Geological Survey of Finland, Special Paper 46 - arkisto.gsf.fi

Applied Quaternary research in the central part of glaciated terrain,
edited by Peter Johansson and Pertti Sarala.
Geological Survey of Finland, Special Paper 46, 135–140, 2007.
LITHOLOGICAL CONTRIBUTION TO HYDRAULIC PROPERTIES OF
TILLS: INTER-SEASONAL DIELECTRIC ASSESSMENT
by
Raimo Sutinen 1 , Matti Piekkari 1 , Aki Tepsa 2 , Markku Virtanen 1 and Pekka Hänninen 3
Sutinen, R., Piekkari, M., Tepsa, A., Virtanen, M. & Hänninen. P.
2007. Lithological contribution to hydraulic properties of tills: interseasonal
dielectric assessment. Applied Quaternary research in the
central part of glaciated terrain. Geological Survey of Finland, Special
Paper 46, 135–140, 5 fi gures.
Composition, particle-size distribution and clay mineralogy of tills
are associated with the lithology of source rock types and the mode of
deposition beneath continental ice sheets. The infl uence of lithological
characteristics on hydraulic properties, particularly on the spatio-temporal
variation of water content in tills, however, has remained obscure.
Inter-seasonal monitoring of the dielectric properties of tills (εTILL) with
varying composition in lithology and particle-size distribution was
carried out from 1995 to 2003 in Finnish Lapland. Two sites were selected
on the basis of similarity in climatic conditions, but dissimilarity
in lithology (felsic granite gneiss-mafi c chlorite-amphibole schist)
and texture (sandy till-silty till), respectively. Inter-annual monitoring
demonstrated that the variation in unfrozen soil water content of tills
followed climatic events, but snowmelt was the major contributor to
the intra-seasonal εTILL. The increase in εTILL was initiated by meltwater
released from snowpack from two weeks to more than three weeks before
the disappearance of snow in both cases. However, the response of
snowmelt to εTILL was clearly site and texture-specifi c, such that maximum
εTILL-peak for sandy till occurred several weeks before εTILL-peak of
silty till. The timing difference of a month was observed between the
latest spring (1996) and earliest springs (2002, 2003). The intra- and
inter-seasonal soil εTILL was signifi cantly lower (F=810, p=0) in sandy
till than that in silty till. Even the maximum εTILL of the sandy site was
minor to minimum for the silty site. It was found that the mean interseasonal
εTILL=7.0±1.36 applies to sandy till and εTILL=24.4±6.56 to silty
till, respectively. We estimated (99% confi dence) that the inter-seasonal
mean of sandy till varies between 6.7