Classification of Covered Karsts

Covered karsts are classified according to the character of the cover (cryptokarst if the cover is impermeable and concealed karst if it is permeable), to the origin of cover deposits (locally deposited or transported there) and to the age of karstification (syngenetic if the depression in the cover and the form in the bedrock are of the same age and postgenetic if not). Covered karsts may develop in structural landforms (synclines, tectonic graben, horsts of various elevations) and in depressions formed by the powers shaping the surface, which could be of karstic origin (doline, ponor, polje, fengcong depressions and intermountain plains of fenglin karst) or of non-karstic origin (valley, abrasional platform and river terrace). The appearance and pattern of covered karst depend on the type of karst. When characterising pattern geosyncline or glaciokarst (folded-nappe structure), block mountains, platform, salt diapir, tundra, taiga, temperate, mediterranean and tropical covered karsts are distinguished. The geosyncline (glaciokarst) and block mountains karst types mainly occur under temperate climate, while the platform and salt diapir may appear on any climatic karst type. According to pattern, covered karst developed from allogenic karst (which can be recent allogenic, rejuvenating allogenic or semi-allogenic), nappe allogenic, horst, cirque, glacial trough, polje, karst hill, cueasta, tropical depression, polygonal, intermountain plain, petrified forest, platform and salt diapir covered karsts are identified. On the recent allogenic karst, in slope direction from the bordering non-karstic surface, cryptokarst, mixed and open karst zones are found. On the rejuvenating allogenic karst, in slope direction from the former terrain of sediment supply, open, mixed and buried karst zones follow each other. On the semi-allogenic karst, in lack of the accumulation of fluvial deposits, the cover sediment does not derive from the non-karstic terrain bordering the karst and is of continuous distribution. On the nappe allogenic karst, buried karst, cryptokarst (with karst windows), concealed karst and open karst zones occur. On horst covered karst, on the neighbouring blocks, concealed, crypto and buried karst terrains alternate (in patches or in continuous distribution). On the glacial trough covered karst, striped or striped-patchy patterns are typical. On the polje karst, continuous or zonal (so-called internal zonal) covered karst develops. On the karst hill covered karst, the patches of covered karst may coalesce, while on cueasta covered karst, the patches of covered karst are arranged in stripes parallel to the cuestas. The tropical depression covered karst and the polygonal covered karst show patchy distribution, while the intermountain plain covered karst is continuous, but can show internal zonation with crypto and concealed karst zones. No or poor zonation can be identified on the platform karst. The covered karst of salt diapir shows patches and develops on the cover uplifted by the rising salt diapir.