Iraqi National Journal of Earth Science

The field survey included three geoelectric traverses on the eastern side of the ‎Tigris River parallel and perpendicular on the axis of the Tairah anticline consisting ‎of seven sites of ( Azimuthal Resistivity Tomography; ART) located above the ‎Quaternary depositions in the southern flank. Two traverses were also conducted in ‎the western side of the river parallel and perpendicular on the east Butmah anticline ‎consisting of four sites located above the recent sediments in the southern flank of it. ‎The sites are chosen taking into account the consideration of the geological, tectonic ‎and topographic data of previous studies and current field reconnaissance trips. ‎
A sympathetic analysis of the resistivity tomography is performed in nine ‎azimuths of the above mentioned locations using fifteen repetitive processing ‎attempts and the mean root squares ranged between 5.8% -11.7%. The eastern side of ‎the study area with different directions indicates electrical horizons, the first reflects ‎a variable resistivity which represents accumulations of top soil, the second band of ‎high resistivity which reflects the river terraces constitutes, while the third horizon ‎represents the clear extension of the mud and limestone deposits of Fatha Formation ‎with a vertical conductive zones in the rock layers at some traverses. As well as the ‎ART on the western side of the study region identified three electric horizons: the ‎first with high resistivity reflecting the surface soil layer, and the second domain of ‎low resistivity representing the sediments of the valley slopes and concentrating on ‎the southern limb of Butmah anticline. The third of heterogeneous resistivity values ‎reflects Fatha Formation deposits covering its exposures at the core of the two ‎anticlines and locating beneath the research traverses.‎
Using the technology of 2D resistivity imaging reveals that the nine orientations ‎around a central point in eleven locations above recent sediments are represented by ‎river terraces and alluvial deposits on the shoulders of the Mosul Dam. The current ‎study concludes the ability to capture fractures, which is of great importance due to ‎their effect on the displacements of the dam's body and Fatha sediments surrounding ‎it.‎

The present study deals with the lithostratigraphy, biostratigraphy and ‎chronostratigraphy of the Eocene- Oligocene boundary in three surface sections in ‎Sinjar anticline, northwestern Iraq. Jaddala Formation composed of marl, marly ‎limestone represents deep Eocene facies, Palani, and Tarjil formations represent ‎Early and Late Oligocene sequences. Sixty-two planktonic foraminiferal species ‎belonging to sixteen genera have been recognized which permit the recognition of ‎four Zones; these are from older at the base: ‎
‎ Globorotalia opima opima Total- Range Zone (P21)‎
‎ Globigerina ampliapertura partial- Range Zone (P20)‎
‎ Pseudohastigerina micra Interval Zone (P 19)‎
Globigerinatheka subconglobata subconglobata Partial Range Zone (P11) (Part).‎
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The Eocene- Oligocene boundary in Sinjar area represents disconformity ‎surface, where the deposition ceased in the Middle Eocene (Lutetian) at the end of ‎Jaddala Formation, then deposition started at the Upper Early Oligocene due to rapid ‎wide transgression, leading to the deposition of Palani (Rupelian) and Tarjil ‎‎(Chatian) formations, which consist of thinly laminated hard white-pale brown ‎intercalation of marly limestone and marl beds.‎

