Drumlin formation within the Bustarfell drumlin field, northeast Iceland: integrating sedimentological and ground‐penetrating radar data

Abstract

Drumlins are important bedforms of former glaciated landscapes as they demonstrate past ice‐flow directions and elucidate processes that operated at the ice/bed interface. Recently mapped drumlins and other streamlined subglacial bedforms in northeast Iceland reveal the flow‐sets of cross‐cutting palaeo‐ice streams that were active within the Iceland Ice Sheet (IIS) during and following the Last Glacial Maximum. Here we study the Bustarfell drumlin field within the Vopnafjörður–Jökuldalsheiði flow‐set. The internal architecture of two drumlins was investigated using sedimentological analysis and ground‐penetrating radar (GPR, 50 and 100 MHz) to illuminate subglacial processes that contributed to drumlin formation, as well as the history and dynamics of the IIS. On the stoss side of one of the drumlins, two subglacial traction till units were identified, separated by a thick unit of deformed glaciofluvial sand and gravel. The core of glaciofluvial material suggests that the drumlin formed around well‐drained patches (sticky spots) in the subglacial bed that retarded the ice flow locally through increased basal drag and encouraged till deposition. Furthermore, our GPR data indicate a combination of erosional and depositional processes. We suggest that the glaciofluvial sediments were deposited as small ice‐marginal fans on the Bustarfell plateau, possibly during the Bølling–Allerød interstadial, and that the drumlins were formed around these fans during a subsequent readvance during the Younger Dryas.

Ice‐stream shutdown during deglaciation: Evidence from crevasse‐squeeze ridges of the Iceland Ice Sheet

“…Furthermore, we would expect that their original height has been extenuated due to the infill of post‐glacial sedimentation and soil around the ridges (Figure 9a; Spagnolo et al, 2012; Finlayson, 2013). Inter‐bedform thickness was observed as being over 2–3 m in Þistilfjörður and has been recorded up to 8 m around drumlins on Bustarfell in northeast Iceland (Aradóttir et al, 2023). For both reasons, we cannot exclude that additional CSRs remain obscured under the post‐glacial sediment cover.…”

“…Due to limited age constraints for the ice‐marginal features and raised shorelines in the two areas, we can only hypothesize the timing for the formation of the CSRs. The SSBs in Bakkaflói and Þistilfjörður are considered to have mainly formed during the LGM, when the ice sheet extended all the way to the shelf edge, as well as during the deglaciation and subsequent YD and Pb readvance (Aradóttir et al, 2023; Benediktsson, Aradóttir, et al, 2022). Since there are examples in both areas of CSRs that are superimposed on SSBs, it is certain that the CSRs post‐date the formation of the SSBs and can thus be associated with the ice‐stream shutdown (Figure 10).…”

“…Ice streams within the IIS during the last glacial maximum (LGM) and the subsequent deglaciation (Figure 1a) have been proposed based on large‐scale geomorphology and glacial striae (e.g., Benediktsson, Aradóttir, et al, 2022; Benediktsson, Brynjólfsson, & Ásbjörnsdóttir, 2022; Bourgeois et al, 2000; Norðdahl et al, 2019; Norðdahl & Pétursson, 2005; Principato et al, 2016; Spagnolo & Clark, 2009) and numerical modelling (Bourgeois et al, 2000; Hubbard et al, 2006; Patton et al, 2017). Recent investigations have focused on streamlined subglacial bedforms (SSBs; such as drumlins and mega‐scale glacial lineations, MSGLs), their cross‐cutting relationships and formation (Aradóttir et al, 2023; Benediktsson, Aradóttir, et al, 2022; Principato et al, 2016).…”

Morphometric analysis of ice scour lakes in Iceland: A proxy for ice sheet dynamics

“…The locations of ice divides (regions with minimal glacial erosion) and the locations of former ice streams within the Iceland Ice Sheet (IIS) have been proposed in modeling studies (Figure 1) (Bourgeois et al, 1998(Bourgeois et al, , 2000Hubbard et al, 2006;Patton et al, 2017). Analyses of streamlined subglacial bedforms, such as drumlins and mega-scale glacial lineations (e.g., Clark, 1993;Spagnolo et al, 2014;Stokes & Clark, 2002), provide additional evidence for paleo-ice flow conditions and paleo-ice streams in Iceland during the Last Glacial Maximum (LGM) (Arad ottir et al, 2023;Benediktsson et al, 2022d;Principato et al, 2016).…”

Utilização de métodos geofísicos para caracterização de depósito de areia em apoio à elaboração de plano de lavra na região de Leme, SP

“…Com o desenvolvimento tecnológico diversos equipamentos com modo de aquisição de registro digital foram construídos, minimizando o custo, otimizando sua portabilidade e tornando-se acessível e atingível a sua aquisição e, por conseguinte, sua utilização(BORGES, 2007). Atualmente, os cientistas têm utilizado o método em vários campos de aplicações, tais como: exploração mineral(DANIELS, 1988;DAVIS & ANNAN, 1988;SCAIFE & ANNAN, 1991;CARNEVALE et al 2005;FRANCKE, 2010;FRANCKE, 2012; CATALKI et al 2012;, RAO et al 2020De BARROS et al 2021), estudos geológicos, geotécnicos(SOLLA et al 2021;D'AMICO et al 2020) , ambientais, arqueológicos (ALMEIDA, 2016PORSANI et al 2017; ), hidrogeológicos (BERES & HAENI, 1991;MAHMOUDZADEDH et al 2012;SRINIVASAN et al 2021), sedimentológicos(BRISTOW & JOL, 2003;LEANDRO et al 2019;DELGADO et al 2022;ARADÓTTIR et al 2022), estudos de rios e lagos, mapeamento de interferências no subsolo urbano, entre outras aplicações(DAVIS & ANNAN 1989;SMITH & JOL, 1995;BENSON, 1995;VAN DAM, 2001;RODRIGUES & PORSANI, 2006;JOL, 2009, LEANDRO et al 2019 QIN et al 2021; JOSAGHANI & SHOKRABADI ,2021) são exemplos pesquisas.…”