Preliminary exploration of phosphate in the Ilam Province
Iran Kanesh Consulting Engineers
The study area is located in the Ilam Province, between 32o to 34o northern latitudes and 46o to 48o eastern longitudes that belongs to the Zagros Mountains. Main potential rocks in the region include marl and shales of pabdeh Formation. First identification of phosphate layer in the Zagros Range occurred at 1942. After this, several exploration projects conducted across the belt that led to identification of some phosphate deposits such as Lar (350 MT at 19% P2O5), Kumeh, Rish, Nil and Sheikh deposits.
At 1975, BRGM executed an exploration project for two years in the Zagros. Their result indicates that the northwestern portion of the Zagros may contain seven phosphate-bearing horizons. These layers are situated in between Ilam and Asmari formations that range between Coniasian and Oliogcene in age. The horizons 1, 2, 3, 4 and 7 have developed in a non-depositional condition or when the structural level has changed, while the fifth and sixth horizons has formed in a coastal condition. Some authors believed that phosphate layers formed in gulf-like basins during the Eocene. The middle portion of the mentioned basin was depositing marl and shale, while its margin was the locus of carbonate deposits. These deposits were named as Pabdeh Formation (James and Wynd, 1965) that contains phosphate layers with marine origin. The extent of this basin was about 2000 Km2 between Sarbalesh anticline in Kazerun to Shelet Anticline at Abdanan.
In this study all exposures of Ilam to Asmari formations in the province were visited and tested with Shapiro solution. Also, seven samples were analyzed. The result show that mineralization exist in Shelet, Farhadabad and Qadah area. The focus of the project was on the Pabdeh Formation. Among the mentioned potentials, Shelet is more favorable. A dark shale layer that is 25cm wide was containing 16.06% P2O5. several other thin layers contained between 10 to 20% P2O5.