Karst Terraines in Iran - Examples from Lorestan

Abstract

Kraški svet predstavlja 13 % ozemlja Irana. Karbonatne kamnine so eocenske, oligo-miocenske, miocenske, jurske in kredne starosti. Večina jih je razvitih v bazenih Mazindarana in Zagrosa. Zaradi prevladujočih tektonskih aktivnosti so kamnine zagroške cone bolj zakrasele. 56 % vseh izvirov je prav v tej coni. Lorestansko in zagroško 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 kraške oblike, kot škraplje, vrtače in jame. Njabolje razvite kraške oblike je videti v skupini Bangeston. Večina izvirov je vzdolž tektonskih linij ali na križišču teh linij. Kemične analize kažejo, da so vode bikarbonatnega tipa. Prestolnica Lorestana, Khorramabad, se oskrbuje z vodo iz kraških izvirov. Prispevek podrobneje obravnava kraško hidrologijo dveh pomembnejših 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.