The present study deals with biostratigraphy, depositional environment and ‎sequence stratigraphy of Kolosh Formation in two sections of Bekher anticline, ‎northeastern Iraq by using the planktonic and benthonic foraminifera. Therefore, (48) ‎species of planktonic foraminifera belonging to (14) genera and (34) species of ‎benthonic foraminifera belonging to (19) genera have been recognized. The detailed ‎planktonic foraminiferal investigation permits the recognition of seven well defined ‎biozones and three subzones; they indicate that Kolosh Formation extends from the ‎Early Paleocene (Danian) to Late Paleocene (Thanetian) age. The depositional ‎environment of the formation was studied throughout relying on the variation in the ‎diversity of planktonic forminifera, as well as throughout the ratio of the planktonic ‎foraminifera to the whole mass of foraminifera, and the ratio of planktonic ‎forminifera to the benthonic formiminifera. The lower part of the formation ‎represents the upper bathyal environment, while the middle part deposited within the ‎outer shelf environment, then deposition basin became within the middle shelf area ‎in the upper parts of the formation.‎
Sequence stratigraphic analysis for the studied sections of Kolosh Formation ‎delineated three sequences which is interpreted as 3rd order sequences, and it is ‎found that the deposition of Kolosh Formation in the Badi section had been occurred ‎in shallower level for most sedimentation intervals compared to the Linwa section ‎which represents a somewhat deeper marine environment.‎

Limestone deposits of Ibrahim Formation in Zurbatiya area, eastern Iraq are assessed ‎as raw materials for the industry of Ordinary Portland Cement (OPC). The ‎deposits are widely exposed in the area close to Iraq-Iran borders. Six samples ‎were collected from selected section of Ibrahim Formation, which consists of a ‎succession of well-bedded white to gray limestone interbedded with gray marl ‎and marly limestone. X-ray diffraction results show that calcite is the dominant ‎mineral followed by quartz and traces of dolomite which appear in limited ‎samples. X-ray fluorescence results revealed a noticeable increase of SiO2, ‎which might be due to the effect of limestone by silicification process, so the ‎rocks are considered to be a siliceous limestone. The other oxides (CaO, Al2O3, ‎Fe2O3, MgO, Na2O, K2O, TiO2, SO3, and P2O5) are within the acceptable limits ‎required for cement industry. Cement chemical parameters indicated that there ‎is a decrease in the lime saturation factor (LSF) and an increase in silica ratio ‎‎(SR) in comparison with the chemical parameters listed by standard ‎specifications due to the increase of silica content. This increase can be ‎adjusted by adding clays, or any other source of low silica content in addition to ‎use iron‏ ‏and alumina as correcting additive materials for the cement mixture.‎

The biostratigraphical importance and systematic palaeontology of Early ‎Turonian to Early Maastrichtian Heterohelicidae Planktic foraminifera from ‎Kurdistan region, NE Iraq are described. Some 24 species from 11 genera are ‎recorded. Species abundance and diversity increase from the Early Turonian to Early ‎Maastrichtian, perhaps signifying cooler sea temperatures in the Arabian sector of ‎the Tethys Ocean during the Early Maastrichtian. Despite the long biostratigraphical ‎ranges of some species, the importance of the biserial and multiserial Planktic ‎foraminifers in Late Cretaceous biostratigraphy is emphasized. From a ‎biostratigraphic perspective, heterohelicids are important for the definition of the ‎Campanian-Maastrichtian boundary in Kurdistan region, with Planoglobulina species ‎being especially important in this respect, as they are in Iran, Turkey and North ‎Africa. ‎

‎67 planktonic foraminiferal species were identified from the Shiranish ‎Formation.On the basis of the stratigraphic distribution of the planktonic foraminiferal ‎assemblages recognited of six biozones within the Shiranish Formation representing an ‎age ranging from Middle Campanian – Early Maastrichtian, these zones are from older at ‎base:‎
‎6 -Planoglobulina acervulinoides Interval Zone.‎
‎5 - Contusotruncana contusa Total Range Zone.‎
‎4 -Gansserina gansseri Interval Zone.‎
‎3 - Globotruncana aegyptiaca Interval Biozone. ‎
‎2 -Globotruncanella havanensis Interval Biozone.‎
‎1 -Globotruncana ventricosa Interval Biozone

