Relationship between mineralogy and the physico-chemical properties of till in central Finland

Abstract

The chemical and physical characteristics of the fine fraction of till were examined in the area of the Raahe-Ladoga metallogenic belt in central Finland. Till, weathered bedrock and rock samples were collected from the area, where element concentrations of fill abruptly ranged from high in an anomalous zone (NE) to low in a non-anomalous zone (SW). The absence of the swelling smectite component from the surface layers of till indicates that the source was not the underlying weathered bedrock. The till with a vermiculitic mixed-layer mineral in the anomalous zone contains more material from old sediments weathered during interstadial or interglacial time than does the till with a low clay content in the non-anomalous zone. The abrupt change in the mineralogical and physical properties of till in the study area is suggested to be attributed to the difference in the transport and accumulation dynamics of overburden during deglaciation. -from Authors