Petrography and Geochemistry of the REE-bearing Fe-Oxide Apatite Assemblages from the Sheytour Deposit East Central Iran

Sheytour deposit that is also known as Gazestan or Anomaly 5a,situated at the Bafq-Posht-e-Badam metallogenic belt in Central Iran.It is one of the Kiruna type magnetite- apatite ore deposits in thisregion. This deposit is host by the low metamorphic green rocks andcalc-alkaline volcanic rocks that mainly consist of rhyolite, trachyte,and trachy-andesite. The diabasic dykes intersected these rocks. TheSheytour IOA deposit with a magmatic origin of iron-apatite hasexperienced multi stage mineralization as various forms includingeuhedral, vein type, and disseminated magnetite ore bodies. It has mostlikely formed by interaction of magmatic-hydrothermal processes.These agents were affected by moderately brine-dominated meteoricfluids, and metasomatic replacement.The intense alteration led to create the low- grade metamorphic greenrocks that are often associated with iron-apatite mineralization. Theapatite has a composition close to a pure fluorapatite with 2.69% F and0.08% Cl on average. Investigation of REE distribution in the Sheytourdeposit, indicated the apatite with monazite inclusion is rich of LREE(2.3% on average). Apatite has a distribution pattern as the same asmagnetite, and poorly mineralized siliceous rocks. Besides ofhydrothermal processes and the fluids associated with lowmetamorphic events that have increased or reduced the REEconcentrations in the Fe-oxide –apatite assemblages, this similarity ismost likely due to existence of monazite or other REE carrier mineralsas individual crystals outside the apatite also in mixed with magnetite.

کلیدواژه ها:

Petrography ، geochemistry ، REE ، IOA deposit ، Sheytour