Geochemistry of Phosphorite and Associated Rocks of Akashat Formation (Middle Paleocene) in Akashat Mine, Iraqi Western Desert. Part II: Trace Elements


Akashat Formation is an important formation due to its content of the Hirri member, which includes phosphorites and phosphatic limestones, that are rich in P2O5. These rocks are mainly composed of apatite and calcite. In addition to other minor and trace minerals like palygorskite, quartz, dolomite and secondary gypsum. All these minerals are hosted the most trace elements in the Akashat rocks. U, Sr, Y and Zr are related to apatite more than other minerals. While Ga, Rb and Ti are almost correlated with the clay minerals. The rest trace elements are distributed among other minerals and organic matter. The hosting of trace elements by a mineral takes place in many cases as substituted in Ca(I), Ca(II) and phosphate tetrahedron in Francolite, Ca site in calcite, in clay mineral phases, or adsorbed on clay mineral faces, organic matters and in the crystal channel of francolite.