Tectonics impact on poljes and minor basins (case studies of Dinaric Karst)

Abstract

The aim of this study is to show tectonic features in selected poljes and minor basins in the Dinaric Karst. Boreholes and gravimetric measurements show thick Neogene loose sediments and the rocky bottom below the sea level - real cryptodepressions. The sediments make parts of a large plain that subsided at the end of the low Pliocene. The recent seismic activity in this area proves the ongoing tectonic process. The deepest (more than 100 m) and the smallest polje in the Slovenian Dinaric karst, Globodol is a dry polje in the piezometric level. Quaternary subsidence of the bottom is the only reasonable explanation of its genesis. On Planinsko polje there are signs ob suballuvial corrosion and the indicators of the Holocene tectonic subsidence. Four poljes in the Ravni kotari (Dalmatia) are shallow basins in the first stage of development, They prove the process of the bottom levelling below the shallow cover of alluvial sediments. An extremely deep small basin is about 450 m deep Red Lake (Hercegovina) and small basins at Črnomelj and Kočevje (Slovenia), 300 m and 100 m deep below the sea level.