Karst Terraines in Iran - Examples from Lorestan

Kraski svet predstavlja 13 % ozemlja Irana. Karbonatne kamnine so eocenske, oligo-miocenske, miocenske, jurske in kredne starosti. Vecina jih je razvitih v bazenih Mazindarana in Zagrosa. Zaradi prevladujocih tektonskih aktivnosti so kamnine zagroske cone bolj zakrasele. 56 % vseh izvirov je prav v tej coni. Lorestansko in zagrosko cono sestavljajo vzporedne antiklinale v katerih so, zaradi tektonskih premikov, kamnine nagubane in razpokane. Nagubanost in prepokanost je osnova vodonosnikov. V Karbonatnih kamninah Lorestana so razvite vse kraske oblike, kot skraplje, vrtace in jame. Njabolje razvite kraske oblike je videti v skupini Bangeston. Vecina izvirov je vzdolž tektonskih linij ali na križiscu teh linij. Kemicne analize kažejo, da so vode bikarbonatnega tipa. Prestolnica Lorestana, Khorramabad, se oskrbuje z vodo iz kraskih izvirov. Prispevek podrobneje obravnava krasko hidrologijo dveh pomembnejsih regij v Lorestanu. In Iran karst terrain covers about 13% of the total area. The carbonate rocks belong to the Eocene, Oligocene- Miocene, Miocene, Jurassic and Cretaceous. Most of the carbonate rocks are developed in the basins of Mazindaran and Zagros. The carbonate rocks in the Zone of Zagros, due to the prevailing tectonic activities, have undergone more processes of karstification. About 56 % of all the springs originated from this zone. In Lorestan the Zagros zone consists of a series of parallel anticlines in which, due to the tectonic movements, the rocks have undergone folding and fracturing. The folding and fracturing have created rich ground water reservoirs. The carbonate rocks of Lorestan show all types of karst features such as karren, dolines and caves. The most developed karstic features are seen in the Bangeston group. Most of the springs are discharged either along the lineaments or at the intersection of the lineaments. The chemical analyses of the samples show that they are of bicarbonate type. The drinking water of the city of Khorramabad (capital of Lorestan) is supplied from the karstic springs. In this paper, the karst hydrology of two important regions of Lorestan are considered.