petrology of ultramafic and related rocks along iraqi zagros thrust zone

Gimo unit is located in the northern part of Mawat ophiolite sequence.
It consists of marble, and the total thickness is about 600 m at Gimo
Mountain (Fig. 2-4)
2-1-3 Geology of Bulfat igneous complex
The Bulfat igneous complex is situated within the Iraqi Zagros Thrust
Zone along Iraq-Iran border, covering an area of about 100 km 2 that
straddles the Iran-Iraq border. The Bulfat igneous complex comprises
mafic and ultramafic igneous rocks (Fig. 2-5). Mafic rock comprises four
types as follow:
1. Olivine gabbro occupies about 26 vol.% of the Bulfat igneous
complex by area. The large intrusion is characterized by gray to
brownish gray color, and consist of fine to medium granulated
plagioclase (67 vol.%, An 57 –An 72 ), olivine (12 vol.%, Fo 64 ), and
pyroxene (1–27 vol.%, Wo 45 En 39 Fs 16 ). Pyroxene contains two
perpendicular sets of exsolution lamella of ilmenite, suggesting
that the rock underwent ultrahigh-pressure metamorphism.
2. Pyroxene gabbro is restricted to high peaks along Iraqi-Iran
border. It consists of coarse-grained pyroxene (Wo 50 En 29 Fs 20 ) and
plagioclase (An 52 –An 77 ).
3. Pyroxene-amphibole gabbro consists of medium grained
plagioclase (An 76 ), amphibole, and uralitized pyroxene.
4. Syenites, nepheline syenites, and pegmatite gabbro are found in
shear zones, forming dyke-like bodies.
The ultramafic rocks form about 8 vol. % of igneous rocks, always
occupying southern and western margins of the Bulfat igneous complex.
The ultramafic rocks can be divided into following two occurrences:
1. Serpentinite belt in the Bulfat area occurs as chain of isolated
intraformational bodies of serpentinite within the volcanosedimentary
rock unit of the Walash-Nupordan Group (Fig. 2-5).
It has a total thickness of 300–500 m, length of 1–1.5 km, and is
surrounded on all sides by metavolcanic rocks of spilite, andesite,
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