Posah Pseudokarst Cave in the Northern Part of Baluchistan and its Development Process

Posah cave is located near Skel-Abad village, beside the Zahedan-Khash road, about 114 km south of Zahedan city and about 22 km in the west of Taftan Mountain in the north of Baluchistan. This cave has been developed in a flysch unit consisting mainly of thin-bedded sandstone and shale layers. The roof of the cave is composed of Taftan lahar, a mudflow poorly sorted and consists mostly of volcanic ash with pyroclastic materials produced by Taftan volcano. The Posah cave is a unique pseudokarst cave in both the region and the whole country. The results of XRD and XRF analyses on two specimens of rocks from the cave have shown that rock units in the area are insoluble. Moreover, there is no significant difference between Ca2+ concentration values in the surface and ground waters. Therefore, it can be concluded that the cave has been developed in insoluble rocks. This paper deals with the development of the cave from a geological point of view.