EquilibriumLine Altitudes of Late Quaternary Glaciers in the Zardkuh Mountain, Iran

Equilibriumline altitudes (ELAs) of former glaciers in the Zardkuh Mountain of the Zagros Mountain Range were reconstructed from glacialgeologic data on former ice limits by using various methods. In the study area various types of glacial landforms such as outwash fans, moraines and well developed glacial cirques are observed. The results suggest that ELA were depressed 1433 m below to present ELA (3067 m asl) during the maximum glacier extension. By comparison of the calculated ELA depressions (DELAs) and the amount of the ELA depression around the world, maximum glacier extension in Zardkuh was correlated with Last Glacial Maximum. The ELAs and DELAs related to youngest moraines in the study area were about 3800 and 700 m asl, respectively. The calculated DELAs are more comparable to the latest phases of Late Glaciations or first phases of Neoglaciations. The study showed that the depression of the annual temperature during the LGM glaciations was about 9.74°C and it was about 4.76 °C probably during the youngest glaciation stage. This study shows that the former glaciers in maximum extension were mostly firnbasin glacier with valley glacier tongue which their tongues had reached to elevation about 2400 m above present sea level, during the LGM.