sheet dynamics during deglaciation of the central Irish Midlands: Evidence of ice streaming and surging from airborne LiDAR

“…The MSGLs also extend eastward, and GSI (2016) and earlier mapping indicated further subglacial lineations and esker fragments aligned parallel to these MSGLs up to 50 km east of area 1. This geometry is consistent with formation along the trunk of a laterally confined glacier or ice stream and resembles MSGL and rectilinear networks identified as the footprint of long-periodicity surging glaciers and surging ice streams elsewhere (Andreasson et al, 2014;Evans et al, 2016;Flink et al, 2017).…”

“…The CSRs are thought to form by the injection of wet basal sediments upward into extensional crevasses, under high basal water pressures (Sharp, 1985;Rea and Evans, 2011). Similar rectilinear ridge networks have been observed on the beds of modern and Quaternary temperate and polythermal glaciers and are associated with surging glaciers and ice streams in onshore and offshore situations (Boulton et al, 1996;Ottesen et al, 2008;Ó Cofaigh et al, 2010;Andreasson et al, 2014;Jónsson et al, 2014;Evans et al, 2014Evans et al, , 2016Cline et al, 2015;Flink et al, 2017). Ice-flow transverse (set 1) ridges in area 1 are somewhat larger than usual; however, similar larger transverse ridges have been observed in front of modern surging glaciers in Svalbard (Boulton et al, 1996;Flink et al, 2017) and on the bed of former ice streams (Evans et al, 2016).…”

Svalbard glaciers re‐advanced during the Pleistocene–Holocene transition

“…However, unlike the terrestrial LGEH glacier deposits that can be indirectly constrained in age remotely, the submarine glacier deposits do not exhibit cross-cutting morphological evidence of a high relative sea level (constituting a minimum constraining age of deposition). Recent work from eastern Spitsbergen suggests glaciers may have extended further than the traditional Neoglacial-LIA maxima during the early Holocene, but the moraines are yet to be well constrained in time (Flink & Noormets 2017;Flink et al 2018). Glacier re-advances of LGEH age are not unique to Svalbard and have been identified at other North Atlantic ice-sheet margins during the last deglaciation.…”

“…Recent work from eastern Spitsbergen suggests glaciers may have extended further than the traditional Neoglacial-LIA maxima during the early Holocene, but the moraines are yet to be well constrained in time (Flink & Noormets 2017;Flink et al 2018). More research is needed to determine whether the marine tidewater setting played a dynamic role or was merely a result of the environment at the time.…”

Multiple Late Holocene surges of a High-Arctic tidewater glacier system in Svalbard

“…Plassen et al, 2004;Ottesen and Dowdeswell, 2006;Mangerud and Landvik, 2007). Other fjords record much older, more extensive tidewater advances (Hald et al, 2004;Evans and Rea, 2005;Kempf et al, 2013;Flink et al, 2017;Larsen et al, 2018). Many of these tidewater glaciers are inferred or known to be of surge-type, raising the question as to whether previous advances (LIA maximum or earlier) were glaciodynamic surges or were in response to climate forcing (e.g.…”