petrology of ultramafic and related rocks along iraqi zagros thrust zone

Chromian spinel forms euhedral grians of 0.5 - 5mm across, and is nearly
opaque to dark reddish brown under polarizing microscope.
3-2-2 Harzburgite
Harzburgite is massive, and occupies 70 % by the area of Mawat
ultramafic bodies (Fig. 3-10). It is characterized by typical equigraularmosaic
texture. Harzburgite consists of olivine, orthopyroxene, and
clinopyroxene. They are partly to completely replaced by talc. Chromian
spinel forms amoeboid grians, of 0.3 – 0.5 mm across, and are nearly
opaque to dark reddish brown in thin section, the minerals contains
inclusions of silicate phases like serpentine and olivine.
3-2-3 Websterite
Webesterite occurs as a pod (10 × 10 cm) within the main
harzburgite body (Fig. 3-11). The rock is characterized by typical
equigraular texture. Webesterite consists of clinopyroxene (2-3 mm
across), orthopyroxene (0.5-1 mm across), olivine (0.1 mm across) and
accessory plagioclase which occur as a fine grain between pyroxenes
(pigeonite + diopside) crystals. These constituent minerals partly
underwent chloritization and sericitization.
3-2-4 Hornblendite
The hornblendite is hosted in harzburgite. Hornblendite bodies are
always lensoidal in form (Fig. 3-12). The dimensions are highly variable,
generally ranging from 2 to 3 m long and 0.5-2 m thick. Most hornblendite
bodies are concordant with the foliation in the host peridotite. The
contacts between the hornblendite and host harzburgites are typically
sharp. All hornblendite lenses have granular texture, and consists mainly
of hornblende (90 vol. %) with some plagioclase (7 vol. %), and contain
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