engleski

Kornat Island rockslide – exposure and weathering of carbonate surface

Kornat Island rockslide occurred ~2400 years ago (as determined by cosmogenic 36Cl analyses) and its carbonate surface has been exposed to environmental conditions. In order to get an insight to weathering process, morphometry of karren features developed on rockslide surface and adjacent surface with different exposure time has been measured and compared. Results show that the surface affected by the rockslide has less grikes with majority inherited from previous weathering stage indicating that exposure time since the rockslide event has not been sufficient to homogenize these features between both rock surfaces. Analysis of morphologies such as tritkarren and rillenkarren indicates that their genesis is likely to occur at decadal to centennial timescale. Due to similarity of kamenitzas and solution pits found on both rock surfaces it is impossible to distinguish the size parameters, but area and depth parameters of both forms are clearly correlated. Therefore we define a morphometric index: A/D ratio as the slope between these two parameters within each population. We suggest that the A/D ratio is related to the evolution/relative age of the karren features since after an initial stage, preferential weathering occurs along the vertical axis in solution pits and laterally in kamenitzas. Therefore, in case of different surfaces affected by the same weathering conditions A/D ratios in kamenitzas and solution pits could serve as indication of time exposed to weathering. These morphologies are likely to be developed in decadal to centennial timescales, but change of their morphology can be tracked at millennial timescale.

Karst ; Weathering ; Morphometry ; Rockslide ; Cosmogenic nuclides ; 36Cl ; Croatia

nije evidentirano