Abstract The Neoproterozoic granite of Gabal Abu Diab,
central Eastern Desert of Egypt, comprises mainly garnetbearing
granite and alkali feldspar granite intruded into
calc-alkaline granodiorite–tonalite and metagabbro–diorite
complexes. The garnet-bearing granite is composed
mainly of plagioclase, K-feldspar, quartz, garnet and
primary muscovite ± biotite. The presence of garnet and
primary muscovite of Abu-Diab granite suggests its
highly fractionated character. Geochemically, the garnetbearing
granite is highly fractionated as indicated from
the high contents of SiO2 (74.85–77.5%), alkalis (8.27 to
9.2%, Na2O+K2O) and the trace elements association: Ga,
Zn, Zr, Nb and Y. This granite is depleted in CaO, MgO,
P2O5, Sr and Ba. The alumina saturation (Shand Index,
molar ratio A/CNK) of 1.0 to 1.1 indicates the weak
peraluminous nature of this garnet-bearing granite. The
geochemical characteristics of the Abu Diab garnetbearing
granite are consistent with either the average
I-type or A-type granite and also suggest post-orogenic or
anorogenic setting. A fluid inclusions study reveals the
presence of three fluid generations trapped into the studied
granite. The earlier is a complex CO2–H2O fluid trapped
in primary fluid inclusions with CO2 contents >60 vol.%.
These inclusions were probably trapped at minimum
temperature >400°C and minimum pressure >2 kb. The
second is immiscible water–CO2 fluid trapped in secondary
and/or pseudo-secondary inclusions. The trapping conditions
were estimated at temperature between 400°C and
170°C and pressure between 900 and 2000 bar.
The latest fluid is low-salinity aqueous fluid trapped
in secondary two-phase and mono-phase inclusions.
The trapping conditions were estimated at temperature
between 90°C and 160°C and pressure <900 bar. The
origin of the early fluid generation is magmatic fluid
while the second and third fluids are of hydrothermal and
meteoric origin, respectively.
Research Abstract
Research Department
Research Journal
Arab J Geosci
Research Member
Research Publisher
Springer
Research Rank
1
Research Vol
4
Research Website
aun.edu.eg
Research Year
2011
Research Pages
763–773