Laboratory modeling of karst phenomena and their rock relief on plaster: subsoil karren, rain flutes karren and caves

Abstract

IzvlečekUDK 911.2:551.435.8 Tadej Slabe, Asami Hada & Martin Knez: Laboratorijsko modeliranje kraških pojavov in njihovega skalnega reliefa na mavcu: podtalne škraplje, dežni žlebiči in jame Proučevanje oblikovanja in razvoja kraških pojavov in njihovega skalnega reliefa z laboratorijskim modeliranjem z mavcem se je spet izkazalo kot koristno in povedno. Nadaljevali smo s proučevanjem podtalnih škrapelj, ki se oblikujejo pod tesnim, slabo prepustnim stikom s prstjo in dežnih žlebičev, ki se oblikujejo z vodo različnih temperatur. Razbrali smo način oblikovanja mavčnih cevi, ki so širše na pritočni kot odtočni strani. Izsledki so pomemben prispevek k razlagi oblikovanja visokih stropnih niš in kotlic v kraških jamah. Tretji poizkus smo izvedli v freatičnih pogojih, ko se je voda pretakala med plastmi različne sestave. Opazovali smo značilen razvoj kanalov med ploščami čistega mavca (apnenčasta plast), med ploščami mavca z dodanimi in s cementom učvrščenimi počasneje topnimi klasti (breča), siporeksom (slabo topna kamnina) in med tremi različnimi ploščami. Ključne besede: laboratorijsko modeliranje, kras, skalni relief, podtalne škraplje, žlebiči, jame. The study of the formation and development of karst phenomena and their rock relief using laboratory plaster modeling has again proven useful and informative. we continued the study of subsoil karren that forms under tight, poorly permeable contact with soil and of rain flutes formed by water at various temperatures. we determined the pattern of the reshaping of plaster tubes that are wider at the flow inlet than at the outlet end. The results are a significant contribution to explaining the formation of high ceiling niches and pockets in karst caves. The third experiment was carried out in phreatic conditions where water in a flume was forced to flow between layers of different composition. During the experiment, we observed the typical development of channels between pure plaster layers (uniform limestone beds), between plaster layers with added Portland cement reinforced fragments (breccia beds), siporex (slowly dissolving beds) and between three different layer types. Key words: laboratory modeling, karst, rock relief, subsoil karren, rain flutes, caves.ACTA CARSOLOGICA 45/2 -2016 TADEJ SLABE, ASAMI HADA & MARTIN KNEZThe modeling of karst phenomena and their rock forms and relief in plaster exposed to different factors in a variety of conditions has often proved useful. The limitations and particularities of plaster modeling often originate in the fact that in most cases the models are smaller than the original phenomena in nature and that more plaster dissolves (more than 2 g of plaster dissolves per 100 g of water at 20 °C). The consequence of the latter is that the forms on plaster are typically smaller than those on limestone and their development cycle is much faster. According to our experience, however, they provide a very useful comparison. Modeling offers various possibilities for the continuous monitoring of the origin and development of rock forms. w...

The hydrodynamic genesis of linear karren patterns

“…For this reason, experimental efforts have mainly focused on reproducing rillenkarren by dissolving blocks of minerals under artificial rain (Glew & Ford 1980; Slabe et al. 2016). Although rain might affect some features of karren formation (as we discuss in the following), our model shows that a water flow – without falling raindrops being involved – is sufficient to generate linear karren forms.…”

“…where the water is very undersaturated (Glew & Ford 1980; Ginés et al. 2009; Slabe, Hada & Knez 2016), we consider a dissolution kinetics that is diffusion controlled. This implies that surface reactions are fast compared to diffusion and that the solute accumulates in a very thin diffusion boundary layer at the solid–liquid interface that is nearly saturated (e.g.…”

Ultra-sharp pinnacles sculpted by natural convective dissolution

“…Further, stone forests have been discovered buried under loose sediment (10), suggesting that surface erosion is not essential to the pinnacle motif. Mineral spires can result from complete submersion under water followed by drainage (11), though the degree of shape development during these stages is unclear. Given the uncertainties regarding which factors are most critical, the study of pinnacle formation may benefit from laboratory experiments in which conditions can be imposed and cleanly controlled and the relevant shape developments observed and measured.…”

The karren peeling off on marbles in Altai (Altai Republic, Russian Federation)

“…Comparative studies of karst geology, forms, and the rock relief of karst phenomena reveal their respective development and deepen our knowledge about the karst formation on different carbonate rocks in diverse conditions of the world (Knez et al 2003(Knez et al , 2010(Knez et al , 2011(Knez et al , 2012(Knez et al , 2015(Knez et al , 2017(Knez et al , 2019Debevec et al 2012;Al Faraj Al Ketbi et al 2014;Gutiérrez Domech et al 2015;Slabe et al 2016).…”