Geologic setting of the Pre-Pliocene basis of the Velenje depression and its surroundings
Geological investigations center on the basement of the Velenje structural depression as well as on the set-up of its surroundings. Several tectonic units combine in the structure of the wider area: the Podgorje-Vitanje graben, the Velunja overthrust appertaining to the large unit of the northern Karavanke Mountains, the central Karavanke Mountains, the Southern Karavanke Mountains, the Velenje depression proper, and the Gorenje-Šoštanj block. The Velenje depression is of neotectonic formation. The bottom of the elongated through extends in NW-SE direction. The northern flank of the depression - involving about one third of its total crosscut length - exhibits the Triassic makeup of the Karavanke Mountains, vvhereas the Southern two thirds consist of the Oligo- Miocene and Miocene strata. The features of the Triassic Karavanke have been investigated at the locality Gabrke-Ležen. Taking part in the structure are the Scythian, Anisian and the Upper Triassic beds, all of them represented by prevailingly calcareous rocks. The Oligo-Miocene and Miocene beds consist of marly clays, sandy clays, sandstones and marls, in places of andesites and dacites, accompanied by pyroclastics as well.