8 57 A. K. Nasser and S. K. Jan Bull. Iraq nat. Hist. Mus. (2008)10 (3): 57-68 THE STUDY OF MINERALOGICAL AND MICROFACIES ANALYSIS SHIRANISH FORMATION WELL (KH-6) ANSAB AREA IN SOUTHERN IRAQ Ali K. K. Nasser* and Sadi K. Jan** *College of Sciences, University of Baghdad **Natural History Museum, University of Baghdad, Baghdad, Iraq ABSTRACT The study of Shiranish Formation rocks in southern part of Iraq at Ansab area well (KH-6) were carried out. The formation is tongued with tayarat formation, which bounded from top and bottom, the upper tongue at thickness 49m. and tongued at depth (476-525m.) the lower tongue at thickness 4m. tongued at (541-537m.). The rocks of this formation were divided into three sedimentary microfacies: 1- Dolomitized formininferal Wackestone facies. 2- Dolomitized formininferal Mudstone facies. 3- Dolostone facies. 34 slides were investigated depending on mineralogical, compositional and biological processes and compared diagenesis which reflect open marine shelf at lower part of formation (F.Z.2) (S.M.F.8), but at the top represent deep shelf margin environment. The most important diagenesis is neomorphism and spary calcite cement deposits within fossils (intragranular) with late dolomitie stage special in dolostone facies (third facies). INTRODUCTION The Shiranish carbonate Formation is considered as one of the rock stratigraphic unit with wide regional extension in the north of Iraq and Syria, represented as one of upper Cretaceous Formation and it was studied in many surface and subsurface sections in different areas of Iraq, but first described by (Henson, 1940) in Islam Shiranish village near Zakho city in the north of Iraq, latitude north 37°-11¯- 32˝and east 42° -5¯-30˝. Rocks of the Shiranish Formation was divided in type section into two units by (Bellen, R. C., 1959);, (Buday, R.T., 1980) and (Kassab, I. J. M. 1973)in 1986, Al-Qayim divided the type section of the Formation into three units depending on rocks compostion, petrographic analysis and chemical properties also the Formation divided into three by secondary units in Singar mountain area(Maala, K. A. 1977), (AI-Shibani, S. K. 1973), (Youkana, A. K. 1976) and (Kassab, et al.1986) depending on foraminifera. Some researches were pointed into extension to the mid and south of Iraq, (A1-Naqib, 1967) in (Darmoian, S. 1974 b.) considered Qurna Formation in the southern area equivalent to Shiranish Formation as in (Bellen, R. C., 1959) . . . .etc. and ( Buday, R. T., 1980) considered as a large tongue for Shiranish Formation, (Darmoian, S. 1975 b.)confirmed that he considered the marine facies of Qurna Formation in the area which described by (Owen, R. M. S., 1985) in Zubair well-3 equivalent for Shiranish and it was fixed by (Al-Mashhadani, A. 1984) the existence of marine facies in the direction of Sudia Arabia boundary in suggested distribution sedimentary facies maps, also Tamar-Agha (Al-Janabi, Safa, A. A. F. 1986) mentioned the existence of this Formation in the southern desert wells, it has been studied one of this well. 58 The Study of Mineralogical We draw a sketch of distributing microfacies for sedimentary basin of the Formation according to Wilson model 1975 (Wilson, J. L., 1975) as in Fig. 3 and the facies were:- 1- Dolornitized Forarniniferal Wackestone Facies: These facies located at the lower part of the Formation (lower tongue) in depth (537-541m.) and in the upper part (upper tongue) the depth (522-525m.) which recognized by the abundant of planktonic Foraminiferal (Globigerinelloides escheri, Heterohelix reussi, Rugoglobigerina rugosa) plate (1-1) inaddidition to echinoderms and shell fragments. Chambers of some fossils were filled by spary calcite cement (intragranular) plate (1-2), rhombohedral shape of dolomite mineral were noticed in matrix of this facies and pyrite appeared in some planktonic foraminifera chamber plate (1-3) and the last represented local suitable environment for mineral pyrite deposition because of abundant organic matter that made reduction alkaline condition and this represented the best location for the crystallization of pyrite mineral (Siesser, W. G., 1967). This facies equivalent to the standard microfacies (S.M.F.8) in Facies Zone (F.Z.2), represented on marine shelf with open water circulation below wave base and normal salinity (30-40%) according to the existence of echinoderms (Wilson, J. L., 1975). 