Cave Sediments in Škocjanske Jame and Unroofed Caves Above Them, Sw Slovenia

0481160 - GLÚ 2019 RIV AU eng C - Konferenční příspěvek (zahraniční konf.)
Zupan Hajna, N. - Mihevc, A. - Pruner, Petr - Bosák, Pavel
Cave Sediments in Škocjanske Jame and Unroofed Caves Above Them, Sw Slovenia.
Proceedings of the 17th International Congress of Speleology, Sydney 2017. Vol. 2. Sydney: Australian Speleological Federation, 2017 - (Moore, K.; White, S.), s. 34-36. ISBN 978-0-9808060-5-2.
[International Congress of Speleology /17./. Sydney (AU), 22.07.2017-28.07.2017]
Institucionální podpora: RVO:67985831
Klíčová slova: mineral composition * cave sediments * unroofed caves * Classical Karst * SW Slovenia
Obor OECD: Geology

Škocjanske jame (the Škocjan Caves, UNESCO World Heritage and RAMSAR) are situated in the area known as the Divaški kras (Divača Karst), the SE part of Kras Plateau (also known as the Classical Karst). The area is extremely rich in surface karst forms, caves and especially in unroofed caves, which were defined from this area for the first time. Clastic fill of unroofed caves and still existing caves consist mainly of weathering products of Eocene flysch rocks and carbonates eroded from the Reka River catchment area. The biggest caves in the area are Škocjanske jame and Kačna jama where underground flow of Reka River may be found. River sinks into Škocjanske jame and water flows about 250 m below the surface toward Kačna jama, then to Labodnica cave (Abisso di Trebiciano) in Italy and finally to Timavo springs N of Trieste. Fluvial deposits and collapse rocks in caves as Škocjanske jame, Divaška jama and Trhlovca were studied by Gospodarič, who correlated them with Pleistocene climate changes but not older than 400 ka. Fluvial sediments on the karst surface originally linked to surface water flows, predecessor of the Reka River, were lately identified as cave deposits. Fluvial sediments and speleothems from the Škocjanske jame, caves and unroofed caves on the surface were sampled. The mineral composition of all studied sediments both in unroofed caves and caves of the region is very similar. In almost all samples relatively equal mineral composition prevailed, indicating the main source from flysch rocks which were differentially weathered. The samples contained quartz, clay minerals and the minerals microcline, plagioclase, muscovite and heavy minerals (tourmaline, rutile) which are typical of Eocene flysch rocks in the Reka River catchment area. The process of flysch transport into the caves continues for few million years, but the intensity varied over time. Large areas of cave sediments on Divača Karst having their origin in flysch rocks shows that in some period flysch rocks weathered intensively and the sediments were transported to the then existing caves. The erosion of flysch rocks was probably accelerated in the colder climate and due to increased rainfall or/and due to tectonic uplifting of the landscape. Mineralogical, sedimentological and paleomagnetic analysis of clastic sediments from various caves of the Divača Karst confirmed their provenance, depositional.
Trvalý link: http://hdl.handle.net/11104/0276765