Stable isotopic technique and hydrochemistry was used in studying the water resources interaction of near Haditha Reservoir area, western Iraq. Throughout the study area, 14 groundwater samples (Bashina, Zwachi springs and Wells), 8 surface water samples from the study area, and 7 spring samples were analyzed for 2 H and 18 O stable isotopes and hydrochemical analysis. In this study, the temperature, altitude and continental effects on the isotopic composition of rain water in Iraq were studied. The climate of the study area is classified as semi-arid to arid region. The results show a variation in the isotopic values of Haditha reservoir and Euphrates river. This variation is due to the effect of the low surface area and the low velocity of water of Haditha Reservoir on the amount of evaporation, compared with the high velocity and the large surface area of Euphrates river. There was a variation in the isotopic values between Bishina and Zwachi springs, due to two factors that appear to modify the isotopic signatures of the springs, namely the lack of hydraulic connection between the springs of Bishina and Zwachi, meaning that they recharge from different sources. The changes in oxygen isotope composition of the groundwater between a deep reservoir and the springs (Bishina) may be caused by the dilution with near surface waters (Haditha reservoir) with different oxygen isotope compositions. The variation in the isotopic content in the studied area indicated that there are various origins of springs recharge and a different interactions of the multiple sources of springs with the mutli-depths of springs water. *‫كمال‬ ، ‫اني‬ ‫البارو‬ 2 ‫ج‬ ‫أنعام‬ ، ‫معه‬ ‫عبدهللا‬ 1 1 ‫اق.‬ ‫العر‬ ، ‫بغداد‬ ، ‫ية‬ ‫الجادر‬ ، ‫بغداد‬ ‫جامعة‬ ، ‫العلؽم‬ ‫كلية‬ ، ‫الجيؽلؽجيا‬ ‫قدػ‬ 2 ‫اق.‬ ‫العر‬ ، ‫بغداد‬ ، ‫ية‬ ‫الجادر‬ ، ‫البيئة‬ ‫وبحؽث‬ ‫السياه‬ ‫تكشؽلؽجيا‬ ‫ية‬ ‫مدير‬ ، ‫التكشؽلؽجيا‬ ‫و‬ ‫العلؽم‬ ‫ة‬ ‫ار‬ ‫وز‬ ‫الخالصة‬ ‫مؼ‬ ‫بالقرب‬ ‫السائية‬ ‫ارد‬ ‫السؽ‬ ‫تداخل‬ ‫اسة‬ ‫در‬ ‫في‬ ‫الييدروكيسيائية‬ ‫التحاليل‬ ‫و‬ ‫ة‬ ‫السدتقر‬ ‫الشعائر‬ ‫تقشية‬ ‫استخدام‬ ‫تػ‬ ‫اخذ‬ ‫تػ‬ ‫اق,‬ ‫العر‬ ‫غرب‬ ‫حديثة‬ ‫ان‬ ‫خز‬ ‫مشطقة‬ 11 ) ‫االبار‬ ‫و‬ ‫وزويجي‬ ‫بذشة‬ ‫مشطقة‬ ‫(يشابيع‬ ‫الجؽفية‬ ‫السياه‬ ‫مؼ‬ ‫نسؽذج‬ ‫و‬ 8 ‫د‬ ‫تست‬ ‫ة),‬ ‫البحير‬ ‫و‬ ‫ات‬ ‫الفر‬ ‫(نير‬ ‫الدطحية‬ ‫السياه‬ ‫مؼ‬ ‫نساذج‬ ‫األوكدجيؼ‬ ‫نعائر‬ ‫اسة‬ ‫ر‬ 18 ‫ودرجة‬ ‫يؽم‬ ‫الديتير‬ ‫و‬ ‫لسياه‬ ‫الشعائري‬ ‫التركيب‬ ‫أيزا‬ ‫و‬ ‫ساعتيؼ‬ ‫لسدة‬ ‫ة‬ ‫السدتقر‬ ‫الشعائر‬ ‫تحليل‬ ‫مؼ‬ ‫الشاتجة‬ ‫ات‬ ‫التأثير‬ ‫و‬ ‫تفاع‬ ‫االر‬ ‫و‬ ‫ة‬ ‫ار‬ ‫الحر‬

Mishrif Formation (Late Cenomanian) has been studied in four oilfields in southern Iraq, and studied samples were examined by mineralogy and geochemistry analysis using XRF and XRD techniques. The mineralogical study reveals that dolomite and calcite are the main minerals in the rock formation in studied oil fields, whereas quartz and clay minerals (kaolinite, montmorillonite and illite) represent secondary minerals composition. For geochemical classification of Mishrif rock, Ca/Mg ratio was applied and this reveals that Calcitic Limestone is a major type in studied samples. The paleo - salinity has been examined by using Ca/Mg and Mg/Ca ratios and they referred to moderate salinity during deposition. Mg/Ca and Mn/Ca ratios have been applied to measure paleo-temperature, so infer a moderate paleo-temperature for Mishrif Formation in studied samples. Based on the comparison between low Sr/Ca and the relatively high Ca/Mg ratios, infer that a dolomitization process played the main role among diagenesis processes.   http://dx.doi.org/10.25130/tjps.25.2020.013

Stable isotopes 18O/16O and 13C/12C in the carbonate rocks of the Mishrif Formation are examined here to define the depositional characters in the basin includes paleo temperatures and paleo depth.      The Mishrif formation (Cenomanian – Early Turonian) has extensive distribution in Iraq and Middle East. Mishrif Formation composed of organic detrital limestone. Four boreholes in four oilfields, Noor – well (11), Amarah – well (14), Buzurgan – well (24), Halfaya – well (8), in south east of Iraq have been studied. The studied samples have negative δ18O isotope values studied well, with Average (-4.11‰), (-4.47‰), (-4.48‰), (-4.18‰) in the studied wells respectively. Carbon Isotope composition positive values in the study samples, with average (2.32‰), (1.84‰), (2.20‰), (2.24‰)  are studied well respectively. The Stable isotope (18O/16O and 13C/12C) of Mishrif Formation provide the first records of      paleotemperature for the (Cenomanian – Early turanian ) which indicate moderate  during deposition.      The plot of depositional environment refers to warm water carbonate sediment and the bulk samples cluster tightly to small positive reflect modal isotope composition of dominant skeletal marine carbonate. The paleo-salinity (Z values) provide the marine deposits in studied samples. As the paleo-temperature was high temperature by (T values). The paleo depth he all studied samples in the four oilfields are fall in the same level which is in the upper part of Thermocline this indicate the moderate depth

Mishrif Formation (Late Cenomanian) has been studied in four oilfields in southern Iraq, and studied samples were examined by mineralogy and geochemistry analysis using XRF and XRD techniques. The mineralogical study reveals that dolomite and calcite are the main minerals in the rock formation in studied oil fields, whereas quartz and clay minerals (kaolinite, montmorillonite and illite) represent secondary minerals composition. For geochemical classification of Mishrif rock, Ca/Mg ratio was applied and this reveals that Calcitic Limestone is a major type in studied samples. The paleo - salinity has been examined by using Ca/Mg and Mg/Ca ratios and they referred to moderate salinity during deposition. Mg/Ca and Mn/Ca ratios have been applied to measure paleo-temperature, so infer a moderate paleo-temperature for Mishrif Formation in studied samples. Based on the comparison between low Sr/Ca and the relatively high Ca/Mg ratios, infer that a dolomitization process played the main role among diagenesis processes.