2- Dolomitized Foraminifera Mudstone facies: These facies were represented in depths (494-522m.), (482-490m.) and in depth (476- 478m.), the matrix of this facies composed of partially or completely micrite alteration to micro spar plate (1-4) in which the complete faces of dolomite crystal (Anhedral) were scattered plate (2-1) because the burial mud deposit under water by the action of pressure that made confined connate water out of pores contributed in magnesium enrichment which necessary for the late dolomite process (Wilson, J. L., 1975). Formed mineral dolomite process in this facies supposed to be late dolomitic process because the size of dolomite mineral particle larger than 0.02 ml, also no combination with gypsum and did not contain fossils that indicate lagonal environment (Fuchtbauer and Goldscmidt, H., 1956) and the percentage of fossils in this facies less than 10% represented by planktonic foraminiferal genus Aegyptice Globotruncana and G-diwi also echinoderms and shell fragment plate (2-2), many fossils in this facies were affected by neomorphism process such as recrystallization and some of their chamber were filled by calcite cement and pointed the existence of Numlite genus plate (2-3) less than 1% in micrite-matrix, this indicated that it comes by transportation from high energy environment into low energy environment and this fades equivalent to Standard Microfacies (S.M.F.3) in the zone (F.Z.3) in which deposited in deep shelf margin environment. 3- Dolostone Facies. This facies found in depth (490-494m.) and (478-482 m.), dolomite mineral with sugar texture and equal crystal sizes represented high percentage more than 75% in matrix plate (2-4) that formed by the action of diagenesis substitution process in carbonate deposits, in which Dolomite mineral crystal formed completely faces (Enhedral) medium sizes between (0.55-0.93mm) particles sizes were increased upward that indicate the diagenesis process becomes more intense (Fuchtbauer and Goldscmidt, 1956) the facies has high porosity as a result of late diagenesis process and reflected condition of Supratidal environment because the lack of fossils in this facies. The percentage of crystal Dolomite minerals in this facies identified and determined through X-Ray diffraction scheme (XRD), Dolomite weight % is calculated by using Royse method (Royse, et al, 1971) fig.4, the percentage of Dolomite mineral more than 75% that indicate the rocks of this facies was Dolomite from mineralogical andlithological point of view. 59 A. K. Nasser and S. K. Jan CONCLUSIONS 1- Shiranish Formation rocks were intertongue with Tayarate Formation in well (KH-6) into three sedimentary mineralogical microfacies:- (a) Dolomitized Foraminiferal Wackestone Facies. (b) Dolomitized Foraminiferal Mudstone Facies. (c) Dolostone Facies. 2- These facies reflected open marine shelf at the lower part of Formation (F.Z.2) (S.M.F.8) but at the upper part represented deep shelf margin environment. 3- These facies assure the existence of diagenesis processes such as Neomorphism (recrystallization) and late Dolomite process in different degrees, which alter to Dolomite rocks or Dolostone facies. 4- Diagram of microfacies distribution of sedimentary basin were drawn according to Wilson model -1975. 