Naslov
The role of denudation in forming unroofed caves, the case of Eagle Cave system (Spain)

Autori
Krklec, Kristina ; Domínguez-Villar, David

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
24th International Karstological School "Classical Karst" Paleokarst: abstracts & guide book / Otoničar, Bojan ; Gostinčar, Petra - Ljubljana : ZRC Publishing, 2016, 20-20

ISBN
978-961-254-914-5

Skup
24th International Karstological School "Classical Karst": Paleokarst

Mjesto i datum
Postojna, Slovenija, 13.06.2016. - 17.06.2016

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
unroofed cave ; denudation ; rock weathering ; rock tablets

Sažetak
Denudation plays important role in evolution of cave systems and can lead to exposure of cave passages to the surface and formation of unroofed caves. In the area of Eagle cave, in central Spain, collapse breccias and flowstone speleothems exposed at the surface indicate the existence of unroofed caves. Their formation is the result of bedrock thinning above caves, triggering the collapses of their ceilings. We consider two end-member hypotheses that may explain this thinning: (1) a progressive denudation at the surface or (2) the collapse of blocks from cave ceilings. In order to evaluate the importance of denudation in the formation of unroofed caves at this site, we buried rock tablets for a year, at the depth of half meter, on top of the cave. Measured denudation rate was 1.75± 0.66 μm/yr, and different local lithologies did not show different weathering. Even if denudation rate could have been higher in the past, fluvial dissection rates are two orders of magnitude higher, causing dissolution of bedrock under the existing caves enabling new collapses. Alternatively, the fall of blocks inside the cave galleries is potentially a more efficient process for the progressive thinning of the cave ceiling before collapse. Therefore, the formation of unroofed caves is likely to be the result of thinning of cave ceilings dominated by collapses from inside the cave.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA