Mineral composition and source of clastic karst sediments

Objectives of the course

We divide clastic cave sediments according to origin as autochthonous or allochthonous. The former originate through the processes of disintegration of cave ceilings and walls, and the latter are brought into the caves from elsewhere, most often by water. Allochthonous mechanical sediments in caves include clay, sand, gravel, and light soil that have their source outside the caves. Relative to their depositing both in caves and on the surface, sediments are subject to the processes of diagenesis and weathering. In almost all samples of sediments from caves, unroofed caves, and the bottom of shafts in the Classical Karst, almost the same mineral composition dominates, indicating their primary origin from Eocene flysch rock that has been weathered to various degrees. The sediments are yellow or red. The yellow sediments that are in contact with water percolating from the surface change colour to red during diagenesis in the oxidation zone. One of the characteristics of the Classical Karst is red soil, which originated on various clastic sediments, limestone, limestone with quartz, and dolomite. In the sediments from caves and unroofed caves no minerals are found that are characteristic of light soil, which reflects the fact that the caves were probably filled with sediment before the deposit/development of loess in Istria.

Prerequisites

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Assessment methods

Oral exam.

Course contents

• Introduction
• Surface clastic sediments on karst in Slovenia and around the world
• Division of clastic cave sediments
• Autochthonous clastic cave sediments
• Allochthonous clastic cave sediments
• Fluvial clastic sediments, their graininess and sedimentation
• Mineral composition of clastic cave sediments and their origin
• Source of soil on karst

Recommended reading

• Durn, G. & Aljinović, D., 1995: Heavy Mineral Assemblage in Terra Rossas from the Peninsula of Istria, Croatia. Abstracts, First Croatian Geologica Congress, 31, Zagreb.
• Gregorič, V., 1967: Minerali glin v nekaterih talnih enotah Slovenskega primorja. Geologija 10, 247–270, Ljubljana.
• Gregorič, V., 1969: Nastanek tal na triadnih dolomitih. Geologija 12, 201–230, Ljubljana.
• Habič, P., 1992: Les Phenomenes Paleokarstiques du Karst Alpin et Dinarique en Slovenie. Karst et evolutions climatiques. Presses Universitaires de Bordeaux, 411–428, Bordeaux.
• Kranjc, A., 1986: Underground fluvial sediments as an example from Škocjanske Jame (Kras, Slovenia). Acta carsologica 14–15, 109–116, Ljubljana.
• Kranjc, A., 1989: Recent fluvial cave sediments, their origin and role in speleogenesis. Opera 4. razreda, SAZU, 167, Ljubljana.
• Melik, A., 1961: Fluvialni elementi v krasu. Geografski zbornik 6, 333–361, Ljubljana.
• Mihevc, A. & Zupan Hajna, N., 1996: Clastic sediments from dolines and caves found during the construction of the motorway near Divača, on the classical Karst. Acta carsologica 25, 169–191, Ljubljana.
• Mihevc, A., 2001: Speleogeneza Divaškega krasa. Zbirka ZRC, 27, 180. Ljubljana.
• Zupan Hajna, N., 1992: Mineral composition of mechanical sediments from some parts on Slovenian karst. Acta carsologica 21, 115–130, Ljubljana.
• Zupan Hajna, N., 1995: A comparison of the mechanical cave sediments from the caves the Škocjanske jame, the Labodnica, the Prevala II and the Mejame. Annales for Istrian and Mediterranean Studies 7, 1995, 117–120, Koper.
• Zupan Hajna, N., 1998: Mineral composition of clastic sediments in some dolines along the new motorway Divača- Kozina. Acta carsologica 27, 277–296, Ljubljana.
• Zupan Hajna, N., 1999: Comparison of some clastic sediments from the surface and caves of Divača Karst, SW Slovenia. – V/In: Karst 99 : Colloque européen : des paysages du karst au géosysteme karstique : dynamiques, structures et enregistrement karstiques. Etudes de géographie physique, supplément 28. CAGEP, 209–214, Aix-en-Provence.
• Zupan Hajna, N., 2005: Klastični sedimenti in prst na Krasu = Clastic sediments and soils on the Kras. V: Mihevc, A. (ur.). Kras : voda in življenje v kamniti pokrajini = water and life in a rocky landscape, (Projekt Aquadapt).: Založba ZRC, ZRC SAZU, 37-43, Ljubljana.