Iraqi National Journal of Earth Science

Ostracode assemblages from Garagu and Ratawi Formations (Lower Cretaceous) from Makhul-2 (Mk-2) and East Baghdad-1 (EB-1) boreholes were studied in details, leading to the conclusion that Garagu Formation deposited under shallow marine sublittoral environment with normal salinity and warm water, while Ratawi Formation deposited in shallow marine environment with anoxic environments.

The average CIA value for the Injana Formation (Late Miocene) sampled across a section consisting of alternating mudstones, siltstones and sandstones deposited mainly in fresh water environment is rather low value (45.6) indicating the very low level of chemical alteration which the source rocks have suffered which is mainly due to semi-arid to arid climate of weathering and also due to nearby position of the basin of deposition. No overall variation in climatic condition was observed along the section from bottom to top .The variation of major and trace elements involved in this study with mean values of CIA for the sandstone, siltstone and mudstone lithologies was attributed to either mobility of the element concerned (Na, K and Rb) or to gravity fractionation of minerals that host the element or to climate of weathering and deposition (P2O5, Ni, Co & TiO2). Major contribution of recycled argillaceous or clay rich sediments to the Injana Formation do not agree with the results reached in the present study.

The microfacies analysis of the Shiranish Formation (Early-Late Maastrichtian) at the Bekhair anticline, Dohuk area, northern Iraq revealed that the succession is composed of alternation of seven microfacies, which are wholly micritic groundmass and rich in Planktonic Foraminifera. Based on the mode of vertical and lateral distribution, the present study deduced that this succession was deposited at Dohuk area by two environmental zones: upper-middle bathyal and outer shelf within one of the half-graben basin, which formed by Lisstric rifts. The latter was formed by the what so-called "piggy-back" basins at Foreland of the Arabian shelf. It is thought that the lithological and thickness variations at the bases of half-graben basin topography are due to tectonic irregularity

The Higran section in northern Iraq exposes the contact between two widely recognized formations. They are the Shiranish and Kolosh Formations, considered to be of Cretaceous (Campanian-Maastrichtian) and Tertiary (Paleocene-Eocene) ages respectively. Samples were taken from above and below the physical contact between the two formations at 5 to 7 cm apart. Planktonic foraminiferal biostratigraphic analysis of the Higran section indicates that the Cretaceous
/Tertiary boundary in this section is hitherto the most complete and expanded section in Iraq up to date. Quantitative high resolution foraminiferal biostratigraphic analysis has shown that a major biotic change in the planktonic foraminifera occurred during the end of the Cretaceous to the beginning of the Tertiary. The Maastrichtian Gansserina gansseri and the Abathomphalus mayaroensis Zones were recognized. The Abathomphalus mayaroensis Zone was subdivided into three subzones they are: Racemiguembelina fructicosa Subzone, Pseudoguembelina hariaensis Subzone and part of Pseudoguembelina palpebra Subzone. The defined Tertiary zones are: Guembelitria cretacea Zone, Parvularugoglobigerina eugubina Zone, Parasubbotina pseudobulloides Zone and part of the Parasubbotina varianta Zone. This study has established the absence of the Plummerita hantkeninoides Zone within the Cretaceous succession indicating a hiatus (Diastem) between the Cretaceous and Tertiary successions. The planktonic to benthonic ratio of the Shiranish Formation across the K/T boundary shows the role of the outer shelf to upper slope environments well above and below the K/T boundary in the section, hence it is characterized by lithologic continuity above and below the missing interval. The planktonic foraminiferal extinction in the Higran section occurred gradually and over relatively long period. Seventeen species (40.5% of the Cretaceous species) became extinct in the Late Maastrichtian before the first appearance of the Tertiary species, whereas nineteen species (45.2%) disappeared exactly with the hiatus that defines the K/T boundary in the studied section. Most of the extinct forms are large, complex, tropical and subtropical. Nevertheless, five species of the small cosmopolitan generalists with simple morphologies (14.3%of the Cretaceous species) survived the K/T boundary and the drastic change in the ecosystem. They did however become extinct in the Early Danian. The fine biostratigraphic analysis also revealed that the K/T boundary is located in the same lithology of blue marls within the Shiranish Formation, rather than at the contact between the Shiranish and Kolosh formations.This study has shown that the well-known Shiranish Formation conventionally taken to be of Cretaceous age, actually extends into the Paleocene in the Higran section. In essence, the turnover of the Cretaceous foraminifera which defines the end of the Cretaceous is located one meter below the physical contact between the Shiranish and the Kolosh formations.

