Application of ground penetrating radar supported by mineralogical-geochemical methods for mapping unroofed cave sediments

Čeru, Teja (avtor), Dolenec, Matej (avtor), Gosar, Andrej (avtor)

Ground penetrating radar (GPR) using a special unshielded 50 MHz Rough Terrain Antenna (RTA) in combination with a shielded 250 MHz antenna was used to study the capability of this geophysical method for detecting cave sediments. Allochthonous cave sediments found in the study area of Lanski vrh (W Slovenia) are now exposed on the karst surface in the so-called “unroofed caves” due to a general lowering of the surface (denudation of carbonate rocks) and can provide valuable evidence of the karst development. In the first phase, GPR profiles were measured at three test locations, where cave sediments are clearly evident on the surface and appear with flowstone. It turned out that cave sediments are clearly visible on GPR radargrams as areas of strong signal attenuation. Based on this finding, GPR profiling was used in several other places where direct indicators of unroofed caves or other indicators for speleogenesis are not present due to strong surface reshaping. The influence of various field conditions, especially water content, on GPR measurements was also analysed by comparing radargrams measured in various field conditions. Further mineralogical-geochemical analyses were conducted to better understand the factors that influence the attenuation in the area of cave sediments. Samples of cave sediments and soils on carbonate rocks (rendzina) were taken for X-ray diffraction (XRD) and X-ray fluorescence (XRF) analyses to compare the mineral and geochemical compositions of both sediments. Results show that cave sediments contain higher amounts of clay minerals and iron/aluminium oxides/hydroxides which, in addition to the thickness of cave sediments, can play an important role in the depth of penetration. Differences in the mineral composition also lead to water retention in cave sediments even through dry periods which additionally contribute to increased attenuation with respect to surrounding soils. The GPR method has proven to be reliable for locating areas of cave sediments at the surface and to determine their spatial extent, which is very important in delineating the geometry of unroofed cave systems. GPR thus proved to be a very valuable method in supporting geological and geomorphological mapping for a more comprehensive recognition of unroofed cave systems. These are important for understanding karstification and speleogenetic processes that influenced the formation of former underground caves and can help us reconstruct the direction of former underground water flows.

• Jezik: Angleški jezik
• Ključne besede: ground penetrating radar (GPR), X-ray diffraction (XRD), X-ray fluorescence (XRF), karst, cave sediments, unroofed caves
• Vrsta gradiva: Članek v reviji
• Tipologija: 1.01 - Izvirni znanstveni članek
• Organizacija: NTF - Naravoslovnotehniška fakulteta
• Status publikacije: Objavljeno
• Različica publikacije: Objavljena publikacija
• Leto izida: 2018
• Št. strani: 25 str.
• Številčenje: Vol. 10, iss. 4, art. 639
• PID: 20.500.12556/RUL-128669
• UDK: 55
• ISSN pri članku: 2072-4292
• DOI: 10.3390/rs10040639
• COBISS.SI-ID: 1401694
• Datum objave v RUL: 22.07.2021

Gradivo je del revije

• Naslov: Remote sensing
• Skrajšan naslov: Remote sens.
• Založnik: MDPI
• ISSN: 2072-4292
• COBISS.SI-ID: 32345133

Licence

• Licenca: CC BY 4.0, Creative Commons Priznanje avtorstva 4.0 Mednarodna
• Povezava: http://creativecommons.org/licenses/by/4.0/deed.sl
• Opis: To je standardna licenca Creative Commons, ki daje uporabnikom največ možnosti za nadaljnjo uporabo dela, pri čemer morajo navesti avtorja.
• Začetek licenciranja: 20.04.2018

Sekundarni jezik

• Jezik: Slovenski jezik
• Ključne besede: georadar, RTG praškovna difrakcija, rentgenska fluorescenčna spektrometrija, kras, jamski sedimenti, brezstrope jame

Projekti

• Financer: ARRS - Agencija za raziskovalno dejavnost Republike Slovenije
• Številka projekta: P1-0011
• Naslov: Regionalna geologija

• Financer: ARRS - Agencija za raziskovalno dejavnost Republike Slovenije
• Program financ.: Young researchers
• Številka projekta: 1000-15-0510