ABSTRACT
Homr Akarem and Homret Mikpid rare-metal granite are associated with Sn, Mo
and F mineralizations. Generally, rare metal granites have special mineralogical and
geochemical compositions. The studied granites are syeno- to alkali feldspar granite in
composition and crystallized from F-rich melt. They were affected by weak to moderate
whole rock hydrothermal alterations.
The studied granites are highly fractionated (SiO2 up to 77 wt. %), and
characterized by high contents of alkalis, Nb, Ta, Sn, Y, Th, Zr, Hf, Rb and F. They are
post-orogenic, subalkaline and metaluminous to slightly peraluminous (ASI 0.93 to
1.07). Homr Akarem and Homret Mikpid granites are characterized by normal REEs
patterns with strong negative Eu anomalies and LREE/HREE ratio is generally < 1,
while Homr Akarem muscovite granite shows moderate negative Eu anomalies and
LREE/HREE > 1. The calculated tetrad effects of Homr Akarem and Homret Mikpid
granites are low (< 0.2). This in addition to the regular distribution of high field strength
elements reflects the magmatic origin. They have A2-subtype affinity which was
probably derived from continental crust of igneous origin.
Fluid inclusions investigation indicates the presence of three fluid generations
trapped the studied granites. The early fluid generation is responsible for the pervasive
alterations (feldspathization and sericitization). The second one is responsible for
chloritization of biotite as well as silicification. The third generation is responsible for
kaolinization process. One fluid generation was detected in Homr Akarem muscovite
granite which is responsible for K-metasomatic alteration (microclinization and
muscovitization).