Sedimentary anisotropy diverges from flute trends in south-east Finnish Lapland Raimo Sutinen ⁎, Eija Hyvönen, Paavo Närhi, Paula Haavikko, Matti Piekkari, Maarit Middleton P. O. Box 77, FIN-96101 Rovaniemi, Finland abstract article info Article history: Received 30 June 2009 Received in revised form 16 February 2010 Accepted 18 February 2010 Available online 1 March 2010 Keywords: Ice stream Flute Electromagnetic Azimuthal conductivity Airborne gamma-ray Lapland Subglacial flutes are parallel-to-ice flow lineations indicative of glacial streamlining, yet their depositional/ erosional origin or sedimentary anisotropy is not fully understood. The flutes, aligned NW–SE with a flow direction to the SE, are superimposed on westerly oriented drumlins, in Kuusamo, south-eastern Finnish Lapland (65°45′N and 29°40′E) and reflect ice stream flow pattern towards the Younger Dryas End Moraines (YDEMs) in Russian Karelia. We investigated bedform morphology (flutes, drumlins and crescentic troughs), as well as sedimentary anisotropy of flute ridges and troughs using digital elevation models (DEMs), airborne radiometric (AR) data, and measurements of azimuthal electrical conductivity (σ a ). The DEM-AR revealed elongation ratios (L/W) from 2:1 to 25:1, yet the highest ratios reached L/W= 48:1. Flutes in the study area fan towards the east and south-east, whereas the drumlins on which they are superimposed show ice flow from the west (280°). The σ a -anisotropy of the flute ridges and troughs indicates sedimentation from 340° to 350°, diagonal with respect to both drumlins and flutes. We found erosional crescentic troughs with down- flow rims indicative of both phases, but failed to find evidence for subglacial meltwater boulder lags or ice- flow erosional bedrock bump sticky spots. We contend that the studied flutes are erosional and date to the YDEM-phase, yet the origin of the precursory sediments may date to Early Weichselian. © 2010 Elsevier B.V. All rights reserved. 1. Introduction 1.1. Flutes, ice streams and subglacial lakes Subglacial flutes are parallel-to-ice flow lineations indicative of ice streaming, yet their depositional or erosional origin and sedi- mentary anisotropy is not fully understood. Anisotropic sediments such as glacial tills, glaciofluvial materials and mass-flow deposits exhibit properties (e.g. clast fabric, magnetic susceptibility, dielectic permittivity and/or electrical conductivity) with different values when measured in different directions (see Sutinen et al., 2009a and references therein). Fluted terrains, often linked to paleo-ice stream- ing, are commonly found time-transgressively arranged inside the Late Glacial Maximum (LGM) and the Younger Dryas End Moraines (YDEMs) (Sutinen, 1992; Kleman et al., 1997; Boulton et al., 2001). Offshore mega-scale glacial lineations and terrestrial fields of drum- lins and (mega-) flutes reflect the former presence of paleo-ice streams beneath the former Fennoscandian Ice Sheet (FIS) (Nordka- lott Project, 1986; Sutinen, 1992; Kleman et al., 1997; Boulton et al., 2001; Ottesen et al., 2008) and Laurentide Ice Sheet (LIS) (Aylsworth and Shilts, 1989; Stokes and Clark, 1999; Munro-Stasiuk and Shaw, 2002; Briner, 2008; Stokes et al., 2007). The internal architecture and structure of elongated subglacial features, drumlins and flutes, may be due to gravel beds (erosional remnants), deformable beds and/or massive sediment flow deposits/conduit infills and the sediments may date back to pre-Late Weichselian (Wisconsinan) (Whittecar and Mickelson, 1977; Sutinen, 1985a; Boulton and Hindmarsh, 1987; Munro-Stasiuk and Shaw, 2002). Therefore the elongation pattern, rather than sedimentary composition, is diagnostic of the former ice streaming direction (e.g. Stokes and Clark, 1999; Briner, 2008; King et al., 2009). The findings from the East Antarctic Ice Sheet (AIS) suggest that the onset of the fast-flowing ice streams may be associated with large subglacial lakes (Bell et al., 2007). These dynamic subglacial water systems exert an important control on the ice streaming as observed in West AIS (Fricker et al., 2007) and acceleration of the flow speed of the outlet glaciers may result from subglacial floods as suggested in East AIS (Stearns et al., 2008). The ice stream tributaries may penetrate as far as 1000 km from the grounding line into the interior the West AIS (Bamber et al., 2000), significantly influencing ice sheet mass balance and dynamics in Antarctica (Conway et al., 2002). Similar influences are also seen in Greenland (Zwally et al., 2002). However, not all ice streams are attributed to subglacial lakes in their onset zones. For an example, soft clay deposits and dilatant till under the Rutford Ice Stream in Antarctica act as deformable beds which give rise to drumlins and mega-scale glacial lineations beneath the streaming ice (King et al., 2007, 2009). Seismic and radar ob- servations have indicated that drumlins are depositional forms and able to form within less than ten years beneath Rutford Ice Stream Sedimentary Geology 232 (2010) 190–197 ⁎ Corresponding author. E-mail addresses: raimo.sutinen@gtk.fi (R. Sutinen), eija.hyvonen@gtk.fi (E. Hyvönen), paula.haavikko@gtk.fi (P. Haavikko), matti.piekkari@gtk.fi (M. Piekkari), maarit.middleton@gtk.fi (M. Middleton). 0037-0738/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.sedgeo.2010.02.008 Contents lists available at ScienceDirect Sedimentary Geology journal homepage: www.elsevier.com/locate/sedgeo