Regional Monitoring of Natural Environment 2004, No 5, 149-157
ORGANIC HORIZON IN PROFILE OF ALLUVIAL FAN FROM BOREAL/ATLANTIC TRANSITION IN PODGRODZIE UPON WISŁOKA RIVER
Anna Budek, Leszek Starkel
Organic horizon and breaks in sedimentation of alluvial fan from Boreal / Atlantic transition in Podgrodzie upon Wisłoka river.
This paper consider the genesis of one loamy organic horizon in the sequence of alluvial fan of small Maga creek, the tributary of Wisłoka river at the margin of Polish Carpathians. This fan represent the Holocene phase with higher frequency of extreme events dated between 8400 and after 7800 yrs 14C BP (fig.1). In this sequence 6 – 9 m thick there were earlier distinguished above 100 flood layers separated by 13 loamy – organic horizons, indicating the breaks in the deposition (fig.2).
The highest of this fossil organic horizon has been studied in detail using micromorphological method. The results have shown that this loamy – organic horizon originated in short time interval and the soil processes changed it in minimal degree (fig.3). Continuous and rapid upbuilding of fan surface excluded the formation of developed soil profile. The organic horizon in the fan sequence has developed as the horizon of local paludification with presence of high groundwater level. However, the weathered quartz grains seem to indicate the existence of pedogenic processes, which also facilitated the decomposition and mineralization of organic matter. Examination of thin section also shows that the process of gleing was weakly developed or was absent, due to higher permeability of the ground, connected a high content of sandy fraction (fig.3).