KLJUČNE BESEDE terestrično lasersko skeniranje, oblak točk, velike jame, prostornina, Slovenija ABSTRACT In this article, we present issues arising from Terrestrial Laser Scanning of large natural ...caves using the example of Skocjan Caves, a UNESCO World Heritage Site. KEY WORDS Terrestrial Laser Scanning, point cloud, large caves, volume, Slovenia 1 INTRODUCTION A project of 3D laser scanning of the cave was carried out by the Karst Research Institute of the ZRC SAZU and the Škocjan Caves Park together with the members of the British Cave Association (BCA) in 2018 and 2019. Cave Škocjanske jame (Škocjan Caves, UNESCO World Heritage and RAMSAR) is 5.8 km long cave near Divača village (Classical Karst, SW Slovenia; Fig. 1). While the volumetric data that could be obtained from LiDAR surveys is incredibly accurate, it was felt that quoting volumetric metrics to 2 decimals (i.e. 0.01 x 106 m3) reflected the issue that chamber boundaries are difficult to define consistently, there are issues in defining the exact boundaries of the cave chambers; therefore we have restricted quoting volume metrics to 2 decimal places (ie. 0.01 x 106m3).
The x-ray powder diffraction identification of clay minerals both in bulk samples and in separated clay fraction confirmed the presence of palygorskite in samples of cave sediments from Wadi Haqil ...(the western slopes of Musandam Mountains; Ras Al-Khaimah Emirate, UAE). Samples contain quartz, gypsum, smectite, kaolinite, calcite, and palygorskite, some of them chlorite, illite, feldspars, and goethite. Calcite dominates in most samples; smectite prevails in clay fraction. After heating, the 001 reflection of chlorite shifts to higher diffraction angles and its intensity decreases; these features indicate that the chlorite represent a Fe-dominant species. Unit-cell dimensions of major phases as refined by the Rietveld method are in agreement with literature data. Chemical composition of palygorskite was derived from unit-cell dimensions as follows: MgO content is 11–14 wt% and Al
2
O
3
10–13 wt%. Clay mineralogy is only hard to ascertain from the scanning electron microscope (SEM) images even after being combined with the energy-dispersive spectrometer data. The SEM was also used to characterize gypsum grains; they often display flow deformation features. Studied cave sediments represent palygorskite-bearing weathering products and desert soils re-deposited from the cave surroundings by slope processes and wind and/or surface runoff. The mixture with other clay minerals, quartz, feldspars, etc. supports this interpretation. Fine-grained quartz fraction is probably wind-blown. Gypsum and calcite are the precipitates (crusts and/or cements), although gypsum can also be re-deposited from omnipresent gypsum-cemented surface sediments.
V vzorcih iz treh različnih jam smo proučevali mikroorganizme, ki jih lahko gojimo v laboratorijskih razmerah. V jami Pečina v Borštu smo prisotnost mikroorganizmov proučevali v preperelem apnencu, ...jamskem srebru in v jamski ponvici, kjer se na površini velikokrat pojavljajo kalcitne ploščice; v Martinski jami v preperelem apnencu, v Snežni jami na Raduhi pa kalcitno jamsko mleko. Podatki o številu mikroorganizmov so bili v nekaterih primerih dopolnjeni πe z identifikacijo širše skupine ali rodu. Rezultati kažejo, da so poleg še nekaterih drugih bakterijskih in glivnih taksonov fluorescentne pseudomonade prevladujoči mikroorganizmi.Various microenvironments in three different caves were screened for the presence of indigenous culturable microorganisms: extremely weathered limestone in Pečina v Borštu and Martinska jama, cave silver and calcite rafts on the surface of subterranean ponds in Pečina v Borštu and calcite moonmilk speleotheme in Snežna jama of Raduha mountain. The counts of viable cells collected are supplemented with laboratory data necessary to establish genus or wider taxonomic group level identity of isolates. Besides other bacterial and fungal groups flourescent pseudomonads are prevailing among isolates.
Clastic and chemogenic cave sediments were sampled and analyzed from Račiška pečina and Pečina v Borštu caves of southwestern Slovenia. Samples were subjected to both thermal and alternating field ...demagnetization; specimens belonging to the same sample of the same layer produce identical results. Unblocking temperatures of 540 to 560°C on average suggests magnetite as the principal carrier of magnetization. These directions also pass a reversals test indicating the demagnetization results are free of secondary overprints and have adequately averaged out paleosecular variation. Normally magnetized clays containing fauna belonging to the MN17 mammal biozone at a depth of ∼ 4 m in Račiška pecina cave indicate these clays were deposited at the beginning of the Olduvai subchron (1.95 Ma). Correlation with the Geomagnetic Polarity Time Scale (GPTS) indicates the base of the speleothems in Račiška pečina terminate in the upper part of subchron C2An.3n with numerous breaks in deposition, lasting up to 250 ka and more. Therefore rates of speleothem growth cannot be calculated. Fold tests on dome-like stalagmites of differing sizes and ages (Pleistocene, Pliocene) from the two caves indicate the domelike structures are primary.
Caves are important markers of surface evolution, since they are, as a general rule, linked with ancient valley bottoms by their springs. However, caves can only be dated indirectly by means of the ...sediments they contain. If the sediment is older than common dating methods, one has to use multiple dating approaches in order to get meaningful results. U/Th dating, palaeomagnetic analysis of flowstone and sediment profiles, cosmogenic dating of quartz pebbles, and mammalian dating allowed a robust estimate of speleogenesis, sediment deposition, climatic change at the surface, and uplift history on the Periadriatic fault line during the Plio-Pleistocene. Our dates indicate that Snežna jama was formed in the (Upper) Miocene, received its sedimentary deposits during the Pliocene in a rather low-lying, hilly landscape, and became inactive due to uplift along the Periadriatic and Sava faults and climatic changes at the beginning of the Quaternary. Although it is only a single cave, the information contained within it makes it an important site of the Southern Alps.
•We present a comprehensive dating approach to sediments of a Slovenian cave.•We interpret the results in the light of climatic change and tectonic uplift.•We show that collaborative work on one single cave can yield results of broader interest.
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