Tektonska zgradba sistema Postojnskih jam = Tectonic structure of Postojnska jama cave system

• Main Author: Šebela, Stanka (auth)
• Format: Electronic Book Chapter
• Language: English; Slovenian
• Published: Ljubljana ZRC SAZU, Založba ZRC 1998
• Series: ZRC 18
• Subjects: Slovenia; Geological surface processes (geomorphology); cave trenches; geological maps; karst caves; karstology; Postojna cave; speleogenesis; studies; tectonic structure; tectonics; geološke karte; jamski rovi; kraške jame; krasoslovje; Postojnska jama; speleogeneza; študije; tektonika; tektonska zgradba
• Online Access: DOAB: download the publication; DOAB: description of the publication

The Postojnska jama cave system represents a union of old, now dry, horizontal cave passages, the Pivka river active passage, and shafts or collapse dolines, which enable surface connection with some cave passages. The present entrance to the cave is formed at the contact between the Postojna basin impermeable Eocene flysch and the Upper Cretaceous limestone. The Pivka river sink entrance is formed along interbedded movements in the horizontal direction, and in the vertical direction it lies in a strong tectonic fault zone of NE-SW direction. The cave passages are formed in tectonic deformations which developed by the formation of the Postojna anticline, as there are interbedded movements, and in later fault deformations, where the main tectonic fault zones directions are the Dinaric NW-SE and cross-Dinaric NE-SW. Besides two main fault directions, the accompanying broken and fissured zones which are the result of the fault Dinaric tectonics are also favourable to cave formation.

Sistem Postojnskih jam predstavlja združbo starih, danes suhih, vodoravnih jamskih rovov, aktivnega rova reke Pivke in brezen oziroma udornic, ki omogočajo povezavo površja z nekaterimi jamskimi rovi. Današnji vhod v jamo je oblikovan na kontaktu med neprepustnim eocenskim flišem Postojnske kotline in zgornje krednim apnencem. Ponorni vhod reke Pivke je v horizontalni smeri oblikovan po medplastnih zdrsih, v vertikalni smeri pa leži v močni tektonsko prelomni coni smeri severovzhod-jugozahod. Jamski rovi so se oblikovali v tektonskih deformacijah nastalih pri formiranju Postojnske antiklinale, kot so medplastni zdrsi ter v kasnejših prelomnih deformacijah, pri čemer so glavne smeri tektonsko prelomnih con Dinarske SZ-JV in prečno Dinarske SV-JZ. Poleg dveh glavnih prelomnih smeri so ugodne tudi spremljajoče porušene in razpoklinske cone, ki so rezultat prelomne Dinarske tektonike.