The pegmatite dikes and associated plutonic rocks stand as a part of the igneous ‎complexes associated with the Bulfat complex, located in the Zagros Suture Zone ‎‎(ZSZ), NE Iraq. The Bulfat complex is a part of the ophiolite-bearing terranes that are ‎allochthonous sheets. The complex represents the upper allochthon of the Albian-‎Cenomenian. The study area is located within Bulfat complex of ZSZ, specifically in ‎the northwestern part of this zone and within the second unit of the Penjween-Walash ‎Subzone. The rock samples were collected from pegmatite dike which is located to ‎the northeast of the Darishmana village, the thickness of dike is about 5 m. ‎
Electron microprobe analyses (EMPA) of plagioclase in 8 spots of dioritic ‎pegmatites ranges between oligoclase (An18.00-An28.23) and andesine (An32.53-‎An33.62). Bulk whole-rock chemical analysis of fourteen samples using ICP-MS ‎analysis reveals alkalinity Index (AI) of pegmatites to be metaluminous (A/NK > 2). ‎Generally, the silica content in these pegmatites is from 46.70 wt. % to 52.67 wt. %.‎
The relatively flat pattern of REEs is characterized by the slight enrichment of ‎LREEs compared to HREEs indicating the common ancestry of the studied ‎pegmatites. Also, the enrichment of these pegmatites in LILEs (Sr, Pb, Rb) and ‎depletion in HFSEs especially (Nb, Ta, Y) indicate the environment of the island arcs. ‎Moreover, the low ratios of (Rb/Sr)N and (Ba/Sr)N refer to that these pegmatites are ‎derived from a basic origin.‎
Tectonic discriminate diagrams show that the tectonic environment of studied ‎pegmatites is I-type, which is the oceanic island arcs environment of sub alkaline ‎rocks. The pegmatites of the present study have a genesis relationship with intrusions ‎close to them in the study area; these intrusions are gabbros of Wadi Rashid that ‎represent the environment of E-MORB. Moreover, the gabbros of Wadi Rashid and ‎studied pegmatites are part of ophiolite-bearing terranes, they are found within upper ‎allochthon thrust sheet. The current study of pegmatites reflects the oceanic island ‎arcs environment, this indicates the existence of double island arcs, the first adjacent ‎to the Arabian shelf, and the second close to the middle of paleo-ridge.‎
Numerous evidences support that the gabbros of Wadi Rashid being as the ‎likely parent to the studied pegmatites such as geochemistry, tectonogenesis, and the ‎close spatial distribution of the pegmatites to the gabbros of Wadi Rashid. Moreover, ‎the studied pegmatites appear to entail further dissection mainly due to the fact that ‎the occurrence of dioritic- and gabbroic-pegmatites with a small-scale in the single ‎intrusion might have its explanation in the liquid associated immiscibility.‎

It is important to determine the location, depth, and shape (dimensions) of cavities under subsurface in the site investigation phase before construction. This study aims to make a study for properties, analysis, and comparison of the results of different electrode configurations that used in 2-D electrical resistivity Tomography surveys to detect subsurface cavities to determining the appropriate and suitable configurations type that must be conducted in the field to obtain best and accurate results. Two-dimensional synthetic models were created for the Geoelectrical resistivity of five different geological features, which reflects the common causes of cavities in nature. These models are (narrow, broad, shallow, and deep) cavities adding to one model for multiple cavities. RES2DMOD program was used to create these models, while the RES2DINV program used in the Inversion method to obtain the true 2-D inverted resistivity sections for six configuration types of the electrode array for 2D electrical resistivity technique, after adding a Gaussian noise ratio of (5%). Generally, we have noticed the possibilities of most tested configuration types for determining electrical anomalies, because of the high contrast between the cavities and the surrounding rocks resistivities values. In addition, the RMS ratio overall does not exceed 5%, hence, this ratio is acceptable and indicates the quality of the inverse process. The Wenner array has high sensitivity to vertical resistivity variations, and the Dipole-dipole array has a high sensitivity to lateral resistivity variations. While the Schlumberger-Wenner have high sensitivity in both lateral and vertical resistivity variations Also, it was noted that the efficiency of all types decreasing with increasing depth of cavities detecting, due to the low percentage of contrast between the cavities and the surrounding rocks. The Wenner beta (WB) configuration is the best choice in terms of inversing true resistivity values, Secondly the Pole-Dipole (PD). While in terms of determining the location and shape (approximately dimensions) of cavities, Dipole-Dipole (DD), Weiner-Schlumberger(WS), Wenner Alpha (WA), Dipole-Pole (DP) respectively. However, in the case of noisy areas, Wenner Alpha (WA) configuration gives the best result.

