Karst and Caves in Salt Diapirs, SE Zagros Mts. (Iran)

Abstract

Na področju Perzijskega zaliva je znanih okoli 200 solnih diapirjev, med njimi mnogo aktivnih. Kraške kamnine predstavljajo največ kamena sol in redkeje sadra ter anhidrid. Kraške oblike, popolnoma primerljive z oblikami v “klasičnih” karbonatnih kamninah, so najbolje razvite v ostankih uravnanih površij. Tako so škraplje, “solution pipes”, vrtače, udorne vrtače, depresije podobne uvalam in poljem, slepe doline, soteske, ponori, izviri in jame. Tod sta bili odkriti in raziskani dve izmed najdaljših jam v soli na svetu. Daljše jame so nastale predvsem v piezometrični gladini, večje pa v diapirjih ob morski obali. Jame pogosto predstavljajo odtok iz depresij, podobnih poljem. V dnu udornih vrtač in v ponorih so tudi strme, skoraj navpične jame. Kraški procesi so omejeni predvsem na sol, redkeje na sadro. Predvsem gre za raztapljanje in odnašanje soli izpod neprepustnega pokrova (gypcrete). V nekaterih diapirjih je dokazano globoko kroženje padavinske vode. About 200 salt diapirs (plugs) have been known in the region of the Persian Gulf. numerous are still active. Karst rocks are represented by a rock salt, less frequently by gypsum and anhydrite. Karst developed especially in relics of planated surfaces. Karst forms are completely comparable with karsts in classical carbonate rocks. Different forms can be distinguished: karren, solution pipes, solution dolines, solution-collapse dolines, uvalalike to polje-like depressions, blind valleys, canyon-like forms, ponors, springs and caves. Two World longest caves in salt were discovered and explored here. Long caves are developed especially in a watertable, large ones in plugs near the seacoast. Caves are often outlets of closed depressions (polje-like). Some caves at bottoms of collapse-solution dolines or swallow holes are subvertical. Karst processes are caused dominantly by dissolution of salt, less frequently of gypsum. The process of subrosion of halite under gypcretes plays the main role. Deep circulation of meteoric waters was proved in some plugs.