Veress Márton: A Bakony természettudományi kutatásának eredményei 23. - Covered karst evolution... (Zirc, 2000)

CONCLUSIONS

CONCLUSIONS 1. The main types of karstification are controlled by the date, extent and rate of uplift, the position of the cavernation zone related to the surface, its width and date of origin and the date of valley inheritance. Since the mountains are constituted of blocks of highly variable geological history, composition and morphology, karstification involves diverse processes. Because of the loose network, low density and small size of karstic features, karstification is not a dominant process in the geomorphic evolution of the mountains. 2. Karstification independent of flowing water (surface karstification) occurs on blocks of the following properties: - Built up of (at least, partly) of well-karstifying limestone of uneven surface and only covered by permeable cover sediments. - Because of rapid uplift, the cavernation zone developed in great depth or reached a great depth by the time of valley superimposition. On these blocks syngenetic karstification is typical and, if occurs on valley floors, involves pseudobathycapture. On blocks where the cavernation zone is close to the surface and slow valley incision prolonged after superimposition, allogenic karstification is observed. During the present exhumation of the mountains, allogenic karstification could only take place in few sites, in the first stage of the present karstification. Today these sites show postgenetic karstification. Independent of the presence or absence of cavernation zone, pseudopostgenetic karstification may also be present on blocks where autogenic karstification occurred for a shorter or longer period and fossilised dolines with partial permeable fill developed. - Among block types, the most favourable for syngenetic karstification are horsts uplifted to summit position and exhumed or cryptopeneplains (landforms similar to semiexhumed horsts in summit position) of relatively high position from which non-karstic, impermeable cover sediments have been partly removed. 3. Syngenetic karstification is chimney development on hidden rock boundaries. Through inheritance surface landforms like covered karst ponors, pseudoponors, dolineswith-ponor and depressions are produced. The features of postgenetic karstification result from the subsidence induced by the transport in depth of unconsolidated sediments filling older karst features or passages. The landforms produced are subsidence pseudodoline, doline-with-pseudoponor, postgenetic doline-with-ponor, pseudodoline above passage and doline-with-pseudoponor above passage. 4. Recent surface karstic features form where the permeable cover sediment (loess) thins out. The precondition to this is an uneven and dissected carbonate basement and removal of cover sediments. The density of karstic landforms remains low even in zones potentially suitable for karstification. Karstification takes place if the basement is dismembered tectonically (on the edge of fault scarps) or dissected by paleokarst elevations (summit level of cone terrains) or paleokarst depressions (along their margins). The location, size and and shape of karstification zones and the frequency and type of karst features on a block are controlled by the way of exhumation (by sheet wash or stream erosion) and the sites of fluvial incision and the position of the latter related to the morphology of the underlying rock. 5. The influence of older, fossilised karst feature assemblage on recent karstification is manifested in the following. - On the summit levels of paleokarst elevations and on the edges of paleokarst depressions hidden rock boundaries form. - Postgenetic karstification may ensue in the fossilised ponors of the one-time authigenic