Have you visited alisadr cave? Do you have any information about it?

Answer 1

Yes and it is very very interesting indeed.Alisadr cave is located 60 km NNW of Hamadan in the Zagros Mountains, Iran (co-ordinates: N 35o18´15,3´´; E 048o18´08,0´´; 1.980 m a.s.l.). The geological map "Kabudar Ahang" scaled 1:250.000 released by the GSI covers the area. The region itself is characterized by a semi-arid climate, with an annual rainfall of approximately 300 mm/yr.

Alisadr Range is part of the western structural units of Iran, the Sanandaj-Sirjan formation (Dumas et al. 1993; Torabi-Teherani 2000). This formation is of Jurassic origin, with alternating bands of schists and sandstones along the base, a blackish-grey band of clay-like limestone interspersed with thin layers of schist, and a lighter crystallised limestone on top, which is a result of the high-temperature, high-pressure metamorphosis related to the volcanic activity in the west of the Alisadr Range.The Alisadr Range itself is the outcrop of a large anticline, with its principal axis oriented in N-S direction. The dip of the layers in the vicinity and within Alisadr Cave is 40-45 degrees, and the length of the Alisadr Rangeis around 2 km. The range peaks at 2.180 m, while the cave entrance is at an altitude of 1.980 m situated in the north of the Alisadr Range.

To the south, the limestone outcrop continues for about 30 km with the Tehalehkand and Sarighayeh Ranges. However, the anticline axis in these southern parts is oriented in N115E direction. Hence, the Alisadr Range has been sheared off from the main range along a large shear zone between Mt. Alisadr and Mt. Tehalehkand, and the northern part has rotated anticlockwise about 25 degrees (Torabi-Teherani 2000).According to Torabi-Teherani (2000), the fracture density in the Alisadr Range is high, with 2-3 fractures per meter. Additionally, several funnel-like sinkholes with a ط of 2-3 m have been observed, both of these features facilitate rapid infiltration of surficial water.Alisadr Cave is developed along the stagnant karst water table. More than 4 km of the cave passages expose the water table (August 2001), with large lakes of crystal-clear water reaching depths of around 15 m. The temperature of the water is around 12 degrees, and with a pH-value of 7 the water is almost saturated with calcite. The level of the water table fluctuates annually by around 0,5-1 m, with a maximum in late spring to early summer. At this time the water may emerge in an outside spring.
The reservoir is recharged by both diffuse surficial infiltration along joints and fractures, which are channelled into blind avens guiding the diffuse recharge down to the lakes, and a small stream entering the cave at the main sinkhole entrance. The second entrance, which is the main tourist entrance of Alisadr Cave, is a large gallery (5 to 10 m wide) leading down to the water level, which is around 12 m below the entrance. The nowadays-dry gallery has been interpreted as an ancient vauclusian spring (Dumas et al. 1993; Torabi-Teherani 2000).Throughout the entire cave, a sequence of up to nine calcite/aragonite ledges can be found, which are located approx. 2,5 m above the current water table. These rims indicate a phase, in which the water table in the cave has been much higher, probably due to a wetter climate (e.g. during the last glacial maximum).

Three main directions guide passage enlargement in Alisadr Cave: N-S, NE-SW, and NW-SE-oriented fractures. The passage evolution has been described as phreatic (Dumas et al. 1993; Torabi-Teherani 2000), with an almost flat ceiling throughout the water-filled passages, numerous ceiling pockets, and an intense corrosion along the cave walls.