Morphological and Physical Properties of Dehydrated Holocene Carbonate Limnic Deposits in Post-Bog Areas of NW Poland

Abstract

Holocene limnic deposits characteristic of the average latitudes have partially outcropped as a result of young glacial sculpture aging. The change of the environment from limnic to telmatic and often the interference of a man associated with the regulation of water relations led to the emergence of limnic deposits that underwent the process of pedogenesis. In this work, 137 samples of carbonate deposits from 6 sites in NW Poland were analyzed in terms of their physical properties. Carbonate sediments were subject to determination of specific and bulk densities, total porosity and air porosity, current and capillary water capacity. On the basis of CaCO 3 content, combustion loss, and non-lime mineral content, the studied sediments were classified into three groups: lacustrine chalk, calcareous gyttja, and clay-calcareous gyttja. Studies have shown that the sediments subject to pedogenesis in the top levels have characteristic morphological features in the form of cracks and numerous channels and iron fills in the form of spotted, streaked or marbled mosaic. The top levels of sediments, as a result of dehydration, clearly increase their bulk density. Properties of the lake chalk were formed mainly by the proportion of organic matter and CaCO 3 , while in the case of carbonate gyttja, the influence of mineral parts of the non-lime substances is also highlighted. In the top of carbonate sediments, there is a decrease in general and capillary porosity and an increase in the share of macropores.

Keywords

• lacustrine chalk
• outcropped carbonate deposits
• pedogenesis
• calcareous gyttja
• clay-calcareous gyttja