The summary of this research is the preparation of surface drainage network map as interpreted from normal color satellite image at a scale of (1:100.000), recorded in 2001. The study area reflects the existence of different types of drainage systems such as (Dendritic, subparallel and pinnate) resulted from the differences in rock type and degree of slopes.
The gully erosion maps of study area which taken from the surface drainage network were compiled using the Surfer 8 program depending upon (Bergsma, 1982) system. The research region was affected by gully erosion and classified into three zones. Zone of slight erosion at rate of 21.17%, medium erosion zone at rate of 58.39%, and severe zone at rate of 20.44%.

Classifying soils into groups with similar behaviour, in terms of simple indices provide a general guidance about engineering properties of the soils. Complemetary physical properties of soil mean any three properties of soil that any two of them will be enough to estimate the third one, for examples Atterberg limits (Liquid Limit %, Plastic Limit % and Plasticity Index %) are substantially complementary physical properties due to the equational relationships between these three properties. Also the size fractions of soil that component from three fractions only (Clay %, Silt % and Sand %) are complementary physical properties because the total sum of these properties will be handred percent. In this study only two of the three complementary physical properties of soil have been converted to standardized values by subtracting each properties from the mean value and dividing the result by the standard deviation . The standardized values values are plotted on two dimensional graph which divided into a uniform area up on the unity standard deviation. Number of samples are measured in each area to draw the contours map which shows the individual groups . this a simple statistical treatment for a complementary physical properties of soils has been applied on soil data from Tulool Al-Bacth/Shirqat road. The resuls shows very satisfactory

Strontium distribution within (90) calcium sulphate samples (20 anhydrite, 25 massive gypsum, 25 selenite and 20 fibrous gypsum) from Fat'ha Formation (Middle Miocene) at four selected localities in northern Iraq were investigated. The study revealed that there was a loss of (182 ppm, 15.50%) strontium during the hydration of anhydrite to gypsum. This loss is attributed to the incapability of monoclinic structure of gypsum to hold all the released strontium from anhydrite. Massive gypsum contains almost twice and (3.46) times strontium than selenite and fibrous gypsum respectively. These differences are related to the different mode of formation of each type. There is a negative correlation between crystal size of gypsum and strontium content. The relationship is linear on a logarithmic scale. Estimated partition coefficients of strontium (KSr G) for the three typs of gypsum are all equal to (0.20) at an estimated temperature and brine concentration of (32ºC) and (X3.4) respectively. Estimated partition coefficient for anhydrite is (0.4) at an estimated temperature and brine concentration of (35ºC) and (X7.5) respectively. Multivariate discriminant analyses proved that strontium is the most discriminating element between (anhydrite and gypsum) and between (massive gypsum, selenite and fibrous gypsum).

ABSTRACT
Thirteen species of Calcareous Nanofossils were identified from the Jaddala Formation from well (KH 12/7) of depth (107-130 m.) west Iraq. The recorded calcareous nannofossils assemblages permits the recognition of two biozones these are (from top to bottom):

2- Discoaster saipanensis Interval zone(Part) (CP14b)
1- Discoaster bifax Interval zone(Part) (CP 14 a)

On the basis of biocorrelation with previous works Middle Eocene (Bartonian) age confirmed for the Jaddala Formation at the studied section.