Rafidain Journal of Science

Surface section of the Jaddala-Avanah Formations (Lower-Middle Eocene) is studied in Sinjar area. Three microfacies were recognized throughout Jaddala Formation, their depositional environment represented outer shelf-middle bathyal zones, likewise three microfacies were recognized within Avanah Formation representing environmental stretch from inner-middle shelf zones. Seven sequences were distinguished in the studied section, six sequences of 4th to 5th order and one of 3rd order. According to sequence stratigraphic analysis the south limb of Sinjar anticline formed part of shelfal deposit of the Eocene Sinjar basin; with repetitive shallowing cycles.

The metastable detrital epidote in northern Iraq is one of the non-opaque heavy minerals found in the Recent sediments of Tigris River and its tributaries, in addition to other rivers and valleys. The petrography revealed that the detrital epidote minerals are dominantly epidote (synonym pistachite), and less abundant zoisite and clinozoisite. Generally, the detrital epidote in the fluviatile sediments constitutes high frequency in most of the selected localities, with an average of 22%. Some localities, especially Lesser Zab River has the highest content of 42.6%, whereas the lowest content is found in Gomel Al-Khazir of 2.5%. By comparing the average of the detrital epidote determined in this study with those averages given by other workers, it seems to be approximately similar to that in the Recent sediments of the main channels of Tigris River (24.4%) and Shatt El-Arab (25.8%), but of lesser value compared with that of Euphrates River (33.7%). The greater difference is noticed in the average content of detrital epidote when compared with that of Aqsu and Adhaim Rivers (66.7%). The present study has determined also the main factors controlling the deposition of detrital epidote together with other heavies. The discussion of the provenance of the detrital epidote revealed that they are most probable products of disintegration of metamorphic rocks essentially, or from metamorphosed igneous rocks, both rock types are of Zagros- and Taurus Ranges in Iraq and Turkey respectively. Moreover, the recycling of the older formations (Kolosh, Tanjero, Injana, Mukdadiya and Bai Hassan) and river terraces, which have had relatively high content of detrital epidotes as documented by many authors.

The present study investigates the location and origin of some natural bridges in northern Iraq. They have been founded in two geological formations, the Sinjar and Al-Fa’tha formations. The rocks are consisting the bridges are in limestone and gypsum respectively.
The natural bridges have usually been considered as temporary phenomena with a short life span and, in general, have either major or minor sizes as in the case of the present study.
The rainfall and the underground water dissolved both the limestone and the gypsum rocks, which are considered classically as highly soluble rocks. The dissolution of rocks, especially their sub-surfaces, caused an underground tunnels and channels and parts of their roofs would collapsed, while the uncollapsed roofs, subsequently constitute natural bridges. The present study concluded that the origin of natural bridges is karstic, but other origins could be invoked. Usually the natural bridges at the present time considered as natural monument, which must be preserved and located on maps so that they could be used as tourists’ attraction sites.

This study is an attempt to evaluate the suitability of the water supply plants of the city of Baghdad, These plants are: A, B, C, D, E, F and G. Important topographical and hydraulic parameters, such as; location of water plant site relative to river (upstream or downstream), type of river section (on straight reach or on bend reach), location of plant site relative to river bank (west side of river or east side of river), type of intake (good or poor), were investigated to assess the operating situation of each water supply station.
The results of the study indicated that the water supply plant is the most suitable one according to the investigated parameters .The Al Karama water supply plant was found to be the most unsuitable one. It is recommended that such plant should be put out of service.

Safra Member (Upper Maastrichtian) represents the upper part of Digma Formation, which outcrops to the west of Ga’ara depression. It consists of dolostone alternating with claystone, marl and thin beds of phosphorites; limestone occupies the upper part of the rocks.
Factor analysis shows that the mineralogical distribution is represented by four groups; the first is dolomite; the second is montmorillonite and fine grained quartz; the third is palygorskite, sepiolite and apatite and the last is calcite. There are two main factors that control the distribution of elements; the first is the offshore environment factor represented by precipitated calcite and the detrital fraction; montmorillonite and fine-grained quartz. The second factor is represented by the effect of brackish water (schizohaline) nearshore environment, which is enriched with Mg, and caused the complete dolomitization of calcite, and the transformation of the outer part of montmorillonite to palygorskite. Some palygorskite grains adsorbed dissolved silica, which has resulted from the dissolution of fine-grained quartz or from amorphous silica and transformed to sepiolite. Apatite has formed due to decreasing in Mg/Ca ratio. In addition to the less effective third factor which is represented by the presence of X-ray amorphous phosphates (collophane) as teeth and fish bones.

Two surface sections of Lower Miocene rocks were studied in Sinjar and Sharafaddin areas NW Iraq. Four formations were recognized (Ibrahim, Hamrin, Serikagni and Euphrates Formations) embracing five microfacies and one lithofacies. Their depositional environment and the recognition of unconformable surfaces elucidated the presence of two sedimentary cycles. The stratigraphic distribution of the planktic foraminifera in Sinjar section permits the recognition of three biozones, which are assigned to Early Miocene age

Riparian clastic beds of fluvial origin in the Injana Formation (Upper Miocene) of Kand anticline exhibit the development of a vertical joint/dike like structure in host sandstone overlying red mudstone. These structures indicate filling from above with sandy carbonate showing texture of floating clastic grains in a micritic calcite stained with red iron oxide pigment. This is capped by siltstone-very fine sandstone enriched with iron oxide and preserved diatom vestiges as chert spheroids; accompanied by oval-irregular vugs lined with microcrystalline calcite. These beds are topped by fossil-barren micritic carbonate of intraclastic texture.
The clastic-carbonate package is interpreted as non-marine fluvial-lacustrine deposits of interchannel depression (pond-lake). Episodic exposure with incipient plant root penetrations, desiccation and differential compaction have led to fissure cracking; otherwise tectonic jointing is entailed. A terminal stage of enlargement by descending water was conducive to the genesis of these joint/dike structures which were filled later by reworked, reshaped and modified sediments sourced from juxtaposed-nearby areas.