The study deals with succession from the upper part of the Late Albian Balambo ‎Formation which is composed of fine-grained dark gray to black calcareous shale, ‎limestone and marly limestone rich in sedimentary structures such as lamination, ‎fissility, and platy structures. Microfacies analysis revealed that mudstone, wackestone ‎, and a few packstone are the main facies in the studied succession. The studied rocks ‎generally are rich in organic matter and pyrite in addition to the dominance of radiolaria, ‎sponge spicules and foraminifera with elongated champers maybe “Schackoina” genus. ‎All these characters indicate deposition in marine conditions with reduced or absent-‎oxygen conditions that relate to the oceanic anoxic event (1d).‎

In the current work, the Gulneri Formation (Early Turonian) was studied in ‎three surface sections (Degala, Dokan and Azmir) from northeastern Iraq. The ‎formation is characterized by grey to black color limestone and marly limestone in ‎the Degala and Dokan sections whereas, in the Azmir section, fissile marl and marly ‎limestone with pale to reddish color are dominated in addition to few beds, which ‎occasionally contain fish remains, with distinct gray color reflecting the very few ‎amount of total organic carbon in these beds. Microfacies analysis revealed that the ‎formation has consisted of three microfacies, mudstone, wackestone and packstone ‎microfacies. The predominance of dwarfish planktonic foraminifera (Heterohilex)‎‏ ‏and thin shell filaments particularly in packstone microfacies represent Heterohelix ‎Shift Event and Filament Event respectively. In addition to these events, fish remains, ‎radiolarian pyritization, planktonic foraminiferal chambers elongation and ‎glauconite are all refer to anoxic environmental conditions that may have been ‎coincided with the Global Cenomanian-Turonian Oceanic Anoxic Event (OAE2).‎

According to the rock’s properties, stratigraphic relationships, ‎thickness variations, and correlation with the previous studies, a tectonic ‎model is proposed for the structure of the Aqra anticline. The area is located ‎within the Iraqi Zagros fold/ thrust belt ZFTB of the northeastern margin of ‎the Arabian Plate. ‎
Stratigraphically, the area comprises formations extended along the ‎period from Early Cretaceous to Pliocene. They are Sarmord, Qamchuqa, ‎Aqra, Kolosh/Khurmala, Gercus, Pila Spi, Fat'ha, Injana, and Makdadiya. ‎These formations were deposited along four tectonostratigraphic ‎Megasequences. The older TMS????not defined??? contains formations that ‎are deposited before the creation of the Zagros foreland basin. Whereas the ‎formations of the following three ones were deposited within that basin. ‎During these times, the foreland basin is differentiated into three distinct ‎parts. They are foredeep, bulge, and fore-bulge, which they were ‎discriminated via listric faults, which are displayed as normal and reverse ‎displacements after and before ophiolite obduction.‎
Some contributions to the tectonostratigraphic model of the area are ‎adopted. They are stages of basin development, determining the time of ‎extension period of the listric faults and detecting the tectonic inversion of ‎these faults. This model is described within the compression tectonic ‎framework of the Arabian/ Eurasian plate s’ collision.‎

A detail paleoenvironmental study of ostracods fauna to investigated the paleoenvironment of Khurmala Formation for two section Northern Iraq; the first (Hjran section) lies near Shaqlawa city, and the second (Dohuk section) lies near Dohuk city. Based on ostracods study conclude that Khurmala Formation were deposited in shelf environment, about (30 – 200) meter in depth.