5- These described facies closer to Qurna Formation in the studying that has been done southern oil well co., then we can consider that Shiranish Formation in this area (southern Iraq) has a type of facies different from the Formation in northern Iraq, under the effect of dominated tectonic condition and water depth in this area. 6- The thickness of this Formation considered less in comparison with thickness of Shiranish Formation in the other part f Iraq, the studying pointed to the average thickness formation in the range (100-400 m.) which the thickness reached about 53 m. in Ansab area. REFERENCES Al-Janabi, S. A. A. F. (1986). Sedirnentology and petrological studies of the upper cretaceous KH-6 at AnsabArea in south Iraq, M. S. C. thesis, university of Baghdad (unpublished). A1-Mashadani, A., 1984, Geadynamic evolution of Iraqi Sedimentary basin, Consequence on the distribution of fluid, Dsc. Thesis Bordeaux. University. France 320p. Al-Shibani, S. K., 1973. Microfacies from shiranish in North eastern (Sulamania Asmar Region Jour. Soc., Iraq, Vol.6, pp. 49-65). Al-Qayim, B., Habib, H. K., and Aal-Dyni, N., 1986. Petrolgy and Geochemistry of shiranish Formation (type section) towards sedimentary facies interpretation. Jour. Geol. Soc. Iraq, vol.19. No3 (7thIGC) pp. 123-136. Bellen, R. C., Dunnigton, H. V., Wetzel, R. and morton, D. H. 1959 Lexique Stratigraphique, International, Asie, Iraq, Vol.3 ,Fasc10a. Buday, R. T., 1980, The Regional Geology of Iraq Vol. Stratigraphy and Paleogeography. Edited by Kassab and Jassim Geosurvy Baghdad. Darmoian, S. 1975b. Stratigraphy and Micro-Paleontology of the apper cretaceouse Arumas, Supper group, South eastern Iraq Jour. Geol. Soc. Iraq. Specissue, pp. 89-l 16. Dunham, R. J., 1962: ClaSSifiCatiOn of carbonate rocks according to depositional texture. AAPG. 1,108-121, Tulsa. Fluegel, E., 1982: Microfacies analysis of limestone, springer-Verlag, Berlin, 633p. 60 The Study of Mineralogical Fuchtbauer und Goldscmidt, H., 1956: Ein Zechstein anhydrite-Profil mit Ein1agerunge Von Montmorillonit and einer abweivhenden serpentin. Vareetaet-Heidelberg Beitr.Miner.Petrogr. , 5, 187-203. Fuchtbauer, H., Muller, G., 1977; Sedimente and sedimentgesteine, E. schweizerbartsche Verlags Buchhandlung. Stuttgart. 784p. Kassab, et al., 1986, The cretaceouse-Tertiary boundary in Iraq, Jour. Geol. Soc. Iraq. Vol.19, No.2 (7th IGC), 7p. 129-167. Kassab, I. J. M., 1973, Plankfonic Foraminiferida of Shiranish Formation Type Loca1ity North Iraq). Jour, Geol. Soc. Iraq, vol. 19.No3 (7th IGC)pp. 123-136. Maala, K. A., 1977. The regional geological mapping of singar area, D. Geo. sur. min., inv., Baghdad (unpub. Rep. No-860). McHargue, T. R., and price, 21982: Dolomite from clay in argillaceoue or shale associated marine carbonates: Jour. sed. petrolgy, Vol.52, No.3, P. 873-886. Owen, R. M. S. and Nasir, S. N. 1958. The stratigraphy of the Kuwait-Basrah area, in week, L. G. (ed), Habitat of oil, Asymposium, AAPG. pub, P. 252- 1278. Siesser, W. G. 1967: Authigenic pyrite and gypsum in south west African Contenetal slop sedimentology, Vol.23, P. 579. Wilson, J. L., 1975: Carbonate facies in Geologic History. Springer-Verlag, Berlin. 471 p. Youkhana, A. K., 1976. Foramini fera and Biostratigraphy of some late Cretaceouse marine Sediments of Northeast Iraq, univ. wales. (ph. D. thesis) 318p. 939pIs. 61 A. K. Nasser and S. K. Jan Fig.1: Location map of stuied well 62 The Study of Mineralogical 63 A. K. Nasser and S. K. Jan 64 The Study of Mineralogical 65 A. K. Nasser and S. K. Jan 66 The Study of Mineralogical 67 A. K. Nasser and S. K. Jan 68 The Study of Mineralogical Bull. Iraq nat. Hist. Mus. (2008)10 (3): 57-68 ش بئر را و الشي خ ص ق ل ي وال حني الد ي ع ن را ة التحلي الم منطقة )KH-6(د ب صا الن ب ا عراق -ا جنو صر م ا ف ك ظ ي ل ي ان ج ن* عل **و س د وم* داد-كلية ا عل ة بغ جامع ي** خ ال بيع ري ف ال ا ح ة بغداد-مت جامع ة ص الخال ص ور ة ت د اس جمت يف ش ريا ب ئر بت و ن الش صا الن ب لعراق ، واليت يظهر )KH-6(و ُ الطيارات الذي حيمع تكوين )صقتال(فيها التكوين على هيئة متالصقة واألسفل األعلىمن ده م يتداخل ٤بسمك م ولسان سفلي ٥٢٥-٤٧٦من عمق م يتداخل ٥٣علوي بسمك لسان .م٥٤١-٥٣٧من العمق :ثالث وحدات سحنية رسوبية دقيقة هي إىلقسمت صخور هذا التكوين .سحنة احلجر الواكي احليايت املتدملت .١ .سحنة احلجر الطيين احليايت املتدملت .٢ .سحنة احلجر الدولومايت .٣ شرحية اعتماداً على املكونات الصخرية ٣٤فحص الشرائح الرقيقة البالغة وذلك من خالل هذه السحنات تعكس بيئة رف أنوقد وجد واملعدنية، واملتحجرات والعمليات التحويرية الالحقة بيئة فتمثل األعلىيف اجلزء أما) S.M.F.8()F.Z.2(من التكوين فلاألسالبحر املفتوح يف اجلزء التبلور إعادةوان اهم العلميات التحويرية هي ) Deep shelf margin(حافة الرف العميق )Neomorphism ( النيومورفزم وترسبات معدن الكالسايت السباري داخل حجرات ).السحنة الثالثة(ولسنون املتحجرات وعملية الدملتة املتأخرة خاصة يف الد