| Abstract: |
The Kab Amiri younger granites comprise: a) biotite granite, b) muscovite-biotite granite which form two concentric zones the inner and outer ones respectively and c) episyenite. The strikes of the faults in Kab Amiri area are NW-SE and NE-SW directions, Episyenite is highly faulted and fractured in NW, NE, and E-W trends and exposed to intensive dissolution of quartz, which left a porous rock easily percolated by later hydrothermal fluids. The quartz leaching is followed by or combined with a complete alThe increase in oxidizing condition (i.e. the sudden change the redox potential) leads to the breakdown of the early formed pyrite into hematite. Precipitation of carbonates was a late feature and followed by chalcedonic quartz.The composition of biotite in the biotite granite of Kab Amiri is siderophyllite and this composition. The studied muscovites of muscovite-biotite granite and episyenite are zinnwaldite and formed after biotite in the muscovite-biotite granite, while the The studied garnet from the muscovite-biotite granite of Kab Amiri classified the garnet as almandine-spessartine garnet, which formed as a result of the reaction between a granitic magma and pelitic rocks.The plagioclase in the biotite granite of Kab Amiri ranges from albite to oligoclase and crystallized under temperature between 700 and 800 ºC, while in the muscovite-biotite granite and episyenite are albite. The plagioclase in muscovite-biotite granite Geochemically, the studied younger granitoids of Kab Amiri area have metaluminous to peraluminous characters and alkaline affinity and belong to post-collision A-type (A2) granitoids. The Kab Amiri granitoids were crystallized at temperature between 700-8The evolution of the biotite granite of Kab Amiri was controlled by the fractionation of K-feldspar and by K-feldspar as well as plagioclase separation for the muscovite-biotite granite. The variation of REE is consistent with the fractionation of allanitThe suggested model presumes that the Kab Amiri magma chamber was a flat, subhorizontal igneous body with domal upper contact. Internal convection leds to accumulation of highly evolved interstitial melts into the apical part of the chamber and less-evolvThe studied albitized episyenite is enriched in Na2O and Al2O3, Sn, Ta and W and depleted in Cs, Rb, Ba and total REE.Albitization, which is associated with carbonatization and illite-chlorite, there are enrichments in Na2O (i.e. albitization) and CaO and MgO indicate the formation of carbonates (i.e. calcite and magnesite). The enrichment of Sn, U, W, Ta, Nb and Y referThe greisnized samples show decrease in alkalis and enrichment in Fe2O3 and MgO, due to the formation of hydrothermal chlorites and sulfides. There are strong enrichments in Sn, Ta and W the three elements indicate the presence of polycrase-Y. On the otheCarbonitization is accompanied by strong enrichment in CaO, MgO, Fe2O3 and MnO indicate the formation of carbonates, chlorite and sulfides. The enrichment in Sn, Sr, Ta, U, W and Y, the enrichment of Sn, U, W and Y refer to the presence polycrase-Y minera
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