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Iraq is the sixth largest oil reserve in the world, with current proven reserves of 115 billion barrels of oil (BBO) and 110 trillion cubic feet (TCF) of gas. The study area is situated within the Kurdistan Region of Iraq which is estimated to contain about 39% of Iraq’s total barrels of oil reserves. Petrographic, organic, and inorganic geochemical analysis of the solid bitumen and host shales from the Middle and Late Jurassic-age Sargelu and Naokelekan Formations of the Banik section, northernmost Iraq, were undertaken with the aim of understanding their derivation and preservation, as well as examining the carbon and oxygen isotopes, and paleoredox proxies under which the solid bitumen and host sediments were deposited. Petrographic analysis of both formations revealed the presence of solid bitumen high reflectance (first phase) and solid bitumen low reflectance (second phase). The equivalent vitrinite reflectance indicates that the solid bitumen of the Sargelu and Naokelekan Formations probably accumulated within the shale reservoirs following oil migration from source rocks located within the same formations. Mineralogical study (XRD and SEM - EDX) revealed that the shales hosting the solid bitumen also contain clay minerals (illite, rectorite, chlorite, montmorillonite, and kaolinite) as well as carbonate minerals, quartz, alkali feldspar, and pyrite. Carbon and oxygen isotope data along with paleoredox indicators suggest that both the solid bitumen sources and host shales in the Sargelu and Naokelekan Formations formed within a shallow-marine setting, most probably under anoxic conditions where water circulation was restricted.

Lithological, petrographic, and geochemical analysis of the Middle to Upper Jurassic succession (i.e. Sargelu and Naokelekan formations) from northernmost Iraq were undertaken. The aim was to provide an updated discussion for their sedimentary and diagenetic histories, as well as examine the evaporation proxies and palaeoredox conditions under which the Sargelu and Naokelekan formations were deposited. Lithologically, the Sargelu Formation comprises massive dolomites, interbedded with shales, rare cherts and one single limestone bed, whilst the Naokelekan Formation consists of shales overlain by limestones and one single dolomite bed. Petrographic analysis of both formations revealed the presence of rare ostracods, bioclastic fragments as well as calcispheres. Five main microfacies were recognized, including bioclastic wackestone, mudstone, dolorudite, dolarenite and dolomicrite microfacies. Mineralogical study (XRD and SEM - EDX) revealed that the shales comprise clay minerals assemblages (illite/muscovite and kaolinite) with some quartz, alkali feldspar and rare pyrite. The Sargelu Formation was probably deposited in a shallow¬ marine environment. In contrast, the Naokelekan Formation is hypothesized to be deposited in a restricted shallow¬ lagoon environment. Palaeoredox indicators suggest that both formations were accumulated under anoxic conditions, most probably in silled basins where water circulation was restricted. Tectonic activity thus resulted in basin compartmentalization across the region, which also explains the marked differences which are often observed.

The Recent sediments from North Iraq are characterized by a higher content of chromite. This paper deals with the mineralogy and geochemistry of chromite in the heavy mineral assemblages from Recent fluvial sediments in an attempt to elucidate its distribution and source rock. The heavy fraction is composed of iron oxides and chromite forming about 50% of the total heavies. Chromite forms up to 80% of the opaque minerals at some areas in North Iraq. The non-opaque heavy minerals are composed of epidote, garnet, tourmaline, rutile, staurolite, kyanite, zircon, olivine, chlorite, muscovite, pyroxene and am-phibole. XRD analysis revealed that chromites are mainly aluminian chromite. Geochemical study shows that chromite is depleted in Fe and enriched in Al, such enrichment being related to the effect of alteration that leaches iron from chromite in the presence of suitable conditions assisting this alteration. Chromite is akin to podiform Alpine-type chromites. Higher concentration of chromite favours the addition of ophiolite complex of the Zagros-Taurus belt as well as recycling of chromite from older formations in North Iraq. Another factor controlling this obvious enrichment of chromite is the hydraulic equivalent and meandering morphology of the rivers. تمتاز الترسبات النهرية الحديثة في شمال العراق بزيادة نسبة معدن الكرومايت ضمن مجموعة المعادن الثقيلة فيها . يهدف البحث الحالي إلى دواسة معدنية وجيوكيميائية معدن الكرومايت في محاولة لمعرفة توزيعه وعوامل اغناءه ومصدره تشتمل المعادن الثقيلة على مجموعتي المعادن المعتمة وغير المعتمة . تؤلف المجموعة الأولى حوالي 50% من مجموع المعادن الثقيلة كما يمثل الكرومايت نسبة أكثر من 85% من مجموع معادنها في شمال العراق . كما تشتمل المعادن غير المعتمة على : ابيدوت، كارنيت، تورمالين، روتايل، ستورولايت، كايانايت، زركون، أوليفين، كلورايت، مسكوفايت، بايروكسن وامفيبول. لقد أوضحت دراسة معدن الكرومايت، بحيود الأشعة السينية أنه من النوع المنيوم كرومايت، كما أظهرت نتيجة تحليله الجيوكيميائي بأنه غني بالألمنيوم وفقير في نسبة الحديد مما قد يعزي إلى تأثير عمليات التغير على الكرومايت ، بفعل عوامل النقل وإعادة الترسيب (دهك الرواسب) الأمر الذي يؤدي إلى زيادة تركيز الالمنيوم على حساب الحديد. إن إغناء الكرومايت في الترسبات الحديثة في شمال العراق قد يعزي إلى تواجده ضمن معقد الاوفيولايت في طوروس - زاجروس وإعادة نقله وترسيبه من عدة تكاوين فتاتية قديمة في شمال العراق ، كما قد تؤدي بعض العوامل الترسيبية والمورفولوجية للأنهار في تركيز وإغناء هذا المعدن .

Heavy minerals analyses were carried out on 10 samples from the clastic Suffi Formation (the Ordovician-Carboniferous unit in the western Iraqi desert). The suite of minerals consists mainly of opaque minerals including pyrite, ilmenite, magnetite and hematite and the non-opaques is represented by zircon, tourmaline, cutile, garnet, epidote, kyanite, staurolite, leucoxene, chlorite and biotite. The nature and occurrence of the above heavy minerals association reflect a source area of the crystalline basement rocks of Iraq. These basement rocks are coomposed of metamorphic rocks and granites complexes. They belong to the Arabian part of African (Nubio Arabian) Precambrian platform. تم تحليل المعادن الثقيلة لعشر عينات من وحدة صوفي القتاتية (وتتبع الاردفين - الكربوني لمنطقة الصحراء الغربية في العراق ) . ويشتمل نطاق التمعدن على معادن معتمة وبتكون من بيريت ، المنبت ، ماجنتيت وهيماتيت وكذلك معادن شفافة تشتمل على الزيركون ، النورمالين الروتيل ، الجارنت ، الابيدوت ، الكيانيت والستروليت ، ليوكسين كلورايت وبيوتيت . ان طبيعة وتواجد هذه المعادن يدل على مصدر صخور تتبع صخور القاعدة في العراق والتي تتكون من صخور متحوله وجرانيت وتتبع الدرع العربي الأفريقي (العربي - النوبي ) من الزمن البريكاميري.