Permafrost research in the granitic massifs of Southern Carpathians (Parâng Mountains)
Popescu, R.; Vespremeanu-Stroe, A.; Onaca, A.; Cruceru, N.
published: Mar 1, 2015
Thermal and geoelectrical methods were used to detect permafrost in rock glaciers, block fields, talus slopes and rockwalls in the granitic alpine area of Parâng Mountains where large rock deposits exist above the timberline. Variability of debris porosity at different sites, with and without permafrost, was preliminary assessed by measuring the clasts dimensions. The lower limits for permafrost occurrence and creep within debris-built landforms were found at 1,950 m and 2,100 m, respectively. The mean annual rock temperatures suggested conducive conditions for permafrost occurrence in northward exposed rockwalls above 2,350 m. DC resistivity profiles revealed relative thin permafrost (5–15 m) with medium to low ice content in tongue shape rock glaciers below 2,050 m, and thicker permafrost (> 20 m) with medium ice content in lobate rock glaciers above the mentioned altitude. It is assumed that about a half of permafrost areas in Parng Mountains are in thermal disequilibrium with the present climate. Our multiple investigations in Southern Carpathians show that the main factor influencing the downslope extension and hence the conventional lower limit of the permafrost specific to granitic massifs is the high porosity of unconsolidated debris deposits.