Radar stratigraphy of the glaciotectonically deformed deposits in the Isoniemi area, Haukipudas, Finland

Abstract

The study of deposits in the central areas of Weichselian Scandinavian Ice Sheet (SIS) is important for understanding behaviour of the ice sheet. This study provides new information on the deposits in the previously poorly known glaciofluvial Isoniemi complex in Haukipudas, Finland, located in the central part of SIS. The deposits are studied using ground penetrating radar (GPR) to delineate the depositional and glaciotectonic environments and events that have occurred in the area. The results are interpreted using the principles of radar stratigraphy and correlated with an earlier sedimentological study from the area. Borehole logs of old boreholes made for ground water and aggregate investigations are used as an aid in the interpretation alongside the previously obtained sedimentological data. GPR data show 10 radar facies separated by seven radar surfaces. The sequence of events interpreted from GPR data and earlier sedimentological study include: 1) deposition of the glaciofluvial sediments, 2) deposition of till and the first stage of deformation by an advancing glacier, 3) retreat of the glacier, and cutting and infilling of the proglacial channels, 4) proglacial deformation forming the Runteli ridge, 5) glacioisostatic uplift close to the water level, 6) possible forming of the rip current channels and 7) reworking of the earlier sediments by wave and sea-ice action.

Keywords

• glaciofluvial features
• sediments
• till
• stratigraphy
• ground-penetrating radar
• glaciotectonics
• deformation
• Quaternary
• Isoniemi
• Haukipudas
• Finland